Multimorbidity classes indicate differential patterns of health care engagement among people who inject drugs

Background: Aging people who inject drugs (PWID) have complex health needs. Health care management could be complicated by persistent substance use, multiple health challenges, and inconsistent access to care. However, we know little about the relationship between chronic multimorbidity and health care engagement in this population. The purpose of this study is to characterize patterns and correlates of chronic disease multimorbidity among PWID.Methods: We conducted a latent class analysis (LCA) using data from the AIDS Linked to the IntraVenous Experience (ALIVE) Study, a community-based observational cohort, to determine classes of multimorbid chronic diseases. We then conducted regressions to determine factors associated with class membership and the impact of each multimorbid class on health events and utilization.Results: Of 1387 individuals included, the majority were male (67%) and Black (81%), with a mean age of 53 years. We identified four classes of multimorbidity: Low Multimorbidity (54%), and Low Multimorbidity Including Psychiatric Comorbidity (26%), Multimorbidity (12%), and Multimorbidity Including Psychiatric Comorbidity (7%). Female sex, baseline age, and receipt of disability were factors significantly associated with membership in all three classes compared to the Low Multimorbidity class. Additionally, PWID in these three classes were signifi-cantly more likely to utilize emergency room and outpatient health care. Membership in both classes with psychiatric comorbidity was associated with significantly higher adjusted odds of receiving medication for opioid use disorder.Discussion: Holistic health care systems can best address the needs of aging PWID with integrated care that provides harm reduction, substance use and mental health treatment together, and wrap around services.