Trends in hepatitis C virus seroprevalence and associated risk factors among men who have sex with men in Montreal: results from three cross-sectional studies (2005, 2009, 2018)

Introduction: To eliminate the hepatitis C virus (HCV) by 2030, Canada must adopt a micro-elimination approach targeting priority populations, including gay, bisexual, and other men who have sex with men (MSM). HCV prevalence and risk factors among MSM populations are context-dependent, and accurately describing these indicators at the local level is essential if we want to design appropriate, targeted prevention and treatment interventions. We aimed first to estimate and investigate temporal trends in HCV seroprevalence between 2005-2018 among Montreal MSM, and then to identify the socio-economic, behavioural, and biological factors associated with HCV exposure among this population. Methods: We used data from three bio-behavioural cross-sectional surveys conducted among Montreal MSM in 2005 (n=1,795), 2009 (n=1,258), and 2018 (n=1,086). To ensure comparability of seroprevalence estimates across time, we standardized the 2005 and 2009 time-location samples to the 2018 respondent-driven sample. Time trends overall and stratified by HIV status, history of injection drug use (IDU), and age were examined. Modified Poisson regression analyses with generalized estimating equations were used to identify factors associated with HCV seropositivity pooling all surveys. We used multiple imputation by chained equations for all missing values. Results: Standardized HCV seroprevalence among all MSM remained stable from 7% (95% confidence interval (CI): 3-10%) in 2005, to 8% (95%CI: 1-9%) in 2009, and 8% (95%CI: 4-11%) in 2018. This apparent stability hides diverging temporal trends in seroprevalence between age groups, with a decrease among MSM <30 years old, and an increase among MSM aged ≥45 years. History of IDU was the strongest predictor for HCV seropositivity (adjusted prevalence ratio: 8.0; 95%CI: 5.5-11.5), and no association was found between HCV seroprevalence and the sexual risk factors studied (condomless anal sex with men of serodiscordant/unknown HIV status, number of sexual partners, and group sex), nor with biological markers of syphilis. Conclusions: HCV seroprevalence remained stable among Montreal MSM between 2005-2018. Unlike other settings where HCV infection was strongly associated with sexual risk factors among MSM subgroups, IDU was the preeminent risk factor for HCV seropositivity. Understanding the intersection of IDU contexts, practices, and populations is essential to prevent HCV transmission among MSM.