To investigate the association between sleep apnea syndrome (SAS) and automobile accidents, and to evaluate potential underlying mechanisms, we prospectively recruited 60 consecutive patients with SAS (apnea-hypopnea index, 58 +/- 3 h-1) and 60 healthy control subjects, matched for sex and age. The number of automobile accidents during the past 3 yr was obtained from participants and insurance companies. We quantified the degree of daytime sleepiness (Epworth scale), anxiety and depression (Beck tests), and we assessed the level of vigilance (PVT 192) and driving performance (Steer-Clear). Patients had more accidents than control subjects (OR: 2.3; 95% CI: 0.97 to 5.33) and were more likely to have had more than one accident (OR: 5.2; 95% CI: 1.07 to 25.29, p < 0.05). These differences persisted after stratification for km/yr, age, and alcohol consumption. Patients were more somnolent, anxious, and depressed than control subjects (p < 0.01), and they had a lower level of vigilance and poorer driving performance (p < 0.01). Yet, we did not find any correlation between the degree of daytime sleepiness, anxiety, depression, the number of respiratory events, nocturnal hypoxemia, level of vigilance, or driving simulator performance and the risk of automobile accidents among SAS patients. In conclusion, patients with SAS have an increased risk of automobile accidents. None of the clinical or physiological markers commonly used to define disease severity appear able to discriminate those patients at higher risk of having an automobile accident.

Daytime sleepiness, impaired cognitive performance and dysphoric mood are often present in patients with obstructive sleep apnoea syndrome (SAS). This prospective controlled study evaluates the effects of treatment with continuous positive airway pressure (CPAP) during 1 yr on daytime functioning in a large group of patients with SAS.The authors studied 80 patients (mean SEM 49 1 yrs) with SAS with a mean apnoea-hypopnoea index of 60 2 h -1 , and 80 healthy control subjects matched for sex and age (46 1 yrs.). Measurements were obtained at the beginning of the study and 12 1 months later, and included: daytime sleepiness (Epworth scale), depression and anxiety (Beck tests), vigilance (Steer-Clear1) and reaction time (Psychometer Vigilance Test 1921). Drug, coffee and alcohol intake, as well as the sleep schedule, were also recorded.Results showed that, before treatment, patients were more somnolent (p<0.001), anxious (p<0.01) and depressed (p<0.001) than control subjects. Also, they had a longer reaction time (p<0.05) and poorer vigilance (p<0.01). The use of CPAP improved significantly the levels of somnolence (p<0.0001) and vigilance (p<0.01), but failed to modify anxiety and depression. Reaction time changes were minor. Variables with a potential confounding effect did not change during the study.These results provide firm evidence to substantiate the use of continuous positive airway pressure in patients with sleep apnoea syndrome. Eur Respir J 2000; 15: 676±681.

Background: Continuous positive airway pressure (CPAP) reduces daytime somnolence in the obstructive sleep apnea syndrome (OSAS) and may contribute to a reduction in the risk of motor vehicle accidents. Objective: To evaluate the effects of CPAP on automobile collisions in patients with OSAS. Methods: We compared the number of motor vehicle accidents in 80 patients with OSAS and 80 healthy subjects during the 2 years before and the 2 years after study entry, at which CPAP treatment was initiated. Results: Patients with OSAS had a 2.6 times higher risk of suffering an automobile collision compared to controls (rate ratio, RR = 2.57; 95% confidence interval, CI = 1.30–5.05). After 2 years of CPAP treatment, the rate of collisions was reduced more than half in patients with OSAS (RR = 0.41; 95% CI = 0.21–0.79), but this occurred also in controls (RR = 0.49; 95% CI = 0.17–1.40). The magnitude of this fall between groups was not different (p for interaction = 0.68), even after adjusting for body mass index, alcohol intake and Epworth scale. Conclusions: Patients with OSAS have an increased risk of suffering a traffic collision. This risk was significantly reduced after their inclusion in the study. Yet, as this reduction also occurred in the control group, this effect may not be due to CPAP therapy.