News Release

Emergency department visits by uninsured patients drop in Illinois after Medicaid expansion

Research to be presented at American Academy of Pediatrics 2018 National Conference & Exhibition suggests Affordable Care Act provision helped families access more comprehensive, ongoing care

Peer-Reviewed Publication

American Academy of Pediatrics

ORLANDO, Fla. - New research adds to a growing body of evidence suggesting that the expansion of Medicaid under the Affordable Care Act (ACA) helped low-income families rely less on emergency department visits for medical care.

The study abstract, "Effect of Affordable Care Act Medicaid Expansion on Emergency Department Visits by Uninsured Patients in Illinois 2009-2015," will be presented on Friday, Nov. 2, at the American Academy of Pediatrics (AAP) 2018 National Conference & Exhibition in Orlando, Fla.

In Illinois, according to the abstract, Medicaid expansion was associated with a significant drop in uncompensated care in emergency department by patients without insurance between 2009 and 2015. The ACA extended Medicaid coverage eligibility to adults with incomes up to 133 percent of the federal poverty level.

"As a result of the ACA, 850,000 people in Illinois gained health insurance during the study period," said abstract author Peter Nguyen, MD, a Pediatric Emergency Medicine Fellow at Michigan State University's Helen Devos Children's Hospital who previously studied in Illinois. "During the same time, we saw a significant drop in emergency department visits by patients without insurance."

Researchers analyzed emergency department visits using data from the Healthcare Cost and Utilization Project and found there were a total of 31.2 million emergency department visit in Illinois during the study period. Of these, 4.1 million were visits by uninsured patients.

Uninsured emergency department visits in the state peaked right before ACA implementation, Dr. Nguyen said, when they accounted for 16 percent the visits. Post-ACA implementation, there was a 40 percent reduction in uninsured emergency department visits.

"This study adds to the growing body of evidence that the ACA can be beneficial in promoting patient-centered care, shifting it from the emergency department to a patient's medical home for ongoing, comprehensive care. This is a healthier situation for everyone," Dr. Nguyen said.

Dr. Nguyen said that proposed policy changes may slow the reduction in uncompensated emergency department visits. "With increasing uncertainty about the long-term plan for the ACA, enrollment has started to decline," he said. "So, it will be interesting to see whether we'll see a rise again in uninsured emergency department visits."

Dr. Nguyen will present an abstract of the study, available below, between 3:15 and 3:30 p.m. ET on Friday, Nov. 2, in Orlando Ballroom L of the Orange County Convention Center in Orlando, FL.

Please note: only the abstract is being presented at the meeting. In some cases, the researcher may have more data available to share with media, or may be preparing a longer article for submission to a journal.


The American Academy of Pediatrics is an organization of 67,000 primary care pediatricians, pediatric medical subspecialists and pediatric surgical specialists dedicated to the health, safety and well-being of infants, children, adolescents and young adults. For more information, visit Reporters can access the meeting program and other relevant meeting information through the AAP meeting website at

Abstract Title:

Effect of Affordable Care Act Medicaid Expansion on Emergency Department Visits by Uninsured Patients in Illinois 2009-2015

Peter Nguyen

Introduction: Medicaid expansion was one of the key provisions of the Affordable Care Act (ACA) designed to reduce the number of people without health insurance. The ACA extended Medicaid coverage to all adult citizens with annual incomes up to 133% of the federal poverty level. Purpose: Our study objective was to study the impact of ACA on Uninsured Emergency Department Visits (UiEDV). Methods: We downloaded aggregated EDV from the Healthcare Cost and Utilization Project (HCUP) website and extracted state of Illinois EDV and sorted the data by year and quarter. We looked for trends in the quarterly UiEDV data and calculated summary statistics to determine the variance and mean. We used generalized linear modeling (Poisson and a customized negative binomial regression (NB)) to model UiEDV using quarterly UiEDV count as a dependent variable and pre and post ACA implementation periods as independent factors. We used log as the link function, and the software calculated the estimated parameter. From the model, we derived the Incidence Rate Ratio (IRR) and its corresponding 95% Confidence Interval (95%CI); we compared both models using Goodness of fit tests Akaike Information Criterion (AIC) and Bayesian Information Citerion (BIC). We used IBM SPSS Version 25â„¢ and Microsoft Excel â„¢ 2016 for data preparation and analysis. Results: For the study period, there were 31,368,200 EDVs. Of these, 4,120,200 were uninsured (mean (SD) 147,150 (6376); variance 1,138,281,481)). The ratio of UiEDV to total EDVs was between 7% and 16%; the peak occurred before ACA implementation. NB modelling demonstrated a IRR of 1.67 (95% CI, 1.53-1.83) of UiEDV pre-ACA compared post-ACA with a 40 percent reduction of UiEDV. Goodness of fit demonstrated lower AIC (629 vs 40361) and BIC 626 vs 40360) when compared both models were compared indicating NB a better model fit. Conclusion: Insurance is a gateway to healthcare access; because of ACA, burden of uncompensated EDVs decreased substantially in Illinois during the study period. Additional studies to look at regional trends, specific groups, continued coverage is needed to quantify the overall effects of ACA.

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