Impact of department volume on surgical site infections following arthroscopy, knee replacement or hip replacement

Objective: To examine the association between surgical department volume and the risk of surgical site infections (SSI) after orthopaedic procedures. Background: A minimum volume regulation of at least 50 knee replacements per year was implemented in 2006 in German surgical departments. Methods: SSI rates were obtained from Krankenhaus-Infektions-Surveillance-System, the German national nosocomial infections surveillance system (January 2003-June 2008). The authors analysed the data by linear regression models. The adjusted ORs were estimated based on general estimating equation models to assess the independent effect of department volume (low, ie, <= 50, medium, ie, >50 and <= 100, and high, ie, >100 procedures annually). Results: A total of 206 surgical departments performed 14 339 arthroscopies, 63 045 knee replacements and 43 180 hip replacements during the 5.5-year study period. SSI rates were significantly higher in departments with a procedure volume of <= 50 arthroscopies and knee replacements. A higher threshold of 100 procedures per year did lead to a significant decrease in SSI rates for all three procedures in the univariate analysis. The multivariate analysis showed that the risk of SSI in low volume departments was sevenfold higher for arthroscopies and twofold higher for knee replacement than in medium volume departments. SSI risk after hip replacement was significantly lower in high volume centres. Conclusion: The authors' findings offer some support for recommendations to concentrate arthroscopy and knee replacement in surgical departments with more than 50 procedures and hip replacement in departments with more than 100 procedures per year in order to reduce SSI.