title: Physician Warnings in Psychiatry and the Risk of Road Trauma: An Exposure Crossover Study.
abstract: OBJECTIVE
  To determine if physician warnings to psychiatric patients alter the subsequent frequency of a motor vehicle crash. A secondary objective was to determine if physician warnings change the subsequent frequency of psychiatric hospitalization.
  
  
  METHODS
  Exposure crossover design of 23,145 psychiatric patients diagnosed with ICD-9 schizophrenia (code 295), mood disorder (296), personality disorder (301), or substance use disorder (303, 304) and warned by their physician about driving safety between April 1, 2006, and March 31, 2011. Each patient was followed for 4 years before the warning and 1 year after the warning. Patients living outside the region or lacking a valid health card number were excluded.
  
  
  RESULTS
  Patients' motor vehicle crash frequency decreased from 11.78 to 8.17 events per 1,000 patients per year after a physician warning, which corresponded to a relative risk of 0.69 (95% CI, 0.59-0.81; P < .001). Psychiatric hospitalization frequency increased from 147 to 289 events per 1,000 patients per year corresponding to a relative risk of 1.97 (95% CI, 1.91-2.03; P < .001).
  
  
  CONCLUSIONS
  Physician warnings are associated with a subsequent decreased frequency of motor vehicle crashes and increased frequency of psychiatric hospitalization. This result suggests that physician warnings are an effective intervention for reducing road trauma but need to be weighed against potential adverse psychiatric health.
authors: Centre for Addiction and Mental Health, CS 501, 250 College St, Toronto, Ontario, Canada, M5T 1R8. andrew.lustig@camh.ca.|Department of Psychiatry, University of Toronto, Ontario, Canada.|Centre for Addiction and Mental Health, Toronto, Ontario, Canada.|Institute for Clinical Evaluative Sciences (ICES), Toronto, Ontario, Canada.|Institute for Health Policy Management and Evaluation, Toronto, Ontario, Canada.
authors: Andrew J
authors: AJ
authors: Lustig
authors: Department of Psychiatry, University of Toronto, Ontario, Canada.|Centre for Addiction and Mental Health, Toronto, Ontario, Canada.|Institute for Clinical Evaluative Sciences (ICES), Toronto, Ontario, Canada.|Institute for Health Policy Management and Evaluation, Toronto, Ontario, Canada.
authors: Paul A
authors: PA
authors: Kurdyak
authors: Centre for Addiction and Mental Health, Toronto, Ontario, Canada.|Institute for Clinical Evaluative Sciences (ICES), Toronto, Ontario, Canada.
authors: Deva
authors: D
authors: Thiruchelvam
authors: Institute for Clinical Evaluative Sciences (ICES), Toronto, Ontario, Canada.|Institute for Health Policy Management and Evaluation, Toronto, Ontario, Canada.|Evaluative Clinical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.|Department of Medicine, University of Toronto, Ontario, Canada.|Division of General Internal Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors: Donald A
authors: DA
authors: Redelmeier
mesh_terms: D000063:Accidents, Traffic / Q000517:prevention & control* / Q000523:psychology* / Q000706:statistics & numerical data; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D019538:Health Care Surveys; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology* / Q000523:psychology*; D008875:Middle Aged; D009864:Ontario; D010353:Patient Education as Topic; D012306:Risk; D012959:Socioeconomic Factors; D014947:Wounds and Injuries / Q000453:epidemiology / Q000517:prevention & control / Q000523:psychology