2137. Risk Factors for Surgical Site Infection After Joint Replacement Surgery: Data from the Swiss National Surveillance System

Surgical site infections (SSIs) are infrequently observed after joint replacement surgery but have devastating consequences. Since 2009, a large network of Swiss hospitals prospectively collects data for the national SSI surveillance system. The aim of this observational study was to identify risk factors for SSI among patients undergoing elective hip and knee arthroplastic procedures. Risk factors for SSI were identified using both univariate and multivariate logistic regression, appropriately adjusted for hospital level correlation effects among the 173 participating hospitals. We included procedural characteristics and risk categories in our analysis. We analyzed a total of 113,495 joint replacement procedures that occurred between June 2009 and September 2017. A 12-month follow-up was completed in 92.5% of cases. Overall, the cumulative SSI rate was 1.3% (n = 1,458), varying from 1.1% for knee to 1.4% for hip arthroplasty. Repeat surgery (unplanned or planned), higher ASA level, and longer than anticipated procedural time were associated with a significantly increased risk of infection (figure). Ninety-one percent of all SSIs (1,328) were detected in the post-discharge follow-up. Risk factors for pre-discharge SSIs were very similar to those mentioned above. Fifty-six percent of SSIs were observed within 30 days, 27% from 30 to 90 days after incision and 17% were observed >90 days after the procedure. The SSI incidence after joint replacement surgery was low, with no significant difference between knee and hip surgery. Almost all SSIs occurred post-discharge, with risk factors being broadly the same, independent of when the infection occurred. Limiting the follow-up period to 90 days would have resulted in missing 17% of SSIs, which argues in favor of extended follow-up. Risk factors for SSI following joint replacement surgery. A. Widmer, Swiss national science foundation: Grant Investigator, Grant recipient.