Reduction in motor vehicle collisions following treatment of sleep apnoea with nasal CPAP

Background-Patients with untreated obstructive sleep apnoea (OSA) have incr eased motor vehicle collisions (MVCs). When successfully treated, they repo rt improved driving and fewer mishaps, but there are few objective data to confirm this. A study was therefore undertaken to examine actual MVC data i n a large group of patients with OSA before and after treatment with contin uous positive airway pressure (CPAP) compared with a control group matched for age, sex, and type of driver's licence (commercial or non-commercial). Methods-Two hundred and ten patients of mean (SD) age 52 (11) years, body m ass index (BMI) 35.5 (10)kg/m(2), apnoea/ hypopnoea index (AHI) 54 (29) eve nts/h were treated with CPAP for at least 3 years. MVC records were obtaine d from the Ontario Ministry of Transportation (MTO) database for patients a nd an equal number of randomly selected control drivers. MVC rates were com pared for 3 years before and after CPAP therapy for patients and for the co rresponding time frames for controls. Results-Untreated patients with OSA had more MVCs than controls (mean (SD) MVCs/driver/year 0.18 (0.29) v 0.06 (0.17), p <0.001)). Following CPAP trea tment the number of MVCs/driver/year fell to normal (0.06 (0.17)) while, in controls, the MVC rate was unchanged over time (0.06 (0.17) v 0.07 (0.18), p=NS). Thus, the change in MVCs over time between the groups was very sign ificant (change = -0.12 (95% CI -0.17 to -0.06), p <0.001)). The MVC rate i n untreated patients (n=27) remained high over time. Driving exposure was n ot different following CPAP. Conclusions-The risk of MVCs due to OSA is removed when patients are treate d with CPAP As such, any restrictions on driving because of OSA could be sa fely removed after treatment.