Emergency room visits skyrocket.

• Position: Medicaid

Adults who are covered by Medicaid use emergency rooms 40% more than those in similar circumstances who do not have health insurance, according to a study that sheds empirical light on the inner workings of health care in the U.S. The study takes advantage of Oregon's recent use of a lottery to assign access to Medicaid, the government-backed health care plan for low-income Americans, to certain uninsured adults.

"When you cover the uninsured, emergency room use goes up by a large magnitude," says Amy Finkelstein, professor of economics at the Massachusetts Institute of Technology, Cambridge, and a principal investigator of the study, which documents that having Medicaid consistently increases visits to the emergency room across a range of demographic groups, types of visits, and medical conditions, including the kinds of conditions that may be most readily treatable in primary care situations.

"In no case were we able to find any subpopulations or type of conditions for which Medicaid caused a significant decrease in emergency department use," Finkelstein relates. "Although one always needs to be careful generalizing to other settings, these results suggest that other Medicaid expansions are unlikely to decrease emergency room use."

The study is highly relevant to the current landscape in the U.S. With...