Impact of participation in a surgical site infection surveillance network: results from a large international cohort study

INTRODUCTION Surveillance of surgical site infections (SSI) is a core component of effective infection control practices, though its impact has not been quantified on a large scale. This study aims to determine the time-trend of SSI rates in surveillance networks. METHODS SSI surveillance networks provided procedure-specific data on numbers of SSIs and operations, stratified by hospitals' year of participation in the surveillance, to capture length of participation as an exposure. Pooled and procedure-specific random-effects Poisson regression was performed to obtain yearly rate ratios (RR) with 95% confidence intervals (CI), and including surveillance network as random intercept. RESULTS Of 36 invited networks, 17 networks from 15 high-income countries across Europe, Asia and Australasia participated in the study. Aggregated data on 17 surgical procedures (cardio-vascular, digestive, gynaecologic-obstetrical, neurosurgical, and orthopaedic) were collected, resulting in data concerning 5,831,737 operations and 113,166 SSIs. There was a significant decrease in overall SSI rates over surveillance time resulting in a 35% reduction at the ninth (final) included year of surveillance (RR 0.65; 95% CI 0.63-0.67). There were large variations across procedure-specific trends, but strong consistent decreases were observed for colorectal surgery, herniorrhaphy, Caesarean section, hip prosthesis, and knee prosthesis. CONCLUSION In this large, international cohort study, pooled SSI rates showed a were associated with a stable and sustainable decrease after joining a SSI surveillance network; a causal relationship is possible, although unproven. There was heterogeneity in procedure-specific trends. These findings support the pivotal role of surveillance in reducing infection rates and call for widespread implementation of hospital-based SSI surveillance in high-income countries.