Antiretroviral drug concentrations in hair are associated with virologic outcomes among young people living with HIV in Tanzania.

OBJECTIVE: We assessed the relationship of self-reported adherence versus antiretroviral therapy (ART) concentrations in hair with virologic outcomes among young people living with HIV.
DESIGN: This was a cross-sectional study that enrolled young people living with HIV age 11-24 years, who attended a youth HIV clinic in Moshi, Tanzania.
METHODS: ART adherence was assessed by self-report, drug concentration in hair samples, and plasma HIV-1 RNA measurements. Those with virologic failure, defined as plasma HIV-1 RNA more than 400 copies/ml, had genotypic resistance assessed. Receiver operating characteristic curves were used to evaluate ART-concentration threshold cutoffs for virologic suppression, after excluding those with known high-level resistance mutations.
RESULTS: Among 280 young people enrolled, 227 were included in the final analysis. Seventy-two (32%) self-reported inadequate adherence and 91 (40%) had virologic failure. Hair ART-concentration (P < 0.001), but not self-reported adherence (P = 0.53), was associated with virologic outcome. Sixty-seven (74%) of those with virologic failure had resistance testing performed, of whom 60% had high-level resistance. Receiver operating characteristic curves demonstrated moderate or high classification performance for association with virologic suppression with specific hair ART-concentration cutoffs for lopinavir (1.8 ng/mg), efavirenz (1.04 ng/mg), and nevirapine (33.2 ng/mg).
CONCLUSION: Hair ART-concentrations were significantly associated with virologic outcomes among young people living with HIV. ART-concentration thresholds associated with virologic suppression are proposed. Hair analysis may provide a noninvasive, cost-effective adherence assessment tool in settings with limited second and third-line treatment options.