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Surgical Site Infections (SSIs) for Operative Procedures in Healthcare

This dataset shows the surgical site infections (SSIs) reported by a hospital to the Center for Disease Control and Prevention National Healthcare Safety Network (NHSN). The data is provided in two tables 1) SSIs for the 5 Operative procedures and 2) SSIs for 24 Operative procedures. All procedure and infection data for surgical procedures performed were downloaded from NHSN for each years data release. The hospital submitted procedure counts and infection counts are displayed.

5 Operative Procedures Methods: SSIs for the 5 Operative procedures without risk adjusted comparisons (Heart transplant, Kidney surgery, Pacemaker Surgery, Spleen surgery, Ovarian surgery)

24 Operative Procedures Methods: The 24 Operative procedures with NHSN Standardized Infections Ratios (SIR) are: Abdominal Aortic Aneurysm Repair, Appendix surgery, Bile Duct, Liver or Pancreatic surgery, Cardiac surgery, Coronary artery bypass graft with both chest and donor site incisions, Coronary artery bypass graft with chest incision only, Gallbladder surgery, Colon surgery, Cesarean section, Spinal Fusion, Open reduction of fracture, Gastric surgery, Hip prosthesis, Abdominal hysterectomy, Knee prosthesis, Kidney transplant, Laminectomy, Liver transplant, Rectal surgery, Refusion of spine, Small bowel surgery, Thoracic surgery, Vaginal hysterectomy, Exploratory laparotomy.

The SIR is calculated by dividing the number of observed infections by the number of predicted infections. The number of predicted infections is calculated using SSI probabilities estimated from multivariate logistic regression models constructed from NHSN data during a baseline time period 2006 through 2008, which represents a reference population’s SSI experience. The SIR calculated only if the number of observed is at least one, to enforce a minimum precision criterion and these SIRs are based on the date of procedure, not the date of event.

The SIR used for this table is risk adjusted SIR that considers only complex SSI identified during hospital Admission or Readmission to the same hospital following inpatient surgeries and hereafter referred to as SIR. A SIR was calculated by CDPH, if the predicted number of infections was less than 1 and greater than or equal 0.2. This SIR and its comparison are not as accurate as SIRs based on a larger number of predicted infections. For a detailed explanation, please see the Technical Notes. The hospital submitted procedure counts and infection counts are displayed along with an SIR and, the 95 percent confidence interval for the SIR and the statistical comparison as follow:

• No difference - no difference in number of observed and predicted infections

• Higher - more infections than predicted, or

• Lower - fewer infections than predicted.

To link the CDPH facility IDs with those from other Departments, like OSHPD, please reference the "Licensed Facility Cross-Walk" Open Data table at

Health and Safety Code (HSC) Section 1288.55 requires California hospitals to report hospital-associated infection (HAI) data to NHSN, and requires CDPH to follow the NHSN risk adjustment process for the interpretation and publication of HAI data. These reports are based on the 29 mandated NHSN-defined SP categories submitted via NHSN and CDPH accepted only hospital SSI data for SP categories that are in the hospital’s NHSN monthly plan. For more information on data collection processes and methods, please see the "SSI Technical Notes" of the healthcare-associated infections (HAI) report on:

Release Date
State of California
Contact Name
CHHS Open Data
Contact Email
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POD Theme
Diseases and Conditions
Facilities and Services
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