Pre-exposure prophylaxis and bacterial sexually transmitted infections (STIs) among gay and bisexual men.

OBJECTIVES: While pre-exposure prophylaxis (PrEP) prevents HIV acquisition among gay, bisexual and other men who have sex with men (GBM), PrEP-using GBM may be more likely to engage in sexual behaviours associated with bacterial STIs. We examined associations between PrEP use, condomless anal sex (CAS), number of anal sex partners, oral sex and bacterial STI diagnoses among GBM living in Canada's three largest cities. METHODS: Among HIV-negative/unknown-status GBM in the baseline of the Engage cohort study, we fit a structural equation model of the associations between any PrEP use, sexual behaviours and bacterial STI diagnosis. We estimated direct and indirect paths between PrEP use and STI via CAS, number of anal sex partners and oral sex. RESULTS: The sample included 2007 HIV-negative/unknown status GBM in Montreal, Toronto and Vancouver. There was a significant direct association between PrEP use and current STI diagnosis (ß=0.181; 95% CI: 0.112 to 0.247; p<0.001), CAS (ß=0.275; 95% CI: 0.189 to 0.361; p<0.001) and number of anal sex partners (ß=0.193; 95% CI: 0.161 to 0.225; p<0.001). In the mediated model, the direct association between PrEP use and STIs was non-significant. However, the indirect paths from PrEP to CAS to STIs (ß=0.064; 95% CI: 0.025 to 0.120; p=0.008), and from PrEP to greater number of anal sex partners to CAS to STIs were significant (ß=0.059; 95% CI: 0.024 to 0.108; p=0.007). CONCLUSIONS: Our study adds to the growing awareness that PrEP use among GBM may be associated with bacterial STIs because PrEP users have more anal sex partners and are more likely to engage in CAS. The results underscore the importance of providing effective STI counselling and regular testing to PrEP users, adapting PrEP care and related STI testing to individual needs, and the need for effective prevention strategies for bacterial STIs.

Longitudinal uptake of the human papillomavirus vaccine among gay, bisexual and other men who have sex with men in British Columbia, Canada 2012-2019.

OBJECTIVES: In 2015, a publicly funded human papillomavirus (HPV) vaccination programme was implemented for gay, bisexual and other men who have sex with men (gbMSM) up to age 26 years in British Columbia, Canada. We assessed trends and correlates of HPV vaccine uptake from 2012 to 2019 in a cohort of gbMSM in Vancouver. METHODS: We recruited sexually active gbMSM aged ≥16 years using respondent-driven sampling from February 2012 to February 2015 and followed them until July 2019. We evaluated self-reported HPV vaccine trends using mixed-effects logistic regression and identified factors associated with uptake using multivariable mixed-effects Poisson regression. RESULTS: A total of 719 participants were recruited and completed the baseline visit, of whom 549 were unvaccinated with at least one follow-up visit. The median age was 33 years and 23% were living with HIV. HPV vaccination increased from 4% in 2012 to 28% in 2019 (p<0.001) among gbMSM >26 years, and from 9% in 2012 to 20% in 2017 (p<0.001) among gbMSM ≤26 years. Vaccination uptake increased after September 2015, following vaccination policy expansion (adjusted rate ratio (aRR)=1.82, 95% CI 1.06 to 3.12). In multivariable models, increased vaccination was associated with age ≤26 years vs ≥45 years (aRR=3.90; 95% CI 1.75 to 8.70), age 27-44 vs ≥45 years (aRR=2.86; 95% CI 1.46 to 5.62), involvement in gay community sports teams (aRR=2.31; 95% CI 1.15 to 4.64) and other groups (aRR=1.71; 95% CI 1.04 to 2.79), awareness of HIV-postexposure prophylaxis (aRR=5.50; 95% CI 1.31 to 23.09), recent sexually transmitted infection testing (aRR=2.72; 95% CI 1.60 to 4.60) and recent sex-work (aRR=2.59; 95% CI 1.08 to 6.19). CONCLUSIONS: Although we observed increases in HPV vaccination uptake from 2012, by 2019 HPV vaccination still remained below 30% among gbMSM in Vancouver, BC. Additional interventions are needed to increase vaccine uptake.

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

OBJECTIVES: To eliminate the hepatitis C virus (HCV) by 2030, Canada must adopt a microelimination approach targeting priority populations, including gay, bisexual and other men who have sex with men (MSM). Accurately describing HCV prevalence and risk factors locally is essential to design appropriate prevention and treatment interventions. We aimed to estimate temporal trends in HCV seroprevalence between 2005 and 2018 among Montréal MSM, and to identify socioeconomic, behavioural and biological factors associated with HCV exposure among this population. METHODS: We used data from three cross-sectional surveys conducted among Montréal MSM in 2005 (n=1795), 2009 (n=1258) and 2018 (n=1086). To ensure comparability of seroprevalence estimates across time, we standardised 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 generalised estimating equations were used to identify factors associated with HCV seropositivity pooling all surveys. RESULTS: Standardised HCV seroprevalence among all MSM remained stable from 7% (95% CI 3% to 10%) in 2005, to 8% (95% CI 1% to 9%) in 2009 and 8% (95% CI 4% to 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 old. Lifetime IDU was the strongest predictor of HCV seropositivity, and no association was found between HCV seroprevalence and sexual risk factors studied (condomless anal sex with men of serodiscordant/unknown HIV status, number of sexual partners, group sex). CONCLUSIONS: HCV seroprevalence remained stable among Montréal MSM between 2005 and 2018. Unlike other settings where HCV infection was strongly associated with sexual risk factors among MSM, IDU was the pre-eminent risk factor for HCV seropositivity. Understanding the intersection of IDU contexts, practices and populations is essential to prevent HCV transmission among MSM.

Using Geosocial Networking Apps to Understand the Spatial Distribution of Gay and Bisexual Men: Pilot Study.

BACKGROUND: While services tailored for gay, bisexual, and other men who have sex with men (gbMSM) may provide support for this vulnerable population, planning access to these services can be difficult due to the unknown spatial distribution of gbMSM outside of gay-centered neighborhoods. This is particularly true since the emergence of geosocial networking apps, which have become a widely used venue for meeting sexual partners. OBJECTIVE: The goal of our research was to estimate the spatial density of app users across Metro Vancouver and identify the independent and adjusted neighborhood-level factors that predict app user density. METHODS: This pilot study used a popular geosocial networking app to estimate the spatial density of app users across rural and urban Metro Vancouver. Multiple Poisson regression models were then constructed to model the relationship between app user density and areal population-weighted neighbourhood-level factors from the 2016 Canadian Census and National Household Survey. RESULTS: A total of 2021 app user profiles were counted within 1 mile of 263 sampling locations. In a multivariate model controlling for time of day, app user density was associated with several dissemination area-level characteristics, including population density (per 100; incidence rate ratio [IRR] 1.03, 95% CI 1.02-1.04), average household size (IRR 0.26, 95% CI 0.11-0.62), average age of males (IRR 0.93, 95% CI 0.88-0.98), median income of males (IRR 0.96, 95% CI 0.92-0.99), proportion of males who were not married (IRR 1.08, 95% CI 1.02-1.13), proportion of males with a postsecondary education (IRR 1.06, 95% CI 1.03-1.10), proportion of males who are immigrants (IRR 1.04, 95% CI 1.004-1.07), and proportion of males living below the low-income cutoff level (IRR 0.93, 95% CI 0.89-0.98). CONCLUSIONS: This pilot study demonstrates how the combination of geosocial networking apps and administrative datasets might help care providers, planners, and community leaders target online and offline interventions for gbMSM who use apps.

An Event-Level Analysis of Condom Use During Anal Intercourse Among Self-Reported Human Immunodeficiency Virus-Negative Gay and Bisexual Men in a Treatment as Prevention Environment.

BACKGROUND: We sought to identify factors associated with condom use during anal intercourse among self-identified human immunodeficiency virus-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 from 2012 to 2014. We analyzed participants' most recent sexual encounter with up to their last 5 sexual partners within the past 6 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 (human immunodeficiency virus treatment optimism). Accounting for clustering at the respondent-driven sampling chain-level and participant-level, factors associated with event-level condom use versus nonuse were determined using a multivariable generalized 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 (odds ratio [OR], 0.95 per month, 95% confidence interval [CI], 0.92-0.98). The 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 (adjusted OR [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, whereas 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: The 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.

Does size really matter? A sensitivity analysis of number of seeds in a respondent-driven sampling study of gay, bisexual and other men who have sex with men in Vancouver, Canada.

BACKGROUND: Respondent-driven sampling (RDS) is an increasingly used peer chain-recruitment method to sample "hard-to-reach" populations for whom there are no reliable sampling frames. Implementation success of RDS varies; one potential negative factor being the number of seeds used. METHODS: We conducted a sensitivity analysis on estimates produced using data from an RDS study of gay, bisexual and other men who have sex with men (GBMSM) aged ≥16 years living in Vancouver, Canada. Participants completed a questionnaire on demographics, sexual behavior and substance use. For analysis, we used increasing seed exclusion criteria, starting with all participants and subsequently removing unproductive seeds, chains of ≤1 recruitment waves, and chains of ≤2 recruitment waves. We calculated estimates for three different outcomes (HIV serostatus, condomless anal intercourse with HIV discordant/unknown status partner, and injecting drugs) using three different RDS weighting procedures: RDS-I, RDS-II, and RDS-SS. We also assessed seed dependence with bottleneck analyses and convergence plots. Statistical differences between RDS estimators were assessed through simulation analysis. RESULTS: Overall, 719 participants were recruited, which included 119 seeds and a maximum of 16 recruitment waves (mean chain length = 1.7). The sample of >0 recruitment waves removed unproductive seeds (n = 50/119, 42.0%), resulting in 69 chains (mean length = 3.0). The sample of >1 recruitment waves removed 125 seeds or recruits (17.4% of overall sample), resulting in 37 chains (mean length = 4.8). The final sample of >2 recruitment waves removed a further 182 seeds or recruits (25.3% of overall sample), resulting in 25 chains (mean length = 6.1). Convergence plots and bottleneck analyses of condomless anal intercourse with HIV discordant/unknown status partner and injecting drugs outcomes were satisfactory. For these two outcomes, regardless of seed exclusion criteria used, the crude proportions fell within 95% confidence intervals of all RDS-weighted estimates. Significant differences between the three RDS estimators were not observed. CONCLUSIONS: Within a sample of GBMSM in Vancouver, Canada, this RDS study suggests that when equilibrium and homophily are met, although potentially costly and time consuming, analysis is not negatively affected by large numbers of unproductive or lowly productive seeds.

Including Online-Recruited Seeds: A Respondent-Driven Sample of Men Who Have Sex With Men.

BACKGROUND: Technology has changed the way men who have sex with men (MSM) seek sex and socialize, which may impact the implementation of respondent-driven sampling (RDS) among this population. Initial participants (also known as seeds) are a critical consideration in RDS because they begin the recruitment chains. However, little information is available on how the online-recruited seeds may effect RDS implementation. OBJECTIVE: The objectives of this study were to compare (1) online-recruited versus offline-recruited seeds and (2) subsequent recruitment chains of online-recruited versus offline-recruited seeds. METHODS: Between 2012 and 2014, we recruited MSM using RDS in Vancouver, Canada. RDS weights were used with logistic regression to address each objective. RESULTS: A total of 119 seeds were used, 85 of whom were online-recruited seeds, to recruit an additional 600 MSM. Compared with offline-recruited seeds, online-recruited seeds were less likely to be HIV-positive (OR 0.34, 95% CI 0.13-0.88), to have attended a gay community group (AOR 0.33, 95% CI 0.12-0.90), and to feel gay community involvement was "very important" (AOR 0.16, 95% CI 0.03-0.93). Online-recruited seeds were more likely to ask a sexual partner's HIV status always versus <50% of the time (AOR 5.21, 95% CI 1.17-23.23), to have watched the Pride parade (AOR 6.30, 95% CI 1.69-23.45), and to have sought sex online (AOR 4.29, 95% CI 1.53-12-12.05). Further, compared with recruitment chains started by offline-recruited seeds, recruits from chains started by online-recruited seeds (283/600, 47.2%) were less likely to be HIV-positive (AOR 0.25, 95% CI 0.16-0.40), to report "versatile" versus "bottom" sexual position preference (AOR 0.56, 95% CI 0.35-0.88), and to be in a relationship lasting >1 year (AOR 1.65, 95% CI 1.06-2.56). Recruits of online seeds were more likely to be out as gay for longer (eg, 11-21 vs 1-4 years, AOR 2.22, 95% CI 1.27-3.88) and have fewer Facebook friends (eg, 201-500 vs >500, AOR 1.69, 95% CI 1.02-2.80). CONCLUSIONS: Online-recruited seeds were more prevalent, recruited fewer participants, but were different from those recruited offline. This may therefore help create a more diverse overall sample. Our work has shown the value of geosocial networking apps for aiding RDS recruitment efforts, especially when faced with slow participation uptake by other means. Understanding the degree to which networks interact will be an important next step in confirming the efficacy of online RDS recruitment strategies.