title: Relative risk of mortality after traumatic brain injury: a population-based study of the role of age and injury severity.
abstract: To test if observed vs. expected mortality differs by age among traumatic brain injury (TBI) cases, a population-based, historical cohort study was conducted in Olmsted County, Minnesota. From all residents with any diagnosis suggestive of TBI 1985-1999, we randomly sampled 7,800 and reviewed their medical records to confirm the event. Confirmed incident cases were categorized by age in years (<16 = pediatric, 16-65 = adult, > 65 elderly) and severity (moderate/severe vs. mild) and followed for vital status through 6/30/2004. We compared observed 6-month and 10-year mortality with expected and tested if the differences varied by age. Of 1,433 confirmed incident cases, 35% were pediatric; 55% were adult; only 9% were elderly; 11.2% of all cases were moderate/severe; the proportions by increasing age group were 11.4%, 8.5%, 26.7%. The proportions who died within 6 months increased with increasing age group, both for moderate/severe (10.3%, 40.3%, 50.0%) and mild cases (0%, 0%, 9.1%); mortality for moderate/severe cases was nearly 40 times that for mild cases, independent of age. Among 6-month survivors, 10-year mortality differed from expected only for adult cases. For all cases, after adjusting for sex, year of TBI, and severity, the difference between observed and expected 10-year mortality was greater for adult cases than for pediatric cases and similar for adult and elderly cases. Elderly individuals account for <10% of TBI cases and >50% of 10-year mortality, yet much of this discrepancy reflects age-associated mortality in general. Findings have implications for (1) reducing the number of excess deaths following TBI and (2) caring for survivors.
authors.affiliation: Department of Psychiatry, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: Julie Testa
authors.initials: JT
authors.lastname: Flaada
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Leibson
authors.forename: Jayawant N
authors.initials: JN
authors.lastname: Mandrekar
authors.forename: Nancy
authors.initials: N
authors.lastname: Diehl
authors.forename: Patricia K
authors.initials: PK
authors.lastname: Perkins
authors.forename: Allen W
authors.initials: AW
authors.lastname: Brown
authors.forename: James F
authors.initials: JF
authors.lastname: Malec
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001930:Brain Injuries / Q000401:mortality* / Q000473:pathology; D015331:Cohort Studies; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D011153:Population; D012306:Risk; D012737:Sex Factors; D016019:Survival Analysis