Colyer, Sean P.Moore, David M.Cui, ZishanZhu, JuliaArmstrong, HeatherTaylor, MatthewEdward, JoshuaHoward, TerryDickie, ChadOlarewaju, GbolahanMontaner, Julio S.G.Hogg, Robert S.Roth, EricLachowsky, Nathan2024-03-202024-03-202020Colyer, S., Moore, D., Cui, Z., Zhu, J., Armstrong, H. L., Taylor, M., Edward, J., Howard, T. L., Dickie, C., Olarewaju, G., Montaner, J. S. G., Hogg, R. S., Roth, E. A., & Lachowsky, N. J. (2020). Crystal methamphetamine use and initiation among gay, bisexual, and other men who have sex with men living with HIV in a treatment as prevention environment. Substance Use & Misuse, 55(14), 2428– 2437. https://doi.org/10.1080/10826084.2020.1833925https://doi.org/10.1080/10826084.2020.1833925https://hdl.handle.net/1828/16238Background: Risk compensation in an HIV Treatment as Prevention (TasP) environment may increase high-risk sexual and substance use behaviours among people living with HIV. Objective: To examine recent crystal methamphetamine use/initiation in a longitudinal cohort of gay, bisexual, and other men who have sex with men (GBMSM) living with HIV in Metro Vancouver, Canada. Methods: Eligible participants were GBMSM aged >15 years who reported sex with another man in the past six months. Participants were recruited using respondent-driven sampling and self-completed a computer questionnaire every six months. We used multi-level generalized mixed-effect models to evaluate trends in recent crystal methamphetamine use (past six months), multivariable logistic regression to identify covariates of recent crystal methamphetamine use, and multivariable survival analysis to identify predictors of crystal methamphetamine initiation. Results: Of 207 GBMSM living with HIV at enrollment, 44.3% reported recent crystal methamphetamine use; this remained stable over the study period (2012-2016). HIV treatment optimism was not associated with crystal methamphetamine use/initiation. Crystal methamphetamine use was positively associated with depressive symptomology, sexual escape motivation, transactional sex, number of anal sex partners, condomless anal sex with seroconcordant partners, STIs, and other substance use. Recent crystal methamphetamine use was negatively associated with viral load sorting. Crystal methamphetamine initiation was predicted by escape motivation, transactional sex, and group sex participation. Conclusion: Results suggest that crystal methamphetamine use among GBMSM living with HIV is prevalent and increased crystal methamphetamine use/initiation is not a consequence of TasP public policyenAttribution-NonCommercial 4.0 Internationalmethamphetaminemen who have sex with men (MSM)HIV/AIDSprospective cohort studystimulanttreatment as preventionPostprint