The effects of the Maryland Medicaid Health Home Waiver on Emergency Department and inpatient utilization among individuals with serious mental illness.

Objective: The Maryland Medicaid health home program, established through the Affordable Care Act's Medicaid health home waiver, integrates primary care services into specialty mental health programs for adults with serious mental illness (SMI). We evaluated the effect of this program on all-cause, physical, and behavioral health emergency department (ED) and inpatient utilization.

Method: Using marginal structural modeling to control for time-invariant and time-varying confounding, we analyzed Medicaid administrative claims data for 12,232 enrollees with SMI from October 1, 2012 to December 31, 2016; 3319 individuals were enrolled in a BHH and 8913 were never enrolled.

Results: Health home enrollment was associated with reduced probability of all-cause (PP: 0.23 BHH enrollment vs. 0.26 non-enrollment, p < 0.01) and physical health ED visits (PP: 0.21 BHH enrollment vs. 0.24 non-enrollment, p < 0.01) and no effect on inpatient admissions per person-three-month period.

Conclusion: These results suggest the Maryland Medicaid health home waiver's focus on supporting physical health care coordination by specialty mental health programs may be preventing ED visits among adults with SMI, although effect sizes are small.