Medicaid expansion and 30-day hospital readmissions: A nationwide study.

In 2010, Congress enacted the Patient Protection and Affordable Care Act (ACA) to enhance health insurance affordability via subsidies and Medicaid expansion (ME). However, not all states adopted ME. We examined national hospital readmissions from 2005 to 2019 to investigate readmission reduction trends based on state ME status. The states were divided into those that expanded Medicaid in 2014 (ME-States) and those that did not until 2019 (non-ME States). Using a difference-in-difference framework and adjusting for hospital and population characteristics, we assessed the relationship between ME and 30-day readmissions following pneumonia, heart failure (HF), and acute myocardial infarction (AMI) hospitalizations. Both before and after the expansion, ME-States had higher mean readmission rates than non-ME-States. After ME, hospitals in ME-States exhibited larger reductions in readmission rates compared to non-ACA States: pneumonia (-0.12%; 95% confidence interval [CI] = -0.19%, -0.04%; p = .002), HF (-0.18%; 95% CI = -0.28%, -0.08%; p = .001), and AMI (-0.23%; 95% CI = -0.32%, -0.13%; p < .001).