Tan, Darrell H.S., Schnubb, Alexandre, Lawless, James, Szadkowski, Leah, Grennan, Troy, Wilton, James, Fowler, Shawn, Hart, Trevor A., Maxwell, John, and Raboud, Janet M.
Background: Preexposure prophylaxis is efficacious at preventing HIV infection, but concerns persist about adherence and sexually transmitted infections (STIs). We assessed preexposure prophylaxis acceptability, adherence and clinical outcomes in a pilot demonstration project. Methods: HIV-uninfected adult gay and bisexual men who scored 10 or higher on a validated HIV risk score (HIV Incidence Risk Index for MSM) and reported condomless receptive anal sex were sequentially enrolled into a 1-year open-label single-arm pilot study of daily oral therapy with tenofovir disoproxil fumarate/emtricitabine in Toronto. The primary outcome was acceptability of preexposure prophylaxis. Secondary outcomes were preexposure prophylaxis adherence (4-d recall, pill count and dried blood spot analysis), HIV seroconversion, STIs and adverse events. Results: Of the 86 men screened, 52 were enrolled. Participants were mostly young (median age 33 yr [interquartile range (IQR) 28–37 yr) white (38 [73%]) gay (49 [94%]) men. Preexposure prophylaxis acceptability was high: all participants reported their experience as "good" or "very good." The median adherence rate was high, at 100% (IQR 95%–100%) by self-report and 96.9% (IQR 93.4%–98.4%) by pill count. Dried blood spot analysis suggested that doses were taken 4–7 days/week at 88.7% (173/195) of month 3–12 visits. No cases of HIV seroconversion occurred, but 25 participants (48%) experienced at least 1 bacterial STI, with incidence rates per 100 person-years of 32.8, 32.8, 8.2 and 8.2 for chlamydia, gonorrhea, syphilis and lymphogranuloma venereum, respectively. No adverse events led to discontinuation of prophylaxis, but the estimated glomerular filtration rate declined by 0.22 mL/min per month. Interpretation: Preexposure prophylaxis was associated with high adherence and acceptability and no HIV infections in this study. Frequent STIs and clinically unapparent toxic renal effects reinforce the need for ongoing vigilance. Trial registration: ClinicalTrials. gov, no. NCT02149888 [ABSTRACT FROM AUTHOR]