Medicaid Expansion Linked to Decline in ICU Stays, Study at ATS Finds

Published on: 

Researchers based at the University of Michigan compared patients admitted to the intensive care unit (ICU) in Medicaid expansion states with those in nonexpansion states, focusing on 18 specific conditions identified as severe illnesses that could be avoided through better preventive care.

A new study finds a connection between Medicaid expansion under the Affordable Care Act (ACA) and fewer stays in the intensive care unit (ICU) for conditions that can be managed through preventive care.

Findings unveiled Tuesday at the American Thoracic Society 2018 International Conference, meeting in San Diego, California, also showed that patients hospitalized with 18 specific conditions—ranging from bacterial pneumonia to congestive heart failure—were more likely to sign up for insurance quickly once Medicaid expansion took effect.

Lead author Andrew Admon, MD, MPH, of the University of Michigan, and colleagues studied data from 5 states, including some that expanded Medicaid and those that did not. They captured 567,160 patient records from these states from 2012 through 2014, and examined rates of the 18 ambulatory care sensitive conditions. Medicaid expansion took effect on January 1, 2014, in the initial group of states that elected to expand coverage to households earning up to 138% of the federal poverty level.


Findings from the study included:

  • Overall, the ICU admission rate for hospitalized patients was 12.1%, while the ICU admission rate for patients with the 18 specific conditions was 20.9%.
  • In expansion states, the percentage of uninsured hospitalized patients fell from 12.7% to 4.5%. Rates of Medicaid coverage rose from 19% to 26.6%.
  • Rates of uninsured and Medicaid patients remained relatively flat in the non-expansion states; 8.5% to
  • In the first year after Medicaid expansion, the difference-in-difference analysis showed expansion states saw a significant decline in risk-adjusted ICU admission rates. Risk-adjusted rates were —3.7%, (–6.3 to –1.0, P <.01) among those with Medicaid or no insurance in 2014.

ACA critics have complained that the exchanges and Medicaid expansion have served as magnets for the sick, and this problem was cited when insurers fled the exchanges in the years after the law took effect. But this new study finds that spending on coverage may be fueling healthcare gains that reduce the costliest forms of care. Uninsured rates plummeted in states that expanded Medicaid, with Kentucky and Arkansas being the most noteworthy examples. Today, 33 states have expanded Medicaid, and 4 more states and considering it, now that the Trump administration allows states to seek waivers to impose work or community service requirements in exchange for benefits.

“While it is first important to validate these results over time and across other states, declines in ICU admission under Medicaid expansion may mean that gains in insurance access have led to early improvements in clinical outcomes,” Admon said in a statement. “This may in turn reduce rates of very costly hospitalizations and alleviate the strain on intensive care units, helping to offset the financial cost of expanding insurance coverage.”

In creating their study population, Admon and colleagues obtained data on all adults 18 to 64 years of age who were discharged from hospitals for the specific conditions, which were identified by the Agency for Healthcare Research and Quality (AHRQ). These are conditions for which severe illness can be prevented with proper early intervention, including maintaining blood glucose in normal ranges, keeping hypertension under control, receiving treatment and management for heart conditions, and receiving annual vaccinations.

These findings align with other results that show Medicaid expansion and overall declining uninsured rates due to the ACA have served to reveal undiagnosed illnesses or catch them at earlier, treatable stages. For example, a well-known study by Quest Diagnostics found a 23% increase in type 2 diabetes diagnoses among Medicaid enrollees in expansion states in 2014, compared to a 0.4% increase in other states. Uncontrolled diabetes is a leading cause of emergency department visits and among the 18 conditions on the AHRQ list. Letting young people stay on parents’ health plans until age 26 allowed enabled more young women with gynecological cancers to have them diagnosed and treated at earlier stages, the journal Obstetrics and Gynecology reported this week.

“Although most research examining the effects of complex policies on healthcare utilization have used hospital admissions and emergency department visits as markers of ambulatory care access and quality, this study used critical illness as an alternative measure,” Admon said. “Because critical illness may be less susceptible to patient and provider decision-making than other types of healthcare utilization, they may be better markers of disease control after a complex policy change such as insurance expansion.”


Admon AJ, Sjoding MW, Lyon SM, Iwashyna TJ, Cooke CR. The effects of Medicaid expansion on rates of ambulatory care-sensitive ICU admission. Presented at the American Thoracic Society 2018 International Conference; San Diego, California; May 18-23, 2018; abstract 9969.