Produced by the Royal College of Physicians of Edinburgh and Royal College of Physicians and Surgeons of Glasgow

Sleep apnoea and road accidents

  • Professor N Douglas, Respiratory Consultant, Royal Infirmary of Edinburgh, Edinburgh, Scotland

Summary

Sleep apnoea is a significantly under-diagnosed condition which causes symptoms of sleepiness and difficulty in concentrating. It can also cause drivers to fall asleep at the wheel. Prof Neil Douglas provides an overview of the link between sleep apnoea and road traffic accidents.

Key Points

  • Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is caused by airway obstructions during sleep. It disrupts sleep and results in sleepiness, impaired thought processes and delayed reaction times during the day.
  • Falling asleep while driving is common. About a fifth of men in the general population have reported falling asleep while driving, but a third of those with OSAHS have had an accident or a near accident due to falling asleep.
  • Drunk normal subjects perform better than sober OSAHS patients on a driving simulator.
  • Treatment for OSAHS can return driving performance to normal.

Declaration of interests: Chair, International Medical Advisory Board of ResMed (a US/Australian company which makes CPAP units to test OSAHS). Professor Douglas's Department has previously received research funding from ResMed.

Sleepiness and difficulty concentrating are the dominant symptoms of the obstructive sleep apnoea/hypopnoea syndrome (OSAHS). These symptoms are worst in monotonous situations such as driving on major roads and motorways, consequently drivers with OSAHS have an increased risk of road accidents. As OSAHS affects 1-4% of drivers this is a significant public health issue. This was highlighted in a recent report by a working party of the European Respiratory Society.

Although OSAHS patients tend to under-report driving difficulties, over one-third report having had an accident or near accident due to falling asleep at the wheel.1 Falling asleep while driving is also common in the general population, with 19% of men admitting to doing so in one study.2

Objective evidence indicates raised accident rates in sleep apnoeics. A study of all drivers presenting to an accident department showed that those with frequent apnoeas were six times more likely to be road accident drivers than subjects without sleep apnoea.3 Retrospective studies in patients prior to the diagnosis of OSAHS being established suggest a three-fold risk of road accidents compared to other drivers.4

There is also convincing evidence from vigilance tasks and driving simulators5 that driving performance is impaired in patients with OSAHS. Indeed drunk normal subjects perform better on a driving simulator than sober OSAHS patients.6 Interestingly the impairment is not just limited to periods when patients actually fall asleep; their response is also impaired when they are awake, reflecting impaired vigilance and delayed reaction times.7

Treatment of OSAHS significantly improves driving performance. Prospective studies have found that therapy with continuous positive airway pressure (CPAP) improves OSAHS patients’ performance on driving simulators8,9 and decreases the frequency and severity of road accidents. A recent analysis10 showed that CPAP not only returned OSAHS patients’ accident rates to the population norm, but also that treating 500 patients with CPAP for five years saved £4·9 million when the expenditure on treatment and follow-up were set against the savings on accident related costs. This is in addition to other well documented benefits of CPAP in terms of sleepiness, quality of life, mood, work performance and blood pressure.

This article was stimulated by the report11 of a Task Force of the European Respiratory Society. This pointed out the need to improve detection and speed of treatment of OSAHS patients in Europe and highlighted the disparity between countries regarding reporting the diagnosis to the driving authorities.

There is clearly a need to identify and treat individuals with OSAHS to reduce accident risk and to allow them to return to driving safely again. However, this must be done sympathetically and quickly. Otherwise, if it became apparent that individuals with suspected OSAHS lost their licence for months or years while waiting for investigation and treatment, many would not come forward for diagnosis. This would perpetuate the current situation where around 90% of patients with possible OSAHS remain undiagnosed and untreated to the detriment of themselves and other road users. Ideally patients with a clinical picture suggestive of OSAHS need to be firmly advised of the dangers of driving when sleepy - preferably in writing - and should be advised not to drive while their investigations and treatment are fast-tracked.

However, the current waiting times for investigation and treatment can range up to four years in the UK. Such delays are driven by erroneous concepts of economies of healthcare delivery, rather than looking at the wider benefits of offering cheap and effective treatment quickly. Hopefully the recent publication of a Scottish Intercollegiate Guidelines Network (SIGN) Guideline on the Management of OSAHS in spring 2003 will help improve service delivery.

References

  1. Engleman HM, Hirst WS, Douglas NJ. Under reporting of sleepiness and driving impairment in patients with sleep apnoea/hypopnoea syndrome. J Sleep Res 1997; 6:272-5.
  2. British Sleep Foundation. Sleepiness when driving. http://www.britishsleepfoundation.org.uk/. 2000.
  3. Teran-Santos J, Jimenez-Gomez A, Cordero-Guevara J. The association between sleep apnea and the risk of traffic accidents. Cooperative Group Burgos-Santander. N Engl J Med 1999; 340:847-51.
  4. George CF. Reduction in motor vehicle collisions following treatment of sleep apnoea with nasal CPAP. Thorax 2001; 56:508-12.
  5. George CF, Boudreau AC, Smiley A. Comparison of simulated driving performance in narcolepsy and sleep apnoea patients. 8Sleep* 1996; 19:711-7.
  6. George CF, Boudreau AC, Smiley A. Simulated driving performance in patients with obstructive sleep apnoea. Am J Respir Crit Care Med 1996; 154:175-81.
  7. Risser MR, Ware JC, Freeman FG. Driving simulation with EEG monitoring in normal and obstructive sleep apnea patients. Sleep 2000; 23:393-8.
  8. George CF, Boudreau AC, Smiley A. Effects of nasal CPAP on simulated driving performance in patients with obstructive sleep apnoea. Thorax 1997; 52:648-53.
  9. Hack M, Davies RJ, Mullins R et al. Randomised prospective parallel trial of therapeutic versus subtherapeutic nasal continuous positive airway pressure on simulated steering performance in patients with obstructive sleep apnoea. Thorax 2000; 55:224-31.
  10. Douglas NJ, George CF. Treating sleep apnoea is cost effective. Thorax 2002; 57:93.
  11. McNicholas WT, Levy P, DeBacker W et al. Public Health and medicolegal implications of sleep apnoea. Eur Resp J 2002; 20:1594-609.