Real-World User Experiences with a Digital Pill System to Measure PrEP Adherence: Perspectives from MSM with Substance Use.

Once-daily oral pre-exposure prophylaxis (PrEP) is highly effective for preventing HIV transmission, but adherence can be challenging for men who have sex with men (MSM) who use substances. A novel method for directly measuring ingestion events is a digital pill system (DPS), which comprises an ingestible radiofrequency emitter that signals a wearable Reader device upon PrEP ingestion, relaying ingestion data to a wearable Reader device and then to a smartphone application. Qualitative interviews were conducted with 15 MSM with non-alcohol substance use following an open-label pilot demonstration trial involving use of the DPS to measure PrEP adherence for 90 days. The purpose of this qualitative investigation was to understand overall user experiences and potential barriers and facilitators to using the DPS to measure PrEP adherence among MSM. The DPS was largely perceived as acceptable, novel, and valuable, with most participants reporting that the system was easily integrated into their daily routines. Technological and design factors, especially related to the wearable Reader, impacted participants' interest in using the technology long-term; several suggested improvements were discussed.Trial Registration ClinicalTrials.gov: NCT03842436.