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A novel point-of-care urine test for PrEP drug levels predicted PrEP discontinuation in young people more accurately than self-reported PrEP adherence.

A novel point-of-care urine test for HIV PrEP drug levels predicted PrEP discontinuation in young MSM and transgender women (YMSM/TGW) more accurately than self-reported PrEP adherence, according to a study published in AIDS.

“[Urine] testing may be a clinical tool for directing preventive interventions towards those likelier to discontinue PrEP despite ongoing HIV vulnerability,” wrote corresponding author Matthew A. Spinelli, MD, MAS, of Zuckerberg San Francisco General Hospital, San Francisco, California, and study coauthors.

The study included a convenience sample of 100 YMSM/TGW who visited a San Francisco AIDS Foundation clinic for 90-day PrEP prescriptions. During the index visit, participants completed a survey and provided a urine sample. The PrEP rapid assay used in the study functions similarly to a rapid strip urine pregnancy test, researchers explained, and previous studies produced results that correlated highly with gold-standard liquid chromatography tandem mass spectrometry (LC/MS/MS) methods of drug level detection.

According to the study, testing revealed that 19% of participants had low levels of PrEP medication in their urine, and 21% discontinued PrEP, defined as 120 days without a PrEP follow-up or prescription after the index visit. Factors associated with future PrEP discontinuation included not having seen a PrEP provider in the 6 months before the index visit and identifying as genderqueer.

Meanwhile, 11% of participants self-reported low adherence to PrEP, which was defined as less than four pills a week. The study found that self-reported low adherence was only 43% sensitive and 84% specific in predicting low levels of PrEP medication and was not linked with PrEP discontinuation.

However, low urine levels of PrEP predicted PrEP discontinuation; researchers reported an adjusted odds ratio of 6.1. Urine testing was 71% sensitive and 90% specific for PrEP discontinuation.

The study found that point-of-care urine testing had a positive predictive value of 98% and a negative predictive value of 100% compared with LC/MS/MS. Participants’ attitudes regarding the point-of-care urine test in the context of a PrEP visit were generally positive.

“Participants also highlighted the importance of the test in ensuring protection after a lapse in PrEP use,” researchers wrote. “Practical suggestions were offered, such as making the test accessible from pharmacies or available for mail-at-home use.”