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Low to moderate blood alcohol level linked to reduced mortality following traumatic head injury

December 19, 2006

Patients who have low to moderate blood alcohol levels may be less likely to die after arriving at the hospital with a traumatic brain injury than those with no alcohol in their bloodstream, according to a report in the December issue of Archives of Surgery, one of the JAMA/Archives journals. However, those with the highest alcohol levels appear to have an increased risk of dying in the hospital.

Alcohol use is a major risk factor for trauma, according to background information in the article. About one-third to one-half of all patients hospitalized with trauma are intoxicated at the time of injury. However, the effect of alcohol on how patients fare after a traumatic brain injury-a leading cause of disability and death among young people-is unclear. Some human and animal studies suggest that alcohol may be neuroprotective, keeping the injury from worsening once it has occurred.

Homer C. N. Tien, M.D., F.R.C.S.C., Sunnybrook Health Sciences Centre, University of Toronto, and colleagues studied 1,158 consecutive patients who were evaluated at an academic level I trauma center for severe brain injury caused by blunt trauma between 1988 and 2003. Tests done when the patients were admitted determined blood alcohol concentration (BAC). This information, as well as data on demographics, type of injury, severity of the injury, length of hospital stay and whether the patient died or left the hospital, was gathered from the hospital's trauma registry. The researchers also assessed a group of 528 patients with severe torso injuries, but no or mild head injuries, as a comparison.

Of the 1,158 traumatic brain injury patients, 740 had a BAC of zero, 315 had low to moderate BAC (0 to 230 milligrams per deciliter) and 103 had high BAC (230 milligrams per deciliter or higher); 403 died in the hospital. Those with a low to moderate BAC were less likely to die than those with no BAC (27.9 percent died vs. 36.3 percent). After adjusting for other factors that could influence the risk of death-including injury severity, blood transfusions and whether the trauma occurred in a motor vehicle crash-BAC was still associated with the risk of death. Those with a low to moderate BAC had 24 percent lower odds of dying in the hospital than those with no BAC. In contrast, those with a high BAC had 73 percent higher odds of dying than those with no BAC. Among patients with torso injuries, BAC was not related to the risk of death.

The authors mention that low to moderate doses of alcohol may protect the brain by stopping the mechanisms that contribute to secondary brain injury, which occurs when traumatized brain cells continue to be deprived of oxygen and worsens the damage caused by the initial event.

"There are major sociologic implications from implying that intoxicated patients with severe traumatic brain injury have better outcomes than non-intoxicated patients," the authors write. "We stress that our study only examined the role of alcohol on outcome in the post-injury phase because we examined only in-hospital deaths." About half of all individuals who die from trauma do so before they arrive at the hospital, they continue. Because alcohol use increases the likelihood of a severe injury, alcohol-related deaths comprise a large percentage of those who die before they have a chance to get to the hospital.

"Overall, people are still at much greater risk of dying if they drive while intoxicated," the authors conclude. "What our study implies is that there may be a role for an alcohol-based resuscitation fluid in improving outcomes in adequately resuscitated patients with severe head injury."

JAMA and Archives Journals