Validity and critical driving errors of on-road assessment for older drivers.

OBJECTIVES We examined the validity of our on-road driving assessment to quantify its outcomes. METHOD Older drivers (N = 127) completed a driving assessment on a standardized road course. Measurements included demographics, driving errors, and driving test outcomes; a categorical global rating score (pass-fail); and the sum of maneuvers (SMS) score (0-273). RESULTS There were significant differences in the SMS (F = 29.9, df = 1, p < or = .001) between drivers who passed the driving test and those who failed. The SMS cutoff value of 230 points was established as the criterion because it yielded the most optimal combination of sensitivity (0.91) and specificity (0.87). The strongest predictors of failure were adjustment to stimuli and lane maintenance errors. CONCLUSION The SMS differentiated between passing and failing drivers and can be used to inform clinical decision making.