Meanwhile, self-reported adherence – a median of 100% in each arm – barely correlated with actual ARV levels (Pearson’s r 0.15).
In the end, “hair levels were the strongest independent predictor of how you did,” said lead investigator Monica Gandhi, MD, associate chief of the Division of HIV, Infectious Diseases, and Global Medicine at the University of California, San Francisco, General Hospital.
Testing for hair levels is already a part of clinical care at UCSF, which has a hair analysis lab. In one case, a 21-year-old man seroconverted after saying he was taking pre-exposure prophylaxis (PrEP) perfectly. After a check of his hair, it turned out that he was, but had caught a drug-resistant virus. Another patient who seroconverted on PrEP turned out to have missed some doses a few months before.
Ideally, hair testing could be used early on to provide extra help to patients who prove to have trouble with adherence. Text messaging – as long as the doctor actually responds – is effective, but so is just bringing people in and asking them how they needed to be helped, Dr. Gandhi said.