By Anthony J. Brown, MD

NEW YORK (Reuters Health) - Warfarin, a common blood thinner used for preventing heart attacks and blood clots may also cause problems for individuals who suffer some form of trauma, particularly the elderly.

In a study, researchers found that trauma patients who were taking warfarin at the time of their injury were at increased risk of dying compared with trauma patients not on the anti-clotting drug.

They also found that it's becoming more common for adult trauma patients to have warfarin in their systems at the time of their injury.

"This is the first study to look at the prevalence of pre-injury warfarin use among patients presenting to US trauma centers," lead researcher Dr. Lesly A. Dossett, from Vanderbilt University Medical Center in Nashville, told Reuters Health.

She said she was "surprised" to see just how common warfarin use was among injured adults and how much it has increased in recent years.

The analysis of over 1.2 million patients logged in the National Trauma Databank indicates that 4.0 percent of injured adults in 2006 were using warfarin, nearly double the 2.3 percent rate seen in 2002.

Among individuals older than age 65, the rate of warfarin use increased significantly from 7.3 percent in 2002 to almost 13 percent in 2006.

Warfarin use was associated with a 30 percent increased risk of death among all trauma patients and a 20 percent increased risk in those 65 and older, according to the study, presented Thursday at the American College of Surgeons annual meeting in Chicago.

However, Dossett cautioned that other factors, such as additional health problems in warfarin users, may explain the heightened risk of death. The study did not make a definitive connection between warfarin use and death after a traumatic injury.

In a statement, Dossett also noted that trauma is a "relatively rare event for elderly patients, so if they have a good solid reason for taking warfarin, no one would suggest that they not take it."

"The biggest question that remains," Dossett told Reuters Health, "is what is the best, safest and most cost-effective way to prevent the increased death rates seen with pre-injury warfarin; in other words, how can we best reverse its effects after injury."

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