Relative risk of injury and death in ambulances and other emergency vehicles

Abstract

This study addresses of the impacts of emergency vehicle (ambulances, police cars and fire trucks) occupant seating position, restraint use and vehicle response status on injuries and fatalities. Multi-way frequency and ordinal logistic regression analyses were performed on two large national databases, the National Highway Traffic Safety Administration’s Fatality Analysis Reporting System (FARS) and the General Estimates System (GES). One model estimated the relative risk ratios for different levels of injury severity to occupants traveling in ambulances. Restrained ambulance occupants involved in a crash were significantly less likely to be killed or seriously injured than unrestrained occupants. Ambulance rear occupants were significantly more likely to be killed than front-seat occupants. Ambulance occupants traveling non-emergency were more likely than occupants traveling emergency to be killed or severely injured. Unrestrained ambulance occupants, occupants riding in the patient compartment and especially unrestrained occupants riding in the patient compartment were at substantially increased risk of injury and death when involved in a crash. A second model incorporated police cars and fire trucks. In the combined ambulance–fire truck–police car model, the likelihood of an occupant fatality for those involved in a crash was higher for routine responses. Relative to police cars and fire trucks, ambulances experienced the highest percentage of fatal crashes where occupants are killed and the highest percentage of crashes where occupants are injured. Lack of restraint use and/or responding with ‘lights and siren’ characterized the vast majority of fatalities among fire truck occupants. A third model incorporated non-special use van and passenger car occupants, which otherwise replicated the second model. Our findings suggest that ambulance crewmembers riding in the back and firefighters in any seating position, should be restrained whenever feasible. Family members accompanying ambulance patients should ride in the front-seat of the ambulance.

Introduction

Response to the scene of an emergency and transportation of sick or injured patients to emergency care facilities is a fundamental component of emergency medical services (EMS) systems (Boyd et al., 1983). Though EMS systems have been in place in some localities for more then 20 years, only in the last 10 years have safety researchers begun to study the practices and impacts of emergency vehicle occupant (EVO) behavior including their use of restraints.

Ambulance crashes have received some attention in EMS and other trade media (Elling, 1989, Spivak, 1998, Burns, 1999, LaDuke, 1999) but few peer-reviewed analytical accounts exist. Pirrallo and Swor (1994) examined ambulance crashes in 4 years of Fatality Analysis Reporting System (FARS) data, and provided an overview of the earlier literature, including a series of sporadic government reports. Auerbach et al. (1987) analyzed a very small sample of ambulance crashes in Tennessee. Notably, approximately one-half of vehicle drivers and front-seat occupants were wearing occupant restraints; over one-half of patients lying prone on a stretcher were restrained while only 15% of bench seat patients were wearing restraints and almost all rear-compartment occupants sitting in the ‘jump seat’ were wearing restraints. Biggers et al. (1996) conducted a retrospective study of 1 year of ambulance crash data from the Houston, Texas fire department. An important finding from this study was that a driver history of prior EMS vehicle crash is a key risk factor for future crashes. Kahn et al. (2001) analyzed 1987–1997 FARS data, focusing on ambulance crashes only and finding that unrestrained rear occupants were most at risk for fatal and/or incapacitating injuries. Just over 4% (4.1%) of Schwartz et al.’s (1993) 439 respondents to a New England survey of emergency medical technicians (EMTs) reported that they had been involved in an ambulance collision. Field data monitoring restraint use suggest that there is frequent sub-optimal utilization of the standard restraint systems fitted in ambulance vehicles for both crew and patient occupants (Cook et al., 1991, Larmon et al., 1993, Levick et al., 2000). Gershon et al.’s (1995) review of EMS worker injuries focused mostly on injury type rather than injury cause though motor vehicle collisions were noted as a source of the most serious EMS worker injuries.

Furthermore, while the ambulance transport environment is hazardous due to high-speed driving and other characteristics (Erich, 2001, Kahn et al., 2001), only recently have limited safety crash test studies been conducted (Levick et al., 1998, Levick et al., 2001a, Levick et al., 2001b; Bull et al., 2001) which suggest that there are predictable and preventable risks to the occupants of the ambulance rear-compartment. These studies also demonstrated that failure to use the restraint systems currently fitted to vehicles creates risk for serious injury to both the occupant who is not restrained and can also create hazards for other restrained or unrestrained occupants (Levick et al., 2001c) and suggested that the use of existing restraints and the consideration of head protection could have a major positive impact on occupant protection. Maguire and Porco (1997a) described a two phase intervention that reduced the collision rate in one agency by 50%, involving a new training program and policy changes regarding increased seat belt usage and minimizing driving risk during lights and sirens transport. The same authors found that 100% of the litigation against one EMS agency resulted from transportation related incidents (Maguire and Porco, 1997b).

This paper reports an analysis of two large national databases, the National Highway Traffic Safety Administration’s FARS and the General Estimates System (GES). The analysis assesses the impacts of emergency vehicle occupant seating position, restraint use and vehicle response status (emergency versus non-emergency) on EVO injuries and fatalities. In addition, we broaden the traditional scope of EMS vehicles and include fire trucks (FT) and police cars (PC) in this analysis and compare the hazards of travel.