ABSTRACT
Hospital readmission within 30 days is undesirable and costly. Most programs and studies have focused on the Medicare population and readmission prevention through discharge planning; less is understood about how Medicaid might reduce readmissions to improve outcomes and control program costs. The objective of this study was to estimate the relationship between the Colorado Medicaid Accountable Care Collaborative (ACC) and 30-day hospital readmission rates. A difference-in-differences design was used to compare 30-day readmissions before and after Medicaid members were enrolled in the ACC program using 2 different control groups: Medicaid members not enrolled and commercially insured. The authors used Probit regressions at the hospital level, controlling for patient characteristics, and clustered errors at the provider level. The study sample included Colorado adults ages 19-64 with qualifying hospital discharge. Analysis data included Medicaid and commercial payer administrative claims data (2009-2015) from Colorado's All-Payer Claims Database. The ACC program significantly reduced 30-day readmissions among Colorado Medicaid patients. Participation in the ACC program reduced the probability of a 30-day readmission by 1.4% (P < 0.001), with the largest effect among maternity and delivery patients. Because the majority of Medicaid members are female, even after Medicaid expansion, and Medicaid covers a disproportionate share of complex births, maternity and delivery readmissions are a fruitful area for reducing Medicaid expenditures. To reduce readmissions, Medicaid programs will need to develop interventions specific to their populations.