BOSTON – Hair is the key to knowing if patients have been taking their HIV antiretrovirals. In fact, hair levels were the strongest independent predictor of virologic control in a major trial of HIV-positive, treatment-naive patients that compared atazanavir, darunavir, and raltegravir-based regimens. Virologic success was similar in all three arms, but the raltegravir regimen was better tolerated than the protease inhibitor arms (Ann Intern Med. 2014 Oct 7;161[7]:461-71).
Because patient self-reporting is notoriously unreliable, the investigators checked hair for adherence. The results for 599 participants followed for a median of 217 weeks were reported at the Conference on Retroviruses and Opportunistic Infections. Hair samples were collected at weeks 4, 8, 16, and then quarterly; concentrations of the three drugs were measured by liquid chromatography-tandem mass spectrometry.
Rates of virologic failure were 26%, 6%, and 3% for patients with hair levels in the lowest, middle, and highest tertiles, respectively. Lower hair antiretroviral (ARV) levels strongly predicted virologic failure (hazard ratio for every twofold decrease in hair level 1.69, 95% confidence interval, 1.43-2.04, P less than .001). Results were consistent across drugs and for each drug individually.
Patients with ARV hair levels in the lowest tertile were 6.8 times more likely to fail than were patients in the highest tertile. The actual level that was considered low depended on the drug.