Acceptability of drug detection monitoring among participants in an open-label pre-exposure prophylaxis study.

In the world of HIV pre-exposure prophylaxis (PrEP) research, there is emerging interest in providing study participants with pharmacokinetic results from drug level testing to guide adherence counseling. The iPrEx randomized control trial was the first study to produce meaningful results of PrEP in humans. In the iPrEx open-label extension (OLE) study, blood plasma samples collected in the first 12 weeks of study participation were tested for the presence of tenofovir/emtricitabine--the drugs which compromise PrEP. Study clinicians shared results (detectable/undetectable) with participants at their 24-week visit. We evaluated the acceptability of receiving these results among a subset of iPrEx OLE participants. We conducted in-depth interviews (n = 59) with participants (those with and those without drug detected) enrolled in Boston, Chicago, and San Francisco to assess their experiences with receiving drug detection feedback. Incorporating drug detection results into the clinical study visit was well received and no negative reactions were expressed. For about half of participants, receiving their drug detection lab result was useful while for others it was not important. In a few cases, no drug detected results led to increased efforts to take PrEP consistently and in most cases enhanced open discussion of missed doses. Participants reported a desire for greater specificity, particularly quantitative drug levels needed for protection. We recommend exploring strategies to increase the salience of drug level results, including using feedback to target adherence counseling, and reducing the time between specimen collection, testing, and receipt of results. Future studies should evaluate the feasibility and impact of providing more specific quantitative drug levels using biomarkers of longer term PrEP exposure, i.e., hair/dried blood spots.