Surgical site infections are the second most common type of healthcare associated infection (HAI) in U.S. hospitals (290,000 per year) and account for the greatest additional healthcare cost, between $3.5 and 10 billion per year. California hospitals are required to report deep incisional and organ/space SSIs and all surgeries in specified surgical procedure categories. Reporting SSI data to CDPH for 2 surgical procedure categories via the Centers for Disease Control and Prevention (CDC) National Healthcare Safety Network (NHSN) was initiated on April 1, 2011. The required surgical procedure categories were expanded to 29 starting on June 1, 2011. In January 2012, a release of SSI data covering April through June, 2011, for 4 surgical procedure categories accompanied the first interactive HAI map on this website. The current SSI data release is the first annual release of data submitted via NHSN which covers surgical procedures performed since April 1 or June 1, 2011 and any subsequent infections reported to CDPH by April 9, 2012.
CDPH is mandated to report SSI data using risk adjustments according to NHSN protocols. For SSI, NHSN developed Standardized Infection Ratios (SIR), a comparison of the observed number of infections to the predicted number based on the national average, for each surgical procedure category. The SIR is risk adjusted by using information reported by hospitals on each surgery performed, including information on patient health, for 24 of the 29 reported surgical procedure categories.
Risk adjusted SIRs allow comparison among hospitals for a surgical procedure category. However, it is important to keep in mind that the NHSN risk adjustment method may not take into account all of the differences in risk of infection for patients in those hospitals. Further, many of these differences are not large and may change with a full year of data.
To view the Key Findings and Public Health Actions for this data release, see 
Key Findings
What’s in Key Findings? This is a summary of the key findings from this data release including introduction, important results and suggested public health actions based on the results displayed in the 35 tables.
TABLES 1 to 12 (3MB) for 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 and gastric surgery.
TABLES 13 to 24 (2MB) for hip prosthesis, abdominal hysterectomy, knee prosthesis, kidney transplant, laminectomy, liver transplant, rectal surgery, refusion of spine, small bowel surgery, thoracic surgery, vaginal hysterectomy, and abdominal surgery.
What’s in Tables 1 to 24? These tables display each hospital that submitted data on the procedure category with the numbers of procedures and infections, the risk adjusted SIR, and its 95 percent confidence interval with a comparison based on the confidence interval indicating an infection count that was lower, no different or higher than predicted.
What’s in Tables 25 to 29? The information displayed is limited to the reported procedure and infection counts as there is no risk adjustment for comparisons.
What’s in Tables 30 to 35? NHSN does not currently provide an appropriately risk adjusted SIR for LTACs and rehabilitation hospitals, which perform few surgeries. Their data are listed in Tables 30 to 32. Table 33 lists hospitals with no surgeries, 34 lists non reporters and 35 lists late reporters.
What’s in Technical Notes? Information on the data sources, definitions, quality assurance and control, data presentation and statistical analysis and descriptions of the laws requiring reporting, the variables that go into risk adjusting and the limitations of these processes are described here.
For more information on SSI, see SSI Information