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Driving Risks in Obstructive Sleep Apnea (OSA)
It is estimated that 1 in every 15 adults has at least moderate
OSA (1). As the risks and
ill effects of this condition are further elucidated, physicians
are rightly asking, “Who should be
restricted from driving?” Equally, the social importance
of driving renders them rightly reluctant to recommend driving
restrictions. Here then is a brief summary of the evidence relating
OSA to motor vehicle accidents (MVAs):
1994 National Commission on Sleep Disorder Research
in the USA reported drowsiness is a factor in 36% of fatal MVAs,
and 42-54% of all MVAs (2).
1997 Terry Young, leading OSA epidemiologist,
reported:
- Males with at least mild OSA [Apnea-Hyponea
Index (AHI) = 5] or habitual snoring were significantly more
likely to
have a crash
in a 5 year period,
- Males and females with moderate OSA (AHI
= 15) had an odds ratio of 7.3 over controls for multiple crashes
over a 5-year period
(3).
1999 A Spanish study showed that:
- The drivers
of crashed vehicles had an odds ratio of 6.3 for at least mild
OSA (AHI = 5) over controls, and that
- The
Epworth Questionnaire (for subjective sleepiness) alone failed
to identify subjects at higher risk for accidents (4).
2000 A second Spanish study showed:
- Among drivers
who often felt sleepy on the road, those with self-reported
MVA(s) in the past 5 years, compared with those without
crashes,
had an odds-ratio of 8.5 for moderate OSA (AHI
= 15 with arousal index = 15) (5).
2001 A study from the University of Western Ontario
showed:
- The risk of MVAs due to OSA is removed when patients are
effectively treated with CPAP (6).
Conclusions
The following guidelines are suggested from the above evidence:
- Uncorrected moderate or severe OSA (AHI = 15 on polysomnography)
is a justifiable reason to restrict driving privileges. In
B.C. a physician is required to report such restriction if he/she
knows
a patient so advised continues to drive.
- Driving restrictions may
safely be lifted once CPAP is being regularly used (at least
6 hrs/night for 6 days/week). Compliance
card technology may help with determination; polysomnography
is not required. Follow-up is for life, with annual compliance
card
reports if possible.
- In patients treated by means other than
CPAP, it would seem reasonable to remove driving restrictions
once the AHI is reduced
to < 15, i.e. OSA is mild. This should be determined
by polysomnography.
- It would seem unreasonable to restrict the
driving of mild OSA patients on this evidence. However,
males with AHI 5-14
should be warned of the risk, treated and followed.
- Although
sleepiness from all causes is a large factor in MVAs, the
Epworth Questionnaire alone fails to effectively
identify
those at risk. History, examination and oximetry
must be considered
together.
Polysomnography is definitive: if advised and refused
driving must be restricted (7).
Richard R.J. Smyth, M.B.B.S., F.R.C.S.
February 2004
References
- Young, T.B. et al. Epidemiology of Obstructive Sleep Apnea.
American Journal of Respiratory Critical Care Medicine 2002;
165: 1217-1239.
- Leger, D. The cost of sleep-related accidents: a report
for the National Commission on Sleep Disorders Research.
Sleep 1994;
17: 84:93.
- Young, T.B. et al. Sleep-Disordered Breathing and
MVAs. Sleep 1997; 20: 608-613.
- Terán-Santos, J. et al.
The Association Between Sleep Apnea and the Risk of Traffic
Accidents. New England Journal of
Medicine 1999; 340: 847-851.
- Masa, J.F. et al. Habitually sleepy
drivers have a high frequency of automobile crashes. American
Journal of Respiratory
Critical
Care Medicine 2000; 162: 1407-1412.
- George, C.F.P. Reduction
in motor vehicle collisions following treatment of sleep
apnea with nasal CPAP. Thorax 2001; 56:
508-512.
- Determining medical fitness to drive; 6th ed.,
CMA publication, p. 25.
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