Gaps in HIV and Hepatitis C Testing Among 3486 HIV-Negative Men Who have Sex with Men in Spain in the Era of Highly Effective Antiviral Therapies.

High uptake of HIV and hepatitis C (HCV) testing in Gay, bisexual, and other men who have sex with men (GBMSM) is needed to interrupt transmission. The objective was to identify subgroups with increased probability of lack of testing among HIV-negative GBMSM in Spain. Cross-sectional study including 3486 HIV-negative GBMSM attending prevention facilities in Madrid and Barcelona, 2018-2020. Data came from self-administered online sociodemographic, health, and risk behaviors questionnaires. Outcomes were lack of HCV (lifetime) and HIV (lifetime, last year) testing. Crude and adjusted prevalences and prevalence ratios were assessed for each outcome using negative binomial regression models. Lifetime lack of HIV and HCV testing prevalence was 6.3% and 35.8%, respectively, while lack of HIV testing in the last year was 22.4%. Prevalences were also substantial in GBMSM with high-risk behaviors. After sociodemographic adjustment, the highest probability of lack of HCV testing (lifetime) and HIV (last year) was among GBMSM with insufficient viral hepatitis knowledge, no history of STI, or HCV (or HIV) testing, aged < 25, non-outness about sex life with men, and less high-risk behaviors. Lack of HCV (lifetime) and HIV testing (last year) among HIV-negative GBMSM in Spain is still high, despite high-risk behaviors.