Association of Medicaid expansion with health insurance, unmet need for medical care and substance use disorder treatment among people who inject drugs in 13 US states

Background and AimsImpoverished people who inject drugs (PWID) are at the epicenter of US drug-related epidemics. Medicaid expansion is designed to reduce cost-related barriers to care by expanding Medicaid coverage to all US adults living at or below 138% of the federal poverty line. This study aimed to measure whether Medicaid expansion is (1) positively associated with the probability that participants are currently insured; (2) inversely related to the probability of reporting unmet need for medical care due to cost in the past year; and (3) positively associated with the probability that they report receiving substance use disorder (SUD) treatment in the past year, among PWID subsisting at <= 138% of the federal poverty line.DesignA two-way fixed-effects model was used to analyze serial cross-sectional observational data.SettingSeventeen metro areas in 13 US states took part in the study.ParticipantsParticipants were PWID who took part in any of the three waves (2012, 2015, 2018) of data gathered in the Center for Disease Control and Prevention's National HIV Behavioral Surveillance (NHBS), were aged <= 64 years and had incomes <= 138% of the federal poverty line. For SUD treatment analyses, the sample was further limited to PWID who used drugs daily, a proxy for SUD.MeasurementsState-level Medicaid expansion was measured using Kaiser Family Foundation data. Individual-level self-report measures were drawn from the NHBS surveys (e.g. health insurance coverage, unmet need for medical care because of its cost, SUD treatment program participation).FindingsThe sample for the insurance and unmet need analyses consisted of 19 946 impoverished PWID across 13 US states and 3 years. Approximately two-thirds were unhoused in the past year; 41.6% reported annual household incomes < $5000. In multivariable models, expansion was associated with a 19.0 [95% confidence interval (CI) = 9.0, 30.0] percentage-point increase in the probability of insurance coverage, and a 9.0 (95% CI = -15.0, -0.2) percentage-point reduction in the probability of unmet need. Expansion was unrelated to SUD treatment among PWID who used daily (n = 17 584).ConclusionsUS Medicaid expansion may curb drug-related epidemics among impoverished people who inject drugs by increasing health insurance coverage and reducing unmet need for care. Persisting non-financial barriers may undermine expansion's impact upon substance use disorder treatment in this sample.