The Effect of Copayments on Non-urgent Emergency Department Visits among Adult Medicaid Enrollees

The Medicaid population is known to use the emergency department (ED) at more than twice the rate of the privately insured population, and it may cost the Medicaid program significantly more to treat conditions in the ED that could be treated in other ambulatory care settings. Growing pressure on state budgets has led state Medicaid programs to consider tools to increase efficiency and decrease costs. Efficiency and cost concerns in Medicaid will become more pressing as many states expand their Medicaid programs under the Patient Protection and Affordable Care Act. One potential tool for encouraging use of appropriate ambulatory settings is the requirement that non-exempt adult Medicaid enrollees pay a copayment for non-emergent use of the ED. While some states have had copayments for non-emergent ED use in place for a number of years, several states have also recently proposed new or increased copayments.

We use variation in Medicaid ED copayments across states and over time to identify the relationship between the requirement of a copayment and non-urgent ED utilization in the Medicaid population. Data on ED visits come from the National Hospital Ambulatory Medical Care Survey (NHAMCS) from 2001 through 2009. State-identified NHAMCS data were accessed through the National Center for Health Statistics Research Data Center. Our sample includes ED visits by adult Medicaid enrollees ages 19-64. We use a triage measure indicating the immediacy with which a patient should be seen as determined by a medical professional (e.g. triage nurse) to categorize visits as non-urgent if they are assigned a triage time of >2 hours.

We estimate models of non-urgent visit status as a function of whether the state has a copayment in place in a given year, individual patient characteristics, state fixed effects, and year fixed effects. In some specifications we also include controls for other cost-sharing policies and for key hospital characteristics. We find that in states and years with a copayment required for non-emergent ED use by adult Medicaid enrollees, visits among this population were significantly less likely to be non-urgent. Our main results suggest a statistically significant 6.3 percentage point decrease in the probability that a given visit is non-urgent when a copayment is in place relative to when there is no copayment required. Results are robust to a number of alternative specifications and sample restrictions.

Our results suggest that copayments for non-emergent use of the ED may be successful at deterring visits for non-urgent conditions.  While previous studies have found that copayments are effective at reducing ED use among privately insured populations, to our knowledge this is the first study to find an effect of copayments on ED utilization in the Medicaid program. Our results provide some support for recent state efforts to implement or increase copayments for ED use in Medicaid in order to decrease costs and encourage more appropriate use of ambulatory care.