Panel Paper:
The Impact of the Maryland Medicaid Health Home Waiver on Emergency Department and Inpatient Utilization Among Individuals with Serious Mental Illness
*Names in bold indicate Presenter
Study Design: We used a difference-in-difference design to compare changes in outcomes among Health Home participants to changes in outcomes in a weighted comparison group of participants with serious mental illness not enrolled in Health Homes. We analyzed longitudinal Medicaid administrative claims data using marginal structural modeling with inverse probability of treatment weighting to control for baseline characteristics and time-varying confounding. We analyzed the effect of Health Home enrollment on the probability and frequency of all-cause, mental health, substance use disorder, and somatic ED visits and inpatient admissions over a 15-month post-Health Home implementation period. We measured the effect of any Health Home exposure as well as the cumulative effect of Health Home enrollment over time.
Population Studied: Maryland Medicaid Health Home enrollees with serious mental illness ages 21-64 (N=3,095) and a comparison group of Maryland Medicaid beneficiaries ages 21-64 who were not enrolled in the Health Home program (N=10,131).
Principal Findings: Any Health Home enrollment was associated with reduced probability of having any somatic ED visit and any inpatient substance use disorder admission. Any Health Home enrollment was also associated with a reduction in the number of ED somatic visits (0.45 to 0.41 per 3 month period) and the number of inpatient substance use disorder treatment days (0.02 to 0.01 per 3 month period). This translates to a reduction of approximately 1600 somatic ED visits and 400 inpatient substance use disorder treatment admissions per 10,000 people per year. Health Home enrollment for longer periods of time was associated with stronger effects. For every additional 3 months of enrollment in a Health Home, the odds were reduced of having any ED somatic visits (OR: 0.97 95% CI: 0.96, 0.99), any inpatient substance use disorder admission (OR: 0.92, CI: 0.85, 0.99), and any ED substance use disorder visit (OR: 0.96, 95% CI: 0.92, 1.00).
Conclusions: Maryland’s Medicaid health home program for people with serious mental illness was associated with reductions in the probability and frequency of somatic ED and inpatient substance use disorder treatment use. Longer enrollment in Health Homes was associated with reduced likelihood of using ED somatic and substance use disorder care and inpatient substance use disorder care. Maryland’s Medicaid Health Home model, in which community mental health programs coordinate somatic, behavioral health and social support services for people with serious mental illness, may prevent costly somatic ED use and substance use disorder-related ED and inpatient care for individuals with serious mental illness, a high-need population. This model could be considered for implementation in other states.
