Assessment of fitness to drive in elderly and cognitively impaired drivers: Adaptation of the Driving Observation Schedule to simulated environments

Abstract

We created a standardized assessment of fitness-to-drive in driving simulation environments through the adaptation of the Driving Observation Schedule (DOS; Vlahodimitrakou et al., 2013), which is a widely used instrument to assess “natural driving”. The Sim-DOS is an observational instrument that intends to overcome some of the practical limitations of the on-road assessment with dual control cars, in terms of safety, costs, and unpleasantness. Via expert consensus, the following was undertaken: (1) DOS behaviors were adapted to a simulated-based environment (signaling, observation of the environment, speed regulation, slow or unsafe reaction, distance interpretation, vehicle/lane positioning); (2) the Sim-DOS scores calculation, which is based on errors, was adapted from DOS to include hazard situations (HS) and free driving scores. The instrument was then piloted with a sample of 34 elderly drivers (70.9 ± 4.1 years old, 60% male, 46.1 ± 6.7 years of driving experience, 74% of them were regular drivers), along with the collection of simulator-produced data on number of harsh events and driving speed. Psychomotor skills of the majority were compromised, with only one participant being above the 80th percentile in the Reaction Times Test score of the Spanish mandatory driving assessment. Participants undertook two consecutive 20-minute long driving scenarios, with low and high traffic density (LTD, HTD). In each scenario, there were periods with and without potentially HS. Assessments were performed by two independent trained observers (intra-class correlation coefficients > 0.94). When exposed to HS, most participants (94.1%) did not perform well (more than nine minor errors), independent of traffic density, with average Sim-DOS HS scores of 12.70 ± 9.3. Compared to LTD scenarios, in HTD scenarios participants drove less smoothly, although slower (p-values<.05). The latter improved their ability to manage hazard situations, thus producing better than expected Sim-DOS scores. During free driving, participants drove more smoothly but performed worse under LTD conditions, driving at higher speed (p-values<.05). Our study provides a validated driving assessment tool for use in driving simulators that will allow for a safer, more ecologic, holistic and informative evaluation of the fitness-to-drive of older adults and patients with neurologic conditions.