title: Psychiatric illness and subsequent traumatic brain injury: a case control study.
abstract: OBJECTIVE
  To determine whether psychiatric illness is a risk factor for subsequent traumatic brain injury (TBI).
  
  
  METHODS
  Case control study in a large staff model health maintenance organisation in western Washington State. Patients with TBI, determined by International classification of diseases, 9th revision, clinical modification (ICD-9-CM) diagnoses, were 1440 health plan members who had TBI diagnosed in 1993 and who had been enrolled in the previous year, during which no TBI was ascertained. Three health plan members were randomly selected as control subjects, matched by age, sex, and reference date. Psychiatric illness in the year before the TBI reference date was determined by using computerised records of ICD-9-CM diagnoses, psychiatric medication prescriptions, and utilisation of a psychiatric service.
  
  
  RESULTS
  For those with a psychiatric diagnosis in the year before the reference date, the adjusted relative risk for TBI was 1.7 (95% confidence interval (CI) 1.4 to 2.0) compared with those without a psychiatric diagnosis. Patients who had filled a psychiatric medication prescription had an adjusted relative risk for TBI of 1.6 (95% CI 1.2 to 2.1) compared with those who had not filled a psychiatric medication prescription. Patients who had utilised psychiatric services had an adjusted relative risk for TBI of 1.3 (95% CI 1.0 to 1.6) compared with those who had not utilised psychiatric services. The adjusted relative risk for TBI for patients with psychiatric illness determined by any of the three psychiatric indicators was 1.6 (95% CI 1.4 to 1.9) compared with those without any psychiatric indicator.
  
  
  CONCLUSIONS
  Psychiatric illness appears to be associated with an increased risk for TBI.
authors.affiliation: Department of Psychiatry, University of Washington, Seattle, Washington, USA. fann@u.washington.edu
authors.forename: J R
authors.initials: JR
authors.lastname: Fann
authors.forename: A
authors.initials: A
authors.lastname: Leonetti
authors.forename: K
authors.initials: K
authors.lastname: Jaffe
authors.forename: W J
authors.initials: WJ
authors.lastname: Katon
authors.forename: P
authors.initials: P
authors.lastname: Cummings
authors.forename: R S
authors.initials: RS
authors.lastname: Thompson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000453:epidemiology / Q000209:etiology*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D001523:Mental Disorders / Q000150:complications*; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors