Association for Public Policy Analysis & Management

Research Objective: In 2014, 26 states and the District of Columbia chose to implement the Affordable Care Act (ACA) Medicaid expansions for low-income adults. The objective of this study is to evaluate whether the state Medicaid expansions were associated with changes in insurance coverage, access to and utilization of health care, and self-reported health.

Study Design: Using data from the 2010 to 2014 National Health Interview Survey (NHIS), we examine coverage, access to and utilization of health care, and self-reported health among 19 to 64 year-olds with family incomes below 138% of the Federal Poverty Level, comparing these outcomes before and after the 2014 Medicaid expansions in expansion and non-expansion states. We examined the following specific measures: health insurance coverage (private, Medicaid, or none); improvements in coverage over the previous year; visits to physicians in general practice and specialists; hospitalizations and emergency department visits; skipped or delayed medical care; usual source of care; diagnoses of diabetes, high cholesterol, and hypertension; self-reported health; and depression.

Findings: In the second half of 2014, adults in expansion states experienced increased health insurance (7.4 percentage points [95% CI, 3.4 to 11.3 percentage points]) and Medicaid (10.5 percentage points [CI, 6.5 to 14.5 percentage points]) coverage and better coverage compared with one year before (7.1 percentage points [CI, 2.7 to 11.5 percentage points]) compared with adults in non-expansion states. Medicaid expansions were associated with increased visits to physicians in general practice (6.6 percentage points [CI, 1.3 to 12.0 percentage points]), overnight hospital stays (2.4 percentage points [CI, 0.7 to 4.2 percentage points]), and rates of diagnosis of diabetes (5.2 percentage points [CI, 2.4 to 8.1 percentage points]) and high cholesterol (5.7 percentage points [CI, 2.0 to 9.4 percentage points]). Changes in other outcomes were not statistically significant.

Discussion: The ACA Medicaid expansions were associated with higher rates of insurance coverage, improved quality of coverage, increased utilization of some types of health care, and higher rates of diagnosis of chronic health conditions for low-income adults. While this study looked at a limited post-ACA timeframe that provided information on short-term changes only, these findings can inform current policy discussions in states that are still considering Medicaid expansion as well as early evaluations and health systems planning in states that have already expanded the program.