“The lifesaving impacts of Medicaid expansion are large: an estimated 39 to 64 percent reduction in annual mortality rates for older adults gaining coverage.”The Affordable Care Act’s (ACA) expansion of Medicaid to low-income adults is preventing thousands of premature deaths each year, a landmark study finds.[1] It saved the lives of at least 19,200 adults aged 55 to 64 over the four-year period from 2014 to 2017. Conversely, 15,600 older adults died prematurely because of state decisions not to expand Medicaid. (See Figure 1; see Table 1 for state-by-state estimates.) The lifesaving impacts of Medicaid expansion are large: an estimated 39 to 64 percent reduction in annual mortality rates for older adults gaining coverage.

The new research fills a void, using a novel dataset to document sizable declines in mortality that smaller surveys could not detect. But its findings are consistent with a large body of research that has already documented that Medicaid expansion improves access to care and health outcomes.[2] For example, research shows that Medicaid expansion increased the share of low-income adults using medications to control chronic conditions like heart disease and diabetes. The new study finds particularly clear evidence of a drop in mortality from conditions like these, which are amenable to medication and other treatment.

This new evidence that thousands of lives are at stake should give states that have not yet expanded Medicaid one more reason to do so. It should also finally put to rest claims that Medicaid doesn’t provide quality coverage, such as Center for Medicare & Medicaid Services (CMS) Administrator Seema Verma’s suggestion that Medicaid expansion gave low-income adults “a[n insurance] card without care.”[3] On top of the already well-documented gains in access to care and financial security, the new study shows that gaining Medicaid coverage is literally a matter of life and death, particularly for people with serious health needs.

Sharp Drop in Premature Deaths After Expansion

The new study, by Sarah Miller, Sean Altekruse, Norman Johnson, and Laura Wherry (researchers at the University of Michigan, National Institutes of Health, Census Bureau, and University of California Los Angeles, respectively), compares mortality rates among 55- to 64-year-olds likely eligible for Medicaid in expansion states to mortality rates among similar older adults in non-expansion states.[4]

A challenge in assessing the impact of Medicaid expansion on mortality is that mortality rates among non-elderly adults are low (about 33 deaths per 10,000 people each year),[5] and only a fraction of those deaths are from “health-care-amenable” causes — preventable deaths that better medical care could help avoid (for example, from heart disease or diabetes) — versus causes less amenable to treatment (such as car accidents). This means that even sizable reductions in health-care-amenable mortality are hard to detect in most data sets.

The authors overcome this challenge in two ways. First, as noted, they focus on older adults, who have higher mortality rates overall and are at greater risk of premature death from treatable conditions. Second, they construct a novel dataset that links the American Community Survey — the largest federal survey with information on income, age, and other determinants of Medicaid eligibility — with administrative death records. The large sample lets them detect small changes in mortality that aren’t evident in other data.

Prior to Medicaid expansion, the study finds, mortality trends among low-income older adults were similar in states that would and would not later expand Medicaid. But they sharply diverged starting in 2014, the first year of expansion. In 2014 the annual mortality rate for low-income older adults in expansion states fell by about 9 deaths per 10,000 people, compared to similar adults in non-expansion states, with the impact growing each year to about 21 deaths per 10,000 people in year 4.[6] (See Figure 2.) These differences amount to about 19,200 lives saved among older adults in expansion states over four years, and about 15,600 lives lost among older adults in states choosing not to expand. By 2017 the annual impact is more than 7,000 lives saved in expansion states and almost 6,000 lives lost in non-expansion states.[7]

Even these estimates may understate the full effects of expansion. First, as the authors note, the effects grow in each year covered by the study (2014-2017), so it appears that “prolonged exposure to Medicaid results in increasing health improvements,” indicating that annual impacts in later years might be larger. Second, the study omits four states and Washington, D.C. that expanded Medicaid under the ACA but did so before 2014. In total, these states now cover about 8.6 million people, or about 20 percent as many as are covered in the expansion states the study does include.[8]

Nonetheless, the estimates show that Medicaid expansion ranks with other major public health interventions in terms of its lifesaving potential. If all states had expanded Medicaid, the number of lives saved just among older adults in 2017 would roughly equal the number of lives that seatbelts saved among the full population, based on estimates from the National Highway Traffic Safety Commission.[9] (See Figure 3.)

These aggregate mortality reductions translate into large drops in the annual risk of premature death for older adults gaining coverage: a 39 to 64 percent decrease in annual mortality rates, the authors estimate.[10] To put that figure in context, it’s close to the gap in mortality rates for older adults with incomes below the poverty line versus those above 400 percent of the poverty line.[11]

The authors conduct several additional analyses to confirm that these gains are the result of expansion. First, they examine mortality trends in expansion and non-expansion states for people over 65, a group that was not affected by Medicaid expansion (since they already had coverage through Medicare), but likely would have been affected by other changes in public health or health care that differed between expansion and non-expansion states. There was no divergence in mortality rates for seniors between expansion and non-expansion states in 2014.

The authors also demonstrate that the mortality reductions were driven by reductions in deaths from “health-care-amenable” causes such as cardiovascular disease, diabetes, and kidney disease, conditions known to be responsive to medical care. As discussed further below, that’s consistent with the drop in overall mortality being driven by the types of gains in access to care that other research has already attributed to expansion.

Findings Consistent With Other Research on Benefits of Expansion

The new study’s results are striking but not surprising, since a large body of research has already documented mechanisms by which Medicaid expansion could be preventing premature deaths, and other studies have found reductions in mortality from pre-ACA coverage expansions.

For example, other studies (summarized in Figure 4) have found that Medicaid expansion resulted in:

Large increases in prescriptions filled for heart disease, diabetes, mental health conditions, and other chronic conditions. [12]

Large increases in the share of low-income adults getting regular check-ups and other preventive care, and large decreases in the share without a personal physician or usual source of care. [13]

Large decreases in the share of low-income adults skipping medications due to cost. [14]

Decreases in the share of low-income adults screening positive for depression. [15]

An increase in the share of people getting surgical care consistent with clinical guidelines, for example less invasive surgical techniques where feasible. [16]

Increases in cancer screenings and early-stage cancer diagnoses. [17]

A decrease in one-year mortality rates for patients diagnosed with end-stage renal disease.[18]

As noted above, the authors find that post-expansion drops in mortality were driven by drops in deaths from the types of conditions expected to improve with health treatment, such as diabetes and cardiovascular disease. Other research finds that access to medications in particular has a large impact on mortality from these conditions.[19]

Meanwhile, studies looking at pre-ACA coverage expansions to low-income adults have found mortality reductions in line with the new estimates. One study found that early Medicaid expansions in New York, Arizona, and Maine led to a (statistically significant) 6 percent reduction in mortality after five years, which translates to roughly 3,200 fewer deaths among 20- to 64 year-olds in those three states in a single year; the study also pointed to the greatest reductions being in deaths by health-care-amenable causes.[20] Another study found that Massachusetts’ Medicaid expansion led to a significant 2.9 percent reduction in all-cause mortality, which translates to roughly 340 fewer deaths among 20- to 64 year-olds in a single year, with the majority of the reduction being deaths in health-care-amenable causes.[21]

The new study’s authors also show that their results are in line with an Oregon study that some cite as evidence that expanding Medicaid to low-income adults does not save lives. In 2008 Oregon expanded Medicaid to a limited number of low-income adults chosen in a lottery from among those eligible, which enables researchers to compare outcomes for those selected to the otherwise similar adults not selected.[22] Mortality among older adults who gained coverage fell by more than two-thirds compared to those who did not, but in the study’s relatively small sample, the drop was not statistically significant. In contrast, with the new study’s larger data set, a similar drop in annual mortality is statistically significant.

Study Highlights Importance of Medicaid Expansion for Remaining States

The study’s design allowed the analysts to provide supplemental, state-level estimates of the mortality impact of expanding Medicaid to low-income adults. [23] These estimates, shown in Table 1 and in the interactive map below, show that the 14 states that have not yet adopted or implemented expansion could be saving hundreds or thousands of lives.

This clear evidence of the lives that are at stake provides yet another reason — on top of the already well-documented improvements in access to care, health outcomes, financial security, and state and hospital finances — for these states to take up expansion without delay.[24]