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Medicaid Increases Emergency-Department Use: Evidence from Oregon's Health Insurance Experiment

January 17, 2014
By Sarah Taubman, Heidi Allen, Bill Wright, Katherine Baicker and Amy Finkelstein

Sarah Taubman, Heidi Allen, Bill Wright, Katherine Baicker and Amy Finkelstein use the Oregon Health Insurance experiment to study the emergency department use of about 25,000 lottery participants over about 18 months after the lottery.

In 2008, Oregon initiated a limited expansion of a Medicaid program for uninsured, low-income adults, drawing names from a waiting list by lottery. This lottery created a rare opportunity to study the effects of Medicaid coverage by using a randomized controlled design. By using the randomization provided by the lottery and emergency-department records from Portland-area hospitals, we studied the emergency department use of about 25,000 lottery participants over about 18 months after the lottery. We found that Medicaid coverage significantly increases overall emergency use by 0.41 visits per person, or 40% relative to an average of 1.02 visits per person in the control group. We found increases in emergency-department visits across a broad range of types of visits, conditions, and subgroups, including increases in visits for conditions that may be most readily treatable in primary care settings.
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Health Care