Background
We sought to identify factors associated with condom-use during anal intercourse among self-identified HIV-negative gay, bisexual, and other men who have sex with men (GBM) in Vancouver, Canada following “treatment as prevention” (TasP) scale-up in 2010.
Methods
Sexually-active GBM were recruited using respondent-driven sampling (RDS) from 2012–2014. We analyzed participants’ most recent sexual encounter with up to their last five sexual partners within the past six months. In addition to individual- and event-level explanatory factors, we assessed potential associations with TasP awareness, TasP-related prevention practice (viral load sorting), and TasP-related attitudes (HIV treatment optimism). Accounting for clustering at the RDS chain- and participant-level, factors associated with event-level condom-use versus non-use were determined using a multivariable generalised linear mixed model built using backward selection and AIC minimization.
Results
Of 513 participants, 436 GBM (85%) reported a total of 1196 anal sex events with 56% condom-use. The proportion of condom-protected sexual events decreased monthly over the study period (OR=0.95 per month, 95%CI:0.92–0.98). TasP practices and attitudes were significantly associated with lower odds of condom-use at the univariate level, but were no longer significant at multivariate level. In the multivariable model, event-level partner methamphetamine use (aOR=0.18, 95%CI:0.06–0.58), frequency of recent anal intercourse with that partner (aOR=0.97 per act, 95%CI:0.95–0.98) and time since first sex with that partner (aOR=0.97 per 6 months, 95%CI:0.95–0.99) were associated with lower odds of condom-use while event-level participant alcohol use (aOR=1.41, 95%CI:1.01–1.98) and no planned future sex with that partner (aOR=1.56, 95%CI:1.08–2.27) were associated with greater odds of condom-use. Event-level receptive-only (aOR=2.10, 95%CI:1.38–3.20) or insertive-only (aOR=2.53, 95%CI:1.64–3.90) sexual positions were associated with greater odds of condom-use compared with reporting both positions.
Conclusions
TasP-related factors were not the most salient predictors of GBM’s condom-use. Health promotion must consider associations between condomless anal sex and substance use and relational factors.