Smartphone-Based Ecological Momentary Assessment to Monitor Opioid Use and Overdose Among People Who Use Opioids: Prospective Observational Feasibility Study.

Background: Opioids account for 76% of drug overdose deaths in the United States, with nearly 80,000 opioid overdose deaths annually. The risk of overdose is dynamic and influenced by rapidly changing behaviors and contexts that are not well captured by retrospective or infrequent assessments. Ecological momentary assessment (EMA) allows repeated near real-time reporting of behaviors and experiences in natural settings. Objective: This study evaluated the feasibility and acceptability of smartphone-based EMA among people who use opioids to monitor opioid use, overdose experiences, and naloxone access. Methods: Participants were recruited through the New Haven Syringe Services Program in New Haven, Connecticut, and completed fixed-time, twice-daily EMA prompts for 30 days using a smartphone app. EMA measures assessed behaviors and experiences occurring within the previous 12 hours, including opioid craving, plans to use drugs, opioid use, overdose experiences, and naloxone access. Feasibility was assessed through recruitment, retention, and EMA completion rates, as well as the reporting of drug use-related behaviors. Acceptability was evaluated using exit surveys assessing ease of use, burden, and privacy, as well as qualitative interviews. Results: Of the 13 screened individuals, 10 were enrolled and completed the baseline assessment. A total of 9 (90%) participants completed EMA and responded to 411 prompts, with an overall compliance rate of a mean of 85.0% (SD 8.7%). Compliance was similar across morning (84.2%, SD 13.1%) and evening (85.8%, SD 11.2%) prompts. Participants reported opioid cravings (274 reports), plans to use illicit drugs (252 reports), and opioid use (411 reports) during the study period. Two participants reported overdose events (5 reports) and were carrying naloxone during each overdose event. Acceptability ratings were high: all participants reported that EMA prompts were easy to understand and private, and most did not find them burdensome. Qualitative feedback further highlighted the ease of use, integration into daily routines, and increased self-awareness, although some participants reported emotional discomfort when reflecting on their substance use. Conclusions: Smartphone-based EMA was feasible and acceptable among people who use opioids recruited through a syringe service program. EMA may support the monitoring of opioid use, overdose experiences, and naloxone access, and it may inform future digital health interventions aimed at reducing harm, including overdose risk, among people who use opioids.