Annual risk-adjusted standardized infection ratio (SIR) of observed over predicted deep incisional primary and organ/space surgical site infections (SSIs), over a 30-day post-operative surveillance period, among hospitalized adults who are >=18 year of age with a date of admission and date of discharge that are different calendar days, and the patient underwent a colon surgery (COLO) or abdominal hysterectomy (HYST) at an acute care hospital or oncology hospital. The 30-day postoperative surveillance period includes SSIs detected upon admission to the facility or a readmission to the same facility or a different facility (other than where the procedure was performed) and via post-discharge surveillance.
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1.5 Measure Type1.6 Composite MeasureNo1.7 Electronic Clinical Quality Measure (eCQM)1.8 Level Of Analysis1.9 Care Setting1.10 Measure Rationale
The use of this measure will promote surgical site infection (SSI) prevention activities that will lead to improved patient outcomes including a reduction of SSIs, avoidable medical costs, and patient morbidity and mortality through a reduced need for antimicrobials and reduced length of stay.
1.11 Measure Webpage1.20 Testing Data Sources1.25 Data SourcesCDC National Healthcare Safety Network (NHSN)
Surgical Site Infection (SSI) Events landing page:
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
Surgical Site Infection (SSI) Event Form: https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
Denominator for Procedure Form: https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
2024 ICD-10-CS Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
2024 Current Procedural Terminology (CPT) Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
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1.14 Numerator
Number of annually observed hospitalized patients who are >=18 years of age with a date of admission and date of discharge that are different calendar days, and the patient underwent a colon surgery (COLO) or abdominal hysterectomy (HYST) and developed a deep incisional primary or organ/space surgical site infection (SSI) within the 30-day postoperative surveillance period. The 30-day postoperative surveillance period includes SSIs detected upon admission to the facility or a readmission to the same facility or a different facility (other than where the procedure was performed) and via post-discharge surveillance.
1.14a Numerator Details1. Determine the patients date of birth and gender.
2. Determine the patients who underwent a colon surgery (COLO) or abdominal hysterectomy (HYST).
• Procedures are defined by ICD-10-PCS procedure codes that comprise the NHSN colon surgery or abdominal hysterectomy category, or the corresponding set of CPT procedure codes used in the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP).
3. Determine if the NHSN operative procedure was performed on a patient whose date of admission to the healthcare facility and the date of discharge are different calendar days.
4. Determine if the patient developed a deep incisional primary, or organ/space surgical site infection.
• Deep Incisional SSI
Date of event occurs within 30 days following the NHSN operative procedure (where day 1 = the procedure date) according to the list in Table 2
AND
involves deep soft tissues of the incision (for example, fascial and muscle layers)
AND
patient has at least one of the following:
a. purulent drainage from the deep incision.
b. a deep incision that is deliberately opened or aspirated by a surgeon, physician* or physician designee or spontaneously dehisces
AND
organism(s) identified from the deep soft tissues of the incision by a culture or non-culture based microbiologic testing method which is performed for purposes of clinical diagnosis or treatment (for example, not Active Surveillance Culture/Testing [ASC/AST]) or culture or nonculture based microbiologic testing method is not performed. A culture or nonculture based test from the deep soft tissues of the incision that has a negative finding does not meet this criterion.
AND
patient has at least one of the following signs or symptoms: fever (>38°C); localized pain or tenderness.
c. an abscess or other evidence of infection involving the deep incision detected on gross anatomical exam, histopathologic exam, or imaging test.* The term physician for the purpose of application of the NHSN SSI criteria may be interpreted to mean a surgeon, infectious disease physician, emergency physician, other physician on the case, or physician’s designee (nurse practitioner or physician’s assistant).
• Organ/Space SSI
Date of event occurs within 30 days following the NHSN operative procedure (where day 1 = the procedure date) according to the list in Table 2
AND
involves any part of the body deeper than the fascial/muscle layers that is opened or manipulated during the operative procedure
AND
patient has at least one of the following:
a. purulent drainage from a drain placed into the organ/space (for example, closed suction drainage system, open drain, T-tube drain, CT guided drainage).
b. organism(s) identified from fluid or tissue in the organ/space by a culture or non-culture based microbiologic testing method which is performed for purposes of clinical diagnosis or treatment (for example, not Active Surveillance Culture/Testing [ASC/AST]).
c. an abscess or other evidence of infection involving the organ/space detected on:
• gross anatomical exam or
• histopathologic exam or
• imaging test evidence definitive or equivocal for infection
AND
meets at least one criterion for a specific organ/space infection site listed in Table 3. These criteria are found in the Surveillance Definitions for Specific Types of Infections (Chapter 17)
Notes:
• Community associated organisms (organisms belonging to the following genera: Blastomyces, Histoplasma, Coccidioides, Paracoccidioides, Cryptococcus and Pneumocystis) and/or organisms associated with latent infections (for example, herpes, shingles, syphilis, or tuberculosis) are excluded from meeting SSI criteria.
• When multiple primary incision sites, for the same operative procedure become infected, report as a single SSI, and assign the deepest level of SSI.
5. Determine the date of surgery.
6. Determine the date of the surgical site infection.
• If the patient has several procedures performed on different dates during the admission, attribute the SSI to the most recently performed procedure.
7. Determine if the surgical site infection occurred within the 30-days following the surgical procedure.
• If SSI criteria is met within the 30-day postoperative period and was detected at a facility other than the facility where the procedure was performed, the SSI should be reported.
8. Determine if the infection was present at time of surgery (PATOS), (i.e., evidence of infection intraoperatively), as PATOS surgical site infections are not included in the calculation of the standardized infection ratio (SIR).
The SSIs that are linked to procedures that are excluded from the denominator are also excluded from the numerator.
• Surgical site infections that are present at the time of surgery (PATOS)
• ASA class VI
• Patients whose admission date and discharge date are the same day.
• Patients <18 years of age
• Patients >= 109 years of age
• Adult patient's, >=18 years of age, BMI is less than 12 or greater than 60.
• Procedures reported in patients with gender reported as Other are excluded from the SSI SIR
• Surgical procedure duration less than 5 minutes or exceeding the IQR5 value.There are multiple items that abstractors are to reference when abstracting SSI data from a record. Please see question 1.11 for all of the links to reference regarding the measure, specifically Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf.
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
Surgical Site Infection (SSI) Event Form: https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
Denominator for Procedure Form: https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
2024 ICD-10-CS Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
2024 Current Procedural Terminology (CPT) Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
NHSN Standard Infection Ratio (SIR) Guide: https://www.cdc.gov/nhsn/2022rebaseline/analysis-resources.html
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
https://www.cdc.gov/nhsn/2022rebaseline/analysis-resources.html
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1.15 Denominator
Number of annually predicted hospitalized patients who are >=18 years of age with a date of admission and date of discharge are different calendar days, and the patient underwent a colon surgery (COLO) or abdominal hysterectomy (HYST) and developed a deep incisional primary or organ/space surgical site infection (SSI) within the 30-day post-operative surveillance period. The 30-day postoperative surveillance period includes SSIs detected upon admission to the facility or a readmission to the same facility or a different facility (other than where the procedure was performed) and via post-discharge surveillance.
1.15a Denominator Details1. Determine patients who underwent a colon (COLO) surgery or abdominal hysterectomy (HYST).
• Procedures are defined by ICD-10-PCS procedure codes that comprise the NHSN colon surgery or abdominal hysterectomy category, or the corresponding set of CPT procedure codes used in the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP).
2. Determine if the patient developed a deep incisional primary, or organ/space surgical site infection within the 30-day postoperative surveillance period.
• Deep Incisional SSI
Date of event occurs within 30 days following the NHSN operative procedure (where day 1 = the procedure date) according to the list in Table 2
AND
involves deep soft tissues of the incision (for example, fascial and muscle layers)
AND
patient has at least one of the following:
a. purulent drainage from the deep incision.
b. a deep incision that is deliberately opened or aspirated by a surgeon, physician* or physician designee or spontaneously dehisces
AND
organism(s) identified from the deep soft tissues of the incision by a culture or non-culture based microbiologic testing method which is performed for purposes of clinical diagnosis or treatment (for example, not Active Surveillance Culture/Testing [ASC/AST]) or culture or nonculture based microbiologic testing method is not performed. A culture or non-culture based test from the deep soft tissues of the incision that has a negative finding does not meet this criterion.
AND
patient has at least one of the following signs or symptoms: fever (>38°C); localized pain or tenderness.
c. an abscess or other evidence of infection involving the deep incision detected on gross anatomical exam, histopathologic exam, or imaging test.* The term physician for the purpose of application of the NHSN SSI criteria may be interpreted to mean a surgeon, infectious disease physician, emergency physician, other physician on the case, or physician’s designee (nurse practitioner or physician’s assistant).
• Organ/Space SSI
Date of event occurs within 30 days following the NHSN operative procedure (where day 1 = the procedure date) according to the list in Table 2
AND
involves any part of the body deeper than the fascial/muscle layers that is opened or manipulated during the operative procedure
AND
patient has at least one of the following:
a. purulent drainage from a drain placed into the organ/space (for example, closed suction drainage system, open drain, T-tube drain, CT guided drainage).
b. organism(s) identified from fluid or tissue in the organ/space by a culture or non-culture based microbiologic testing method which is performed for purposes of clinical diagnosis or treatment (for example, not Active Surveillance Culture/Testing [ASC/AST]).
c. an abscess or other evidence of infection involving the organ/space detected on:
• gross anatomical exam or
• histopathologic exam or
• imaging test evidence definitive or equivocal for infection
AND
meets at least one criterion for a specific organ/space infection site listed in Table 3. These criteria are found in the Surveillance Definitions for Specific Types of Infections (Chapter 17)3. Determine the date of surgery.
4. Determine the date of the surgical site infection.
5. Determine the patient’s assigned American Society of Anesthesiologists’ (ASA) score.
• Patients with an ASA of 6 are excluded.
6. Determine if the patient has a diagnosis of diabetes that is managed with insulin or a non-insulin anti-diabetic agent.
7. Determine the surgery start time and surgery finish time.
8. Determine if the procedure was assigned as an emergent or urgent surgery.
9. Determine if the patient had general anesthesia.
10. Determine the patient’s data of birth, height and weight, and gender.
11. Determine if the NHSN operative procedure was performed on a patient whose date of admission to the healthcare facility and the date of discharge are different calendar days.
12. Determine if any portion of the skin was closed by primary closure or non-primary closure.
13. Determine if a scope was used during the procedure.
14. Determine if a blunt or penetrating injury (i.e., trauma) occurred prior to the start of the procedure.
15. Determine the wound classification for the surgical wound.
16. Determine if the infection was present at time of surgery (PATOS), (i.e., evidence of infection intraoperatively), as PATOS surgical site infections are not included in the calculation of the standardized infection ratio (SIR).
The logistic regression model is the specific type of model used for surgical site infection risk adjustment. At a high level, the model uses a set of fixed parameters (adjustment variables) to predict the log-odds of a surgical site infection following an inpatient procedure. To obtain the total number of predicted SSIs, the following steps are completed in NHSN:
1. Determine the log-odds for each procedure
2. Convert the log-odds into a probability, or risk of infection (𝑝̂), for each procedure
3. Sum the risk of infections across all procedures in a given timeframeThe sum of the risks from a set of procedures will amount to the total number of predicted infections for that same set of procedures. Each risk factor’s contribution to the standardized infection ratio (SIR) varies, as represented by the parameter estimate for each factor. Parameter estimates describe the relationship between the variable and the risk of SSI; positive parameter estimates indicate that the risk of SSI increases with increasing values of the variable. Negative parameter estimates indicate that the risk of SSI decreases with increasing values of the variable.
The general formula for the logistic regression model is
log (λ) = α + 𝛽𝛽1𝑋𝑋1 + 𝛽𝛽2𝑋𝑋2 + ··· + 𝛽𝛽i𝑋𝑋i , where:
α = Intercept
βi = Parameter estimate
Xi = Value of risk factor (categorical variables: 1 if present, 0 if not present)
i = Number of predictorsThe probability of SSI is calculated using the logistic regression model above, by utilizing the relationship between the log-odds and the probability (risk). The probability of SSI is calculated for each procedure and then summed across all procedures to give the total number of predicted SSIs for this population.
The number of predicted events calculated under the 2022 baseline for SSI is risk adjusted based on the following variables found to be statistically significant predictors of SSIs per procedure.
COLO
Table. Colon Procedures, Complex 30-Day Model
Parameter Parameter Estimate Standard Error P-value
Intercept -5.5134 0.1039 <.0001
Scope: No 0.6402 0.0271 <.0001
Scope: Yes REFERENT - -
Procedure duration: 67-107 (Min) 0.2344 0.0521 <.0001
Procedure duration: 108-145 (Min) 0.3900 0.0515 <.0001
Procedure duration: 146-232 (Min) 0.5221 0.0490 <.0001
Procedure duration: 233-296 (Min) 0.6950 0.0556 <.0001
Procedure duration: ≥297 (Min) 0.8690 0.0541 <.0001
Procedure duration: ≤66 (Min) REFERENT - -
Trauma: Yes 0.3607 0.0520 <.0001
Trauma: No REFERENT - -
ASA score: 3/4/5 0.3089 0.0281 <.0001
ASA score: 1/2 REFERENT - -
Patient’s age: 18-39 years 0.5080 0.0532 <.0001
Patient’s age: 40-62 years 0.3765 0.0443 <.0001
Patient’s age: 63-79 years 0.1970 0.0438 <.0001
Patient’s age: 80-109 years REFERENT - -
Surgical wound class: Contaminated/Dirty 0.1707 0.0245 <.0001
Surgical wound class: Clean-Contaminated REFERENT - -
Total number of beds1: ≥319 beds 0.0958 0.0248 0.0001
Total number of beds1: <319 beds REFERENT - -
Emergency: Yes 0.1097 0.0300 0.0003
Emergency: No REFERENT - -
Medical School Affiliation1: Major 0.0723 0.0259 0.0052
Medical School Affiliation1:
Graduate/Undergraduate/None REFERENT - -
Sex at birth (prior to 2025, reported as gender): Male 0.1212 0.0231 <.0001
Sex at birth (prior to 2025, reported as gender): Female REFERENT - -
BMI: ≥40 0.1111 0.0427 0.0093
BMI: <40 REFERENT - -
Oncology Hospital2: Yes 0.3658 0.0831 <.0001
Oncology Hospital2: No REFERENT - -
Anesthesia: Yes 0.1708 0.0823 0.0380
Anesthesia: No REFERENT - -
1 Total number of beds and medical school affiliation are reported on the Annual Hospital Survey.2 Based on NHSN enrollment as HOSP-ONC.
HYST
Table . Abdominal Hysterectomy Procedures, Complex 30-Day Model
Parameter Parameter Estimate Standard Error P-value
Intercept -6.4524 0.1514 <.0001
Procedure duration: 80-136 (Min) 0.4701 0.0755 <.0001
Procedure duration: 137-188 (Min) 0.7385 0.0804 <.0001
Procedure duration: ≥189 (Min) 0.9316 0.0794 <.0001
Procedure duration: ≤79 (Min) REFERENT - -
BMI: ≤30 0.2188 0.0476 <.0001
BMI: <30 REFERENT - -
Patient’s age: 18-47 years 0.6110 0.0569 <.0001
Patient’s age: 48-55 years 0.3018 0.0690 <.0001
Patient’s age: 56-109 years REFERENT - -
ASA score: 2 0.3276 0.1300 0.0118
ASA score: 3/4/5 0.5465 0.1338 <.0001
ASA score: 1 REFERENT - -
Scope: No 0.1667 0.0449 0.0002
Scope: Yes REFERENT - -
Medical School Affiliation1: Major 0.0934 0.0473 0.0483
Medical School Affiliation1: Graduate/Undergraduate/None REFERENT - -
Oncology Hospital2: Yes 0.5740 0.1552 0.0002
Oncology Hospital2: No REFERENT - -
Diabetes: Yes 0.1466 0.0634 0.0208
Diabetes: No REFERENT - -
1 Medical school affiliation is reported on the Annual Hospital Survey.
2 Based on NHSN enrollment as HOSP-ONCTable. IQR5 Values, in Minutes, for NHSN Operative Procedures
NHSN Operative Procedure IQR5 (in minutes) IQR5 (in hours and minutes)
Minutes Hours Minutes
COLO 783 13 3
HYST 608 10 8There are multiple items that abstractors are to reference when abstracting SSI data from a record. Please see question 1.11 for all of the links to reference regarding the measure, specifically Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf.
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
Surgical Site Infection (SSI) Event Form: https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
Denominator for Procedure Form: https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
2024 ICD-10-CS Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
2024 Current Procedural Terminology (CPT) Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
NHSN Standard Infection Ratio (SIR) Guide: https://www.cdc.gov/nhsn/2022rebaseline/analysis-resources.html
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
https://www.cdc.gov/nhsn/2022rebaseline/analysis-resources.html1.15d Age GroupAdults (18-64 years)Older Adults (65 years and older)
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1.15b Denominator Exclusions
• Procedures that develop a postoperative surgical site infection (SSI) and the infection is present at the time of surgery (PATOS), the SSI event and surgical procedure are excluded
• ASA class VI
• Patients whose admission date and discharge date are the same day.
• Patients <18 years of age
• Patients >= 109 years of age
• Adult patient's, >=18 years of age, BMI is less than 12 or greater than 60.
• Procedures reported in patients with gender reported as Other are excluded from the SSI SIR
• Surgical procedure duration less than 5 minutes or exceeding the IQR5 value.There are multiple items that abstractors are to reference when abstracting SSI data from a record. Please see question 1.11 for all of the links to reference regarding the measure, specifically Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf.
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
Surgical Site Infection (SSI) Event Form: https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
Denominator for Procedure Form: https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
2024 ICD-10-CS Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
2024 Current Procedural Terminology (CPT) Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
NHSN Standard Infection Ratio (SIR) Guide: https://www.cdc.gov/nhsn/2022rebaseline/analysis-resources.html
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
https://www.cdc.gov/nhsn/2022rebaseline/analysis-resources.html
1.15c Denominator Exclusions Details• Determine the patient’s date of birth.
• Determine if an infection was present at time of surgery (PATOS): PATOS denotes that there is evidence of infection visualized (seen) during the surgical procedure to which the subsequent SSI is attributed. The evidence of infection must be noted intraoperatively and documented within the narrative portion of the operative note or report of surgery to be eligible for PATOS.
• Determine the ASA physical status: Assessment by the anesthesiologist of the patient’s preoperative physical condition using the American Society of Anesthesiologists’ (ASA) Physical Status Classification System11. Patients are assigned an ASA score of 1-6 at time of surgery. Patients with an ASA score of 1-5 are eligible for NHSN SSI surveillance. Patients that are assigned an ASA score of 6 (a declared brain-dead patient whose organs are being removed for donor purposes) are not eligible for NHSN SSI surveillance.
• Determine if the procedure was performed in the outpatient setting: An NHSN operative procedure performed on a patient whose date of admission to the healthcare facility and date of discharge are the same calendar day.
• Determine if the patient’s gender was reported as Other.
• Determine the patient’s BMI: Patient’s with a BMI that is less than 12 or greater than 60.
• Determine the surgical procedure duration: The IQR5, also called the procedure duration cutoff point, is used as an indicator of an extreme outlier for procedure durations when calculating the SSI SIRs. The IQR5 is calculated as five times the interquartile range (Q1-Q3) above the 75th percentile. Procedures with a duration greater than the IQR5 were excluded from the baseline data and will be excluded from all SSI SIR calculations.Table 4. IQR5 Values, in Minutes, for NHSN Operative Procedures, Adult and Pediatric Patients
NHSN Operative Procedure IQR5 (in minutes) IQR5 (in hours and minutes)
Minutes Hours Minutes
COLO 783 13 3
HYST 608 10 8There are multiple items that abstractors are to reference when abstracting SSI data from a record. Please see question 1.11 for all of the links to reference regarding the measure, specifically Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf.
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
Surgical Site Infection (SSI) Event Form: https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
Denominator for Procedure Form: https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
2024 ICD-10-CS Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
2024 Current Procedural Terminology (CPT) Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
NHSN Standard Infection Ratio (SIR) Guide: https://www.cdc.gov/nhsn/2022rebaseline/analysis-resources.html
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
https://www.cdc.gov/nhsn/2022rebaseline/analysis-resources.html
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OLD 1.12 MAT output not attachedAttached1.13a Data dictionary not attachedYes1.16 Type of Score1.16a Other Scoring Method
Ratio
1.17 Measure Score InterpretationBetter quality = Lower score1.18 Calculation of Measure ScoreThe standardized infection ratio (SIR) is a risk-adjusted measurement of surgical site infections (SSIs), which adjusts for various facility and/or patient-level risk factors that contribute to SSIs. The SIR is calculated by dividing the number of observed SSIs by the number of predicted SSIs. An individual SIR is produced for colon surgery (COLO) and abdominal hysterectomy (HYST).
SIR = Observed (O) HAIs / Predicted (P) HAIs1. For colon surgery (COLO) and abdominal hysterectomy (HYST), calculate the following separately:
a. Total the number of annual observed SSIs.
b. Calculate the number of predicted SSIs for the facility using a logistic regression model and risk factors found to be statistically significant predictors of SSIs.
c. Divide the number of observed SSIs by the number of predicted SSIs to obtain the standardized infection ratio (SIR).There are multiple items that abstractors are to reference when abstracting SSI data from a record. Please see question 1.11 for all of the links to reference regarding the measure, specifically Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf.
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
Surgical Site Infection Event (SSI): https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
Surgical Site Infection (SSI) Event Form: https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
Denominator for Procedure Form: https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
2024 ICD-10-CS Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
2024 Current Procedural Terminology (CPT) Procedure Code Mapping to NHSN Operative Procedure Codes: https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
NHSN Standard Infection Ratio (SIR) Guide: https://www.cdc.gov/nhsn/2022rebaseline/analysis-resources.html
https://www.cdc.gov/nhsn/acute-care-hospital/ssi/index.html
https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf
https://www.cdc.gov/nhsn/forms/57.120_SSI_BLANK.pdf
https://www.cdc.gov/nhsn/forms/57.121_DenomProc_BLANK.pdf
https://www.cdc.gov/nhsn/xls/icd10-pcs-pcm-nhsn-opc.xlsx
https://www.cdc.gov/nhsn/xls/cpt-pcm-nhsn.xlsx
https://www.cdc.gov/nhsn/2022rebaseline/analysis-resources.html
1.19 Measure Stratification DetailsN/A
1.26 Minimum Sample SizeN/A
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7.1 Supplemental Attachment
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StewardCenters for Disease Control and PreventionSteward Organization POC EmailSteward Organization URLSteward Organization Copyright
https://www.cdc.gov/nhsn/index.html
Measure Developer Secondary Point Of ContactPaula Farrell
CDC NHSN
ROYBAL BLDG 16 Rm 3344 MS H16-3
Atlanta , GA 30333
United StatesMeasure Developer Secondary Point Of Contact Email
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2.1 Attach Logic Model2.2 Evidence of Measure Importance
While advances have been made in infection control practices, including improved operating room ventilation, sterilization methods, barriers, surgical technique, and availability of antimicrobial prophylaxis, SSIs remain a substantial cause of morbidity, prolonged hospitalization, and death. In 2022, 3,052 general acute care hospitals reported a total of 7,355 colon surgical site infections to CDC’s National Healthcare Safety Network, which signified a 14% decrease in SIR from the national baseline in 2015 (Centers for Disease Control and Prevention). Also in 2022, 2,789 general acute care hospitals reported a total of 1,695 abdominal hysterectomy surgical site infections to CDC’s National Healthcare Safety Network, which signified a 5% decrease in the SIR from the national baseline in 2015 (Centers for Disease Control and Prevention). Multiple studies provide strong empirical support for the association between colon and abdominal hysterectomy SSI prevention practices, specifically appropriate dosing, timing and choice of preoperative parenteral antimicrobial prophylaxis, preoperative glycemic control, normothermia maintenance, and antiseptic prophylaxis, and the reduction of colon and abdominal hysterectomy SSIs.
Hysterectomy is the second most common surgical procedure performed on women of reproductive age in the United States (Davidson, et. al, 2020). SSI was determined to be the most common reason for unplanned hospital readmission after hysterectomy, with 28.8% of readmissions attributable to infection (Merkow, et. al, 2015). A large study at an academic medical center that performs approximately 300 abdominal hysterectomies per year found that the implementation of an SSI prevention bundle that includes interventions which focus on the preoperative, intraoperative and postoperative period reduced their hysterectomy SSI rate. Education was initiated at the preoperative visit regarding SSI risk and prevention. Women were instructed on surgical site shaving, smoking cessation, diabetic medication use, and preoperative antiseptic skin cleansing with 4% chlorhexidinegluconate (CHG) cleanser. On the day of surgery patient normothermia is maintained, prophylactic antibiotics are administered within 1 hour of skin incision and re-dosed as necessary, and hair at the surgical site is removed with electric clippers. Intraoperatively, scrubbed surgical team members are double gloved for the entire procedure and a new sterile closing tray is brought to the surgical field for fascia and skin closure. Postoperatively, an insulin order set is used to maintain euglycemia in all diabetic patients, the surgical dressing is removed on the second postoperative day and patients are provided with discharge education regarding wound care and infection symptoms. The study collected data from 952 patients that underwent adnominal hysterectomy. Prebundle initiation the SSI rate was 6.18% and after bundle implementation SSI rate declined to 2.51% (P = .02). Superficial SSIs in this group declined significantly from 3.73% prebundle to 0.90% postbundle (P = .02) (Davidson, et.al, 2020). A study conducted at Michigan Medicine also found that implementation of an SSI prevention bundle that included a standard surgical prep, appropriate antibiotic use, and use of a standard closure tray reduced their abdominal hysterectomy SSI SIR from 2.99 in 2013 to 0.233 in 2017. Another study at a large academic medical center in Chicago found that after initiation of a prevention bundle that included preoperative and postoperative patient instructions, preoperative and postoperative chlorhexidine skin preparation, glove and gown changes for wound closing, and plastic abdominal wall protectors reduced the sites reduced their abdominal hysterectomy SSI rate from 6 pre-bundle to 2 post-bundle (Guo, et. al, 2020). Yale New Haven Hospital also saw a reduction in their hysterectomy SSI rate after implementation of an SSI prevention bundle that consisted of chlorhexidine-impregnated preoperative wipes, standardized aseptic surgical preparation, standardized antibiotic dosing, perioperative normothermia, and surgical dressing maintenance. During the study 2,099 hysterectomies completed; there were 61 SSIs (4.51%) in the pre-bundle implementation period and 14 (1.87%) in the post-bundle implementation period (Andiman, et. al., 2018).
SSI prevention bundles have also been shown to reduce colon surgery SSIs. The bundles include a chlorhexidine prescrub followed by chloraPrep, appropriate surgical site hair removal, maintaining normothermia, antibiotic prophylaxis, betadine wound wash, antibiotic infused irrigation, and use of closure tray. A large study at an 865-bed academic medical center found that implementation of this bundle reduced their colon SSI rates 26 infections to 13 infections (Albert, et. al, 2019). A recent 2020 study found that implementation of the colon surgery SSI prevention bundle reduced the facilities colon SSI SIR by 85% (Martinez, et. al, 2020). Post bundle implementation patients had significantly lower superficial (odds ratio: 0.91 [0.74-0.98]; P = 0.045) and deep SSI (odds ratio:0.97 [0.65-0.99]; P = 0.048) than pre bundle implementation patients (Martinez, et. al, 2020). Post bundle implementation patients also had shorter length of stay (P = 0.049) and lower readmission rate (P = 0.098) compared with pre bundle implementation patients (Martinez, et. al, 2020). Finally, a study at a 487-bed medical center found that after implementation of a colon surgery SSI prevention bundle that the facilities colon SSI SIR decreased from 3.08 to 0.45 (Guerrero, et. al, 2021).This evidence supports a link between processes included in colon surgery and abdominal hysterectomy SSI prevention practices and the reduction of these SSI.
• Albert H, Bataller W, Masroor N, Doll M, Cooper K, Spencer P, Winborne D, Zierden EM, Stevens MP, Scott M, Bearman G. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections. Am J Infect Control. 2019 Jun;47(6):718-719.
• Andiman SE, Xu X, Boyce JM, Ludwig EM, Rillstone HRW, Desai VB, Fan LL. Decreased Surgical Site Infection Rate in Hysterectomy: Effect of a Gynecology-Specific Bundle. Obstet Gynecol. 2018 Jun;131(6):991-999.
• Centers for Disease Control and Prevention. (2022). Colon Surgical Site Infections. https://arpsp.cdc.gov/profile/nhsn/colon
• Centers for Disease Control and Prevention. (2022). Abdominal Hysterectomy Surgical Site Infections. https://arpsp.cdc.gov/profile/nhsn/hyst
• Davidson C, Enns J, Bennett C, Sangi-Haghpeykar H, Lundeen S, Eppes C. Reducing abdominal hysterectomy surgical site infections: A multidisciplinary quality initiative. Am J Infect Control. 2020 Nov;48(11):1292-1297.
• Guerrero MA, Anderson B, Carr G, Snyder KL, Boyle P, Ugwu SA, Davis M, Bohnenkamp SK, Nfonsam V, Riall TS. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients. Patient Saf Surg. 2021 Apr 8;15(1):15.
• Guo XM, Runge M, Miller D, Aaby D, Milad M. A bundled intervention lowers surgical site infection in hysterectomy for benign and malignant indications. Int J Gynaecol Obstet. 2020 Sep;150(3):392-397.
• Martinez C, Omesiete P, Pandit V, Thompson E, Nocera M, Riall T, Guerrero M, Nfonsam V. A Protocol-Driven Reduction in Surgical Site Infections After Colon Surgery. J Surg Res. 2020 Feb;246:100-105.
• Merkow RP, Ju MH, Chung JW, Hall BL, Cohen ME, Williams MV, Tsai TC, Ko CY, Bilimoria KY. Underlying reasons associated with hospital readmission following surgery in the United States. JAMA. 2015 Feb.
• Nomides, N., Shuman, E. Dogan, T. Preventing Surgical Site Infection Related to Abdominal Hysterectomy: We Got This! American Journal of Infection Control, 2019 June; Volume 47, Issue 6, S31.
The following guideline supports the measure and is evidence based- Centers for Disease Control and Prevention Guideline for the Prevention of Surgical Site Infection, 2017
The guideline recommendations include specific interventions and practices to reduce surgical site infections (SSI). Evidence supports a link between processes included in SSI prevention practices, such as appropriate catheter use, proper techniques for catheter insertion and maintenance, and the reduction of SSIs.Berríos-Torres SI, Umscheid CA, Bratzler DW, Leas B, Stone EC, Kelz RR, Reinke CE, Morgan S, Solomkin JS, Mazuski JE, Dellinger EP, Itani KMF, Berbari EF, Segreti J, Parvizi J, Blanchard J, Allen G, Kluytmans JAJW, Donlan R, Schecter WP; Healthcare Infection Control Practices Advisory Committee. Centers for Disease Control and Prevention Guideline for the Prevention of Surgical Site Infection, 2017. JAMA Surg. 2017 Aug 1;152(8):784-791.
Recommendations were categorized using the following standard system that reflects the level of supporting evidence or regulations:
• Category IA: A strong recommendation supported by high to moderate–quality evidence suggesting net clinical benefits or harms.
• Category IB: A strong recommendation supported by low-quality evidence suggesting net clinical benefits or harms or an accepted practice (eg, aseptic technique) supported by low to very low–quality evidence.
• Category IC: A strong recommendation required by state or federal regulation.
• Category II: A weak recommendation supported by any quality evidence suggesting a trade-off between clinical benefits and harms.
• No recommendation/unresolved issue: An issue for which there is low to very low–quality evidence with uncertain trade-offs between the benefits and harms or no published evidence on outcomes deemed critical to weighing the risks and benefits of a given intervention.Parenteral Antimicrobial Prophylaxis
1A.1. Administer preoperative antimicrobial agents only when indicated based on published clinical practice guidelines and timed such that a bactericidal concentration of the agents is established in the
serum and tissues when the incision is made. (Category IB–strong recommendation; accepted practice.)
1A.2. No further refinement of timing can be made for preoperative antimicrobial agents based on clinical outcomes.(No recommendation/unresolved issue.)
1B. Administer the appropriate parenteral prophylactic antimicrobial agents before skin incision in all cesarean section procedures. (Category IA–strong recommendation; high-quality evidence.)
1C.The literature search did not identify randomized controlled trials that evaluated the benefits and harms of weight-adjusted parenteral antimicrobial prophylaxis dosing and its effect on the risk of
SSI. Other organizations have made recommendations based on observational and pharmacokinetic data, and a summary of these recommendations can be found in the Other Guidelines section of
the narrative summary for this question (eAppendix 1 of the Supplement). (No recommendation/unresolved issue.)
1D. The search did not identify sufficient randomized controlled trial evidence to evaluate the benefits and harms of intraoperative redosing of parenteral prophylactic antimicrobial agents for the prevention
of SSI. Other organizations have made recommendations based on observational and pharmacokinetic data, and a summary of these recommendations can be found in the Other Guidelines section of the narrative summary for this question (eAppendix 1 of the Supplement). (No recommendation/unresolved issue.)
1E. In clean and clean-contaminated procedures, do not administer additional prophylactic antimicrobial agent doses after the surgical incision is closed in the operating room, even in the presence of a drain. (Category IA–strong recommendation; high-quality evidence.)Glycemic Control
3A.1. Implement perioperative glycemic control and use blood glucose target levels less than 200 mg/dL in patients with and without diabetes. (Category IA–strong recommendation; high to moderate–quality evidence.)
Normothermia
4. Maintain perioperative normothermia. (Category IA–strong recommendation; high to moderate–quality evidence.)
Oxygenation
6B. For patients with normal pulmonary function undergoing general anesthesia with endotracheal intubation, administer increased FIO2 during surgery and after extubation in the immediate postoperative period. To optimize tissue oxygen delivery, maintain perioperative normothermia and adequate volume replacement. (Category IA–strong recommendation; moderate-quality evidence.)
Antiseptic Prophylaxis
8A.1. Advise patients to shower or bathe (full body) with soap (antimicrobial or nonantimicrobial) or an antiseptic agentonat least the night before the operative day. (Category IB–strong recommendation; accepted practice.)
8A.2. Randomized controlled trial evidence suggested uncertain trade-offs between the benefits and harms regarding the optimal timing of the preoperative shower or bath, the total number of soap or antiseptic agent applications, or the use of chlorhexidine gluconate washcloths for the prevention of SSI. (No recommendation/unresolved issue.)
8B. Perform intraoperative skin preparation with an alcohol-based antiseptic agent unless contraindicated. (Category IA–strong recommendation; high-quality evidence.)Blood Transfusion
11B. Do not withhold transfusion of necessary blood products from surgical patients as a means to prevent SSI. (Category IB–strong recommendation; accepted practice.)
Postoperative Antimicrobial Prophylaxis Duration With Drain Use
19. In prosthetic joint arthroplasty, recommendation 1E applies: in clean and clean-contaminated procedures, do not administer additional antimicrobial prophylaxis doses after the surgical incision is
closed in the operating room, even in the presence of a drain. (Category IA–strong recommendation; high-quality evidence.)
SHEA/IDSA/APIC Practice Recommendation
Strategies to prevent surgical site infections in acute-care hospitals: 2022 Update
Summary of Recommendations to Prevent Surgical Site Infections (SSIs)Quality of Evidence
HIGH: Highly confident that the true effect lies close to that of the estimated size and direction of the effect, for example, when there are a wide range of studies with no major limitations, there is little variation between studies, and the summary estimate has a narrow confidence interval.
MODERATE: The true effect is likely to be close to the estimated size and direction of the effect, but there is a possibility that it is substantially different, for example, when there are only a few studies and some have limitations but not major flaws, there is some variation between studies, or the confidence interval of the summary estimate is wide.
LOW: The true effect may be substantially different from the estimated size and direction of the effect, for example, when supporting studies have major flaws, there is important variation between studies, the confidence interval of the summary estimate is very wide, or there are no rigorous studies.Reference: Calderwood MS, Anderson DJ, Bratzler DW, Dellinger EP, Garcia-Houchins S, Maragakis LL, Nyquist AC, Perkins KM, Preas MA, Saiman L, Schaffzin JK, Schweizer M, Yokoe DS, Kaye KS. Strategies to prevent surgical site infections in acute-care hospitals: 2022 Update. Infect Control Hosp Epidemiol. 2023 May;44(5):695-720.
Essential practices
1. Administer antimicrobial prophylaxis according to evidence-based standards and guidelines. (Quality of evidence: HIGH)
2. Use a combination of parenteral and oral antimicrobial prophylaxis prior to elective colorectal surgery to reduce the risk of SSI. (Quality of evidence: HIGH)
3. Decolonize surgical patients with an anti-staphylococcal agent in the preoperative setting for orthopedic and cardiothoracic procedures. (Quality of evidence: HIGH)
Decolonize surgical patients in other procedures at high risk of staphylococcal SSI, such as those involving prosthetic material. (Quality of evidence: LOW)
4. Use antiseptic-containing preoperative vaginal preparation agents for patients undergoing cesarean delivery or hysterectomy. (Quality of evidence: MODERATE)
5. Do not remove hair at the operative site unless the presence of hair will interfere with the surgical procedure. (Quality of evidence: MODERATE)
6. Use alcohol-containing preoperative skin preparatory agents in combination with an antiseptic. (Quality of evidence: HIGH)
7. For procedures not requiring hypothermia, maintain normothermia (temperature > 35.5°C) during the perioperative period. (Quality of evidence: HIGH)
8. Use impervious plastic wound protectors for gastrointestinal and biliary tract surgery. (Quality of evidence: HIGH)
9. Perform intraoperative antiseptic wound lavage. (Quality of evidence: MODERATE)
10. Control blood-glucose level during the immediate postoperative period for all patients. (Quality of evidence: HIGH)
11. Use a checklist and/or bundle to ensure compliance with best practices to improve surgical patient safety. (Quality of evidence: HIGH)
12. Perform surveillance for SSI. (Quality of evidence: MODERATE)
13. Increase the efficiency of surveillance by utilizing automated data. (Quality of evidence: MODERATE)
14. Provide ongoing SSI rate feedback to surgical and perioperative personnel and leadership. (Quality of evidence: MODERATE).
15. Measure and provide feedback to HCP regarding rates of compliance with process measures. (Quality of evidence: LOW)
16. Educate surgeons and perioperative personnel about SSI prevention measures. (Quality of evidence: LOW)
17. Educate patients and their families about SSI prevention as appropriate. (Quality of evidence: LOW)
18. Implement policies and practices to reduce the risk of SSI for patients that align with applicable evidence-based standards, rules and regulations, and medical device manufacturer instructions for use. (Quality of evidence: MODERATE)
19. Observe and review operating room personnel and the environment of care in the operating room and in central sterile reprocessing. (Quality of evidence: LOW)Additional approaches
1. Perform an SSI risk assessment. (Quality of evidence: LOW)
2. Consider use of negative pressure dressings in patients who may benefit. (Quality of evidence: MODERATE)
3. Observe and review practices in the preoperative clinic, post-anesthesia care unit, surgical intensive care unit and/or surgical ward. (Quality of evidence: MODERATE)
4. Use antiseptic-impregnated sutures as a strategy to prevent SSI. (Quality of evidence: MODERATE)Approaches that should not be considered a routine part of SSI prevention
1. Do not routinely use vancomycin for antimicrobial prophylaxis. (Quality of evidence: MODERATE)
2. Do not routinely delay surgery to provide parenteral nutrition. (Quality of evidence: HIGH)
3. Do not routinely use antiseptic drapes as a strategy to prevent SSI. (Quality of evidence: HIGH)Unresolved issues
1. Optimize tissue oxygenation at the incision site
2. Preoperative intranasal and pharyngeal CHG treatment for patients undergoing cardiothoracic procedures
3. Use of gentamicin-collagen sponges
4. Use of antimicrobial powder
5. Use of surgical attire
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2.6 Meaningfulness to Target Population
Please accept these comments from the Patient Safety Action Network regarding the following HAI measures; we are commenting on all of them together:
- Catheter-Associated Urinary Tract Infections (CAUTI)
- Central Line Associated Blood Stream Infections (CLABSI
- 30-Day Post-Operative Colon Surgery (COLO) and Abdominal Hysterectomy (HYST) Surgical Site Infection (SSI)
- Methicillin-resistant Staphylococcus aureus (MRSA) Bacteremia LabID Event
- Clostridioides difficile (CDI) LabID Event
- Antimicrobial Use Measure
Fundamentally, each of these measures is important and essential to preventing infections. If we do not measure and publicly report these events in a continuous, standardized way, we cannot truly know or understand when actual progress is made.
There are several target populations for these measures. First, members of the public who may need to use the services of a local hospital at any given point without warning or who have an interest in seeing how their hospital compares to others on hospital acquired infections. The published HAI measures provide that public service. Second, patients being treated at a hospital who are infected might not benefit from the past published HAI measures, but they probably are interested in accountability. One of the first questions many ask is “will my infection be counted?” The next question typically is, “how can we prevent it from happening again to someone else?” To them, these measurements are very important.
The value and meaningfulness of these outcome measures lie in tracking reduction of patient harm over time using individual hospitals’ HAI measures. Progress means fewer infections at each point of measurement with a goal toward no infections. Unfortunately, these measures are rarely presented on a continuum demonstrating whether each hospital has reduced this harm over the years. And they are no longer presented with the actual numbers of infections, which reflect actual infections reported and not an estimate.
We also believe the value of these measures is lowered because of the way they are reported to the public. It appears that the standardization using an SIR of 1.0 as the baseline has established that as the status quo, even though the baseline has been adjusted over time. We wonder how often hospitals accept SIRs of around 1.0 as acceptable. Further, the use of risk adjustment skews the real results in each of these measures, i.e., the patients who got infected. We would rather see a stratified presentation that compares similar hospitals together – without risk adjustments. We believe that would be more meaningful to the public.
Also, the terms used to present the data lead to confusion, such as predicted number of infections and better than/no different/worse than the national benchmark. Many hospitals’ data is “not available,” without context (the hospital failed to report, the hospital does not have enough cases to rate, etc).
Even with these limitations, the measures are important to retain because of their value to patients who expect to be free from preventable harm when hospitalized. You ask about the full meaning of these measures to patients, but that requires some understanding of what happens to them following a hospital acquired infection. These events affect each person in a different way. It can mean a round of antibiotics; a longer stay in the hospital or the need to seek further treatment; continued chronic conditions, including recurrences of the infection; significant medical debt; losing a job due to missing work as a consequence of an infection; losing one’s home due to mounting medical bills and other debts; permanent disability; sepsis that is only survived after intense medical care; and death. This should clearly explain why all these measures are meaningful to patients.
Frankly, we need more infection measures so that all hospital acquired infections are accounted for, like what is done in California. It seems to us that every time federal agencies ask for feedback about these measures, the result is less information to the public.
The 30-Day Post-Operative Colon Surgery (COLO) and Abdominal Hysterectomy (HYST) Surgical Site Infection (SSI) Standardized Infection Ratio serves as a broad, objective measure of healthcare-associated infection (HAI) burden within many patient care locations. HAI reduction has been a national priority set by U.S. Government going back to 2008 with the U.S. Department of Health and Human Services (HHS) National Action Plan to Prevent Health Care-associated Infections: Roadmap to Elimination.1 While there has been overall progress in reducing these specific HAIs, there is room for improvement in both the surveillance and prevention of SSIs.
Measuring SSIs has also been a priority for CMS as indicated by the use of the measure in four CMS Programs including Hospital Acquired Condition Reduction Program, Hospital Value-Based Purchasing, Hospital Inpatient Quality Reporting, and Exempt Cancer Hospital Quality Reporting.
- U.S. Health and Human Services (HHS) National Action Plan to Prevent Health Care-associated Infections: Roadmap to Elimination. Accessed August 3, 2023 at https://www.hhs.gov/oidp/topics/health-care-associated-infections/hai-action-plan/index.html
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2.4 Performance Gap
Data Source and date of data
The dataset used for testing is the 2023 Center for Disease Control’s (CDC) National Healthcare Safety Network (NHSN) data, which collects healthcare infection data from facilities throughout the United States.
Number of Measured Entities
HYST-649 facilities
COLO-1787 facilities
Number of Encounters is the number of procedures for the operative type listed.
HYST-171,193 procedures
COLO-306,844
2.4a Attach Performance Gap Results
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3.1 Feasibility Assessment
This is a maintenance measure and the measure specifications have not changed. There are no feasibility issues.
3.3 Feasibility Informed Final MeasureThis is a maintenance measure and the measure specifications have not changed. There are no feasibility issues.
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3.4 Proprietary InformationNot a proprietary measure and no proprietary components
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4.1.3 Characteristics of Measured Entities
Reliability Testing:
COLO: 1788 facilities meeting criteria of >=1 predicted event. below are basic measures at the hospital level
Bedsize Frequency Percent
<319 1144 63.98
>=319 644 36.02
Medical Type
Major Medical 1059 59.23
Non-Major Medical 729 40.77
Census Region
Midwest 387 21.64
Northeast 309 17.28
South 713 39.88
West 379 21.20HYST: 649 facilities meeting criteria of >=1 predicted event.
Bedsize Frequency Percent
<319 230 35.44
>=319 419 64.56
Medical Type
Major Medical 479 73.81
Non-Major Medical 170 26.19Census Region
Midwest 139 21.42
Northeast 103 15.87
South 293 45.15
West 114 17.57
Validity Testing:
Any acute care hospital or critical access hospital that reported 2023 data to NHSN for both COLO and HYST SSIs, and had at least one predicted event for each, was included in the analysis for a total of 607 facilities. Bed size, medical type, and census region of included facilities are broken down below.Bed size # Facilities Percent
<319 188 30.97
>=319 419 69.03
Medical Type
Major Medical 460 80.84
Non-Major Medical 147 24.22
Census Region
Midwest 133 21.91
Northeast 101 16.64
South 263 43.33
West 110 18.12
Validation Studies:
I. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections. Study was based in a 865-bed tertiary academic hospital.
Albert H, Bataller W, Masroor N, Doll M, Cooper K, Spencer P, Winborne D, Zierden EM, Stevens MP, Scott M, Bearman G. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections. Am J Infect Control. 2019 Jun;47(6):718-719.II. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients. Study was based in a 487-bed acute-care level 1 Trauma Center.
Guerrero MA, Anderson B, Carr G, Snyder KL, Boyle P, Ugwu SA, Davis M, Bohnenkamp SK, Nfonsam V, Riall TS. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients. Patient Saf Surg. 2021 Apr 8;15(1):15.III. Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System. Five hospital system in the state of Washington.
Harris J. (2018). Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System. AORN journal, 107(5), 592–600.IV. Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention. Tertiary hospital that performs total abdominal hysterectomies.
DeCesare, Julie Z. MD; Morton, Ashley BS. Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention [13Q]. Obstetrics & Gynecology 127():p 142S-143S, May 2016.Risk Adjustment:
• Includes only in-plan, inpatient colon and abdominal hysterectomy procedures in adult patients (i.e., ge 18 years of age)
• Includes only Deep Incisional Primary SSIs and Organ/Space SSIs with an event date within 30 days of the procedure
• Includes SSIs regardless of detection method
COLO: Description of entities in the analytic dataset
Total number of Facility beds Frequency Percent
<319 2673 80
>=319 668 20
Medical Type
Major Medical 1327 40
Non-Major Medical 2014 60
Region
Midwest 834 24.96%
Non-Mainland 4 0.12%
Northeast 510 15.26%
South 1286 38.49%
West 707 21.16%HYST: Description of entities in the analytic dataset
Total number of Facility beds Frequency Percent
<319 2336 78
>=319 659 22
Medical Type
Major Medical 1245 42
Non-Major Medical 1747 58
Region
Midwest 736 24.60%
Non-Mainland 6 0.20%
Northeast 473 15.81%
South 1149 38.40%
West 628 20.99%
4.1.1 Data Used for TestingReliability Testing: The dataset used for testing is the 2023 Center for Disease Control’s (CDC) National Healthcare Safety Network (NHSN) data, which collects healthcare infection data from facilities throughout the United States.
Validity Testing: The dataset used for testing is the 2023 Center for Disease Control’s (CDC) National Healthcare Safety Network (NHSN) data, which collects healthcare infection data from facilities throughout the United States.
Validation Studies:
I. Albert H, Bataller W, Masroor N, Doll M, Cooper K, Spencer P, Winborne D, Zierden EM, Stevens MP, Scott M, Bearman G. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections. Am J Infect Control. 2019 Jun;47(6):718-719.
Dates of data used in testing: December 2015-July 2017
II. Guerrero MA, Anderson B, Carr G, Snyder KL, Boyle P, Ugwu SA, Davis M, Bohnenkamp SK, Nfonsam V, Riall TS. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients. Patient Saf Surg. 2021 Apr 8;15(1):15.Dates of data used in testing: January 2016-December 2017.
III. Harris J. (2018). Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System. AORN journal, 107(5), 592–600.
Dates of data used in testing: January 2013-July 2017.
I. DeCesare, Julie Z. MD; Morton, Ashley BS. Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention [13Q]. Obstetrics & Gynecology 127():p 142S-143S, May 2016.
Dates of data used in testing: January 2013-June 2015.
Risk Adjustment:
The annual 2022 NHSN aggregate data was used as the baseline to update the risk adjusted SIR model for the Complex 30-day SSI SIR model. The data includes in-plan colon and abdominal hysterectomy denominator and numerator data entered as according to NHSN’s surveillance definitions. The data used to update the risk adjusted models also includes facility level information from the enrollment into NHSN form, as well as data from the annual facility survey.4.1.4 Characteristics of Units of the Eligible PopulationReliability Testing: In the 1788 Hospitals meeting threshold there were a total of 306844 colo procedures, age and gender information is below:
Age Group (years) Frequency Percent
18-39 29689 9.68
40-62 114510 37.32
63-79 128296 41.81
80-109 34349 11.19
Gender
Female 159402 51.95
Male 147442 48.05I
n the 649 Hospitals meeting threshold there were a total of 171193 HYST procedures, age and gender information is below:
Age Group (years) Frequency Percent
18-47 76270 44.55
48-55 34186 19.97
56-109 60737 35.48
Gender
Female 171096 99.94
Male 97 0.06
Validity Testing:
The 607 facilities included in the validity analysis performed a total of 160,423 HYST procedures and 165,617 COLO procedures during 2023. Age group at time of procedure and gender of patients undergoing these procedures are below.HYST:
Age Group (years) Frequency Percent
18-47 70,006 43.64
48-55 32,092 20
56-109 58,325 36.36
Gender
Female 160,333 99.94
Male 90 0.06COLO:
Age Group (years) Frequency Percent
18-39 18,066 10.91
40-62 63,525 38.36
63-79 67,295 40.63
80-109 16,731 10.1
Gender
Female 87,251 52.68
Male 78,366 47.32
Validation Studies:
I. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections.
Data was captured on colon surgery patients. Demographic data on patients was not available for analysis as demographic data is not collected in the NHSN Module.Albert H, Bataller W, Masroor N, Doll M, Cooper K, Spencer P, Winborne D, Zierden EM, Stevens MP, Scott M, Bearman G. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections. Am J Infect Control. 2019 Jun;47(6):718-719.
II. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients.
All patients that underwent elective and emergent colon operations between January 1, 2016, and December 31, 2017 were included. Patient with a blunt and penetrating trauma and those presenting with colon perforation and class IV wounds were excluded.Guerrero MA, Anderson B, Carr G, Snyder KL, Boyle P, Ugwu SA, Davis M, Bohnenkamp SK, Nfonsam V, Riall TS. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients. Patient Saf Surg. 2021 Apr 8;15(1):15.
III. Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System
Patients undergoing elective colon surgery were included in the study.
Harris J. (2018). Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System. AORN journal, 107(5), 592–600.
V. Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention.
Women undergoing total abdominal hysterectomies.
DeCesare, Julie Z. MD; Morton, Ashley BS. Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention [13Q]. Obstetrics & Gynecology 127():p 142S-143S, May 2016.
Risk Adjustment:
Characteristics of Units of Eligible Population in analytic dataset: COLOAge Group (years) Frequency Percent
18-39 31626 9.80
40-62 121583 37.67
63-79 133515 41.37
80-109 36010 11.16
Gender
Female 167139 51.79
Male 155595 48.21Characteristics of Units of Eligible Population in analytic dataset:: HYST
Age Group (years) Frequency Percent
18-47 123562 48.93
48-55 51595 20.43
56-109 77376 30.64
Gender
Female 252307 99.91
Male 226 0.09
4.1.2 Differences in DataReliability Testing: The dataset used for testing is the Center for Disease Control’s (CDC) National Healthcare Safety Network (NHSN) 2023 dataset, which collects healthcare infection data from facilities throughout the United States. Only facilities with a calculated SIR were included in the analysis (facilities with >=1 predicted SSI event were included).
Validity Testing: The dataset used for testing is the Center for Disease Control’s (CDC) National Healthcare Safety Network (NHSN) 2023 dataset, which collects healthcare infection data from facilities throughout the United States. Only facilities with both a HYST and COLO SSI SIR were included in the analysis (facilities with >=1 predicted SSI event were included).Validation Studies:
I. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections.Colon SIR data was reported by the facility to NHSN from December 2015 to July 2017.
Albert H, Bataller W, Masroor N, Doll M, Cooper K, Spencer P, Winborne D, Zierden EM, Stevens MP, Scott M, Bearman G. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections. Am J Infect Control. 2019 Jun;47(6):718-719.
II. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients.
Colon SIR data was reported by the facility to NHSN from January 2016 to December 2017.
Guerrero MA, Anderson B, Carr G, Snyder KL, Boyle P, Ugwu SA, Davis M, Bohnenkamp SK, Nfonsam V, Riall TS. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients. Patient Saf Surg. 2021 Apr 8;15(1):15.
III. Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System
Colon SIR data was reported by the facilities to NHSH from January 2013 to July 2017.
Harris J. (2018). Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System. AORN journal, 107(5), 592–600.
IV. Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention.
Abdominal hysterectomy SSI data was reported to NHSN from January 2013 to June 2015.
DeCesare, Julie Z. MD; Morton, Ashley BS. Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention [13Q]. Obstetrics & Gynecology 127():p 142S-143S, May 2016.Risk Adjustment:
The 2022 national aggregate data was reviewed for all potential data quality issues including outlier values prior to performing the risk adjusted modeling of the SIR denominator for the Complex 30-day SSI model. Based on the surveillance protocol for SSIs, procedure records were excluded from modeling consideration if the procedure/infection met the criteria
• Surgical site infections that are present at the time of surgery (PATOS)
• ASA class VI
• Outpatient colon and abdominal hysterectomy procedures
• Patients <18 years of age
• Patients > 109 years of age
• Adult patient's, >=18 years of age, BMI is less than 12 or greater than 60.
• Surgical procedure duration less than 5 minutes or exceeding the IQR5 value.
The IQR5, also called the procedure duration cutoff point, is used as an indicator of an extreme outlier for procedure durations when calculating the SSI SIRs. The IQR5 is calculated as five times the interquartile range (Q1-Q3) above the 75th percentile. Procedures with a duration greater than the IQR5 were excluded from the baseline data and will be excluded from all SSI SIR calculations.Table 4. IQR5 Values, in Minutes, for NHSN Operative Procedures, Adult and Pediatric Patients
NHSN Operative Procedure IQR5 (in minutes) IQR5 (in hours and minutes)
Minutes Hours Minutes
COLO 783 13 3
HYST 608 10 8• Records with missing risk factors
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4.2.1 Level(s) of Reliability Testing Conducted4.2.2 Method(s) of Reliability Testing
Signal-to-noise reliability testing was performed to distinguish measure scores between facilities (Adams J.L. 2009). The annual standardized infection ratio (SIR) is defined as the sum of observed (O) events at the facility divided by the sum of predicted (P) events calculated from the risk-adjustment model. Signal-to-noise reliability testing denotes between-facility variance and within-facility variance (Adams J.L. 2009). Each facility SIR represents the between-facility variance; total variance of the data across eligible facilities with predicted number ≥1. The within-facility variance of the SIR for each facility was then calculated as Var(O/P) where P is a constant, a nuisance factor with no random variation. O was assumed to follow a Poisson distribution with rate parameter approximated by P. The result is Var(O/P) = Var(O)/P2 = P/P2 = 1/P. Signal to noise reliability scores can range from 0 to 1. A reliability of zero implies that all the variability in a measure is attributable to measurement error. A reliability of one implies that all the variability is attributable to real difference in performance.
References:
- Adams, J. L. (2009). The reliability of provider profiling: a tutorial. RAND.
4.2.3 Reliability Testing ResultsReliability testing results for both COLO and HYST are included in the attached PDF.
4.2.3a Attach Additional Reliability Testing ResultsTable 2. Accountable Entity–Level Reliability Testing Results by Denominator-Target Population SizeAccountable Entity-Level Reliability Testing Results Overall Minimum Decile_1 Decile_2 Decile_3 Decile_4 Decile_5 Decile_6 Decile_7 Decile_8 Decile_9 Decile_10 Maximum Reliability Mean Performance Score N of Entities 4.2.4 Interpretation of Reliability ResultsSignal-to-Noise reliability scores vary across facilities from zero to one, with a score of zero indicating that all variation is attributable to noise (variation across patients within facilities) and a score of one indicating that all variation is caused by real differences in performance across facilities.
The median reliability score for HYST SSI was 0.66 and for COLO SSI was 0.68. The median signal-to-noise reliability score demonstrates substantial agreement. Our interpretation of the results is based on the standards established by Landis and Koch (1977):
• < 0 – Less than chance agreement
• 0 – 0.2 Slight agreement
• 0.21 – 0.39 Fair agreement
• 0.4 – 0.59 Moderate agreement
• 0.6 – 0.79 Substantial agreement
• 0.8 – 0.99 Almost Perfect agreement
• 1 Perfect agreement
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4.3.1 Level(s) of Validity Testing Conducted4.3.2 Type of accountable entity-level validity testing conducted4.3.3 Method(s) of Validity Testing
Validity Testing: A Pearson correlation coefficient was calculated to assess a hypothesized linear relationship in the positive direction between annual Standardized Infection Ratios (SIR) for COLO and HYST SSIs. The annual standardized infection ratio (SIR) is defined as the sum of observed (O) events at the facility divided by the sum of predicted (P) events calculated from the risk-adjustment model. Each facility that reported both COLO and HYST SSI data for 2023 with at least 1 predicted event was included. If a facility reported only COLO or only HYST or did not have at least 1 predicted event for both HAIs, they were excluded from the analysis. Correlation coefficients range from -1 to +1, where a coefficient of -1 implies a perfect negative correlation, 0 implies no correlation, and +1 implies a perfect positive correlation. A significance threshold of 0.05 was used to test the result.
We hypothesized that there would be a positive correlation between HYST and COLO SSI SIRs because there is overlap in the infection prevention practices preventing both types of SSIs (for example, administration of prophylactic antibiotics, maintaining normothermia, controlling blood glucose, etc.). However, there are some procedure-specific SSI prevention recommendations, such as use of both an oral and IV prophylactic antibiotic for COLO, or use of vaginal antiseptic prep for HYST, and the surgeons performing the COLO and HYST procedures may be different at a single institution. Thus, we predicted that while the correlation would be positive, it would be a weak correlation.
Validation Studies:
Empirical validity testing at the accountable entity level was performed by evaluating published studies from facilities that implemented colon SSI and abdominal hysterectomy SSI prevention activities and hypothesized that these approaches would reduce their NHSN COLO SIR and HYST SIR.
I. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections.The facility implemented six bundle elements modeled after the Enhanced Recovery After Surgery (ERAS) project to reduce colon surgical site infections. The interventions included (1) patient hair removal in the perisurgical unit (2) maintaining normothermia (body temperature >35.5°C), (3) antibiotic prophylaxis (2,000 mg cefoxitin OR a combination of 500 mg metronidazole and 2,000 mg cefazolin for patient weight=120 kg, 3,000 mg cefazolin for weight >120 kg), (4) use of surgical wound protectors, (5) wound irrigation with antibiotic solution, and (6) skin closure protocol (closure tray with surgeon gown and glove change). The facility hypothesized that implementation of these interventions would decrease their COLO SIR. A 2-proportion z test was conducted to compare the mean SSI rates pre- and postintervention.
Albert H, Bataller W, Masroor N, Doll M, Cooper K, Spencer P, Winborne D, Zierden EM, Stevens MP, Scott M, Bearman G. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections. Am J Infect Control. 2019 Jun;47(6):718-719.
II. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients.
A colon SSI bundle was implemented January 1, 2017. The bundle included preoperative, intraoperative, and postoperative interventions, which the facility hypothesized would decrease their COLO SSI SIR. The preoperative bundle included: for patients undergoing elective surgery, oral antibiotics (neomycin and flagyl) the day before surgery, use of a mechanical bowel prep was left to the discretion of the surgeon, patients were bathed with chlorhexidine gluconate (CHG) wipes upon entering the preoperative ready room and patient warming was initiated, and prophylactic intravenous (IV) antibiotics were administered within 60 min prior to skin incision. Intraoperatively, the OR temperature was maintained at 70 degrees, body hair at the surgical site was removed with clippers and the skin was prepped with chlorhexidine and alcohol-based products. Surgical personnel scrubbing into the case were required to have natural nails and underwent standard hand sterilization technique prior to gowning. Post-incision duel-ringed wound protectors were utilized on all open cases and wound protectors were placed at incision sites during laparoscopic cases. At incision closure all surgical team members scrubbed during the case changed gowns and gloves prior to closing fascia. A new closing tray was utilized on a new table and were used for fascia and wound closure and intraoperative dressings were placed. Postoperatively the bundle focused on euglycemia and proper wound coverage. The SSI’s that developed were grouped into either a pre-bundle or post-bundle category and a chi-square test or independent sample t-test was used to evaluate difference between groups. Statistically significant results were set to a p-value < 0.05 at an alpha of 0.05.
Guerrero MA, Anderson B, Carr G, Snyder KL, Boyle P, Ugwu SA, Davis M, Bohnenkamp SK, Nfonsam V, Riall TS. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients. Patient Saf Surg. 2021 Apr 8;15(1):15.
III. Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System
The five-hospital system convened a multidisciplinary team to identify interventions to reduce SSI’s after colon surgery. The team hypothesized, based on a literature review, that an ERAS bundle that promotes interventions during the preoperative, intraoperative, and postoperative phases of care would reduce the systems NHSN COLO SSI SIR. Prior to surgery the interventions focused on optimizing patient’s nutrition, completing a bowel prep and preoperative antibiotics. Intraoperatively the interventions focused on normothermia, IV fluids for hypovolemia, and a separate fascia closing tray. Postoperatively the interventions again focused on nutrition, pain control, and ambulation.
Harris J. (2018). Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System. AORN journal, 107(5), 592–600.
IV. Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention.
The facility implemented evidence-based methods to prevent abdominal hysterectomy SSI and implemented a bundle that focused on the preoperative, perioperative, and postoperative phases of care.
DeCesare, Julie Z. MD; Morton, Ashley BS. Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention [13Q]. Obstetrics & Gynecology 127():p 142S-143S, May 2016.4.3.4 Validity Testing ResultsValidity Testing:
The 607 facilities had a weak, but significant positive correlation (rho= 0.2486, p<0.0001).
Validation Studies:
I. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections.
In the 10 months prior to implementation, there were 26 infections and 212 colorectal procedures (12.26 infections per 100 procedures). After intervention, there were 13 infections and 258 procedures (5.04 infections per 100 procedures). The facilities COLO SSI SIR decreased from 1.67 to 0.62 after implementation of the ERAS bundle (P 0.004).
The implementation of an evidence-based colorectal SSI prevention bundle resulted in a significantly lower SSI rates compared with the 10 months prior to intervention. This study demonstrates that implementation of a colon SSI prevention bundle led to a significant reduction in the reported COLO SSI SIR. A SIR > 1.0 represents that more SSIs were observed than predicted, a SIR < 1.0 represents that fewer SSIs were observed than predicted, and a SIR= 1.0 represents the same number of SSIs were observed as predicted. The result of the study supports the hypothesis that the measure score correctly reflects the quality of care provided and adequately identifies differences in quality.
Albert H, Bataller W, Masroor N, Doll M, Cooper K, Spencer P, Winborne D, Zierden EM, Stevens MP, Scott M, Bearman G. Infection prevention and enhanced recovery after surgery: A partnership for implementation of an evidence-based bundle to reduce colorectal surgical site infections. Am J Infect Control. 2019 Jun;47(6):718-719.
II. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients.
Prior to bundle implementation in 2015 the facilities COLO SSI SIR was 3.08. After bundle implementation in 2017 the COLO SSI SIR decreased to 0.45 and was statistically significant (p<0.0001). The implementation of a colon SSI prevention bundle across the surgical continuum of care resulted in a statistically significant lower COLO SSI SIR. A SIR > 1.0 represents that more SSIs were observed than predicted, a SIR < 1.0 represents that fewer SSIs were observed than predicted, and a SIR= 1.0 represents the same number of SSIs were observed as predicted. This study supports the hypothesis that the measure score correctly reflects the quality of care provided and adequately identifies differences in quality.
Guerrero MA, Anderson B, Carr G, Snyder KL, Boyle P, Ugwu SA, Davis M, Bohnenkamp SK, Nfonsam V, Riall TS. Adherence to a standardized infection reduction bundle decreases surgical site infections after colon surgery: a retrospective cohort study on 526 patients. Patient Saf Surg. 2021 Apr 8;15(1):15.
III. Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System
Prior to implementation of the bundle in 2013, the healthcare facilities COLO SSI SIR was 0.848. After bundle implementation in 2014, the SIR decreased to 0.25 and the facilities maintained lower rates of colon SSI through 2017 with a SIR of 0.27. The facilities also reported a 74.6% reduction in readmission rates and a 22.73% reduction in length of stay.
After implementation of a colon SSI reduction bundle the health system saw a significantly lower COLO SSI SIR. A SIR > 1.0 represents that more SSIs were observed than predicted, a SIR < 1.0 represents that fewer SSIs were observed than predicted, and a SIR= 1.0 represents the same number of SSIs were observed as predicted. The data from this study supports the hypothesis that the measure score correctly reflects the quality of care provided and adequately identifies differences in quality.Harris J. (2018). Success of a Colorectal Surgical Site Infection Prevention Bundle in a Multihospital System. AORN journal, 107(5), 592–600.
- Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention.
IV. During the facilities pre-intervention period from January 2013 to June 2014 the overall HYST SSI SIR was 1.5. During the post-intervention period, the facilities HYST SSI SIR decreased to 0.44, 0.42, and 1.36 for the 3rd quarter 2014, 4th quarter 2014, and 1st quarter 2015, respectively. In the 2nd quarter of 2015, no SIR was given because the value was less than 1.0. The facilities bundled interventions across the operative period led to a significant reduction in SSI following total abdominal hysterectomy. A SIR > 1.0 represents that more SSIs were observed than predicted, a SIR < 1.0 represents that fewer SSIs were observed than predicted, and a SIR= 1.0 represents the same number of SSIs were observed as predicted. This data supports the hypothesis that the measure score correctly reflects the quality of care provided and adequately identifies differences in quality.
DeCesare, Julie Z. MD; Morton, Ashley BS. Evidence-Based Prevention of SSI Following Total Abdominal Hysterectomy Using a Multi-Factorial Intervention [13Q]. Obstetrics & Gynecology 127():p 142S-143S, May 2016.
4.3.5 Interpretation of Validity ResultsValidity Testing:
The HYST SSI standardized infection ratio (SIR) and COLO SSI SIR are surgery-associated Healthcare Associated Infection outcome measures. Implementation of infection prevention strategies, such as prevention bundles or checklists for SSI prevention have led to lower SIRs. Many of the prevention bundles should be implemented similarly in the OR regardless of surgical type; however, other factors may vary based on surgical type, such as the recommendation for both oral and IV antibiotic prophylaxis in colon cases or use of vaginal antiseptics for hysterectomy cases. Additionally, the surgeons who perform HYST procedures may be different from those who perform COLO procedures at some hospitals. We hypothesized that there will be a weak positive correlation between the COLO SSI SIR and HYST SSI SIR. We predicted only a weak correlation between the two measures as some facilities may choose to focus quality improvement on the prevention of a single HAI (COLO SSI or HYST SSI) due to resource limitations, or due to the differences in the procedures. The significant positive correlation (rho= 0.2486, p<0.0001) of the relationship between COLO SSI SIR and HYST SSI SIR demonstrates that the SIRs are valid measures of healthcare quality, as they are both driven by clinically relevant patient care practices and evidence-based infection prevention strategies implemented by the healthcare facilities.
Validation Studies:
The result of the validation studies support the hypothesis that the measure score correctly reflects the quality of care provided and adequately identifies differences in quality as the implementation of various prevention strategies or bundles (improvement in the quality of care that patients received) lead to improvements in facility SIRs.
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4.4.1 Methods used to address risk factors4.4.2 Conceptual Model Rationale
Previously published literature by Brandt C. et al. and Anderson DJ, et. Al have documented variable rates of surgical site infection based on facility and procedure-specific risk factors. To allow for a meaningful measure that offers fair comparisons, the standardized infection ratio (SIR) is calculated using a multivariate logistic regression model that accounts for facility and procedure-level factors found to be statistically significant predictors of SSI risk in the 2022 baseline data. This method of risk adjustment offers a stronger, more robust, and more reliable metric for measuring SSI incidence than traditional or stratified SSI rates described in the NHSN model paper below.
All applicable variables that are collected in NHSN as part of SSI surveillance were considered for inclusion in the Complex 30-day multivariate logistic regression model: procedure duration, BMI, patient age, ASA score, use of scope, facility’s medical school affiliation, facility type, patient diagnosis of diabetes, facility bed size, patient’s wound class, emergency status of procedure, use of anesthesia, trauma classification, type of wound closure, and patient gender. Race, ethnicity, urbanicity/rurality, Medicare/Medicaid status, indices of social vulnerability, and marker of functional status-related risk are not collected in the NHSN for each patient undergoing an inpatient colon procedure (COLO) or abdominal hysterectomy (HYST), and therefore could not be assessed for inclusion in the risk model. Thus, the SIR cannot fully account for all potential patient characteristics that could lead to differences in risk of SSI. Despite this, the Complex 30-day SIR is still a strong and valid measure for SSI incidence; the risk adjustment models are robust models that accounts for patient characteristics and underlying comorbidities (e.g., age, diabetes, gender) and were developed from nationally representative SSI COLO (322,698 procedure records) and HYST (252,533 procedure records) data reported to CDC from approximately 3,000 acute care and critical access hospitals. The C-statistic for the COLO risk adjustment model is 0.636, and for HYST, 0.627, indicating moderate model discrimination.Brandt C, Hansen S, Sohr D, Daschner F, Ruden H, Gastmeier P. Finding a method for optimizing risk adjustment when comparing surgical-site infection rates. Infect Control Hosp Epidemiol 2004;25:13–18.
Anderson DJ, Chen LF, Sexton DJ, Kaye KS. Complex surgical site infections and the devilish details of risk adjustment: important implications for public reporting. Infect Control Hosp Epidemiol 2008;29:941–946. 12
Centers for Disease Control and Prevention. (2019). The standardized infection ratio and its use in the National Healthcare Safety Network (NHSN). National Healthcare Safety Network (NHSN). https://www.cdc.gov/nhsn/pdfs/datastat/ssi_modelpaper.pdf
4.4.2a Attach Conceptual Model4.4.3 Risk Factor Characteristics Across Measured EntitiesTable. Descriptive statistics on the population used in the COLO Complex 30-day SSI SIR modeling
N Mean Min. Q1 Med Q3 Max
Age at time of procedure 322,734 61.6 18 52 63 73 106
BMI value 322,734 28.4 12 23.6 27.4 32.1 60.0
Procedure duration 322,734 168.7 5 99 146 213 783
Total number of facility beds 322,734 398.0 6 204 335 535 1342
Table. Descriptive statistics on the population used in the HYST Complex 30-day SSI SIR modeling
N Mean Min. Q1 Med Q3 Max
Age at time of procedure 252,533 50.5 18 41 48 59 102
BMI value 252,533 31.7 12.0 25.9 30.6 36.4 60.0
Procedure duration 252,533 139.9 5 86 120 172 608
Total number of facility beds 252,533 395.5 6 193 342 537 1342
Table. Descriptive statistics of the risk factors reported by patients considered for modeling of the Complex 30-day SSI SIR
Risk Factors Collected on NHSN Denominator COLO HYSTForm Considered for Model
Gender
Male 155,595 (48.2%) 226 (0.1%)
Female 167,139 (51.8%) 252,307 (99.9%)
Surgical Wound Class
Clean 0 (0.0%) 27,727 (11.0%)
Clean Contaminated 225,192 (69.8%) 220,801 (87.4%)
Contaminated 52,026 (16.1%) 2,519 (1.0%)
Dirty 45,516 (14.1%) 1,486 (0.6%)
Anesthesia
No 7,568 (2.3%) 6,605 (2.6%)
Yes 315,166 (97.7%) 245,928 (97.4%)
ASA
1 3,666 (1.1%) 12,424 (4.9%)
2 93,811 (29.1%) 143,560 (56.9%)
3 177,462 (55.0%) 92,438 (36.6%)
4 43,184 (13.4%) 3,954 (1.6%)
5 4,611 (1.4%) 157 (0.1%)
Diabetes
No 256,926 (79.6%) 219,472 (86.9%)
Yes 65,808 (20.4%) 33,061 (13.1%)
Closure
Primary closed 16,350 (5.1%) 3,153 (1.3%)
Other 306,384 (94.9%) 249,380 (98.8%)
Emergency
No 262,779 (81.4%) 247,433 (98.0%)
Yes 59,955 (18.6%) 5,100 (2.0%)
Trauma
No 312,559 (96.9%) 251,641 (99.7%)
Yes 10,175 (3.2%) 892 (0.4%)
Scope
No 194,395 (60.2%) 130,822 (51.8%)
Yes 128,339 (39.8%) 121,711 (48.2%)
Facility Types
Critical Access Hospitals 2,356 (0.7%) 1,705 (0.7%)
Children Hospitals 175 (0.1%) 411 (0.2%)
General Acute Care Hospitals 314,173 (97.4%) 238,033 (94.3%)
Military Hospitals 230 (0.1%) 214 (0.1%)
Oncology Hospitals 3,898 (1.2%) 2,774 (1.1%)
Orthopedic Hospitals 0 (0.0%) 4 (0.0%)
Surgical Hospitals 1,518 (0.5%) 3,052 (1.2%)
Women Hospitals 233 (0.1%) 3,411 (1.4%)
Women/Children Hospitals 151 (0.1%) 2,929 (1.2%)The descriptive results summarized in the table provide key insights into the patient population and facility characteristics included in the modeling of the Complex 30-day SSI SIR model using the 2022 national aggregate data.
For COLO:
• Age at Procedure: In the 2022 national aggregate data, the average age at time of the procedure of patients undergoing COLO surgeries is 61.6 years, with a median age of 63. This indicates that the population skews toward older adults, with 50% of patients between the ages of 52 and 73. The age range spans from 18 to 106 years, with notable variability as shown by the 10th and 90th percentiles (40 and 80 years, respectively). This highlights the diverse age distribution of the patient.
• Patient BMI: The mean BMI of 28.4 suggests that, on average, the population is classified as overweight, with a median BMI of 27.4. The BMI range varies from 12 to nearly 60, indicating the presence of both underweight and obese individuals in the dataset. Most patients fall within a BMI range of 20.5 to 37.5, as indicated by the 10th and 90th percentiles. This distribution emphasizes the need to consider BMI as a factor influencing procedural outcomes.
• Procedure Duration: The average duration of the procedure is approximately 169 minutes, with a median of 146 minutes. Procedure times range widely, from as short as 5 minutes to as long as 783 minutes. The interquartile range (99 to 213 minutes) suggests a significant variation in the time required for different cases, which may reflect differences in case complexity or facility efficiency.
• Total Number of Facility Beds: The facilities in this dataset vary greatly in size, with an average of 398 beds and a median of 335 beds. The number of beds ranges from very small facilities with 6 beds to large hospitals with over 1,300 beds. The distribution (10th percentile: 113 beds; 90th percentile: 784 beds) indicates that while many facilities are large, a considerable portion operates with fewer resources, potentially affecting procedural throughput and capacity.
For HYST:
• Age at Procedure: The average age of patients undergoing the procedure is approximately 50.5 years, with a median age of 48. This indicates a relatively younger patient population compared to previous data, with ages ranging from 18 to 102 years. The 10th percentile at 36 years and the 90th percentile at 70 years further illustrate the diversity in age, suggesting that while most patients are under 60, there are still a significant number of older patients.
• Patient BMI: The mean BMI is 31.7, categorizing the average patient as obese, with a median BMI of 30.6. The BMI values range from a low of approximately 12 to a high of 60, indicating a wide variety of body types within this population. The 10th and 90th percentiles (22.5 and 42.6, respectively) show that while many patients are within a higher BMI range, there is also a significant presence of patients with lower BMI values. This underscores the relevance of BMI in evaluating procedural outcomes and potential health risks.
• Procedure Duration: The average duration of the procedure is about 139.9 minutes, with a median of 120 minutes. Procedure durations vary widely from as short as 5 minutes to as long as 608 minutes. The interquartile range (from 86 to 172 minutes) indicates variability in the complexity and length of the procedures performed. This information is crucial for understanding potential operational efficiencies and resource allocation in the facilities.
• Total Number of Facility Beds: The facilities represented have an average of 395 beds, with a median of 342 beds. This suggests a mix of facility sizes, ranging from small institutions (as low as 6 beds) to large hospitals (up to 1,342 beds). The 10th percentile at 100 beds and the 90th percentile at 799 beds indicate that while many facilities are large, a significant number operate on a smaller scale, which may impact their ability to accommodate patients and resources for procedural care.
Overall, the 2022 data year includes a patient population that is primarily older and overweight, undergoing procedures of varying complexity in facilities ranging from small to very large hospitals. The variability in patient and facility characteristics underscores the importance of adjusting for these factors when interpreting outcomes from the measure.
4.4.4 Risk Adjustment Modeling and/or Stratification ResultsAll required risk factors on the NHSN procedure form and some facility level information were considered for the risk adjustment of the SIR denominator. The denominator factors include:
• Age at time of procedure
• Anesthesia
• ASA
• BMI (calculated from Height and Weight)
• Closure
• Diabetes
• Procedure duration
• Emergency
• Gender
• Trauma
• Surgical wound class
• Scope
The facility factors are:
• Self-identified facility type
• Affiliation to medical school status and type
• Total number of Facility bedsEach potential risk factor was tested for association with the outcome using Wald, Likelihood Ratio and Type III Chi-square tests at significant level for entry ≤ 0.25. This initial analysis was repeated by adding successive model parameters guided by a statistician that assess model fit using AIC, BIC, and Deviance and where possible evaluated model prediction using the c-index (Logistic) and pseudo-adjusted R-squared. Model diagnostics were used to assess potential multicollinearity by variance decomposition and the conditional index. Data points were assessed for high influence and leverage. Linearization and monotonicity were assessed using splines or other regularization methods. Each resulting model from this process were fit using Backward elimination (or selection) to detect any possible associations not identified in the former forward stagewise selection process and to seek additional confirmation of any factor associations. Variables were retained in the final model if p<0.05 and confirmed by both forward stagewise and backward selection approaches. Next, the best model was validated via bootstrap sampling that relied on 1000 replications selected randomly with replacement. If the confidence interval of the beta estimate for a variable contained 0 (equivalent to the odds or rate ratio containing 1) using the 2.5 and 97.5 percentiles that variable would be removed from the final model. For Colo only 2 variables did not meet the entry criteria into our final model: Closure and Diabetes. For HYST there were 7 variables that did not meet the entry criteria: Bedsize, Wound class, Emergency, Anesthesia, trauma, closure, and gender. Finally, the model discrimination was computed with the c-index and model calibration was tested with the hosmer-lemeshow test (Logistic) and pseudo-adjusted R-squared.
4.4.4a Attach Risk Adjustment Modeling and/or Stratification Specifications4.4.5 Calibration and DiscriminationDiscrimination of risk models were assessed using the c-statistic, and calibration was visually assessed using decile observed/expected plots and using the hosmer-lemeshow test. The Hosmer-Lemeshow test compared observed/expected rates within deciles (or n groups in general)
4.4.5a Attach Calibration and Discrimination Testing Results4.4.6 Interpretation of Risk Factor FindingsThe final validated predictive model for both COLO and HYST included facility level factors and procedural and patient level factors. The factors included in the final validated model for COLO are facility type (oncology hospital vs. others), total bed size and medical school affiliation status. The patient/procedural factors are scope, procedure duration, trauma, diabetes, ASA score, age at time of procedure, surgical wound class, emergency, gender, BMI, and anesthesia.
The factors included in the final validated model for HYST are facility type (oncology hospital vs. others) and medical school affiliation status. The patient/procedural factors are procedure duration, ASA score, age at time of procedure, diabetes, scope, and BMI.
For COLO procedures, the risk of infection was found to increase with advancing age, longer procedure durations, and higher BMI. Patients with diabetes, elevated ASA scores, anesthesia use, absence of scope, or trauma were more likely to develop SSIs. Additionally, COLO surgeries performed in oncology hospitals, facilities with ≥319 beds, or those affiliated with major medical schools were associated with a higher likelihood of SSIs.
For HYST procedures, the risk of infection was also found to increase with advancing age, longer procedure durations, and higher BMI. Patients with higher ASA scores, absence of scope, or were diabetic were more likely to develop SSIs. Furthermore, HYST surgeries performed in oncology hospitals, or those affiliated with major medical schools were associated with a higher likelihood of SSIs.
Each of the factors that were included in the final validated models based on the steps outlined above were significantly associated with the SSI outcome and improve the model fit. All other factors evaluated were not found to be significantly associated with the SSI outcome and were removed from the model.It is known that the power of the Hosmer-Lemeshow test increases as sample size increases. We have over 500,000 observations for both COLO and HYST models, so it is likely that Hosmer-Lemeshow tests will show significant results even when there were small differences between observed and predicted. In order to assess the impact of number of groups on Hosmer-Lemeshow for our large sample size procedures, we look at Hosmer-Lemeshow p-values for different number of groups (10, 20, 30, 40, 50 and 100 respectively). Hosmer-Lemeshow tests consistently indicate the risk adjust model fits the data well (p>0.05) for COLO. For HYST risk adjust model, majority of groups tested had p>0.05 which indicates the model fits the data well.
Reference: Paul P., Pennell M. and Lemeshow S. Standardizing the power of the Hosmer-Lemeshow goodness of fit test in large data sets. Statistics in Medicine. 2012. (wileyonlinelibrary.com) DOI: 10.1002/sim.5525
4.4.7 Final Approach to Address Risk FactorsRisk adjustment approachOnRisk adjustment approachOffConceptual model for risk adjustmentOffConceptual model for risk adjustmentOn
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5.1 Contributions Towards Advancing Health Equity
The equity criteria is optional and we are not submitting data on equity.
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6.1.1 Current StatusYes6.1.3 Current Use(s)6.1.4 Program DetailsHospital Inpatient Quality Reporting Program (HIQR), https://www.cms.gov/medicare/quality/initiatives/hospital-quality-initiative/inpatient-reporting-program, Under the Hospital Inpatient Quality Reporting Program, CMS collects quality data from hospitals paid under the Inpatient Prospective Payment System, , Over 4,000 Medicare-certified acute-care hospitals across the nation., Facility, Inpatient/HospitalNational Healthcare Safety Network (NHSN) Center for Disease Control and Prevention (CDC), http://www.cdc.gov/nhsn/, The CDC NHSN healthcare-associated infection tracking system provides facilities, states, regions, and the nation with data needed to identify problem, Acute care hospitals, Facility inpatient/hospitalCare Compare Sponsor: U.S. Centers for Medicare and Medicaid Services, https://www.medicare.gov/care-compare/?providerType=Hospital&redirect=true, For people with Medicare or their caregivers who want to choose a Medicare provider, such as a physician, hospital, nursing home, and others, this too, Over 4,000 Medicare-certified acute-care hospitals, long-term acute care hospitals and over 1,100 acute rehabilitation hospitals across the nation., Facility, Inpatient/HospitalHospital-Acquired Condition Reduction Program (HACRP) Sponsor: U.S. Centers for Medicare and Medicaid Services, https://www.cms.gov/Medicare/Quality-Initiatives-Patient-Assessment-Instruments/Value-Based-Programs/HAC/Hospital-Acquired-Conditions.html, The Hospital-Acquired Condition Reduction Program encourages hospitals to improve patients’ safety and reduce the number of conditions people experien, General acute-care hospitals across the nation., Facility, Inpatient/HospitalThe Prospective Payment System (PPS)-Exempt Cancer Hospital Quality Reporting (PCHQR) Program Sponsor: U.S. Centers for Medicare and Medicaid Servic, https://qualitynet.cms.gov/pch/pchqr, The PCHQR program is intended to equip consumers with quality-of-care information to make more informed decisions about healthcare options. It is also, Eleven cancer hospitals across the nation., Facility, Inpatient/HospitalHospital Value-Based Purchasing Program Sponsor: U.S. Centers for Medicare and Medicaid Services, https://www.cms.gov/medicare/quality/value-based-programs/hospital-purchasing, The Hospital Value-Based Purchasing (VBP) Program is part of our ongoing work to structure Medicare’s payment system to reward providers for the quali, Over 3,000 hospitals across the country., Facility, Inpatient/Hospital
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6.2.1 Actions of Measured Entities to Improve Performance
Implementing SSI prevention strategies is facility-specific, as facilities may have different capabilities for implementing improvements. Facilities should review best practices and available guideline recommendations to determine which prevention strategies they will be able to implement. For instance, a facility with an increased SSI Standardized Infection Ratio (SIR) could implement an organization-wide program to perform intraoperative skin preparation on surgical patients with an alcohol-based antiseptic agent, unless contraindicated, which is a recommendation based on clinical guidelines to prevent SSI.
The difficulty in implementing prevention strategies and achieving decreased outcomes is based on support from the facilities leadership and the overall capabilities of the facility.
6.2.2 Feedback on Measure PerformanceFacilities provide feedback they are generating Standardized Infection Ratio (SIR) analysis reports, within CDC NHSN monthly, and that they use their SIR to determine if process improvement initiatives should be implemented to reduce SSIs.
State health departments have advised that they publicly report facilities SIRs, which allows patients and families within the state to select high-quality facilities. State health departments also utilize SSI SIRs to target specific facilities with higher SIRs for additional support in initiating prevention activities.
Feedback from reporting facilities and state health departments on measure performance and implementation is received via email to the CDC NHSN Helpdesk. Additionally, during live training and educational sessions, an online survey is provided to attendees to provide feedback on the measure.
6.2.3 Consideration of Measure FeedbackFor any measure revision recommendations received, CDC NHSN will perform a literature review to determine if the recommendation is based on current guidelines and practices. If literature is found to support the revision, we then turn to subject matter experts to advise on further revisions and make updates to the measure specifications as appropriate.
Measure specifications are evaluated continuously, and at least annually. NHSN user questions provide a continuous flow of feedback from Infection Preventionists and facility leadership entities, prompting the NHSN team to provide precise terminology in the protocol, conduct literature searches, and seek expert opinion.
The 2022 rebaseline risk adjusted Complex 30-day COLO model considered the full set of risk factors gathered on the procedure form, along with some facility level factors. CDC carefully considered user feedback regarding the use of the extended set of factors, which includes trauma, emergency, and surgical wound class during the model development process. The final 2022 rebaseline COLO model found trauma, emergency, and surgical wound class to be positive predictors of infection following colon surgery.
6.2.4 Progress on ImprovementBetween 2015 and 2021, the COLO and HYST SSI SIRs showed a reduction from the 2015 baseline, with COLO SIRs demonstrating a more consistent decline over time compared to HYST SIRs. The consistent reduction of SIRs was interrupted by the COVID-19 pandemic as has been well documented in two peer-reviewed journal articles, providing detailed evidence and insights on the impact of COVID-19 on HAI data. There was a statistically significant difference between the 2015 COLO SIR (1.003) compared to the 2021 SIR (0.855) under the 2015 baseline (p < 0.0001), which reflects improved infection control across facilities. Additionally, a reduction in the number of facilities with COLO SIRs significantly above the national average and an increase in those performing better than predicted suggests a broader improvement in infection prevention practices.
However, some areas require further attention. The rate of improvement in HYST SIRs, while positive, is slower and inconsistent compared to COLO SIRs. For example, the percentage of facilities with significantly higher SIRs for HYST remained relatively stable between 2015 and 2021. This indicates a need for targeted interventions to help these underperforming facilities reduce infections.
See tables uploaded in section 7.1 Supplemental Attachment for data.
Weiner-Lastinger LM, Pattabiraman V, Konnor RY, et al. The impact of coronavirus disease 2019 (COVID-19) on healthcare-associated infections in 2020: A summary of data reported to the National Healthcare Safety Network. Infection Control & Hospital Epidemiology. 2022;43(1):12-25. doi:10.1017/ice.2021.362
6.2.5 Unexpected FindingsPatient medical records and other sources of patient data must be reviewed to determine if the patient meets the necessary criteria for an SSI. It is possible that reviewers may miss symptoms or fail to identify that patients meet criteria thereby underreporting SSI events. Data collectors might also intentionally underreport SSIs. Both actions would result in an SIR that is calculated to be lower than actual. Alternatively, patients may be identified as having an SSI when in fact they do not meet SSI criteria and thereby calculate an SIR that is higher than actual. Numbers of operative procedures may be collected inaccurately thereby impacting the SIR. In addition, it is possible SIRs may be miscalculated. The NHSN reporting tool includes business logic to minimize misclassification of SSI.
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Enter a comment below
Rationale for Exclusion of Colon Trauma Cases
OrganizationMemorial Hermann Texas Medical Center/McGovern Medical School UTHealth HoustonFollow-up on comment
Thank you for your comment on the SSI measure. The NHSN Patient Safety Component SSI Protocol is available to all acute care/critical access hospitals including those performing surgeries related to trauma, which are relatively low volume [approximately 3.2% with the 2022 rebaseline]. The 2022 baseline for the Complex 30-day model uses trauma, among other factors, as a predictor of infection following colon surgery (COLO). COLOs reported as Trauma = Yes are compared to those reported with Trauma = No to assess the likelihood/risk of infection. The results of the 2022 baseline model for COLO using the Complex 30-day SSI SIR model show that COLOs reported as Trauma = Yes is the risk group while those reported with Trauma = NO is the referent group. The factor trauma is an important risk indicator for SSIs in COLO surgical procedures, as it was found significant (p<0.001) in our multivariable model. Trauma patients therefore are given additional patient risk in calculating the SIR. The summation of patient risk is calculated in the denominator of the SIR (expected occurrence of SSIs). Therefore, a HIGHER patient risk will bring down the SIR ratio. While it may not be possible to control for the trauma itself, surveillance for these events is a critical part of developing effective strategies for prevention of SSIs. Details of the 2022 rebaseline Complex 30-day model for COLO and HYST are published in the new SIR Guide.
OrganizationCenters for Disease Control and Prevention (CDC) National Healthcare Safety Network (NHSN)753 30-Day Post-Operative Colon Surgery (COLO) and Abdominal Hys
The American Medical Association (AMA) believes that the current reliability of this measure is insufficient. Specifically, testing demonstrated that reliability is 0.511 for hysterectomies and 0.436 for colon surgeries. Applying a case minimum to ensure that minimum reliability achieves at least 0.7 is needed. There is also a need for the measure to exclude trauma related cases as there are different factors that must be considered from elective cases. We ask the committee to consider our concerns during their review.
OrganizationAmerican Medical AssociationFollow-up on Comment
Reliability
We thank the reviewer for the opportunity to comment on the above subject. As a clarification, on the Endorsement and Maintenance guidebook (page 45, Endorsement and Maintenance (E&M) Guidebook) when using a signal to noise methodology to estimate reliability, a value of 0.6 is used as a marker of acceptable reliability. Using our colon surgery model, we had a mean reliability of 0.687 with the value of 0.6 marking the 30th percentile, meaning 70% of our hospitals in the frame are above the suggested threshold. The numbers are similar for abdominal hysterectomy with a mean reliability of 0.661 and the 30th percentile being approximately 0.6 (0.591 specifically). For all hospitals in the data set to meet the reliability threshold of 0.6, a much higher surgical procedure or case volume for each facility during a single year would be required. There are two possible strategies that could be employed to meet this more stringent requirement, and each have substantial consequences. First, we could require data to be pooled over 2 or more years of data. This would allow surgical volume to increase for all participating facilities; however, it impacts the ability to measure temporal change over time as data would be smoothed and is inconsistent with our annual measures. The second strategy would require setting a higher minimum case volume for facilities to report before they received a calculated SIR. This would greatly reduce the number of facilities to be included in this measure and allow those excluded to receive no performance assessment. Furthermore, to force sufficient volume will essentially require facilities to have more SSI events. It is important to note that the CDC already requires a minimum of 1 Predicted SSI event for a hospital to be evaluated. To achieve the value of 0.6 for every hospital would eliminate an additional 30% of facilities and greatly impact performance measurement.
Trauma Cases
The NHSN Patient Safety Component SSI Protocol is available to all acute care/critical access hospitals including those performing surgeries where Trauma=Yes, and this comprises approximately 3.2% of all procedure data used for the 2022 rebaseline. The 2022 baseline for the Complex 30-day model uses trauma status, among other factors, as a predictor of SSI following colon surgery (COLO). Colon procedure reported with Trauma = Yes are compared to those reported with Trauma = No to assess differences in the risk of SSI both as an individual factor and in the presence of other significant risk factors. The results of the 2022 baseline model for COLO using the Complex 30-day SSI SIR model show that COLOs reported as Trauma = Yes is the risk group while those reported with Trauma = No is the referent group. The factor Trauma = Yes is an important risk indicator for SSIs in COLO surgical procedures, as it was found significant (p<0.001) in our multivariable model. Trauma patients therefore are given additional patient risk in calculating the SIR. The summation of patient risk is calculated in the denominator of the SIR (expected occurrence of SSIs). Therefore, a HIGHER patient risk will bring down the SIR ratio. Given that trauma status is an integral part of SSI surveillance following all surgical procedures in NHSN and the fact that trauma status was found to be a significant factor to predict SSI it would be entirely unacceptable to exclude trauma patients from this and any SSI-related NHSN measure. Furthermore, it is critical for hospitals performing colon or other surgical procedures to measure SSI risk among trauma cases as this increases accountability, accounts for trauma status in performance measurement, and raises awareness for prevention practices that can ultimately lead to decreased SSI incidence. Details of the 2022 rebaseline Complex 30-day model for COLO and HYST are published in the new SIR Guide.
OrganizationCenters for Disease Control and Prevention (CDC) National Healthcare Safety Network (NHSN)
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Dear Vizient team,
I am writing to bring attention to an important issue that significantly impacts Level 1 trauma centers, including Memorial Hermann Hospital in the Texas Medical Center. The current Surgical Site Infection (SSI) surveillance structure poses substantial challenges for trauma centers that manage a high volume of complex cases. Despite rigorous adherence to preventative colon bundles and best practices, the nature of trauma cases—often involving severe injuries and pre-existing contamination—renders them inherently high-risk for SSIs compared to elective or non-trauma colon surgeries.
Currently, the inclusion of trauma-related colon surgeries within SSI surveillance metrics results in inflated standardized infection ratios (SIRs) when compared to facilities that do not manage such cases. This disparity creates an uneven playing field. Analysis of our data from January 2023 to September 2024 reveals that of the 55 colon SSIs reported, 40% were related to trauma cases involving bowel perforation at the time of the index procedure. Despite the inherent risk, only 18% of these trauma-related SSIs could be coded as "present at the time of surgery" (PATOS), highlighting a significant gap in how these cases are represented within the current framework.
This inconsistency impacts the ability to accurately measure and compare surgical outcomes across diverse healthcare facilities. Grouping trauma cases with non-trauma colon surgeries disproportionately inflates SIRs for trauma centers and can misrepresent their performance. This results in unwarranted penalties and shifts focus away from targeted, data-driven improvement efforts. Our analyses indicate that excluding trauma-related colon SSIs would reduce our SIR by 75%, underscoring the profound effect these cases have on our metrics.
To ensure fair and effective surveillance, we recommend a revision in reporting practices to exclude trauma-related colon surgeries or implementing a separate category for these high-risk cases. Such a revision would allow institutions like ours to better evaluate performance, prioritize relevant prevention strategies, and drive meaningful improvements in patient care.
I appreciate your attention to this matter and your commitment to supporting healthcare institutions in delivering safe, effective care.
Thank you for considering this important issue.
Sincerely,
Luis Ostrosky, MD, FACP, FIDSA, FSHEA, FECMM, CMQ
Professor of Medicine and Memorial Hermann Endowed Chair
Vice Chairman for Healthcare Quality, Department of Internal Medicine
Chief, Division of Infectious Diseases
McGovern Medical School
Medical Director of Epidemiology - Memorial Hermann Texas Medical Center
Misti Ellsworth, DO
Associate Professor, Pediatrics
Infection Prevention - Children’s Memorial Hermann Hospital
Division of Pediatric Infectious Diseases
McGovern Medical School at UTHealth Houston
Bela Patel, MD, FCCP, FCCM, ATSF
Professor, Graham Distinguished University Chair
Vice Dean, Healthcare Quality
Director, Division of Critical Care Medicine
McGovern Medical School at UTHealth Houston
Chief Medical Officer – Memorial Hermann
Robert Yetman, MD
Professor of Pediatrics
Vice-Chair, Clinical Operations
McGovern Medical School at UTHealth Houston
Chief Medical Officer – Children’s Memorial Hermann Hospital