There is a popular perception that insurance coverage will reduce overuse of the emergency department (ED). Both opponents and advocates of expanding insurance coverage under the Affordable Care Act (ACA) have made statements to the effect that EDs have been jammed with the uninsured and that paying for the uninsured population's emergency care has burdened the health care system as a result of the expense of that care. It has therefore been surprising to many to encounter evidence that insurance coverage increases ED use instead of decreasing it. Two facts may help explain this unexpected finding. First, there is a common misperception that the uninsured use the ED more than the insured. In fact, insured and uninsured adults use the ED at very similar rates and in very similar circumstances-and the uninsured use the ED substantially less than the Medicaid population. Second, while the uninsured do not use the ED more than the insured, they do use other types of care much less than the insured.
Keywords: Emergency Department; Medicaid; Uninsured.