Understanding healthcare engagement for people who inject drugs.

People who inject drugs (PWID) are at an increased risk of multimorbid mental health and chronic diseases, which are frequently underdiagnosed and under-treated due to systemic barriers and ongoing substance use. Healthcare engagement is essential to address these conditions and prevent excess morbidity and mortality. The goal of this study was to understand how PWID engage in care for their chronic health conditions and substance use treatment given the known historic and pervasive barriers. We conducted 24 semistructured qualitative interviews informed by the Behavioral Model for Vulnerable Populations between July-September 2019. Participants were sampled across a range of comorbidities, including co-occurring mental health disorders. Thematic analysis was conducted to explore experiences of healthcare engagement for multimorbid chronic diseases, mental health, and treatment for substance use disorder. Mean age for participants was 58 years; 63% reported male sex and 83% reported Black race. Interviews yielded themes regarding healthcare access and wraparound services, positive patient-provider relationships, service integration for substance use treatment and mental health, healthcare needs alignment, medication of opioid use disorder stigma, and acceptance of healthcare. Taken together, participants described how these themes enabled healthcare engagement. Engagement in care is crucial to support health and recovery. Clinical implications include the importance of strengthening patient-provider relationships, encouraging integration of medical and mental health services, and counseling on substance use treatment options in a non- stigmatizing manner. Additionally, policy to reimburse wrap-around support for substance use recovery can improve care engagement and outcomes related to chronic diseases, mental health, and substance use among PWID. No Patient or Public Contribution: While we acknowledge and thank ALIVE participants for their time for data collection and sharing their perspectives, no ALIVE participants, other people who use drugs, and service users were involved in data collection, analysis or interpretation of data, or in preparation of the manuscript.