The impact of Medicaid expansion on emergency department wait times

To estimate the impact of Medicaid expansion on emergency department (ED) wait times.

We used 2012-2017 hospital-level secondary data from the CMS Hospital Compare data warehouse.

We used a state-level difference-in-differences approach to identify the impact of Medicaid expansion on four measures of ED wait times: time before being seen by a provider; time before being sent home after being seen by a provider; boarding time spent in the ED waiting to be discharged to an inpatient room; and the percentage of patients who left without being seen. We compared outcomes in states that expanded Medicaid with those in states that did not expand Medicaid.

Our sample included all US acute care hospitals with EDs in states that did not ever expand Medicaid or that fully expanded Medicaid in January of 2014.

Medicaid expansion was associated with a 3.1-min increase (SE: 0.994, baseline mean: 30.8 min) in the time spent waiting to see an ED provider, a relative increase of 10%. Patients who were eventually sent home after being seen by a provider experienced a 7.5-min increase (SE: 1.8, baseline mean 142.1 min) in wait time. Boarding time rose by 3.8 min (SE 1.9, baseline mean 111.4 min). The percentage of patients who left without being seen rose by 0.3 percentage points (SE: 0.09, baseline mean 2.0), a relative increase of 15.3%.

This study provides multistate evidence that Medicaid expansion increased ED wait times for patients, indicating that ED crowding may have worsened post-expansion. Future work should aim to uncover the mechanisms through which insurance expansion increased ED wait times to provide policy direction.