Substance use homophily among geosocial networking application using gay, bisexual, and other men who have sex with men.

Geosocial networking applications (GSN apps) represent important virtual contexts in which gay, bisexual, and other men who have sex with men (MSM) seek affiliation. These apps allow users to create and view public profiles, send photos, and text messages, and connect with other users based on shared interests and geographic proximity. The present study examined substance use homophily among a sample of 295 MSM recruited via a popular GSN app. Comparisons of social network members met via GSN app versus elsewhere and associations between both individual and network characteristics and recent binge drinking, marijuana use, and illicit substance use were explored using bivariate tests of association and multivariate logistic regression analyses. High rates of recent binge drinking (59 %), marijuana use (37 %), and illicit substance use (27 %) were observed among participants. GSN app use greater than 1 year and showing naked chest or abs in a profile picture were positively associated with recent illicit substance use. In multivariate analyses, the strongest predictors of binge drinking (AOR 3.81; 95 % CI 1.86-7.80), marijuana use (AOR 4.12; 95 % CI 2.22-7.64), and illicit substance use (AOR 6.45; 95 % CI 3.26-12.79) were the presence of a social network member who also engaged in these behaviors. Social network interventions that target binge drinking, marijuana use, and illicit substance use may be delivered via GSN apps to reduce the prevalence of substance use and related risks among MSM in these virtual contexts.