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Risk and severity of motor vehicle crashes in patients with obstructive sleep apnoea/hypopnoea
  1. A T Mulgrew1,
  2. G Nasvadi2,
  3. A Butt1,
  4. R Cheema1,
  5. N Fox1,
  6. J A Fleetham1,3,
  7. C F Ryan1,3,
  8. P Cooper2,
  9. N T Ayas1,3,4
  1. 1UBC Hospital Sleep Disorders Program, Respiratory Division, University of British Columbia, Vancouver, Canada
  2. 2Insurance Corporation of British Columbia, 151 West Esplanade, North Vancouver, Canada
  3. 3Respiratory Division, Department of Medicine, University of British Columbia, Vancouver, Canada
  4. 4Centre for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Canada
  1. Dr N Ayas, Diamond Health Centre, 2775 Laurel St, Vancouver, British Columbia, Canada V6R 1M9; najib.ayas{at}


Background: Obstructive sleep apnoea/hypopnoea (OSAH) appears to be associated with an increased risk of motor vehicle crashes (MVCs). However, its impact on crash patterns, particularly the severity of crashes, has not been well described. A study was undertaken to determine whether OSAH severity influenced crash severity in patients referred for investigation of suspected sleep-disordered breathing.

Methods: Objective crash data (including the nature of crashes) for 783 patients with suspected OSAH for the 3 years prior to polysomnography were obtained from provincial insurance records and compared with data for 783 age- and sex-matched controls. The patient group was 71% male with a mean age of 50 years, a mean apnoea-hypopnoea index (AHI) of 22 events/h and a mean Epworth Sleepiness Scale score of 10.

Results: There were 375 crashes in the 3-year period, 252 in patients and 123 in controls. Compared with controls, patients with mild, moderate and severe OSAH had an increased rate of MVCs with relative risks of 2.6 (95% CI 1.7 to 3.9), 1.9 (95% CI 1.2 to 2.8) and 2.0 (95% CI 1.4 to 3.0), respectively. Patients with suspected OSAH and normal polysomnography (AHI 0–5) did not have an increased rate of MVC (relative risk 1.5 (95% CI 0.9 to 2.5), p = 0.21). When the impact of OSAH on MVC associated with personal injury was examined, patients with mild, moderate and severe OSAH had a substantially higher rate of MVCs than controls with relative risks of 4.8 (95% CI 1.8 to 12.4), 3.0 (95% CI 1.3 to 7.0) and 4.3 (95% CI 1.8 to 8.9), respectively, whereas patients without OSAH had similar crash rates to controls with a relative risk of 0.6 (95% CI 0.2 to 2.5). Very severe MVCs (head-on collisions or those involving pedestrians or cyclists) were rare, but 80% of these occurred in patients with OSAH (p = 0.06).

Conclusion: Patients with OSAH have increased rates of MVCs, and disproportionately increased rates of MVCs are associated with personal injury.

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  • Funding: This research was funded by a Michael Smith Foundation for Health Research Unit award and a British Columbia Lung Association operating grant. AM is supported by a CIHR/BC Lung Fellowship and by the CIHR/HSFC IMPACT training scheme. NA is supported by a Michael Smith Foundation for Health Research Scholar Award, a CIHR/BC Lung Association New Investigator Award and a Departmental Scholar Award from the University British Columbia.

  • Competing interests: None.

  • Ethics approval: The study was approved by the university ethics board and all patients provided written informed consent.