Performance of a whole blood immunoassay for tenofovir detection and correlation with self-reported pre-exposure prophylaxis use in HIV-negative men who have sex with men interested in blood donation.

BACKGROUND

In 2023, the United States Food and Drug Administration revised its blood donor eligibility policy for men who have sex with men (MSM) from a 3-month deferral to individual assessment. Human Immunodeficiency Virus (HIV) pre-exposure prophylaxis (PrEP) use remains a reason for deferral, and nondisclosure is a concern.

STUDY DESIGN AND METHODS

In a cross-sectional study of sexually active MSM from 8 U.S. cities who were interested in future blood donation, we assessed the performance of an enzyme-linked immunosorbent assay for detecting tenofovir (TFV) in whole blood (WB) and plasma and the correlation with self-reported PrEP use.

RESULTS

Of 1548 individuals, 48% reported oral PrEP use. The WB assay identified 95% of PrEP users, while the plasma assay detected 88%. The WB assay performed well up to 14 days after the last reported dose. Receiver operating characteristics curve analysis showed an area under the curve of 0.96 (95% confidence interval [CI]: 0.95-0.97) using WB and 0.88 (95% CI: 0.86-0.90) using plasma. Specificity was 80% for WB and 66% for plasma. Detection rates for TFV disoproxil fumarate/emtricitabine (FTC) formulations were 99% in WB and 98% in plasma, compared to 93% and 86% for the TFV alafenamide/FTC formulation.

DISCUSSION

High concordance between self-reported oral PrEP use and TFV detection was observed among PrEP users, suggesting the potential utility of WB as a biomatrix for TFV detection to support screening strategies. Given the expanded eligibility for MSM, who may be PrEP users, to donate blood, further examination of undisclosed PrEP use is important.