Research Activities, September 2013
Study reveals differences in mortality rates of patients transported to trauma centers by private car versus those transported by ambulance
Contrary to expectations, a new statewide study of 91,132 injured persons in Pennsylvania found that the 90.4 percent of individuals taken to accredited trauma centers by an emergency medical services (EMS) ambulance were twice as likely to die than the 9.6 percent brought by private vehicle. This was despite the fact that pre-hospital time for persons transported by EMS was substantially shorter than for those taken by private vehicle (66.2 vs. 245.5 minutes).
Individuals transported by EMS were, on average, about a year older, were 2.9 percent more likely to be male, and had higher injury severity scores (ISS—mean patient ISS was 13.7 for EMS vs. 9.2 for private vehicle transport).
In analyses that did not adjust for patient factors, patients transported by EMS were 5.2 times more likely to die than those transported by private vehicle. Also, the increased death rate remained 90 percent higher for EMS patients, even after adjusting for injury severity. When the researchers analyzed death rates by type of transportation and type of injury, patients transported by EMS still had higher death rates for both blunt-force trauma (by 120 percent) and penetrating wounds (by 70 percent).
The researchers also examined the effect of the level of prehospital care in the EMS transport on mortality for all patients: whether care was classified as advanced life support or basic life support; by level of care; and ISS values for severe (ISS greater than 15 or greater than 25) versus nonsevere (ISS 15 or less, or 25 or less) trauma. The probability of transport by EMS or private vehicle was also analyzed by locale of trauma (major cities, other cities, suburbs, or rural/small towns).
The findings were based on retrospective analysis of data from 2003 through 2007 from the Pennsylvania Trauma Outcome Study. The study was funded in part by AHRQ (HS17960).
More details are in "Characteristics and outcomes of injured patients presenting by private vehicle in a state trauma system," by Nicholas J. Johnson, M.D., Brendan G. Carr, M.D., M.S., Rama Salhi, M.H.S., and others in the February 2013 American Journal of Emergency Medicine 31(2), pp. 275-281.