The Association of Climatic Factors with Rates of Surgical Site Infections: 17 Years' Data From Hospital Infection Surveillance.

Background: Surgical site infections (SSI) are among the most common healthcare- associated infections. The aim of our explorative study was to determine how selected climatic factors are associated with SSI rates.

Methods: SSI rates were calculated for operative procedures included in the surgi- cal site infection surveillance component (OP-KISS) of the German Nosocomial Infection Surveillance System (Krankenhaus-Infektions-Surveillance-System, KISS) during the years from 2000 to 2016. The surgeries were associated with department-related and patient-related data. Data of the German Meteorological Service (Deutscher Wetterdienst, DWD), including outdoor temperature and rainfall, were used to analyze the association between climatic factors and rates of SSI. Analyses focused on temperature which showed strong correlations with other climatic parameters. A descriptive analysis was performed, using the chi-squared test. Adjusted odds ratios (AORs) were calculated for SSI rates in relation to tem- perature, using a multivariable logistic regression model.

Results: For the altogether 2 004 793 included operative procedures, 32 118 SSIs were documented. Temperatures ≥ 20 °C were associated with a significantly higher occurrence of SSI compared to temperatures <5 °C (AOR: 1.13; 95% confi- dence intervals [1.06; 1.20]). This increase was found for gram-positive pathogens (AOR: 1.13 [1.03; 1.23]) and, even more pronounced, for gram-negative pathogens (AOR: 1.20 [1.07; 1.35]). The association was strongest for superficial SSI caused by gram-negative pathogens (AOR: 1.38 [1.16; 1.64]).

Conclusion: An association between climatic factors and SSI rates was demon- strated. The predicted rise in global temperatures by up to 4 °C by the end of this century compared to preindustrial levels may increase the likelihood of SSI and should be taken into consideration in future preventive strategies.