To test the hypothesis that a prehospital time threshold (PhTT) exists that when exceeded, significantly increases the mortality of trauma patients transported directly from the scene of injury to a trauma center rather than to the closest hospital.

Review of data contained within the Illinois Trauma Registry encompassing the period from fall 1989 through spring 1991.

A total of 5,215 injured persons with an Injury Severity Score (ISS) >10, cared for in an Illinois level-I or -II trauma center outside of the city of Chicago.

Injury severity expressed as ISS, scene time (ST), transport time (TrT), total emergency medical services time (TEMST), and outcome were determined for each patient. Patients were stratified into groups on the basis of ISS.

Patient outcomes were significantly different statistically between ISS groups (p <0.001, X2). Mean ST and TEMST, but not TrT, were significantly different statistically between ISS groups (p <0.001, analysis of variance). Lower ISS was associated with longer times. Mean ST, TrT, and TEMST were significantly different statistically between survivors and nonsurvivors (p <0.001, two-sample t-tests). Survival was associated with longer times. Each of the mean times remained significantly different between survivors and nonsurvivors after controlling for severity of injury (p <0.001, two-way analysis of variance).

No PhTT beyond which time patient transport to the closest hospital would have decreased mortality was identifiable, because no prehospital time <90 minutes exerted a significant adverse effect upon survival.