Concentrations of ART in Scalp Hair Correlate with Virologic Response

When it comes to measuring adherence to an antiretroviral (ART) regimen for HIV, scientists may have a new tool in their arsenal: hair.

A study by investigators at several US universities and medical schools asserts that, compared with plasma or dried blood spots, scalp hair samples offer a superior view of long-term ART adherence and are not influenced by variables such as food, other medications, dose timing, or other factors. It’s also very easy to obtain hair samples and store them at room temperature and, unlike bodily fluids, they’re not considered biohazards, and so, require fewer precautions when being handled.

The study team analyzed the results of the AIDS Clinical Trials Group (ACTG) Study A5257, conducted by multiple researchers at facilities nationwide. This trial enrolled 1,809 people with HIV in the United States and Puerto Rico who had never before received treatment or had received treatment for no more than 10 days. The subjects were randomized to take tenofovir disoproxil fumarate/emtricitabine with either atazanavir/ritonavir, darunavir/ritonavir, or raltegravir and were followed for 96 weeks. Plasma concentrations of HIV-1 RNA of at least 1,000 copies/mL between 16 weeks and 24 weeks after starting, or levels of at least 200 copies/mL at 24 weeks and beyond, signaled virologic failure.

At a point, after the trial began, hair collection was added during some of the participant visits. A total of 599 study participants agreed to have their hair sampled, with 20 or 30 strands taken from the scalp at 8, 16, and 24 weeks, and every 3 months thereafter. Lab analysis revealed that lower concentrations of ART found in hair samples were strongly correlated with virologic failure. Subjects with the lowest concentrations of ART in their hair had virologic failure rates of 26% after 2 years. Those in the middle had virologic failure rates of 6%, while those with the highest concentrations of ART in their hair had virologic failure rates of just 3%. The investigators found these correlations to be true regardless of which of the 3 treatment regimens the subjects had been assigned.

Why might hair analysis be the wave of the future when it comes to knowing which patients are taking ART as directed? “Blood levels reflect only short-term dosing so may not give you insight into patterns of the patient’s adherence over time,” Monica Gandhi, MD, MPH, professor of medicine at the University of California San Francisco and the lead author of the study, told Contagion^®. “Moreover, a patient can start taking their medications regularly before a study visit (e.g., “white coat adherence”) and their blood levels will look good, but this does not mean that they are taking the drug regularly over time, which a hair level can tell you.”

While virologic failure is a valuable clue that a person with HIV is not being compliant with his or her medication regimen, a window of opportunity has closed by the time that failure is discovered. “We hope to be able to start measuring ART levels in hair in patients in resource-limited settings prior to virologic failure, with a low hair level of ART triggering intensive counseling of the patient regarding adherence and other adherence interventions,” said Dr. Gandhi. “The hope is that we can avert virologic failure in the future by acting on a hair ART level early on.”

Patients who show a low hair ART level might receive counseling, text messages, or differently packaged medication such as blister packs that prompt users with numbered and easily popped out pills. Obstacles to implementing a program of hair testing for all people with HIV is that not all of them will agree to have their hair analyzed (62% of subjects consented in this study), and inexpensive point-of-care tests revealing hair ART concentration are not yet available, according to Dr. Gandhi. “We are working on both of those aspects.”

Editor’s Note: This article expands on past Contagion^® coverage of a presentation delivered at the 25th Conference on Retroviruses and Opportunistic Infections (CROI).

Ms. Saloman is a health writer with more than 20 years of experience working for both consumer-and physician-focused publications. She is a graduate of Brandeis University and the Medill School of Journalism at Northwestern University. She lives in New Jersey with her family.