Patterns of a Rectal Microbicide Placebo Gel Use in a Preparatory Stage for a Phase I Trial Among Young Men Who Have Sex with Men.

We examined young gay, bisexual, and other men who have sex with men's (YGBMSM) usage patterns of a pre-coital, applicator-administered rectal placebo gel. An ethnically diverse sample of 94 YGBMSM (aged 18-30 years) were asked to insert hydroxyethylcellulose placebo gel rectally before receptive anal intercourse (RAI) and report their gel use through an interactive voice response system (IVRS) across 12 weeks. We used trajectory analyses to characterize participants' use of the rectal gel over the 12 weeks, and examine whether these trajectories varied based on participants' sociodemographic characteristics, sexual behaviors, application and insertion behaviors, and experiences using the placebo gel. A cubic model was the best fit for these longitudinal data, with two distinct trajectories of gel use observed. The first trajectory ('High with Varying Gel Use per Week') represented YGBMSM (N = 38; 40.3%) who reported using the rectal gel on several occasions per week. The second trajectory ('Low and Consistent Gel Use per Week') represented participants (N = 56; 59.7%) who reported a consistent average use of one gel per week. Participants in the High with Varying Gel Use Trajectory reported trying out a greater number of positions when inserting the gel across the 12-weeks than peers in the Low and Consistent Gel Use Trajectory. YGBMSM reporting more RAI occasions during the trial were more likely be present in the High with Varying Gel Use Trajectory than peers in the Low and Consistent Gel Use Trajectory. Future research examining how to facilitate gel application and adherence among YGBMSM is merited.