The risk of death after head injury remained significantly increased for as long as 13 years, irrespective of the severity of the injury, results of a case-control study showed.
Overall, patients with a history of head injury had more than a twofold greater risk of death than did two control groups of individuals without head injury.
Among young adults, the risk disparity ballooned to more than a fivefold difference, Scottish investigators reported online in the Journal of Neurology, Neurosurgery and Psychiatry.
“More than 40% of young people and adults admitted to hospital in Glasgow after a head injury were dead 13 years later,” Dr. Thomas M. McMillan, of the University of Glasgow, and coauthors wrote in the discussion of their findings. “This stark finding is not explained by age, gender, or deprivation characteristics.”
“As might be expected following an injury, the highest rate of death occurred in the first year after head injury,” they continued. “However, risk of death remained high for at least a further 12 years when, for example, death was 2.8 times more likely after head injury than for community controls.”
Previous studies of mortality after head injury have focused primarily on early death, either during hospitalization or in the first year after the injury. Whether the excess mortality risk persists over time has remained unclear, the authors noted.
Few studies have compared mortality after head injury with expected mortality in the community. To provide that missing context, McMillan and coauthors conducted a case-control study involving 757 patients who incurred head injuries of varying severity from February 1995 to February 1996 and were admitted to a Glasgow-area hospital.
For comparison, the investigators assembled two control groups, both matched with the cases for age, sex, and socioeconomic status and one matched for duration of hospitalization after injury not involving the head.
One control group was comprised of persons hospitalized for other injured and other comparison group included healthy non-hospitalized adults.
The cases comprised 602 men and 155 women who had a mean age of 43, and almost 70 percent were in the lowest socioeconomic quintile.
At the end of follow-up, 305 of the head-injured patients had died, compared with 215 of the hospitalized control group, and 135 of healthy, non-hospitalized adults.
Mortality after one year remained significantly higher in the head-injury group—34 percent versus 24 percent among the hospitalized comparison group and 16 percent for the healthy non-hospitalized adults.
Overall, the head-injury group had a death rate of 30.99/1,000/ year versus 13.72/1,000/year in the community controls and 21.85/1,000/year in the hospitalized-other injury control group.
The disparity was greater among younger adults (15 to 54), who had a rate of 17.36/1,000/year versus 2.21/1,000/year in the community controls. Older adults in the head injury group had a death rate of 61.47/1,000/year compared with 39.45/1,000/year in the community controls.
“Demographic factors do not explain the risk of death late after head injury, and there is a need to further consider factors that might lead to health vulnerability after head injury and in this way explain the range of causes of death,” the authors wrote in conclusion. “The elevated risk of mortality after mild head injury and in younger adults makes further study in this area a priority.”