HIGH ACCURACY OF A REAL-TIME URINE ANTIBODY-BASED TENOFOVIR POINT-OF-CARE TEST COMPARED TO LABORATORY-BASED ELISA IN DIVERSE POPULATIONS.

BACKGROUND: Therapeutic drug monitoring measures antiretroviral adherence more accurately than self-report but has not been available at the point-of-care (POC) until now. We compare a novel POC test for urine tenofovir to laboratory-based enzyme-linked immunosorbent assay (ELISA) testing in diverse patient populations urine pre-exposure prophylaxis (PrEP). SETTING: Urine samples were analyzed using ELISA and the POC lateral flow immunoassay (LFA) test from two cohorts of PrEP users taking tenofovir disoproxil fumarate/emtricitabine: the Partners PrEP Study, which recruited Kenyan and Ugandan heterosexual men and women, and the IBrEATHe Study, which recruited U.S. transgender women and men using gender-affirming hormone therapy. METHODS: We calculated the sensitivity, specificity, and accuracy of the POC test compared to ELISA at a cut-off of 1,500 ng/mL. RESULTS: Overall, 684 urine samples were tested from 324 participants in the two cohorts. In Partners PrEP, 454 samples from 278 participants (41% women) were tested with a median age of 33 years. In IBrEATHe, 231 samples from 46 individuals (50% transwomen) were tested with a median age of 31 years. Comparison of the LFA read-out to ELISA yielded 100% sensitivity (97.5% one-sided confidence interval (CI)=99.3%), 98.3% specificity (95% CI=95.2%-99.7%), and 99.6% accuracy (95% CI=98.7%-99.9%). CONCLUSION: The sensitivity, specificity, and accuracy of a novel POC test for urine tenofovir all exceeded 98% when compared to a laboratory-based ELISA method when tested in diverse patient populations. Given the LFA's high accuracy and expected low cost, this POC test is a promising tool to support antiretroviral adherence that could be widely scalable to real-world clinical settings.