epworth sleepiness scale for screening of the drowsy driving: comparison with the maintenance of wakefulness test in an Iranian sample of commercial drivers

ABSTRACT

Traffic fatalities are a major cause of morbidity and mortality in Iran. Occupational sleep medicine field needs more cost-effective and applicable tests for screening purposes. This study reports on a pilot screening study for drowsy drivers in an urban Iranian sample of commercial drivers. The Maintenance of Wakefulness Test [MWT] measures the ability to remain awake objectively. Sleep latency in MWT is a reasonable predictor of driving simulator performance in drivers. In this study, we evaluate whether the Epworth Sleepiness Scale [ESS] and MWT are equally useful in drivers with possible Excessive Daytime Sleepiness [EDS]. 46 consecutive road truck drivers in a transportation terminal entered into this study. The ESS score of patients with normal and abnormal MWT was 3.24 +/- 2.4 and 4.08 +/- 3 respectively which was not significantly differenced [P value = 0.34]. No significant correlation was found between the ESS and sleep latency in MWT [r=-0.28, 95%CI= -0.58 to 0.02]. By using the receiver operating characteristic analysis, the area under the curve was found to be 0.57 [95% confidence interval = 0.37- 0.77] which is not statistically acceptable [P value=0.46]. Our finding showed that the MWT and ESS do not measure the same parameter