Abstract
BackgroundThe HIV epidemic in the United States (US) disproportionately affects gay, bisexual, and other men who have sex with men (MSM). Pre-exposure prophylaxis (PrEP) using co-formulated tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) has demonstrated high efficacy in reducing HIV incidence among MSM. However, low adherence was reported in major efficacy trials and may present a substantial barrier to successful PrEP implementation. Rates of adherence to PrEP in “real-world” clinical settings in the US remain largely unknown.MethodsWe reviewed demographic and clinical data for the first 50 patients to enroll in a clinical PrEP program in Providence, Rhode Island. We analyzed self-reported drug adherence as well as drug concentrations in dried blood spots (DBS) from patients who attended either a three- or six-month follow-up appointment. We further assessed drug concentrations and the resistance profile of a single patient who seroconverted while taking PrEP.ResultsOf the first 50 patients to be prescribed PrEP, 62% attended a follow-up appointment at three months and 38% at six months. Of those who attended an appointment at either time point (70%, n = 35), 92% and 95% reported taking ±4 doses/week at three and six months, respectively. Drug concentrations were performed on a random sample of 20 of the 35 patients who attended a follow-up appointment. TDF levels consistent with ±4 doses/week were found in 90% of these patients. There was a significant correlation between self-reported adherence and drug concentrations (r = 0.49, p = 0.02). One patient who had been prescribed PrEP seroconverted at his three-month follow-up visit. The patient’s drug concentrations were consistent with daily dosing. Population sequencing and ultrasensitive allele-specific PCR detected the M184V mutation, but no other TDF- or FTC-associated mutations, including those present as minor variants.ConclusionIn this clinical PrEP program, adherence was high, and self-reported drug adherence accurately reflected drug concentrations as measured by DBS.
Highlights
The HIV epidemic continues to be a significant public health concern in the United States (US), with over 1.2 million persons currently living with HIV and the number of newly diagnosed cases approaching 50,000 annually [1]
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Clinical trials of emtricitabine (FTC) co-formulated with tenofovir disoproxil fumarate (TDF) as Pre-exposure prophylaxis (PrEP) have demonstrated a greater than 90% reduction of HIV acquisition risk among men who have sex with men (MSM) who were adherent to the medication [2,3,4]
Summary
The HIV epidemic continues to be a significant public health concern in the United States (US), with over 1.2 million persons currently living with HIV and the number of newly diagnosed cases approaching 50,000 annually [1]. Sub-optimal adherence may lead to the development of drug resistance [2,5,6,7,8] which has the potential to impact subsequent treatment outcomes [9] Another major finding from the initial efficacy studies was the significant discordance between self-reported adherence and serum drug levels. In the Pre-exposure Prophylaxis Trial for HIV Prevention among African Women (FEM-PrEP) [5] and Vaginal and Oral Interventions to Control the Epidemic (VOICE) [6] studies among African women, self-reported adherence was high (95%), but fewer than 40% had plasma drug concentrations indicative of adherence [5]. Pre-exposure prophylaxis (PrEP) using co-formulated tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) has demonstrated high efficacy in reducing HIV incidence among MSM. Rates of adherence to PrEP in “real-world” clinical settings in the US remain largely unknown
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