An Event-Level Analysis of the Interpersonal Factors Associated With Condomless Anal Sex Among Gay, Bisexual, and Other Men Who Have Sex With Men (MSM) With Online-Met Partners.

The interpersonal determinants of condomless anal sex (CAS) within online-initiated sexual relationships remain poorly understood. Therefore, respondent-driven sampling was used to recruit a prospective cohort of sexually active gay, bisexual, and other men who have sex with men (MSM), aged ≥ 16 years in Vancouver, Canada. Follow-up occurred every 6 months, up to seven visits; at each visit participants reported their last sexual encounter with their five most recent partners. Stratified by self-reported HIV status, individual-level, interpersonal, and situational covariates of event-level CAS with partners met online were modeled using generalized estimating equations (GEE). CAS was reported during 32.4% (n = 1,015/3,133) of HIV-negative/unknown men's events, and 62.1% (n = 576/928) of HIV-positive men's events. Social (i.e., collective identity, altruism, network size social embeddedness) and situational (i.e., number of encounters, location, comparative age, seroconcordance, substance use) factors were identified as important correlates of CAS. Implications include the need for HIV prevention addressing social contexts associated with CAS.