Racial/Ethnic Differences in Association Between Medicaid Expansion and Causes and Costs of Readmission After Acute Ischemic Stroke.

Objective: The purpose of this study was to examine whether the relative frequency of leading causes and total associated costs of readmission after acute ischemic stroke changed with Medicaid expansion, and how these changes differed by racial/ethnic group.

Methods: We used a difference-in-differences approach to compare changes in the relative frequency of leading causes of unplanned 30-day readmission and to examine changes in the costs associated with unplanned readmission between expansion states (AR, MD, NM, and WA) and non-expansion states (FL and GA). To estimate the differential effect of Medicaid expansion by race/ethnicity on the causes and cost of readmission, we added a time*treatment*race interaction. Multinomial logistic regression was performed to analyze the changes in readmission cause. Gamma log-link modeling was used to study changes in readmission costs for expansion compared to non-expansion states.

Results: The final multinomial model showed an association between expanded Medicaid and the relative frequency of sepsis readmission for White patients. According to predictive margins, White patients in expansion states had an estimated increase of 3.3 percentage points in the share of readmissions for sepsis but not for White patients in non-expansion states. In contrast, non-White patients in expansion states had a decrease of 1.8 percentage points in the share of readmissions for sepsis. Overall, Medicaid expansion was associated with a net increase of 6.7 percentage points in the share of readmissions for sepsis among non-Hispanic Whites relative to all other groups. In the final gamma model, Medicaid expansion was associated with a decrease in readmission costs overall. According to predictive margins, the net cost reduction in expansion versus non-expansion states was an average of $2509.

Conclusions: Medicaid expansion is associated with an overall decrease in unplanned readmission costs and an increase among readmitted White patients in the likelihood of readmission for sepsis.