Importance: The Patient Protection and Affordable Care Act (ACA) expanded Medicaid eligibility at the discretion of states to US individuals earning up to 138% of the federal poverty level (FPL) and made private insurance subsidies available to most individuals earning up to 400% of the FPL. Its national impact remains debated.
Objective: To determine the association of the ACA with ambulatory quality, patient experience, utilization, and cost.
Design, setting, and participants: This cross-sectional study used difference-in-differences (DiD) analyses comparing outcomes before (2011-2013) and after (2014-2016) ACA implementation for US adults aged 18 to 64 years with income below and greater than or equal to 400% of the FPL. Participants were respondents to the Medical Expenditure Panel Survey, a nationally representative annual survey. Data analysis was performed from January 2021 to March 2022.
Exposures: ACA implementation.
Main outcomes and measures: For quality and experience, this study examined previously published composites based on individual measures, including high-value care composites (eg, preventive testing) and low-value care composites (eg, inappropriate imaging), an overall patient experience rating, a physician communication composite, and an access-to-care composite. For utilization, outpatient, emergency, and inpatient encounters and prescribed medicines were examined. Overall and out-of-pocket expenditures were analyzed for cost.
Results: The total sample included 123 171 individuals (mean [SD] age, 39.9 [13.4] years; 65 034 women [52.8%]). After ACA implementation, adults with income less than 400% of the FPL received increased high-value care (diagnostic and preventive testing) compared with adults with income 400% or higher of the FPL (change from 70% to 72% vs change from 84% to 84%; adjusted DiD, 1.20%; 95% CI, 0.18% to 2.21%; P = .02) with no difference in any other quality composites. Individuals with income less than 400% of the FPL had larger improvements in experience, communication, and access composites compared with those with income greater than or equal to 400% of the FPL (global rating of health, change from 69% to 73% vs change from 79% to 81%; adjusted DiD, 2.12%; 95% CI, 0.18% to 4.05%; P = .03). There were no differences in utilization or cost, except that receipt of primary care increased for those with lower income vs those with higher income (change from 65% to 66% vs change from 80% to 77%; adjusted DiD, 2.97%; 95% CI, 1.18% to 4.77%; P = .001) and total out-of-pocket expenditures decreased for those with lower income vs those with higher income (change from $504 to $439 vs from $757 to $769; adjusted DiD, -$105.50; 95% CI, -$167.80 to -$43.20; P = .001).
Conclusions and relevance: In this cross-sectional national study, the ACA was associated with improved patient experience, communication, and access and decreased out-of-pocket expenditures, but little or no change in quality, utilization, and total cost.