Copayments and Emergency Department Use Among Adult Medicaid Enrollees.

A number of state Medicaid programs have recently proposed or implemented new or increased copayments for nonemergent emergency department (ED) visits. Evidence suggests that copayments generally reduce the level of healthcare utilization, although there is little specific evidence regarding the effectiveness of copayments in reducing nonurgent ED use among Medicaid enrollees or other low-income populations. Encouraging efficient and appropriate use of healthcare services will be of particular importance for Medicaid programs as they expand under the Patient Protection and Affordable Care Act. This analysis uses national data from 2001 to 2009 to examine the effect of copayments on nonurgent ED utilization among nonelderly adult enrollees. We find that visits among Medicaid enrollees in state-years where a copayment is in place are significantly less likely to be for nonurgent reasons. Our findings suggest that copayments may be an effective tool for reducing use of the ED for nonurgent care.