Motor vehicle accidents in CPAP-compliant obstructive sleep apnea patients-a long-term observational study

Purpose Obstructive sleep apnea (OSA) has been associated with a 2- to 7-fold risk of motor vehicle accidents (MVAs). Continuous positive airway pressure (CPAP) treatment may reduce MVA risk. We further explored this issue in long-term CPAP users and untreated controls. Methods We used both before-after and case-control study designs. The observational cohort consisted of CPAP-treated and untreated patients matched for gender, age, and apnea-hypopnea index. All MVAs reported to the police were identified. Results A total of 2060 patients (75.8% male, mean age 56.0 +/- 10.5 years) were included. The CPAP-treated patients (N = 1030) were screened for MVAs for a median of 9.0 years before and after treatment. The median CPAP usage was 6.4 h/day. The control patients (N = 1030) were screened for MVAs for a median of 6.5 years after discontinuation of CPAP. No significant differences were observed between the incidences of MVAs per 1000 person years before treatment (3.2), after treatment (3.9), or in controls (2.6). Compared with controls, patients who had MVA after treatment had a higher body mass index (BMI), but did not differ in terms of other baseline characteristics, sleep study data, or accident conditions. In the majority of these patients, daytime sleepiness was reduced, whereas BMI tended to increase during treatment. Conclusions The MVA incidence did not change after CPAP treatment. Among the patients who had MVA, BMI was the only baseline characteristic that differed between the groups and tended to further increase after CPAP treatment. Differences in sleep study data or accident conditions were not observed.