Correlates of self-reported and biomarker based adherence to daily oral HIV preexposure 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 selfreported 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.