had slighter higher mortality between the ages of 45 and 60 years, but the difference was not significant (p = 0.6). Similar results were seen when cases were divided by severity of coma (p > 0.6).
Confirming the results of Walker et al., Weiss and colleagues (1982) found that mortality was nonsignificantly (p = 0.08) higher in older TBI veterans with posttraumatic epilepsy than in older TBI veterans without posttraumatic epilepsy; moreover, posttraumatic epilepsy had a marked effect in reducing life expectancy (p = 0.01) in veterans with TBI compared with control veterans. Men with TBI were more likely to die of cerebrovascular disease than the controls (19% vs 12%; p = 0.01), particularly men younger than 60 years old (p = 0.015), but that difference did not correlate with the severity of the TBI.
Corkin et al. (1984) continued work begun by Teuber and colleagues in 1948 on a cohort of 190 World War II veterans with penetrating TBI. Corkin et al. (1984) compared those veterans with a control group of 106 veterans who had peripheral nerve injury, matched for age at injury, years of formal education, and preinjury intelligence-test scores. As of 1983, 28.4% of the veterans with penetrating TBI and 17.0% of those with peripheral nerve injury had died—a statistically significant difference (p = 0.03). However, when veterans with head injuries were categorized by whether they had posttraumatic epilepsy, only those with epilepsy had significantly higher mortality than the controls (p = 0.0002). Such factors as the site of the brain lesion, age at injury, and preinjury and postinjury intelligence scores did not affect survival, although veterans with more education lived longer.
Rish and colleagues (1983) followed 1,127 male Vietnam veterans who had penetrating head injuries for 15 years. Over the 15-year period, 90 deaths (8%) had occurred: 46 in the first year after injury, 9 during the second year, and then 1–4 per year. Most deaths occurred early in the first year after trauma and were the result of the injury or coma sequelae. After 3 years, compared mortality in the head-injured Vietnam veteran population approached the norm, according to actuarial projections for North American men 21–35 years old. Length of coma was the best predictor of long-term outcome, and posttraumatic epilepsy was not a significant factor in mortality in the first 15 years, although each seizure event carried its own inherent risk.
Mortality in TBI patients can be studied from the time of injury, from the time of discharge from inpatient acute-care hospitals, or from the time of admission into or discharge from inpatient rehabilitation. Rates in cohorts of patients at those different points of entry into a study will be different. For example, rates in patients from the time of injury will be greatest because they include early deaths. In contrast, survivors of the acute phase who are studied during rehabilitation are likely to have lower mortality.
Brown et al. (2004) carried out a study to determine whether mortality from TBI was affected by the severity of the injury. Their population-based retrospective cohort study identified all Olmsted County, Minnesota, residents who had a diagnosis indicative of a potential TBI, and they reviewed the medical records from the Rochester Epidemiology Project for 1985–1999 (see Chapter 5). The review confirmed 1,448 cases of TBI—164 (11%) moderate to severe and 1,284 (80%) mild. There were 68 deaths in the moderate-to-severe TBI group. The Kaplan–