Urine Test Shows Predictive Values for PrEP Adherence

Anthony Calabro, MA

In a recent study presented at the Conference on Retroviruses and Opportunistic Infections 2023 in Seattle, WA, researchers calculated the predictive values of urine point-of-care tenofovir (POC-TFV) tests, self-reported recent pre-exposure prophylaxis (PrEP) use, and TFV-diphosphate (TFV-DP) in dried blood spots.

Although the accuracy of self-reported PrEP use can be called into question at times, self-reporting is one of the most frequently used reporting methodologies in research. Considering the suboptimal metrics associated with self-reporting PrEP adherence, the authors of the current study set out to determine whether urine POC-TFV could be used as an alternative approach.

The authors found that “the urine POC-TFV assay had excellent predictive values for adherence in a real-world cohort, while self-reported adherence did not add significantly to prediction.”

For the study, researchers invited participants who were current PrEP users in the RADAR community-cohort study of young men and transgender women who have sex with men. During three monthly visits, participants completed a survey of daily PrEP use in the prior 7 days and provided dried blood spot and urine samples. The researchers tested dried blood spot samples for TFV-DP to estimate the average dosing over the prior month and emtricitabine-triphosphate (FTC-TP) to assess recent dosing, which was defined here as the past 2 to 3 days. A urine POC-TFV test was performed to determine recent adherence, which was defined here as  the past 4 to 7 days.

In a subset of 73 PrEP-users who contributed 126 observations, self-reported adherence was over-reported (87% for four or more doses in last 7 days), compared with urine TFV (69%), DBS FTC-TP (68%), and DBS TFV-DP (67%). Although self-reporting overestimated longer-term adherence, it had better results for short-term adherence metrics. And in multivariable logistic regression analyses, the urine assay was a significant predictor of dried blood spot TFV-DP (OR = 30.2, p < .0001). The study results also showed that self-reporting did not add significantly to prediction.

Considering the results of the study, plus the overall cost effectiveness associated with urine POC-TFV, the test may be useful as an adherence assay moving forward.

“The POC assay provides results in several minutes to enable same-visit counseling and intervention, requires no specialized training, and is projected to be low-cost,” the authors concluded. “It could also be used for research where objective short term adherence metrics are needed.”



Mustansk B, D'Aquila R, Gandhi M, Ryan D, Spinelli MA, Newcomb M. Urine point-of-care TFV test shows strong predictive clinical and research utility. Presented at: Conference on Retroviruses and Opportunistic Infections (CROI); February 19-22, 2023; Seattle, WA. Accessed March 3, 2023.