Gender-related risk factors for surgical site infections. Results from 10 years of surveillance in Germany.

Background: Surgical site infections (SSI) are among the most frequently occurring healthcare-associated infections worldwide. Various analyses to determine risk factors have been conducted in the past, generally attributing a higher SSI-risk to male patients. However, when focusing on specific procedures, this is not always true. Our objective was to identify for which procedures male or female sex represents an independent risk factor for SSI and which parameters may explain these differences. Methods: We used the database of surgical procedures from the German national nosocomial infection surveillance system. We included procedures conducted between 2008 and 2017. We excluded procedures solely executed for one sex (e.g. mastectomy) and procedures with 20,000 or fewer operations. The observed outcome was the occurrence of SSI. All models were adjusted for confounders, which were eliminated with backward selection. The following factors were included in the analysis: age, ASA score, wound contamination class, duration of surgery, and season. All models contained the investigated factor sex. Results: Sixteen procedure types with 1,266,782 individual procedures and 18,824 SSI were included. Overall, the incidence rate ratio and the adjusted odds ratio for SSI were significantly higher for male patients. The included individual procedures were grouped into five surgical categories. For orthopedics and traumatology as well as abdominal surgery, SSI-rates were significantly higher for male patients. For heart and vascular surgery, SSI-rates were significantly higher for female patients. Other included surgical categories and individual procedures yielded diverse results. Similar results were found when solely analyzing deep and organ-space SSI. Multivariable analysis for attributable gender-related risk factors revealed differences with regard to underlying risk factors. Conclusions: SSI-rates differ by sex for certain procedures. When examining underlying risk factors, differences between male and female patients can be demonstrated. Our analysis considered a limited number of parameters, which were not sufficient to fully explain the observed differences. Further studies are required to obtain a more comprehensive understanding of the topic and to include gender-specific aspects into future SSI-prevention strategies.