Impact of ACA on ED use

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October 8, 2015 by dailybolusoflr

Contributors: Erin Kane, MD, Scott Levin, PhD, Susan Peterson, MD

On behalf of the Science of Healthcare Delivery FAST

  • There is controversy about how expanded insurance coverage affects the use of the Emergency Department.
  • Some theorize that improved health insurance should reduce ED visits, as patients should have better access to primary care. Others point out that classic economic theory predicts that when cost (to patient) goes down, consumption goes up, so expanded insurance coverage may increase ED use
  • In addition, having insurance is not sufficient to achieving access to primary care, since there is a shortage of primary care physicians and wait times to see one are often significant
  • Separate from insurance status issues, ED use has been rising faster than population growth. 
  • ED visit rate is double what would be expected from US population growth alone

Data from Massachusetts

  • In Massachusetts, healthcare reform under Governor Mitt Romney expanded coverage, and analyses of the effect of coverage on ED use were mixed. 
  • The state’s 2006 health care reform was a model for ACA and reduced the <65 uninsured population in MA by 7.7 percentage points between 2006 and 2009
  • An analysis published in NEJM in 2011 showed that ED use increased in Massachusetts after reform but also increased by similar amounts in New Hampshire and Vermont (which did not have insurance expansions)
  • A 2014 analysis by Smulowitz et al published in Annals of Emergency Medicine found that increasing coverage was associated with an increase in ED use; this was true across all demographics, and the increase was greater in areas that had a greater increase in coverage. 

Data from Oregon

  • In 2008, Oregon had a limited expansion of Medicaid for uninsured, low income adults; since not everyone could receive insurance, it was assigned by lottery
  • Researchers used this arrangement to follow the two groups. Analysis published in Science in 2014 showed that Medicaid coverage significantly increases overall emergency use by 0.41 visits per person (40%)

Data from early implantation of the ACA

  • An analysis published in Health Affairs in 2014 is one of the first to look at the impact of ACA nationwide
  • This study looked at only young adults ages 19-25 and found that there was a modest relative decrease in the number of ED visits for young adults; the change in the number of visits was driven by fewer visits among ED users, not by changes in the number of people who ever visited the ED


  • The impact of expanded insurance coverage on ED use is unclear
  • It may differ among different patient populations, and factors beyond insurance status may affect ED use (e.g., PCP availability, health literacy, prior patterns of health care utilization)


  1. Chen C, G Scheffler, A Chandra. Massachusetts’ Health Care Reform and Emergency Department Utilization. NEJM 2011: e25(1-3)
  2. Hernandez-Boussard T, CS Burns, NE Wang, LC Baker, and BA Goldstein. The Affordable Care Act Reduces Emergency Department Use by Young Adults: Evidence from Three States. Health Affairs 2014 (33): 9, 1648-54.
  3. Smulowitz PB, J O’Malley, X Yang, BE Landon. Increased Use of the Emergency Department After Health Care Reform in Massachusetts. Annals of Emergency Medicine 2014; 64 (2): 107-115e3
  4. Taubman SL, HL Allen, BJ Wright, K Baicker, AN Finkelstein. Medicaid Increases Emergency Department Use: Evidence from Oregon’s Health Insurance Experiment. Science 2014; 343: 263-8.

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