• Center on Health Equity and Access
  • Clinical
  • Health Care Cost
  • Health Care Delivery
  • Insurance
  • Policy
  • Technology
  • Value-Based Care

Studies Show Medicaid Expansion Is Improving Health, While Jury Still Out on Chronic Disease


A batch of studies appearing in recent months have linked Medicaid expansion with lower death rates in renal failure, more efforts to quit smoking, and earlier detection of cancer. There are mixed outcomes in chronic disease, but an important clinical trial in Oregon shows that over the long haul, Medicaid expansion makes a difference.

As recently as March, when the Kaiser Family Foundation issued a policy brief on Medicaid expansion, authors wrote that it was too early to say whether extending coverage to another tier of low-income families would do more than improve access. Would coverage translate into better health?

In the second half of 2018, a new batch of studies shows that successes of Medicaid expansion are starting to emerge. Results of studies involving chronic disease are mixed so far, but some findings suggest the value of treating patients with diabetes and hypertension will pay off down the road, as this population ages.

A major study published in August found that Medicaid expansion has made it easier to catch cancer early, and this is helping to shrink disparities. Studies published in recent months have found connections between Medicaid expansion and efforts to quit smoking and lower death rates from renal failure.

These results combine with those of an earlier study from 2017, included in the Kaiser report, which found that Medicaid patients who received cardiac surgery in Michigan, an expansion state, had fewer postoperative problems than those from Virginia, which had not expanded Medicaid.

Unlike Medicare, the healthcare program for seniors funded entirely by the federal government, Medicaid is jointly funded by the federal government and the states, and the eligibility rules for the program for those with low incomes and the disabled vary greatly.

Under the Affordable Care Act, Medicaid expansion sought to extend coverage to families earning up to 138% of the federal poverty line, but the Supreme Court allowed states to decide whether to extend coverage. The 2010 law provided incentives for states to expand Medicaid starting in January 2014, and even today the federal government pays most of the cost of adding this new group to the rolls. Through the first 2 years of expansion, about 10.7 million newly eligible people signed up, as well as 3.4 million who had been eligible but had never enrolled.

To be sure, as the number of states without Medicaid expansion dwindles to just 14, following successful ballot measures in Nebraska, Idaho, and Utah, expansion is more palatable to conservative states than it was under the Obama administration. CMS leaders in the Trump administration allow states to impose work rules and just announced the terms of 1332 waivers that seem designed to give conservative states maximum flexibility (although some measures are being challenged by advocacy groups).

While there was no question that the first wave of expansion increased the number of people with access to health coverage—and stabilized finances at many safety net hospitals—the long-term goal of healthcare isn’t to send people to the doctor, but to keep them healthy. And some who question the merits of expansion have been waiting for that part of the equation to materialize.

The March report from Kaiser said that people who gained coverage under expansion certainly felt it made a difference, but health benefits to those being treated for chronic conditions may take years to measure. “Studies show improved self-reported health following expansion, and multiple new studies demonstrate a positive association between expansion and health outcomes,” the Kaiser authors wrote. “Further research is needed to more fully determine effects on outcomes given that it may take additional time for measurable changes in health outcomes to occur.”

Since then, the following studies have appeared:

  • A November 2018 study in Health Economics used a panel of household purchases to examine the effects of state-level Medicaid expansion on consumption of goods that represent health risks. The authors were examining whether the availability of health coverage could increase risky behavior “due to ex ante moral hazard,” but found this was not the case. “We find compelling evidence that the Medicaid expansions reduced cigarette consumption and increased smoking cessation product use among the Medicaid-eligible population,” the authors wrote.1
  • Results published this week in JAMA found an association between Medicaid expansion and reduced 1-year mortality among patients with end-stage renal disease (ESRD).2 The difference-in-differences analysis examined data from 236,246 nonelderly patients with ESRD who began dialysis between January 2011 and March 2017. In expansion states, mortality fell from 6.9% before expansion to 6.1% afterward; in states without expansion, mortality rates were 7.0% before expansion and 6.8% afterward. Authors called for more work to determine if there is a causal link in this finding.
  • A well-publicized study in JAMA Oncology examined records in cancer registries from 2.47 million patients across 40 states from 2010 to 2014, and researchers found that while the percentage of patients without insurance dropped in all states, the drop was steeper in states with Medicaid expansion.3 The drops were greatest in states with high baseline uninsured states that expanded Medicaid, such as Kentucky. “In expansion states, the decreases in the percentage of uninsured patients were higher among minorities and patients in high-poverty or rural areas, diminishing or eliminating disparities,” the authors wrote. “In contrast, sociodemographic disparities in the percentage of uninsured patients remained high in nonexpansion states. Stage at diagnosis shifted slightly to earlier stage for most cancer types in Medicaid expansion states.”

A pair of studies involving patients with chronic disease shows the differences that emerge over time: One study published in June 2018 that compared Behavioral Risk Factor Surveillance System data from 2013 and 2015 found at that point, Medicaid expansion had improved access to care but at that point had not improved outcomes.4

But results from a clinical trial in Oregon that is tracking the effect of Medicaid expansion on patients with chronic conditions treated in community health centers find that ongoing care is working.5 After 24 months of care, compared with uninsured patients, those in the Medicaid expansion cohort with diabetes and hypertension were significantly more likely to have controlled measures; a hyperlipidemia group showed improvement, but it was not significant.

Researchers who presented a study at last spring’s meeting of the American Thoracic Society emphasized the need to evaluate the effect of Medicaid expansion over time. Andrew Admon, MD, MPH, found that despite the early concerns about waves of new Medicaid enrollees showing up in emergency departments, these patients eventually found their way to a primary physician; Admon’s results showed that Medicaid expansion was now leading to a decline in conditions that can be managed through preventive care.

Indeed, one of most stunning findings since the start of Medicaid expansion was a 2015 study from Quest Diagnostics, which appeared in Diabetes Care.6 Authors found a 23% jump in diagnoses of type 2 diabetes among Medicaid enrollees in the first year in expansion states, compared with almost no increase among Medicaid enrollees in nonexpansion states. A follow-up study in Health Affairs found that fills for newer diabetes therapies and insulin were rising in expansion states, suggesting that patients there are achieving greater glycemic control on a population wide level.

As the Kaiser authors wrote last March, the full value of Medicaid expansion will not be known for some time. Ironically, the policy differences among the states create an opportunity for researchers to study the expansion’s effects. “We will continue to monitor and update these findings as additional studies and state experiences provide insight into how various factors shape coverage, access to care, and costs in Medicaid expansion states and as states continue to consider expansion and reshape Medicaid coverage,” the policy brief stated.


1. Cotti C, Nesson E. Impacts of the ACA Medicaid expansion on health behaviors: evidence from household panel data [published November 15, 2018]. Health Econ. doi: 10.1002/hec.3838.

2. Swaminathan S, Sommers BD, Thorsness R, Mehrotra R, Lee Y, Trivedi AN. Mortality among patients with end-stage renal disease. JAMA. 2018;320(21):2242-2250. doi: 10.1001/jama.2018.16504.

3. Han X, Yabroff KR, Ward E, Brawley OW, Jemal A. Comparison of insurance status and diagnosis stage among patients with newly diagnosed cancer before vs after implementation of the patient protection and Affordable Care Act [published online August 23, 2018]. JAMA Oncol. doi: 10.1001/jamaoncol.2018.3467.

4. Luo H, Chen ZA, Xu L, Bell RA. Healthcare access and receipt of clinical diabetes preventive care for working-age adults with diabetes in states with and without Medicaid expansion: results from the 2013 and 2015 BRFSS [published online June 20, 2018]. J Public Health Manag Pract. doi: 10.1097/PHH.0000000000000832.

5. Hatch B, Marino M, Killerby M et al. Medicaid’s impact on chronic disease biomarkers: a cohort study of community health center patients. J Gen Intern Med. 2017;32(8):940-947. doi: 10.1007/s11606-017-4051-9.

6. Kaufman HW, Chen Z, Fonseca VA, McPhaul MJ. Surge in newly identified diabetes among Medicaid patients in 2014 within Medicaid expansion states under Affordable Care Act. Diabetes Care. 2015;38(5):833-837.

Related Videos
Shrilla Banerjee, MD, FRCP
Donna Fitzsimons
Milind Desai, MD, MBA
Milind Desai
Stephen Nicholls
G.B. John Mancini, MD
Stephen Nicholls, PhD, MBBS
G.B. John Mancini, MD, University of British Columbia
Related Content
© 2024 MJH Life Sciences
All rights reserved.