Effects of the ACA Medicaid Expansion on Racial Disparities in Health and Health Care


This issue brief builds on a previous literature review that broadly investigated the effects of Medicaid expansion by examining how the expansion has affected racial disparities in health coverage, access to care, health outcomes, and economic outcomes. It is based on KFF’s review of 65 studies which examined the impacts of Medicaid expansion by race/ethnicity and were published beginning in January 2014 (when the coverage provisions of the ACA went into effect) through July 2020.1 This brief groups findings into four broad categories: coverage; access to and use of care; health outcomes and quality of care; and economic measures. (Appendix A provides a list of citations for each of the included studies, grouped by the four categories of findings.) Across categories, most research focused on disparities for Black and Hispanic individuals, leaving significant gaps in research to understand impacts for other groups of color.

This review only discusses findings related to changes in racial/ethnic disparities associated with Medicaid expansion. An additional body of work has examined effects of the ACA broadly and suggests significant decreases in disparities following the ACA, but did not examine effects of the Medicaid expansion specifically or differential effects by state Medicaid expansion status. While these studies are not included in this brief, expansion may have played a significant role in the effects found in these studies. (See Methods for more details.)

Key Findings: Effects of Medicaid Expansion

Disparities in Health Coverage

Across the 29 studies that examined how Medicaid expansion has affected disparities in health coverage, 21 found that Medicaid expansion helped narrow but did not eliminate racial/ethnic disparities in health coverage. Studies varied in the groups they examined and the metrics they included to assess coverage. Some of these studies had mixed results; for example, finding disparities narrowed for one racial/ethnic group but that expansion had no effect on or widened disparities for another group. Similarly, findings sometimes varied by measure; for example, some studies found disparities in uninsured rates decreased but those in Medicaid coverage did not, or vice versa. The few studies that did not find expansion had any positive effect on coverage disparities (including a few that found increased disparities) generally considered effects for a targeted population or only used data from the first year of expansion.2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22

Most studies examined changes in coverage disparities for Black and Hispanic individuals but did not provide findings for other groups of color. There was slightly stronger and more consistent evidence of narrowed coverage disparities for Black individuals compared to Hispanic individuals. A smaller number of studies considered how expansion affected coverage disparities for other groups of color, and findings for these groups were mixed.23,24,25,26 A few studies further found variation in how Medicaid expansion affected coverage disparities by country of origin, language, and gender.27,28,29

Several studies found decreased racial/ethnic coverage disparities among cancer patients and survivors. Specifically, studies suggest that expansion was associated with decreased coverage disparities among Black and Hispanic patients with newly diagnosed cancer; patients with lung, breast, or prostate cancer; patients with head and neck cancer; and women with endometrial cancer.30,31,32,33,34,35 Study authors explain that racial/ethnic disparities in cancer care and outcomes are longstanding and may be mitigated by increases in insurance coverage.

Disparities in Access to and Use of Care

Most of the 24 studies that examined how Medicaid expansion affected access to and use of care found that it was generally associated with improvements in these measures for some groups but more limited evidence that it reduced disparities that existed prior to the expansion. Ten studies found that Medicaid expansion was associated with narrowed disparities in at least one measure of access for at least one group of color. Within these studies, findings often varied by racial/ethnic group and measure; for example, finding reductions in disparities for some groups and in some measures but not others. The remaining studies did not find expansion reduced access disparities. Two studies found disparities widened for one more or more measures due to larger improvements among White individuals compared to people of color.36,37  Most studies considered disparities for Black and Hispanic individuals; few considered effects for other groups.38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59 Studies focused on several types of measures:

  • Access to primary care: While most studies found overall improvements in the share of people having a usual source of care, a personal doctor, and a recent doctor’s visit, they generally did not find expansion was associated with narrowed racial disparities in these measures or had mixed findings across groups, with improvements for one group but not another.60,61,62,63,64,65
  • Affordability of care: Studies generally found improvements in affordability of care across groups, but mixed findings regarding effects on disparities. Several studies found that expansion decreased the gap between Black and White individuals in ability to afford care, but studies generally did not find a narrowing of disparities in affordability between Hispanic and White individuals.66,67,68,69,70,71,72,73
  • Receipt of preventive care: In contrast to narrowed disparities in coverage among cancer patients associated with expansion, studies did not find expansion was associated with reduced disparities in cancer screening rates, cancer stage at diagnosis, and utilization of cancer surgery.74,75,76,77 One study also found that expansion did not affect disparities in receipt of the flu shot, while other studies found it was associated with narrowed disparities in HIV testing rates and in perforated appendix admission rates (which provide insight into the extent to which patients are able to obtain care earlier to prevent perforation).78,79,80
  • Utilization of health care services: Most studies that consider utilization of services such as surgery for specific conditions find no effect of expansion on disparities.81,82,83,84,85,86,87,88 In contrast, a few studies found decreased disparities for at least one racial group in utilization of other specific services, including heart transplant listing rates, high-risk cancer surgery, and receipt of naltrexone or counseling without medication to address opioid use disorder (although this final study also suggested that White adults were more likely than adults of color to receive buprenorphine for opioid use disorder).89,90,91

Disparities in Health Outcomes & Quality of Care

Studies suggest that Medicaid expansion narrowed disparities in some health outcomes for Black and Hispanic individuals, particularly related to infant and maternal health. Research in these areas generally did not examine effects for other groups of color. Studies suggest larger improvements for Black and, in some cases, Hispanic individuals as compared to White individuals in rates of infant mortality and other adverse birth outcomes and maternal mortality, helping to narrow but not eliminating disparities in these measures.92,93,94,95,96  Other studies also found disparities narrowed for at least one group in measures of self-reported health and one-year mortality among end-stage renal disease patients initiating dialysis, but findings were mixed across groups.97,98,99 Other research found no effect on survival rates among women with endometrial cancer across racial/ethnic groups.100 No studies found increased disparities in health outcomes, although two studies found increased disparities in certain measures of quality of hospital care.101,102

Disparities in Payer Mix and Other Economic Outcomes

The limited number of studies that considered effects of expansion on disparities in economic measures had mixed results but suggested some narrowing of differences in the payer mix for provider reimbursement for health care services (the proportion of uninsured patients vs. Medicaid patients) by patient race/ethnicity and for measures of individual economic well-being. Research found greater increases in Medicaid-insured visits and/or decreases in uninsured visits among people of color compared to White people for a variety of specific conditions, although a few other studies suggested that expansion had no effect on or widened disparities in reimbursement patterns for other conditions.103,104,105,106,107,108,109,110  A few studies examined disparities in employment and other measures of individual economic well-being. For example, studies suggested that expansion was associated with gains in employment, student status, and volunteerism that reduced racial disparities.111,112 However, findings varied across racial and ethnic groups.113  Overall, research in this area remains limited.


Prior to the ACA, there were significant disparities in health and health care. The ACA Medicaid expansion provided an opportunity to reduce longstanding disparities in health coverage, which may contribute to improvements in and narrowed disparities in access to and use of care and health outcomes. This review of the literature finds that Medicaid expansion has helped to narrow but has not eliminated disparities in coverage. It also shows that Medicaid expansion was associated with improvements in measures of access to care, use of care, health outcomes, and certain economic measures across racial/ethnic groups, but its effects on disparities were often mixed across groups and/or measures. This review further shows that most studies only examined effects for Black and Hispanic individuals, leaving continued gaps in data and research for other groups.

Together these findings illustrate that the Medicaid expansion has contributed to reductions in longstanding racial disparities in health coverage. They further suggest that, while increased coverage can help improve access to care and contribute to improvements in health, coverage alone is not enough to eliminate disparities in these measures. This finding reflects that a broad range of social and economic factors beyond health coverage and health care influence and drive health. As such, the findings point to the importance of ongoing efforts to address health disparities considering a broad array of factors within and outside the heath sector, including historic and ongoing racism and discrimination.

This literature review includes studies, analyses, and reports published by government, research, and policy organizations using data from 2014 or later. This brief includes studies that examine impacts of the Medicaid expansion by race/ethnicity (even if impacts on racial/ethnic disparities were not the primary focus of the study). It excludes studies on impacts of ACA coverage expansions generally (not specific to Medicaid expansion alone), studies investigating potential effects of expansion in states that have not (or had not, at the time of the study) expanded Medicaid, and reports from advocacy organizations and media sources.

To collect relevant studies, we conducted keyword searches of PubMed and other academic health/social policy search engines as well as websites of government, research, and policy organizations that publish health policy-related research. We also used a snowballing technique of pulling additional studies from reference lists in previously collected studies. While we tried to be as comprehensive as possible in our inclusion of studies and findings that meet our criteria, it is possible that we missed some relevant studies or findings. For each study, we read the final paper/report and summarized the population studied, data and methods used, and findings. In instances of conflicting findings within a study, or if a reviewer had questions about specific findings, multiple reviewers read and classified the study to characterize its findings. In the issue brief text, findings are broken out and reported separately in four broad categories: Medicaid expansion’s impact on coverage disparities; disparities in access to and use of care; disparities in health outcomes and quality of care; and disparities in economic metrics. Studies may be cited in multiple categories or in multiple places within a category. Appendix A provides a list of citations for each of the included studies, grouped by the four categories of findings.

Executive Summary Appendix

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