Antiretroviral Concentrations in Small Hair Samples as a Feasible Marker of Adherence in Rural Kenya

Abstract

Antiretroviral hair levels objectively quantify drug exposure over time and predict virologic responses. We assessed the acceptability and feasibility of collecting small hair samples in a rural Kenyan cohort. Ninety-five percentage of participants (354/373) donated hair. Although median self-reported adherence was 100% (interquartile range, 96%-100%), a wide range of hair concentrations likely indicates overestimation of self-reported adherence and the advantages of a pharmacologic adherence measure. Higher nevirapine hair concentrations observed in women and older adults require further study to unravel behavioral versus pharmacokinetic contributors. In resource-limited settings, hair antiretroviral levels may serve as a low-cost quantitative biomarker of adherence.