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June 23, 2017

Medicaid expansion led to more ED visits, less uncompensated care, study finds

Daily Briefing

The Affordable Care Act's (ACA) Medicaid expansions led to a rise in ED visits and a shift in hospitals' payer mixes, according to a study published Monday in the Annals of Emergency Medicine.

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Study details

For the study, researchers from several institutions, including Vanderbilt University School of Medicine and the University of Michigan-Ann Arbor, assessed the effect the ACA's Medicaid expansions had on both ED visits and ED payers—such as Medicaid, uninsured patients, and private insurance. The researchers also sought to determine whether the size of a state's Medicaid population correlated with trends in ED visits.

The researchers reviewed data from the Agency for Healthcare Research and Quality to compare ED visits per capita and identify the share of ED visits per payer in 14 Medicaid expansion states, as well as 11 non-expansion states, after 2014.  

Expansion states included:

  • Arizona;
  • California;
  • Hawaii;
  • Iowa;
  • Illinois;
  • Kentucky;
  • Maryland;
  • Minnesota;
  • North Dakota;
  • Nevada;
  • New Jersey;
  • New York;
  • Rhode Island; and
  • Vermont.

Non-expansion states included:

  • Florida;
  • Georgia;
  • Indiana;
  • Kansas;
  • Missouri;
  • North Carolina;
  • Nebraska;
  • South Carolina;
  • South Dakota;
  • Tennessee; and
  • Wisconsin.

The researchers controlled for economic characteristics and state-level demographics.


According to the study, Medicaid expansion states experienced a greater increase in ED visits than non-expansion states. The researchers found that, after 2014, total ED use per 1,000 residents increased by 2.5 visits more in Medicaid expansion states than in non-expansion states. The researchers said the largest increases in ED visits occurred in states that experienced the most significant increases in Medicaid enrollment.

For example, Kentucky and Nevada—two states with historically low Medicaid eligibility thresholds for adults—saw the largest increases in ED visits. In contrast, Hawaii and New York—two states with higher Medicaid eligibility thresholds—experienced slight changes in ED visits. According to the study, non-expansion states experienced little change in both ED visits and Medicaid enrollment.

The researchers also found that the percentage of ED visits covered by Medicaid increased by 8.8 percentage points in expansion states when compared with non-expansion states, while the percentage of uninsured visits decreased by 5.3 percentage points in expansion states when compared with non-expansion states. According to the researchers, the percentage of ED visits covered by private insurance in expansion states remained stable, but rose by "several percentage points" in non-expansion states.

The researchers said, "In states that expanded Medicaid, hospitals have experienced shifts in payer mix from uninsured to Medicaid, leading to reductions in hospital uncompensated care, and improved financial positions." They added that the study's findings are consistent with the results of the Oregon Health Insurance Experiment, which found that expanding Medicaid had a positive and sustained effect on ED visits (Lagasse, Healthcare Finance News, 6/20; Nikpay et al.,  Annals of Emergency Medicine, June 2017).

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