Occupational therapy assessment of open-road driving performance: validity of directed and self-directed navigational instructional components.

OBJECTIVE The purpose of this study was to validate an assessment tool used by occupational therapists to evaluate on-road driving performance. METHODS The driving assessment was conducted over a 15-km route that consisted of a range of traffic situations and contained both directed and self-directed navigational instruction. The driving performance of four groups of drivers of different ages and visual characteristics was assessed independently by an occupational therapist and driving instructor using a range of scoring criteria. RESULTS The occupational therapist scores were significantly affected by the drivers' age and visual characteristics (directed navigation, F(3,133) = 6.05, p = 0.001; self-directed navigation, F(3,133) = 5.04, p < 0.002), and these group differences were greater for self-directed navigational instruction. The occupational therapist scores were highly correlated with the driving instructor's global driver safety rating (r = 0.76, p < 0.001). DISCUSSION The driving assessment instrument was a valid measure of on-road driving performance relative to an independent global driving safety evaluation. The instrument provided detailed information regarding driving performance and highlighted areas of difficulty, particularly when drivers followed self-navigational instruction.