RELIABILITY OF THE WASHINGTON-UNIVERSITY ROAD TEST - A PERFORMANCE-BASED ASSESSMENT FOR DRIVERS WITH DEMENTIA OF THE ALZHEIMER-TYPE

Objective: To assess the reliability and stability of a standardized r oad test for healthy aging people and those with dementia of the Alzhe imer type (DAT).Design: A prospective study involving patients with DA T and age-matched healthy controls in which subjects' driving performa nce was evaluated by several raters in an initial and a follow-up road test. Setting: Urban medical school and urban highways and streets. S ubjects: a convenience sample of 58 controls, 36 subjects with very mi ld DAT, and 29 subjects with mild DAT. Results: Analysis of road test ability of controls (2 subjects [3%] failed the test), very mild DAT s ubjects (7 subjects [19%] failed), and mild DAT subjects (It subjects [41%] failed) disclosed a significant association between driving perf ormance and dementia status (chi(2)[4] = 20.65 [N = 123]; P < .001; Ke ndall tau-b = 0.306). Interrater reliability for assessment of driving performance ranged from kappa = 0.85 to 0.96. One-month test-retest s tability on the road test was 0.76 (quantitative scoring) and 0.53 (cl inical judgment). Conclusions: Dementia adversely affects driving perf ormance even in its mild stages, although some persons with DAT seem t o drive safely for some time after disease onset. A traffic-interactiv e, performance-based road test that examines cognitive behaviors provi des an accurate and reliable functional assessment of driving ability.