Assessing fitness to drive—A validation study on patients with mild cognitive impairment

Figures & data

Table 1. Descriptive results of patients with MCI who pass and patients with MCI who fail the on-road assessment on selected measures of clinical interviews, neuropsychological assessment, and driving simulator rides (M ± SD).

Predictors^a	Pass (n = 12)	Fail (n = 6)
Clinical interviews^b
Clinical Dementia Rating
CDR Orientation	0.333 ± 0.389	0.500 ± 0.316
CDR Judgment and Problem Solving	0.417 ± 0.359	0.417 ± 0.376
Anamnesis
Judgment driving safety^c	1.25 ± 0.45	1.33 ± 0.52
Driving questionnaire
Recent driving experience^d	2.75 ± 1.42	3.33 ± 1.63
Neuropsychological assessment^e
MMSE
Total score	27.25 ± 2.90	26.67 ± 1.86
RT S2
Reaction time (ms)	262.75 ± 53.58	270.50 ± 54.16
Hazard perception
Number of correct trials	16.50 ± 3.34	10.83 ± 4.49
Traffic theory
Response time (s)	6.22 ± 1.16	7.45 ± 1.13
Driving simulator rides^f
Intersection ride
Minimum speed intersection 2 (km/h)^g	5.27 ± 9.53	5.04 ± 12.21
Number of collisions	0.42 ± 0.67	1.00 ± 0.89
Merging ride
Deceleration rear car (km/h)	−0.03 ± 0.09	−2.11 ± 3.26
Time headway (s)	0.91 ± 0.39	1.80 ± 0.64

^aPrediction equation for fitness to drive (complete approach) = Clinical interviews ^* 0.328 + Neuropsychological assessment ^* −0.620 + Driving simulator rides ^* 0.483.

^bPrediction equation for fitness to drive (clinical interview) = CDR Orientation ^* 0.675 + CDR Judgment and Problem Solving ^* 1.036 + Judgment driving safety ^* 1.250 + Recent driving experience ^* −0.576.

^cJudgment about driving safety whether participant is (1) still driving as safely as when the participant was middle-aged, (2) driving less safely compared to when the participant was middle-aged, or (3) drives unsafely.

^dKilometres driven in the previous 12 months: (1) less than 1,000 km, (2) 1,000–5,000 km, (3) 5,000–10,000 km, (4) 10,000–20,000 km, (5) 20,000–30,000 km, (6) 30,000–50,000, (7) more than 50,000 km.

^ePrediction equation for fitness to drive (neuropsychological assessment) = MMSE ^* 0.129 + RT S2 RT ^* −0.003 + Correct trials of Hazard Perception ^* 0.206 + Response time of traffic theory ^* −0.310.

^fPrediction equation for fitness to drive (driving simulator rides) = Minimum speed intersection 2 ^* 0.021 + Number of collisions ^* 0.738 + Deceleration rear car ^* −0.367 + Time headway ^* 0.732.

^gIntersection with need to give right of way; the traffic lights at this intersection turn yellow and subsequently red.

Figure 1. ROC curves presenting diagnostic accuracies of clinical interviews, neuropsychological assessment, and driving simulator rides for the prediction of fitness to drive.

Table 2. Classification accuracy of the final predictor variable (including clinical interviews, neuropsychological assessment, and driving simulator rides) in detecting patients being unfit to drive (n = 6) relative to patients being fit to drive (n = 12).

Cutoff	Sensitivity	Specificity	Positive predictive value	Negative predictive value
−0.6	66.7	83.3	66.7	83.3
−0.8	66.7	83.3	66.7	83.3
−1.2	100.0	83.3	75.0	100.0