Association Between Medicaid Managed Care Coverage of Substance Use Services and Treatment Utilization

IMPORTANCE: Medicaid insures a disproportionate share of adults with substance use disorder (SUD) and is thus uniquely positioned to facilitate access to care. Many enrollees receive coverage through Medicaid managed care (MMC) plans, which receive capitated payments in exchange for coverage of a defined set of benefits. Historically, coverage of substance use services has been carved out of MMC plans and financed fee-for-service (FFS) by state Medicaid programs, but in recent years, many states have opted to carve in this benefit. Little is known about whether MMC coverage of substance use services, relative to FFS coverage, is associated with changes in utilization. OBJECTIVE: To examine the association between changes in MMC coverage of substance use services and admissions for substance use treatment. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study examined changes in admissions for substance use treatment in 2 states after coverage of substance use services was either carved into (Nebraska) or carved out of (Maryland) comprehensive MMC coverage. Synthetic control methods were used to compare changes in admissions between states that did and did not alter MMC coverage of substance use services. Data on substance use treatment admissions were obtained from the Treatment Episode Data Set—Admissions from 2010 to 2019. EXPOSURES: Carve-outs or carve-ins of coverage for both inpatient and outpatient substance use services from comprehensive MMC coverage. MAIN OUTCOMES AND MEASURES: Reported substance use treatment admissions per 100 000 residents and admissions by treatment type (ie, rehabilitation or residential, outpatient, and detoxification) per 100 000 residents. RESULTS: Maryland’s carve-out was associated with an additional mean 787.1 (95% CI, 624.6-1141.7) substance use admissions per 100 000 residents during 2015 and 2016, a relative increase of 104.4% (95% CI, 64.4%-154.1%) compared with its synthetic control. This increase was concentrated among changes in outpatient services utilization. In Nebraska, the carve-in was associated with a mean decrease of 97.2 (95% CI, −23.4 to 213.6) admissions per 100 000 residents, a relative decrease of 33.2% (95% CI, −54.1% to 29.6%) compared with its synthetic control and was concentrated primarily among admissions for detoxification services. CONCLUSIONS AND RELEVANCE: The results of this cross-sectional study suggest that carving out coverage of substance use services and financing them through FFS coverage may be associated with overall increases in treatment utilization but with heterogeneous associations across states and treatment types.