Driving Errors in Parkinson’s Disease: Moving Closer to Predicting On-Road Outcomes

Age-related medical conditions such as Parkinson’s disease (PD) compromise driver fitness. Results from studies are unclear on the specific driving errors that underlie passing or failing an on-road assessment. In this study, we determined the between-group differences and quantified the on-road driving errors that predicted pass or fail on-road outcomes in 101 drivers with PD (mean age 5 69.38 ± 7.43) and 138 healthy control (HC) drivers (mean age 5 71.76 ± 5.08). Participants with PD had minor differences in demographics and driving habits and history but made more and different driving errors than HC participants. Drivers with PD failed the on-road test to a greater extent than HC drivers (41% vs. 9%), x2(1) 5 35.54, HC N 5 138, PD N 5 99, p \u3c .001. The driving errors predicting on-road pass or fail outcomes (95% confidence interval, Nagelkerke R2 5.771) were made in visual scanning, signaling, vehicle positioning, speeding (mainly underspeeding, t (61) 5 7.004, p \u3c .001, and total errors. Although it is difficult to predict on-road outcomes, this study provides a foundation for doing so