The difference, which was seen in both drivers and passengers of crashed vehicles, in victims of all kinds of crashes, and in people whose blood-alcohol levels were under the legal limit to drive, suggests that alcohol does something to the body that increases its vulnerability to injury.
The new results will be published in the April issue of the journal Alcoholism: Clinical & Experimental Research by a team from the U-M Health System and the U-M Transportation Research Institute.
They represent the most in-depth clinical study to date demonstrating the connection between alcohol use and injury severity: Earlier population and animal studies have suggested the effect, but it has never been thoroughly examined in a clinical setting.
Among other things, the researchers hope their finding could improve emergency medical treatment for all types of injuries, if first-responders, doctors and nurses ask whether patients have been drinking when they triage and evaluate them.
They also hope it will spur research on exactly what alcohol does to the human body on the microscopic level – perhaps leading to therapies that could reduce the impact of injury in people with alcohol in their systems.
"Drivers and passengers who had any level of alcohol in their bodies were, on average, more than one and a half times as likely to experience a serious injury as someone who hadn't been drinking, and their injury severity was 30 percent higher, controlling for the severity of the crash they were in, whether they were wearing their seat belt, or whether they had a high alcohol tolerance," says Ronald Maio, D.O., M.S., a U-M emergency medicine physician who helped lead the study. Maio directs the U-M Injury Research Center.
"We as a society may be grossly underestimating the burden of injury attributable to alcohol, and the need for more research and preventive efforts," Maio adds. "Until we can learn more about this effect and how it can be prevented, anyone who drinks before getting in a motor vehicle, even as a passenger, should give themselves more time to sober up, and stop drinking long before they leave."
The data were drawn from 1,362 motor vehicle crash victims ages 18 years or older who came to the emergency rooms of two different Michigan hospitals and were treated and released, admitted to the hospital, or died from their injuries.
The patients had been driving or riding in cars, vans or pickup trucks; motorcycle accidents were excluded. Just over three-quarters of the patients had been driving the vehicle at the time of the crash. Twenty-one percent of the patients had been drinking prior to the crash.
The study took into account the patients' medical conditions, their scores on a standard scale of injury severity, results from tests of their blood alcohol levels, answers to questions about their alcohol use, and information from police reports on the nature and severity of the crashes they were in, including seatbelt use, which allowed them to estimate the strength of the crash forces.
Part Two: Still a Mystery