Background The effect of obstructive sleep apnea (OSA) on prevalent cardiovascular disease (CVD) among professional drivers has not been systematically investigated. Thus, this study used a large professional driver cohort to assess the effectiveness of nocturnal oxygen saturation for prediction the subsequent 8-year CVD risk.

Methods The Taiwan Bus Driver Cohort Study (TBDCS) recruited 1,650 professional drivers from a large bus company in Taiwan in 2005. The subjects were interviewed in person and completed the overnight pulse oximeter survey. This cohort was linked to the National Health Insurance Research Dataset and 192 CVD cases were found from 2005 to 2012. Primary outcomes were CVD events, nocturnal oxygen desaturation index (ODI), and working patterns. ODI3 or ODI4 are the hourly average number of desaturation episodes, which are defined as at least 3% or 4% decrease in saturation from the average saturation in the preceding 120 seconds, and lasting > 10 seconds.

Results ODI4 and ODI3 levels increased the 8-year CVD risk, even adjusting for CVD risk factors (HR: 1.36, 95% CI: 1.05 to 1.78; p = 0.022, and HR: 1.40, 95% CI: 1.03 to 1.90; p = 0.033). ODI4 and ODI3 thresholds of 6.5 and 10 events/hour revealed differences of CVD risks (HR: 1.72, 95% CI: 1.00 to 2.95; p = 0.048, and HR: 1.76, 95% CI: 1.03 to 3.03; p = 0.041). Moreover, the ODI levels had an increased risk for cardiovascular disease (not including hypertensive disease) and hypertensive disease (not including essential hypertension).

Conclusion This study concludes that ODI level for a sign of OSA is an independent predictor of future 8-year risk of CVD. This finding has an important implication to encourage health or labour service organisations that early recognition and active treatment of OSA could reduce future CVD risk.