The Introduction of a New Screening Tool for the Identification of Cognitively Impaired Medically At-Risk Drivers

Abstract

The number of drivers with a cognitive impairment due to dementia or other age-associated pathologies will increase significantly over the next 3 decades. Physicians are well placed to identify medically at-risk drivers, but are hampered by the lack of a valid, easy to administer screening tool. This research develops and validates a brief screening tool for use in the primary care setting to identify drivers with cognitive impairment with or without dementia. Initial Study Participants: A cohort of 146 consecutive referrals from community-based family physicians, diagnosed with an undifferentiated cognitive impairment or dementia, as well as 35 community dwelling healthy controls. Validation Study: A cohort of 192 consecutive referrals carrying the same diagnosis as above and 52 community dwelling healthy controls. Criterion Measure: Pass/fail on an On-Road evaluation. Predictor Measures: Subtests of the DemTect, a screening test for cognitive impairment or dementia developed by Kalbe and colleagues. 1 Initial Study: Three of the DemTect measures predicted On-Road outcomes (R2 = .262). Regression results were used to develop a simple scoring algorithm, with cut-points then derived by identifying those most at risk for failing and passing the On-Road assessment, and those needing a driving assessment for determination of driving competency. 89 individuals scored in the indeterminate range, with 49 and 43 predicted to fail and pass, respectively—86% and 84% of those predicted to fail and pass did subsequently fail and pass. Validation Study: 123 individuals scored in the indeterminate range, with 66 and 55 predicted to fail and pass, respectively—80% and 87% of those predicted to fail and pass did subsequently fail and pass. Conclusions: The SIMARD A Modification of the DemTect (Screen for the Identification of cognitively impaired Medically At-Risk Drivers) is a brief paper and pencil screening tool with a high degree of accuracy that can be used for immediate decisions in the clinical setting.

It is premature to test older drivers with the SIMARD-MD

“…Possible scores range from 0 to 18, with one point added to the score in the absence of post-secondary education; higher scores reflect better cognition. The SIMARD-MD relies on three of these sub-tests (number trans-coding, semantic verbal fluency, and delayed recall) and a modified scoring algorithm resulting in scores ranging from 0 to 130 where higher represents better cognition (Dobbs & Schopflocher, 2010).…”

“…Hence, adoption of the SIMARD-MD as a tool to determine fitness-to-drive appears premature. Drivers: A modification of the DemTect" (SIMARD-MD) (Dobbs & Schopflocher, 2010), is a tool that can be administered in a physician's office. As far as we know, BC is the only province to promote its use and it was not specified why this tool was chosen over other tools currently used by health professionals.…”

Comparison of the SIMARD MD to Clinical Impression in Assessing Fitness to Drive in Patients with Cognitive Impairment

“…(19) The original DemTect was developed as a screening tool for MCI and early dementia, and included a number of subtests. (18) The SIMARD MD uses three of the six DemTect subtests: the Supermarket Task, Repeat of the Word List, and the Number Conversion test.…”

Evaluating the SIMARD MD a New Screening Tool to Identify Cognitively Impaired Drivers

“…Bédard et al's comparison (see Figure 1) presents ROC curves from two different tests: (A) two cut points from some type of combination of time scores from the Trail Making Test Part A and accuracy scores from the standardized MMSE and (B) two cut points for the SIMARD MD, putatively derived from the Dobbs and Schopflocher publication. 2 However, the two studies used different criteria (road outcomes from what appears to be a standard novice driver road test in the Bédard et al study 1 vs pass/fail outcomes from an on-road driving assessment specifically developed to assess cognitively impaired drivers in the Dobbs and Schopflocher studies 2 ). In addition, the two tests were evaluated using different populations (a sample of drivers who "volunteered to participate" [p 337] in the 2008 Bédard et al study, 3 compared to a mix of drivers diagnosed with cognitive impairment with or without dementia [about twothirds of the sample] and healthy controls [about one-third of the sample] in the Dobbs and Schopflocher studies 2 ).…”

“…Careful consideration was given to the selection of the population for the Dobbs and Schopflocher studies. 2 The average age of the participants was 77 in the initial study and 75 for the validation study, with the majority of the sample (81% and 79%, respectively) cognitively impaired. These sample characteristics were selected because they are representative of the population for which the tool was designed (patients seen in the clinical setting for concerns about cognitive driving competence and/or patients coming in for driver medicals).…”