Do EMS times associate with injury severity?

In this study, emergency medical services times, along with other crash-related explanatory variables, have been used to investigate influential factors on injury severity. To overcome the complexity of emergency medical services times impact on crash outcome, the interaction effects of EMS times and injury location on the body were also investigated in a separate model. This study utilized the linked data of police-reported crash data and emergency medical services runs, including 2192 crash injuries that transferred to hospital. A random-effects ordered probit approach was implemented to identify effective factors on crash injury severity. Three models of (1) crash-related variables, (2) crash-related and emergency medical services times and (3) crash-related, emergency medical services times and interaction effects of EMS times and injury location on the body were developed. Although the outcome could not find the impact of faster emergency medical services times on injury severity in the second model, in the third model, faster response time and slower on-scene time were associated with decreasing the severity of entire-body injuries. We discuss why this may be the case.