Predictors of steering simulation performance in patients undergoing investigation for Obstuctive Sleep Apnoea (OSA)

The raised rate of road accidents in OSA has stimulated a search for predictors of driving performance. 34 patients investigated for possible OSA (age 47.8 SD10.1, BMI 29.6 SD 6.3, ESS 11.9 SD4.0, >4%SaO2 dips/hr 10.4 SD 13.1) performed a steering simulation, including responses to peripheral events. Subjects performed a modified maintenance of wakefulness test (MWT 28.5 SD9.9 mins). The eventual diagnosis ranged from normal to severe OSA. Two steering simulation parameters (SD of steering error from the theoretical perfect path, and reaction time) were correlated against age, measures of sleepiness (ESS, MWT) and measures of OSA severity (autonomic arousals/hr, >4%SaO2 dips/hr, and body movements/hr). R age ESS MWT autonomic >4% body values arousals SaO2 movements /h dips/h /h steering 0.39* 0.28 -0.36* 0.23 0.22 0.40* error reaction 0.11 0.33 -0.04 0.35* 0.32 0.27 time * p <0.05. There were no correlations between the number of self-reported accidents or driving experience, and the steering error or reaction time. Steering error and reaction time did not have the same pattern of correlation with potential predictors, perhaps suggesting different impairment factors. Although correlations exist, they are not close and the prediction of individual driving performance remains imprecise.