Sexually transmitted infection test positivity and associated factors in individuals tested at anonymous clinics in North Rhine-Westphalia state, Germany, 2021

Background Sexually transmitted infections (STIs) are increasing globally. To improve understanding of the epidemiology of STIs in key populations, we analysed sentinel surveillance data on STI test positivity among individuals tested using subsidised tests at anonymous walk-in clinics in North Rhine-Westphalia (NRW), Germany. Methods This was a cross-sectional analysis of sentinel surveillance data from all 53 local health authority anonymous walk-in clinics in NRW during 2021. Test positivity for HIV, syphilis, chlamydia, and gonorrhoea was analysed by key population group. We used univariable and multivariable logistic regression to examine factors associated with each infection. Results Among 11,560 consultations, overall STI test positivity was 6.6%. Chlamydia was the most frequently detected (6.4%), followed by gonorrhoea (2.7%), syphilis (0.9%), and HIV (0.6%). We observed disparities in STI test positivity among key population groups. Men-who-have-sex-with-men (MSM) (aOR 1.93; 95%CI 1.38–2.68), sex work (aOR 2.77; 95%CI 1.9–3.96), and having an STI-positive partner (aOR 1.71; 95%CI 1.30–2.22) were associated with increased STI risk. Coinfections were rare (0.4%) and predominantly occurred among MSM. Conclusions Anonymous walk-in clinics reach diverse high-risk populations with substantial STI burdens. Findings support targeted prevention strategies for key populations and highlight the importance of comprehensive STI screening in anonymous settings for surveillance and case detection.