Does Medicaid Improve Health?

This perennial policy question has resurfaced, particularly after the US House of Representatives recently passed a budget blueprint tasking the committee overseeing Medicaid and Medicare with cutting $880 billion over the next 10 years.¹ This issue was also a focal point during state deliberations on whether to adopt Medicaid expansions under the Affordable Care Act (ACA). Since the ACA’s passage in 2015, 40 states and the District of Columbia have expanded Medicaid, with a few adopting it through citizen ballot initiatives, while 10 states have not.² Because of the staggered implementation of Medicaid expansion, Medicaid is far more studied than other forms of coverage. Whether this focus is fair or not is debatable,³ but Medicaid skeptics often cite research my colleagues and I conducted 15 years ago—the Oregon Health Insurance Experiment (OHIE)—as evidence against expansion. More recently, some have used this research to justify targeting Medicaid spending⁴ to offset the continuation of the 2017 tax cuts, which disproportionately benefit higher-income Americans.

The OHIE leveraged an Oregon lottery in 2008 to allocate 10 000 Medicaid slots, allowing us to estimate the causal impact of Medicaid on uninsured nonelderly adults. Our findings showed that, compared with being uninsured, Medicaid increased health care utilization across all types of care, improved self-reported health, reduced clinical depression, and improved financial stability.⁵ However, we found no statistically significant differences in blood sugar control, high blood pressure, or cholesterol.⁶ Mortality is a rare event among nonelderly adults (0.8% of our control sample died during the study period), and while our non‒statistically significant point estimates suggested a reduction in mortality attributable to Medicaid, the wide confidence intervals indicated that we lacked the power to draw any conclusions.⁵

One key takeaway from the OHIE is that Medicaid did what insurance is supposed to do: it increased access to care and protected the finances of low-income adults. Although we did not observe improvements in specific metrics like diabetes or blood pressure control, the improvements we did see in self-reported health are significant and offer a broader picture of Medicaid’s impact. Increases in health care utilization are suggestive of better long-term health outcomes, but more research was needed. Fortunately, this is not the end of the causal empirical basis for understanding the relationship between Medicaid and health outcomes.

MEDICAID’S IMPACT ON MORTALITY

In the past 15 years, several rigorous studies have been conducted with sufficient power to detect population-level health improvements associated with Medicaid—most importantly, its effects on mortality. For instance, Sommers et al. found a 6.1% relative reduction in mortality when comparing a 10-year cohort of individuals in three Medicaid expansion states compared with neighboring states without expansion.⁷ Miller et al. linked large-scale federal survey data with administrative death records and similarly estimated a 9.4% reduction in mortality related to Medicaid expansion.⁸ Wherry and Meyer used a regression discontinuity approach from a Medicaid expansion that only applied to children born after a certain date and found a 13% to 20% reduction in mortality rates among Black adolescents later in life.⁹

A timely and rigorous study in this issue of AJPH further strengthens this accumulating body of evidence, focusing on Medicaid’s role during the COVID-19 pandemic. In just under two weeks at the start of the pandemic, 9 million Americans filed for unemployment, and employment trends did not return to normal until 2022.¹⁰ In the United States, employment is closely tied to both income and health insurance. This poses a unique test of Medicaid as part of the safety net.

In their study, reported in this issuer of AJPH, Han et al. (p. 890) used data from the National Center for Health Statistics and the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program Mortality database to compare mortality trends in Medicaid expansion versus nonexpansion states during the pandemic. They found that while all-cause mortality increased among adults aged 20 to 64 years during the pandemic, the rise was slower in Medicaid expansion states than in nonexpansion states. Specifically, they found that Medicaid expansion was associated with a net decrease of 31.8 deaths per 100 000 person-years following the pandemic, compared with mortality rates in nonexpansion states. This difference in trends was statistically significant overall and for deaths related to chronic illnesses like heart and liver disease, though similar non‒statistically significant trends were observed for 11 of 14 major causes of death. The protective effect of Medicaid was consistent across age, sex, and race.

POLICY CONSIDERATION FOR LIFE-SAVING POTENTIAL OF MEDICAID

This study is significant for several reasons. First, because Medicaid expansions are funded at 90% by the federal government, and the federal government can run deficits while most states are constitutionally required to maintain a balanced budget, the program was able to grow in response to the increased need caused by rising unemployment. This was not the case in nonexpansion states, where Medicaid eligibility remained limited.¹¹ Current Republican proposals to change the federal share of Medicaid expansion could place additional pressure on states during times of economic insecurity, such as public health emergencies, national recessions, or natural disasters. In fact, 12 states have “trigger laws” that could end Medicaid expansion if the federal cost-sharing parameters change.¹²

Second, consider a counterfactual scenario in which Medicaid work requirements were in place during the COVID-19 pandemic. Low-income Americans who became uninsured when they lost their jobs would have been further penalized by these requirements. This study suggests that if COVID-19 did not claim their lives, chronic diseases and other health issues could have. Third, this study highlights the benefits of continuous Medicaid coverage, which was especially relevant during the pandemic when re-enrollment requirements were paused and people did not churn off and on the program because of minor fluctuations in income or the administrative burden of reapplying.

Finally, it is important to consider that mortality before the age of 65 years is considered premature—13 years below the US life expectancy and more than 15 years below that of the United Kingdom, a country with a universal health insurance scheme.¹³ Excess mortality because of uninsurance represents more than a decade of time lost with family and loved ones. With 10 states still refusing to expand Medicaid and the program under significant legislative threat, this research serves as a reminder that Medicaid is a crucial part of the public health safety net and, quite literally, saves lives.