ASSESSING THE
DRIVER
Cathy Brighton, BScOT (C)
Overview:
The author developed a power
mobility assessment in 1999 with the support of the North Shore Health
Region. It is an assessment tool that
involves a logical process along with clinical reasoning to address the
client’s individual needs. It enables
an Occupational Therapist (OT) to assess the complex skills involved in
operating a power mobility device in a timely manner and arrive at a well
supported recommendation as a conclusion.
A power mobility device (PMD) may be the most valuable piece of equipment that an OT can procure for a client with mobility issues. It can be a lifeline to mobility. The PMD can also be a danger to the client and the general public when not handled safely. In Canada, use of PMD’s is largely unregulated by any government body.
OT’s are commonly asked to assess a client’s ability to use a PMD, decide if a PMD should be recommended and to prescribe the appropriate features. Due to the risks and complexity of driving a PMD, the decision to recommend provision of a PMD should be taken very seriously. An OT has a duty to protect the safety of both clients and third parties. To minimize liability, assessment should be consistent and standardized.
An OT is expected to assess the skills involved in driving a PMD. An analysis of the performance components of driving a PMD revealed complex visual, perceptual and cognitive components. OT assessment should reflect these components. Physical assessment is well understood and it was not the intention to study it in depth for this project. The purpose was to develop an assessment that reflects complex driving skills. A review of the literature did not identify an assessment that addressed these skills. The goal was to develop an assessment tool that would reflect driving skills, improve the practice standard and be evidence based. This goal would better serve client and public safety and demonstrate a consistent and standardized approach.
Components of the PMD Assessment Tool:
Six components are briefly outlined below along with rationale, when indicated:
Part 1. Client Data: General background information including medical history, client’s identification of mobility issues, mobility status, use of prescription and non-prescription drugs and safety awareness.
Part 2. Physical/Functional Screen: This is a functional assessment. It includes a functional strength and range of motion guide, mobility assessment, driving history and instrumental activities of daily living.
This part concludes with a recommendation regarding continuation of the assessment. Given the information and observations gathered thus far, an OT may select appropriate pre-driving assessments for the individual according to clinical judgement. Consideration should be given to administering the pre-driving screen to confirm or clarify the individual’s vision, perceptual and cognitive status.
Part 3. Pre-driving assessment: This screens vision, perception, cognition and behaviour. This component is unique to this assessment. Clinical reasoning determines the extent of screening of vision, perception and cognition. It is important that screening is done in that order.
Selections for the
Pre-driving Assessment:
· Vision: Near and far acuity, visual fields, contrast sensitivity and peripheral vision are screened in a functional manner. In a literature search, there was no standardized test available for community OT practice. Therefore a functional screen was developed. Wearing corrective lenses, binocular vision is screened. Simple tools are used such as a sales flyer for visual fields, small vision chart for near acuity, finger test for peripheral vision, C-chart for distance vision.
Rationale: Visual field loss has a much bigger impact on vision function than acuity loss. Although visual acuity is important, significant loss of visual field and contrast sensitivity have the most impact on mobility and visual function. Visual acuity, contrast sensitivity and visual field all begin to decrease after the age of 50. Additionally, the peripheral visual field appears to decline at a faster rate than the central visual field. (A minimum of 20/80 is needed to do the perceptual test, MVPT, described below.)
Perception: The Motor-Free Visual Perceptual Test (MVPT) and Trailmaking A and B tests are used.
Rationale: The MVPT is a standardized test with norms from age 18 to 80. It is designed to measure visual perception per se, including spatial relationships, visual discrimination, figure ground, visual closure, visual memory and visual perceptual processing time. It is the strongest predictor of failure of on-road evaluation for driving automobiles. This test takes under 20 minutes to administer and is available in a one inch binder.
Trailmaking A and B assesses visual attention and scanning, visual planning and sequencing. Trail B also requires mental flexibility and concentration. It is also predictive of automobile driving performance. It is a paper and pencil test, includes 4 sheets of paper. It takes about 10 minutes to administer. The norms range for clients from age 15 to 79.
The MVPT and Trailmaking A and B have been shown to be the best combination of 2 tests for predicting ability to drive with stroke clients.
· Cognition: The Mini-mental Status Examination (MMSE), Clock Drawing Test(CDT) and four selected instrumental activities of daily living (IADLs) will be used.
Rationale: The MMSE is a highly recognized, standardized method to grade cognitive mental status. It assesses orientation, attention, immediate and short-term recall, language and the ability to follow simple verbal and written commands. There is a moderate correlation between the MMSE and driving performance. Norms range from 18 to >84. It consists of one piece of paper. It takes 10 to 15 minutes to administer. The CDT is a quick screening test for dementia. It demands planning, executive function, attention and concentration. It does frontal lobe testing whereas the MMSE does not. There are several scoring systems with norms but it has valuable qualitative aspects. It requires a piece of paper. It takes a few minutes to complete.
Four out of 11 IADL’s were selected from the Assessment of Living Skills and Resources (ALSAR). These are: telephoning, transportation, medication management and money management. There are norms for the ALSAR for the entire assessment (all 11 IADL’s). It is an interview that focuses on the accomplishment of tasks necessary for independent living. A person’s level of independence in IADL’s is an indicator of competency.
It has been reported that the MMSE and CDT used together provide impressive results in detecting dementia. An even more promising approach can be taken by adding IADL’s.
· Behaviour Screen: This simply screens the presence of 4 behaviours, which are relevant to safe driving. They are: distractibility, inattention, mental slowness, and difficulty in following directions.
Rationale: Research demonstrates that when observed behaviours were added to automobile pre-screening evaluation, the sensitivity and specificity of the evaluations were enhanced. Behaviours relevant to driving were identified through the research and included in the pre-driving assessment.
Part 4. Recommendations: Based on the outcome of the pre-driving assessment, it is determined whether or not to proceed with an “On-Road” Driving Performance assessment or whether further information is needed i.e. collaboration with family physician, referral for further visual, perceptual or cognitive testing.
This plan will be discussed with the client and the action plan will be identified. The client’s agreement is required for the process to continue.
If the plan is to proceed with the “On-Road” Driving Assessment, the client is supplied with safety guidelines, to be reviewed prior to the “On-Road” Driving Assessment.
Part 5. The “On-Road” Driving Performance Assessment:
Prior to proceeding with “On-Road” Driving Assessment, the OT reviews the safety guidelines of driving a PMD with the client.
The “On-Road” Driving Performance Assessment was designed for community use and is client-centred. The client is involved in selecting the assessment items that are relevant to the intended plan for use and in determining the action plan. It addresses all aspects of safety.
Part 6. Final Recommendations and Action Plan: The OT and client discuss the outcome and determine a plan, which identifies an action plan.
CLOSING REMARKS: This assessment has been in use since June 2000. It has been distributed on request, across Canada to over 75 community health authorities. The North Shore and Vancouver Health Regions have endorsed this assessment for home care OT’s. Three one-day workshops have been held to train OT’s in administering and interpreting the assessment results. A feedback survey and validity study are to be completed.
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