The antiretroviral concentration in hair is a strong predictor of virologic outcomes in individuals with HIV, according to a study recently published in Clinical Infectious Diseases. Furthermore, monitoring hair antiretroviral levels can provide warning of imminent antiretroviral failure.
This study included 599 participants who were randomly assigned to receive atazanavir/ritonavir (RTV), darunavir/RTV, or raltegravir. Researchers collected hair from these participants at months 2, 4, 8, and then quarterly and analyzed it using liquid-chromatography-tandem mass spectrometry.
Virologic failure was the primary endpoint of this study and was defined as plasma HIV-1 RNA greater than 1000 copies per mL between 16 and 24 weeks or greater than 200 copies/mL after the 24th week. Multivariable model covariates included sex, age, viral load pre-treatment, level of education, and race or ethnicity.
Those with lower antiretroviral concentrations in their hair were at increased risk of virologic failure, with a hazard ratio of 2.43 for each halving of hair concentration (95% CI, 1.96-3.13; P <.0001). This was the same across each individual drug after adjustments. Virologic failure showed associations with less education, being African-American, and viral loads before treatment began of greater than 100,000 copies/mL.
At 96 weeks, virologic failure across the 3 treatment arms was 16.3%. Those with the lowest hair concentrations had a 26% rate of virologic failure, the middle tertile had a 6% rate of failure, and the upper tertile had a 3% rate of failure, yielding a relative hazard ratio of 6.8 between the lowest and highest tertiles.
The study researchers conclude that “hair levels are a strong independent predictor of virologic outcomes in a large randomized clinical trial of three different [antiretroviral therapy] regimens for the initial treatment of HIV.”
Multiple authors declare potential conflicts of interest. For a full list of authors’ disclosures, please refer to original reference.
Gandhi M, Ofokotun I, Bacchetti P, et al. Antiretroviral concentrations in hair strongly predict virologic response in a large HIV treatment-naive clinical trial [published online September 3, 2018]. Clin Infect Disord. doi: 10.1093/cid/ciy764