Characteristics of Men who have Sex with Men and Women Attendees to Sexual Health Services in Barcelona and Madrid (2018–2021)

Abstract Background Men who have sex with men and women (MSMW) represent a key population in HIV prevention and sexual health. Despite being described as a “bridge population,” they are often categorized as bisexual or grouped within broader MSM or LGBT+ labels. Methods This cross-sectional study analysed data from 3,548 MSM recruited between 2018 and 2021 at two sexual health clinics and two community-based services in Barcelona and Madrid. Participants were classified as frequent or occasional MSMW based on lifetime penetrative intercourse with women and compared to exclusively MSM. Poisson regression models with robust variance were explored, adjusting or stratifying by living openly their sexuality. Additional models examined disclosure as a dependent variable among MSMW and those recently sexually active with women. Results Overall, 7.2% were frequent MSMW and 30.3% occasional. Frequent MSMW were older (median age: 38 vs. 33), less open about their sexuality, reporting fewer risk practices and lower engagement with sexual health services. Occasional MSMW were more often linked to substance use, regardless disclosure. Non-disclosed MSMW were less likely to be vaccinated for hepatitis A/B and more likely to report paying for sex when recently active with women. Conclusion One in three MSM in this study were lifetime MSMW—a heterogeneous group posing challenges for sexual health services. Recognizing behavioural diversity and disclosure dynamics is essential for tailored interventions and improved access to care. Policy implications This recognition has informed changes in regional epidemiological surveys to improve sexual practices surveillance, avoiding misalignment with identity categories.