Feasibility and Acceptability of Digital Pills to Monitor PrEP Adherence in MSM With Substance Use (DigiPrEP)

This study deploys a novel digital pill with Emtricitabine/Tenofovir (TDF/FTC) among MSM with substance use to monitor PrEP adherence. The investigators will enroll N=15 HIV uninfected MSM with self reported substance use who are on PrEP or initiating PrEP to use digital pills over encapsulating TDF/FTC for 3 months. The investigators will assess the feasibility of using digital pills in this study population as well as understand the acceptability of digital pills for adherence measurement using semi-structured individual interviews. Additionally, the investigators will measure adherence over time, as well as episodes of suboptimal PrEP adherence.

Eligible study participants will be screened and enrolled at Fenway Health (Boston, MA). Participants will complete a quantitative assessment on their history fo substance use, sexual risk and PrEP adherence, and be trained to use the digital pill for 90 days and instructed to take PrEP daily during the course of the study. Participants will return each month for a study visit to assess their use of the technology. At study visit 1 and 3, we will obtain dried blood spots (DBS) to measure drug levels and to confirm adherence detected by the digital pill. The investigators will also obtain drugs of abuse screens from DBS. At the final study visit (3 months), participants will undergo a semi-structured qualitative interview to understand the user response to digital pills.

Participants' engagement with the digital pill system (DPS) was measured over the 90-day study period. The percentages for the total expected ingestions recorded by DPS each month were compared.

The total number recorded ingestions recorded by the digital pill system (DPS) - which included both the number of Reader-detected and manually-reported ingestions - was collected. The Reader-detected ingestions count was used to reflect the number of times the DPS was operated correctly. Successful DPS operation was defined as ingestion of a digital pill, proper use of the wearable Reader, and confirmation of the ingestion on both the Reader and the app. Cumulative data collected at months 1, 2, and 3 are reported in the data table below.

Accuracy of the digital pill system (DPS) in measuring PrEP adherence. To analyze the performance of the DPS, the ground truth of PrEP ingestion events was defined as the pill counts obtained each month (i.e., the number of unused pills returned, subtracted from the number of pills previously dispensed). The number of DPS-recorded ingestions - which included the number of both Reader-detected and manually-reported ingestions - was compared with the aggregate pill count at each monthly timepoint; this was defined as the overall performance metric for the DPS. Cumulative data collected at months 1, 2, and 3 are reported in the data table below.

The total number of manually reported ingestions was collected. The percentages for instances of manually reported ingestions were calculated. The two instances for manually recording ingestions included, a lack of engagement with the Reader or failure to use the Reader properly, and when reported ingestion was not detected by the Reader despite supporting use metrics indicating proper Reader use. Cumulative data collected at months 1, 2, and 3 are reported in the data table below.

The total number of instances in which ingestions were successfully detected by the Reader (i.e., the radio frequency emitter was activated, and the ingestion was recorded by the DPS) was collected. The total number of instances in which manually reported ingestions were not detected by the Reader, despite supporting use metrics (e.g., accelerometer data) indicating proper Reader use was also collected. These counts were combined and interpreted as the number of times that the DPS was operated correctly. Cumulative data collected at months 1, 2, and 3 are reported in the data table below.

We dichotomized TFV-DP levels using a cutoff of ≥700 fmol/punch to indicate at least four doses of PrEP ingested per week. Using TFV-DP in DBS <700 vs ≥700 fmol/punch as a dichotomous variable, and considering the granular continuous adherence data from the digital pill, we then calculated a point biserial correlation between TFV-DP in DBS and digital pill adherence. Additionally, drug concentrations of tenofovir diphosphate as measured in dried blood spot collection at months one and three were compared to DPS-recorded PrEP adherence.

Number of Participants That Completed Qualitative Interview to Evaluate Acceptability of Digital Pills

Acceptability was assessed via individual, semi-structured, qualitative exit interviews conducted at the end of the 90-day study period. The qualitative interview guide was grounded in the Technology Acceptance Model. Questions explored participants' experiences using the digital pill system (DPS), including facilitators and barriers to use, engagement with the technology, and willingness to use the DPS long-term.

Inclusion Criteria: MSM (cisgender male) Self-reported use of non-alcohol substances of abuse in past 6 months Currently taking PrEP Has qualifying laboratory tests (Cr, hepatitis B immunization, STI testing and syphilis) Age 18 or older Exclusion Criteria: Does not speak English HIV positive Identifies as transgender Estimated creatinine clearance <60ml/min Active hepatitis B treatment Does not own a smartphone Taking proton pump inhibitors History of Crohn's disease or ulcerative colitis History of bowel surgery, gastric bypass, bowel stricture History of GI malignancy or radiation to abdomen Unable/unwilling to ingest digital pill

Chai PR, Goodman GR, Bronzi O, Gonzales G, Baez A, Bustamante MJ, Najarro J, Mohamed Y, Sullivan MC, Mayer KH, Boyer EW, O'Cleirigh C, Rosen RK. Real-World User Experiences with a Digital Pill System to Measure PrEP Adherence: Perspectives from MSM with Substance Use. AIDS Behav. 2022 Jul;26(7):2459-2468. doi: 10.1007/s10461-022-03594-9. Epub 2022 Jan 28.

Chai PR, Mohamed Y, Bustamante MJ, Goodman GR, Najarro J, Castillo-Mancilla J, Baez A, Bronzi O, Sullivan MC, Pereira LM, Baumgartner SL, Carnes TC, Mayer KH, Rosen RK, Boyer EW, O'Cleirigh C. DigiPrEP: A Pilot Trial to Evaluate the Feasibility, Acceptability, and Accuracy of a Digital Pill System to Measure PrEP Adherence in Men Who Have Sex With Men Who Use Substances. J Acquir Immune Defic Syndr. 2022 Feb 1;89(2):e5-e15. doi: 10.1097/QAI.0000000000002854.