News Release

Increase in visits to emergency departments persists following Medicaid expansion

Peer-Reviewed Publication

Harvard T.H. Chan School of Public Health

Boston, MA - Visits to hospital emergency departments (EDs) not only jumped by 40% in Oregon after Medicaid coverage was expanded there in 2008--but the increase persisted for at least two years, according to a new study led by health economists at Harvard T.H. Chan School of Public Health and the Massachusetts Institute of Technology.

The study also found no evidence that the newly insured are more likely to substitute doctor's office visits for trips to the ED; rather, it found that Medicaid makes it more likely that individuals will use both types of care.

The study will appear in the October 20, 2016 issue of the New England Journal of Medicine.

"Our finding that Medicaid increased ED visits generated a lot of debate about whether this might just be a temporary spike; now we know that the increase in ED visits persisted for at least the first two years of Medicaid coverage," said Amy Finkelstein, the John and Jennie S. MacDonald professor of economics and co-Scientific Director of J-PAL North America at MIT, who led the study with Katherine Baicker, C. Boyden Gray Professor of Health Economics at Harvard Chan School.

The researchers examined new evidence from the Oregon Health Insurance Experiment, a unique, randomized controlled evaluation of the effects of Medicaid expansion. Oregon's lottery provided an unprecedented opportunity to separate out the effects of Medicaid from confounding factors to assess the impact of coverage on a wide range of outcomes, from health care use to financial security to mental and physical health.

Prior results from the Oregon Health Insurance Experiment showed that extending Medicaid coverage led to increased health care use across a range of settings--there were more doctors' office visits, prescription drugs used, and hospitalizations. There was also a 40% increase in ED use in the first 15 months after people gained coverage. The results also showed that Medicaid substantially improved financial security and reduced depression, but had no detectable effect on physical health or on employment.

Many observers thought that the higher rate of ED use would decrease over time as more newly insured patients gained access to primary care doctors. But the new study found otherwise. Not only did the rise in emergency department visits among the newly insured persist for two years, but those people were also more likely to use a combination of office and ED visits.

"For policymakers thinking about expansions, our results suggest that a typical Medicaid program will increase health care use across settings -- including the ED -- for at least two years, and that it won't lead people to go to the doctor instead of the ED," said Baicker.


Funding for the Oregon Health Insurance Experiment came from the Assistant Secretary for Planning and Evaluation in the Department of Health and Human Services, the California HealthCare Foundation, the John D. and Catherine T. MacArthur Foundation, the National Institute on Aging (P30AG012810, RC2AGO36631 and R01AG0345151), the Robert Wood Johnson Foundation, the Sloan Foundation, the Smith Richardson Foundation, and the U.S. Social Security Administration (through grant 5 RRC 08098400-03-00 to the National Bureau of Economic Research as part of the SSA Retirement Research Consortium). The Centers for Medicare and Medicaid Services' provided matching funds for the original evaluation.

"Effect of Medicaid Coverage on ED Use--Further Evidence from Oregon's Experiment," Amy N. Finkelstein, Sarah L. Taubman, Heidi L. Allen, Bill J. Wright, and Katherine Baicker, New England Journal of Medicine, October 20, 2016, doi: 10.1056/NEJMp1609533

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