Correlates of self-reported and biomarker based adherence to daily oral HIV pre-exposure prophylaxis among a cohort of predominantly men who have sex with men in Nigeria

INTRODUCTION: HIV pre-exposure prophylaxis (PrEP) significantly reduces the risk of HIV acquisition. However, studies have demonstrated discordance between self-reported measures and biomedical benchmarks of PrEP adherence. We estimated the correlation between self-reported PrEP adherence and PrEP biomarkers and explored factors associated with adherence among men who have sex with men (MSM) in Nigeria. METHODS: TRUST-PrEP, an open-label, prospective study; conducted in Abuja between April 2018 and May 2019. MSM ≥ 18 years with substantial HIV risk were enrolled. Participants reported PrEP adherence in the last month using a 4-point scale from “poor” to “perfect” and serum samples for PrEP biomarkers were collected at months 3 and 9. Serum tenofovir concentration was measured by liquid chromatography-tandem mass spectrometry and considered protective for adherence if ≥ 4.2 ng/ml. Spearman’s rank correlation was used to estimate correlation between self-reported adherence and measured tenofovir levels. Generalized estimating equations with a logit link was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for associations between self-reported adherence and laboratory-measured adherence. RESULTS: A total of 219 MSM with median age 23 (interquartile range 20–27) years had at least one PrEP biomarker assay. Only 66/219 (30%) had at least one record of protective tenofovir concentration. Correlation between tenofovir and self-reported adherence at 3 and 9 months were 0.1 and 0.02 respectively. Furthermore, 17/219 (8%,) and 49/219 (22%) had serum tenofovir of 4.2–35.4 ng/mL and ≥ 35.5 ng/mL, corresponding to at least 4 and 7 days’ PrEP use in a week, respectively. PrEP adherence was higher among participants introduced to PrEP in the clinics compared with communities (aOR: 8.35, 95%CI: [3.24, 21.5]) and those with same-sex practices family disclosure (aOR: 3.60 95% CI: [1.73, 7.51]). CONCLUSION: Self-reported PrEP adherence poorly correlated with biomarkers. Facilitating clinic-based PrEP introduction and disclosure of same-sex practices to family among MSM may improve PrEP adherence.