Meier estimated 30-day case-fatality rate was 29.3% (95% CI, 22.0–35.9). The 68 deaths, compared with mortality in the 1990 Minnesota white population, were significantly more than the 12.8 expected (relative risk [RR], 5.29; 95% confidence interval [CI], 4.11–6.17); but the 14 deaths in those with moderate or severe TBI who survived for the first 6 months after injury did not differ significantly from the 12.7 expected (RR, 1.10; 95% CI, 0.60–1.85; p = 0.72). There were 78 deaths in the mild-TBI group, and the Kaplan–Meier estimated 30-day case-fatality rate was 0.2% (95% CI, 0.0–0.4). Over the full followup period, the 78 deaths were significantly greater than the 58.8 expected (RR, 1.33; 95% CI, 1.05–1.65; p = 0.012); but the 69 deaths in the people with mild cases who survived 6 months after injury were not significantly different from the 58.6 expected (RR, 1.18; 95% CI, 0.92–1.49; p = 0.173).
Selassie et al. (2005) studied a representative sample of 3,679 TBI patients within a year of their discharge from any of 62 acute-care hospitals in South Carolina in 1999–2000 to document mortality within 15 months of discharge. Patients were stratified on the basis of TBI severity and hospital size. Of the sample, 3,371 (91.6%) were alive, and 308 (8.4%) had died within about 15 months of their discharge. Deaths were confirmed by using the Social Security Death Index (SSDI) and were classified as TBI-related or not. Of the 308 deaths, 17% were classified as TBI-related, and 63% of them occurred within the first 3 months after discharge, compared with 47% of the non-injury-related deaths. Findings indicate that the older the person, the higher the likelihood of early death. Males were more likely than females to die after TBI hospitalization if they were younger than 35 years old or older than 54 years old, but mortality was higher in females in the age range of 35–54 years. The authors also report that the severity of the TBI influenced mortality, as did the place of treatment. Patients who were treated in hospitals with trauma centers were less likely to die within 15 months after hospital discharge than patients treated in hospitals without trauma centers.
In a retrospective cohort study, Baguley et al. (2000) assessed mortality in 476 people who had sustained severe TBI over a 10-year period compared with an age- and sex-matched sample of the general Australian population. Patients with TBI, resulting primarily from closed head trauma due to motor-vehicle collisions, were admitted into a rehabilitation hospital 1986–1996. Twenty-seven of the 476 patients with TBI had died by August 1997, for a mortality rate of 5.7%. The median interval between injury and death was 17 months (range, 45 days–108 months after injury). Mortality in the TBI group was significantly associated with a lower level of functional independence on the basis of the Functional Assessment Measure (p < 0.001) slightly significantly with male sex (p < 0.078), with greater age (38 vs 32 years of age; p < 0.055), and with a premorbid psychiatric history (p < 0.064), but not significantly with a history of premorbid substance abuse (p < 0.308). In the general-population sample, the mortality rate was 1.5%. A Fisher’s exact test indicated that significantly more people (p < 0.001) with TBI died (compared with the general population), with most deaths occurring in the first 12 months after injury. The leading causes of deaths were cardiorespiratory events (8 of 27) and infection (6 of 27). The study is limited by the short followup period of about 5 years, the use of data from only one state in Australia, and the lack of functional assessment of and preinjury data on 52% of the deceased and 22% of the living TBI patients.