People involved in side-impact crashes are three times more likely to suffer a traumatic brain injury than people involved in head-on collisions

Jul 29 2004

Occupants of automobiles involved in side-impact crashes are three times more likely to suffer a traumatic brain injury than people involved in head-on or other types of collisions, according to a University of Rochester study published online for the August edition of Annals of Emergency Medicine.

Lead author Jeffrey Bazarian, M.D., MPH, also found that brain injuries from side-impact crashes are usually more severe. Bazarian and colleagues analyzed a sample of all crashes reported by police to the National Highway Traffic Safety Administration (NHTSA) for the year 2000 to determine the relative risk for brain injuries. Bazarian is an attending physician in the Strong Memorial Hospital Emergency Department who has been studying several aspects of brain trauma. Three years ago the National Institutes of Health funded him to start the nation’s first Emergency Department-based registry of traumatic brain injuries.

Other key findings from the NHTSA analysis:

• Traumatic brain injury is the cause of death in 51 percent to 74 percent of single-vehicle side collisions, and 41 percent to 64 percent of multiple vehicle side-impact crashes.
• Better head protection could reduce all crash-related brain injuries by up to 61 percent, and fatal or critical brain injuries by up to 23.5 percent. In raw numbers, that would translate into 2,230 fewer deaths or critical injuries each year.
• Seatbelt use, not frontal air bags, was associated with a reduced risk of brain injury after a crash.
• Doctors, nurses and emergency personnel who treat accident victims should learn the direction of the crash and consider a side impact to be a risk factor for serious brain injury, even if the patient shows no initial symptoms.
• Females were found to be at higher risk for brain injuries. The study cites previous research suggesting that males may benefit from more neck strength and thus less head movement, and better body position in the vehicle due to greater height and weight.

Federal regulators have recently begun discussing new rules for side air bags, which are not available as standard equipment in most vehicles at this time. Consumers must pay about $400 extra to have them installed. Crashes on the side of a vehicle cause 10,000 deaths each year in the United States.

“We believe our study results are important for drivers, emergency responders, automakers and legislators, who rely on accurate information about the risks associated with motor vehicle crashes, Bazarian says. “If the sides of cars can be made as safe as the front, many fatal and non-fatal brain injuries could be prevented. Increasing the number of vehicles with side air bags that protect the head would be an important step in the right direction.”

Bazarian and fellow researchers from the UR Department of Community and Preventive Medicine believe their analysis is the first population-based study to find that a side-impact crash is a risk factor for a traumatic brain injury. The data came from real accidents logged by the NHTSA, rather than from crash tests with dummies. The difference is notable, Bazarian explains, because it’s difficult to accurately simulate a brain injury in a dummy.

The data included 5,483 vehicles containing 6,780 occupants, but the analysis was generally restricted to the 1,115 people who were occupants of a vehicle in which at least one person was severely injured. Researchers accounted for factors such as vehicle type, seatbelt and air bag use, and alcohol use by the driver.

A traumatic brain injury is defined as having a loss of consciousness, amnesia or confusion at the time of injury, or any injury that results in skull fracture (the side of the skull is thinner and less protective), or intracranial bleeding. Head injuries can be mild to severe, and often produce long-term health problems.