PURPOSE: The objective of the study was threefold: to investigate (1) the psychometric properties of data gathered with the Performance Analysis of Driving Ability (P-Drive); (2) the predictive validity of P-Drive in relation to a summed decision of passing or failing a medical driving evaluation; and (3) the success of adopting and implementing P-Drive in a clinical setting.

RATIONALE: Driving is a highly valued occupation that is easily disrupted by aging or cognitive impairment. There is a critical need for a valid and reliable assessment to evaluate on-road performance.

DESIGN: Mixed design with both a cross-sectional quantitative and qualitative data collection

PARTICIPANTS: A consecutive sample of 99 drivers with neurological impairment referred for a driving evaluation and occupational therapists trained for conducting on-road tests.

METHOD: Drivers were observed and scored by trained occupational therapists. A survey to participating occupational therapists were sent out via e-mail.

ANALYSIS: P-Drive data were analyzed with Rasch analysis using Winsteps. Receiver operating characteristic curves were used to set cutoff scores. Surveys from participating occupational therapists were analyzed with qualitative methods.

RESULTS: Data from 96% of drivers showed goodness of fit, evidence of person response validity. Only one item, controlling speed (driving too slow), failed to conform to the expectations of the Rasch model. P-Drive was able to separate the drivers into at least four different strata (reliability coefficient = .92). A cut-off raw score of 81 was optimal with high sensitivity of 93% and specificity of 92%. Although only 9 occupational therapists (of 19 initially trained) contributed data for analysis, 17 of 18 therapists who responded to a survey 30 mo after training reported using the assessment. Results suggest that data gathered with P-Drive yielded evidence of psychometric properties and that a cutoff could differentiate between pass and fail. Furthermore, P-Drive was implemented successfully in clinical settings although it took longer than a year from initial training to full implementation.

DISCUSSION: One item, controlling speed (the driver drives too slow), failed to conform to Rasch model expectations, and this could be due to chance. However, this item needs to be rewritten and clarified in the manual to make sure that it is not a scoring error present.

Even though the results suggest cutoff scores, importantly, a cutoff score is only a guide and should always be confirmed by clinical judgment.

Although only 9 of 19 possible occupational therapists contributed protocols for this study, almost all were administering P-Drive 30 mo after the course. These findings suggest that it takes time to successfully adopt a new assessment tool into the clinical setting.

IMPACT STATEMENT: P-Drive seems to be a valid and reliable assessment tool to evaluate on-road performance and is critically needed. Results suggest that P-Drive could be implemented in clinical practice. P-Drive could discriminate between pass and fail, but further studies are needed to confirm a suggested cutoff.