Does apnea impair your patient’s ability to drive?

Evidence-based medicine provides no easy answers for a physician who must decide whether to report an obstructive sleep apnea patient to the state department of motor vehicles. Numerous studies have failed to identify a method for determining which individuals with obstructive sleep apnea are more likely to have motor vehicle accidents. There is no correlation between symptoms and objective measures of vigilance or performance. People with the disorder  are more likely to be in a motor vehicle accident, but the overall risk is low. In one report, patients had more crashes than did a control group during a 3-year period (odds ratio 2.6). Some patients had two and three crashes, but most did not have any accidents, and no physiologic markers predicted which patients were at greater risk. How individuals respond to sleep loss varies. In study after study, objective measures such as scores on the Epworth Sleepiness Scale, Karolinska Sleepiness Scale, respiratory disturbance index, and the apnea-hypopnea index did not predict reaction time or driving performance. He cited a US Department of Transportation-commissioned review of the literature from 1960 to 2000 (Report no. DOT HS 809 690), which concluded that commonly used measures of sleep apnea severity “are not very useful” in identifying people at risk for crashes. In a more recent trial, 20 obstructive sleep apnea patients and 40 controls took a battery of tests, including a driving simulator, said that almost all the apnea patients had some impairment of vigilance or attention, but no one test predicted ability to remain awake and stay attentive.

Effectiveness of measures to counteract night drowsiness also is highly variable. Drinking caffeine or taking a nap helped most participants in another study, but the effects ranged widely among individuals. A doctor referred physicians treating sleep apnea patients to recommendations of the American Thoracic Society and a statement on commercial drivers from a Joint Task Force of the American College of Chest Physicians, the American College of Occupational and Environment Medicine, and the National Sleep Foundation. The thoracic society calls on physicians to know the applicable laws in their state, to give high-risk drivers a warning of risk, and to report high-risk drivers who insist on driving before being treated for obstructive sleep apnea or who fail to comply with treatment. They noted that the joint statement gives an apnea-hypopnea index of 5 or more during titration and  of 10 or more, “depending on clinical findings,” as objective measures for when commercial drivers should be allowed to return to work. They questioned whether the thresholds were realistic given the inconclusive literature. The statement also calls for evaluation of compliance with treatment. In the absence of an easy method for predicting when a patient poses a danger, they urged physicians to rely on their clinical judgment. Two important considerations, they suggested, are whether the patient perceives a risk and whether he or she is willing to take actions to reduce it, such as treatment. Many people recognize that they become drowsy behind the wheel, but think that this is normal and do not perceive their condition as dangerous.

North Carolina law does not require obstructive sleep apnea patients who pose a risk to be reported. Nonetheless, they reported a school bus driver suspected of having the disorder. Her license was suspended while he confirmed the diagnosis, and it was reinstated after they started treatment.

They got to live with their self, and do what they think is right. Don’t be afraid to use your clinical judgment because nothing is a strong predictor of risk.