The impact of Medicaid expansion on spending and utilization by older low-income Medicare beneficiaries

Health Serv Res. 2023 Oct;58(5):1024-1034. doi: 10.1111/1475-6773.14155. Epub 2023 Apr 3.


Objective: To examine indirect spillover effects of Affordable Care Act (ACA) Medicaid expansions to working-age adults on health care coverage, spending, and utilization by older low-income Medicare beneficiaries.

Data sources: 2010-2018 Health and Retirement Study survey data linked to annual Medicare beneficiary summary files.

Study design: We estimated individual-level difference-in-differences models of total spending for inpatient, institutional outpatient, physician/professional provider services; inpatient stays, outpatient visits, physician visits; and Medicaid and Part A and B Medicare coverage. We compared changes in outcomes before and after Medicaid expansion in expansion versus nonexpansion states.

Data collection/extraction methods: The sample included low-income respondents aged 69 and older with linked Medicare data, enrolled in full-year traditional Medicare, and residing in the community.

Principal findings: ACA Medicaid expansion was associated with a 9.8 percentage point increase in Medicaid coverage (95% CI: 0.020-0.176), a 4.4 percentage point increase in having any institutional outpatient spending (95% CI: 0.005-0.083), and a positive but statistically insignificant 2.4 percentage point change in Part B enrollment (95% CI: -0.003 to 0.050, p = 0.079).

Conclusions: ACA Medicaid expansion was associated with more institutional outpatient spending among older low-income Medicare beneficiaries. Increased care costs should be weighed against potential benefits from increased realized access to care.

Keywords: Medicaid; Medicare; access/demand/utilization of services; aging/elderly/geriatrics; health policy/politics/law/regulation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Aged
  • Health Services Accessibility
  • Humans
  • Insurance Coverage
  • Medicaid*
  • Medicare*
  • Patient Protection and Affordable Care Act
  • Poverty
  • United States