Age as a risk factor for surgical site infections: German surveillance data on total hip replacement and total knee replacement procedures 2009 to 2018

Background: Older age is frequently cited as a risk factor for healthcare-associated infections in general, and surgical site infections (SSIs) specifically. Aim: We aimed to investigate the correlation between age and SSI occurrence. Methods: Data on total hip replace-ment (THR) and total knee replacement (TKR) surger-ies and resulting SSIs documented in the German national surveillance network from a 10-year period from 2009 to 2018 were selected for analysis. SSI rates and adjusted odds ratios (AOR) were calculated and a multivariable analysis to determine risk factors for SSI occurrence was conducted. Results: A total of 418,312 THR procedures resulting in 3,231 SSIs, and 286,074 TKR procedures with 1,288 SSIs were included in the analyses. For THR, SSI rates were higher in older age groups when compared with the reference age group of 61-65 years. A significantly higher risk was observed in the 76-80 years age group (AOR: 1.21, 95% CI: 1.05-1.4). An age of <= 50 years was associated with a significantly lower SSI risk (AOR: 0.64, 95% CI: 0.52-0.8). For TKR, a similar correlation was observed, with the exception of the youngest age group (<= 52 years), which was shown to have an SSI risk equal to that of the knee prosthesis reference age group (78- 82 years). Conclusion: A strong correlation between increasing age and SSI occurrence was observed for both procedure types. The results of our analyses pro-vide a basis to consider future targeted SSI prevention measures for different age groups.