Study Design, Setting and Population

This study was a secondary analysis of longitudinal data from a cohort of MSM who initiated PrEP through the PHSKC STD Clinic between October 2014 and April 2017. Per PHSKC and Washington State (WA) PrEP guidelines (14) the PHSKC STD Clinic has provided PrEP to patients at high risk for acquiring HIV since October 2014. This group includes transgender persons who have sex with men and MSM who report any of the following risk factors in the past 12 months: diagnosis of rectal gonorrhea or early syphilis; use of methamphetamine or amyl nitrites (poppers); or exchanging sex for money or drugs. PrEP is also recommended for patients who are in ongoing sexual relationships with HIV-positive partners who are not virally suppressed. STD Clinic clinicians evaluate patients for PrEP eligibility, and those who meet the recommended criteria are offered PrEP through the clinic.

At the PrEP initiation visit, patients complete a behavioral questionnaire by computer-assisted self- interview (CASI), are tested for HIV and STIs, and are given a PrEP prescription. Clinic staff verify the initial prescription fill. Patients return one month after PrEP initiation, then quarterly for clinical follow up and monitoring. At quarterly visits patients are tested for HIV and STIs, complete behavioral questionnaires, and receive new 3-month prescriptions for PrEP. If patients are unable to attend a follow-up appointment in person, STD Clinic clinicians can call in one 30-day prescription refill. Clinic staff attempt to determine reason for PrEP discontinuation for all patients who stop attending follow-up appointments or stop using PrEP. Patients are categorized as lost to follow-up if clinic staff are unable to reach them after three attempts.

PrEP patients were included in this analysis if they initiated PrEP during the study period, and completed a questionnaire during their initial visit and at least one follow-up visit. If patients stopped and re- started PrEP during the study period, the longest series of completed questionnaires was used. This study was approved by the University of Washington Institutional Review Board.