Alignment Between HIV Vulnerability and Pre-exposure Prophylaxis Use in a Longitudinal Study of Young, Black Men Who Have Sex with Men
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Zihan Guo1, Darren Whitfield2, O Winslow Edwards1
1Department of Epidemiology, Emory University, Atlanta, GA, USA.
Abstract:
When taken as a daily pill, pre-exposure prophylaxis (PrEP) requires sufficient levels of adherence to confer strong protection against HIV. For protection against HIV transmission via anal sex, this corresponds to at least 4 daily pills per week for those on a daily dosing regimen. Measuring oral PrEP adherence requires valid assessments of pill-taking; it also requires assessments of contemporaneous sexual behavior because PrEP adherence is only functionally relevant in the context of contemporaneous HIV vulnerability. We conducted an online cohort study of Black, PrEP-using men who have sex with men (MSM) to assess the alignment between self-reported PrEP adherence and condom use and concordance between self-reported PrEP adherence and laboratory-assessed adherence. Data collection occurred from 2021 to 2023. Participants completed 11 weekly surveys to report PrEP use and sexual behavior for the preceding 7 days. At the end of follow-up, they were asked to submit a dried blood spot sample for laboratory analysis. There were few periods of self-reported non-adherence, but, among these, condomless sex was frequent. Self-reported adherence was not predictive of laboratory-assessed adherence. Despite their cost, studies of PrEP adherence should incorporate laboratory measurements of adherence whenever feasible.
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