The Affordable Care Act and Ambulance Response Times

Background

While the effects of health insurance expansions on utilization and other patient outcomes have been studied extensively, less attention has been paid to the supply-side of the market and whether provider capacity constraints create challenges as the demand for medical care increases. We contribute to the small but growing literature on supply-side adjustments to insurance expansions by investigating the effect of the ACA on ambulance response times. If the demand for ambulances increased because of the ACA, there are several reasons to suspect that the supply response would be muted, particularly in the short run: EMS personnel require considerable training, new ambulances are quite expensive, and the capital-intensive nature of the service makes it difficult to expand capacity by increasing hours. These factors make congestion a likely short-run outcome for the ambulance system post-ACA.

Objectives

We study the effect of the ACA on ambulance response times to fatal traffic accidents. Presumably, congestion in the ambulance system due to any cause will cause slowing of ambulance responses to all emergencies, including motor vehicle accidents. To the extent that this measure is influenced by the ACA insurance expansion, we identify the effect of the ACA on ambulance response times.

Data and Methods

We utilize difference-in-differences and dose-response models that have become standard in the ACA literature to identify the effect of insurance expansion on ambulance response times. Measures of insurance coverage come from the U.S. Census Bureau. The response time measure is obtained from the National Highway Traffic Safety’s Fatality Analysis Reporting System (FARS). The FARS data is a census of all motor vehicle accidents that resulted in at least one fatality and contains time-stamps for notification and arrival of emergency services. We draw additional data from various other sources for a battery of robustness checks.

Results

We find that the average ambulance response in the average county was slowed by 1.8 minutes due to the ACA. Ambulances in the average county were also 9.6 percent more likely to arrive slower than the 8-minute response time goal recommended by clinicians. Though this slowdown was not likely responsible for any additional deaths due to traffic accidents (as measured by our data and implied by the outside literature), if this slowdown of ambulance services occurred for all ambulance dispatches, then there were likely considerable additional fatalities due to more time-sensitive emergencies such as heart failure.