At-Home Point-of-Care Urine Tenofovir Testing for Adherence Monitoring: Feasibility and Comparison with Adherence Metrics in Dried Blood Spots.

BACKGROUND: Scalable, low-cost strategies for monitoring antiretroviral therapy adherence are increasingly important, particularly in decentralized and telehealth-based care settings. This study assessed both the feasibility and performance of at-home, point-of-care (POC) urine tenofovir (TFV) testing for adherence monitoring, using tenofovir diphosphate (TFV-DP) levels in dried blood spots (DBS) as a pharmacological standard of adherence. SETTING: This study was conducted within the LetSync cohort of people with HIV in primary romantic relationships, primarily Black men who have sex with men, across the U.S. METHODS: Participants self-collected POC urine TFV testing and DBS samples over five timepoints across eight months. Adequate adherence was defined as TFV-DP ≥4 doses/week in DBS. Generalized estimating equation models evaluated associations between urine TFV results and DBS-based adherence, as well as the probability of sample return over time. RESULTS: Among 86 participants and 341 paired samples, detectable urine TFV was strongly associated with adequate adherence in DBS (aRR = 2.86; 95% CI: 1.37-5.99). The urine POC test demonstrated high sensitivity (97%) and positive predictive value (85%), with lower specificity (31%). Across timepoints, urine samples showed higher return rates compared to DBS (aRR = 1.04; 95% CI: 1.01-1.08). Participants with detectable viral load had lower return rates for DBS compared to urine. CONCLUSIONS: At-home POC urine TFV testing is a sensitive and feasible approach for monitoring adherence. Its simplicity and consistently high return rates support its potential as a practical adherence monitoring tool, particularly in settings where VL testing is infrequent or logistically limited.