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Cognitive Tests for driver screening

Kate Radford PhD, MScOccupational Therapist

Senior Lecturer University of Central Lancashire

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Content of presentation

13.45-14.00 Cognitive assessment for driver screeningWhy is it needed ?Where does it fit (with existing procedures)?Relevance Vs functional assessmentBasic principles of assessment

14.05-14.35 Introduction to some commonly used testsWhat are they, what do they measure/ assess, administration, common questions/ problems

14.40-15.05 Practical session (Group work)

15.05- 15.15 Questions and feedback

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Learning Outcomes

• Become familiar with basic concepts of cognitive assessment

• Consider the relevance of cognitive assessment and fit with existing procedures

• Discuss experiences of using cognitive tests• Explore practical issues in administration.

Scoring and interpretation

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Why do we need cognitive tests / screening?

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1.The presence of brain damage is a poor predictor of driving ability.

Giddens et al. 1983, Galski et al. 1992

Haselkorn et al. 1998

2. Driving is a complex ability and Ax is a complex issue - (Mazer et al, 2004, Brooks and

Hawley 2005, Heikkila and Tampani 2005)

3. Driving is an over-learned skill

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Fitness to Drive?

Visual Deficits preclusion

Physical disabilities adaptations

Cognitive deficits problem

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• Cognitive deficits = hidden disabilities

• Assessment may provide insight into performance that may be difficult to measure or capture functionally.

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The Hierarchical Model ofTask Performance in Car Driving

Strategical planning, decision making (beforedriving)

Tactical on the road decisions e.g.slow down

Operational perceptions and actions that occur during driving

Tim

e Pressu

re

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Screening - 2 tier process

• Driving specific questions in Clinical Setting • E.g. Does the client have a car? Does the client have a valid

license?• Does the client still drive?

YESYES NONO

Level 1: Screening Process

Screen for problems:

• Medical history and medication• Vision and perception• Cognition• Psychomotor skills

If transport is an important issue for the person and family, alternative methods should be discussed

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Screening - 2 tier process

No significant impairments affect driving ability

Screen for problems and potential to impact on safe driving

? Driving AbilitiesSignificant impairments affect driving ability

Safe to drive Declaration of unfit to drive

Driving Assessment

If Yes…

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Level 2: Specialist Assessment

In-house Assessment•Medical History, Physical profile, Cognitive Assessment•Visual/Perceptual Assessment, Behavioural assessment

In/Out Evaluation - Are adaptations needed?

Stationary behind-the-wheel assessment•Access to controls•Determine adaptive equipment needs

ON-ROAD ASSESSMENT

Off-road (Closed Course) Evaluation

SAFENot Yet Safe

UNSAFE

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In practiceIn practice

Many stroke/TBI survivors resume driving without assessment or advice

Ebrahim et al. 1988Pidikiti & Novack 1991

Fisk et al. 1997Hawley, 2001Johnston et al. 2004Mazer et al. 2004

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Practicalities: the UK licensing system

Relies on:• The doctor/medical professional

knowing the basics of the licensing system

• The doctor/medical professional informing you of your legal obligation to inform the DVLA

• The driver informing the DVLA of any medical condition that may infringe fitness to drive

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Growing problem

• Every year in the UK 130,000, people have a stroke (NAO, 2005); 25,000 of working age.

• One million people a year sustain a traumatic brain injury; of these 21,600 will have moderate or severe brain injury.

• The population is ageing• Increase in the numbers of car

owners/drivers

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Dementia Incidence

• Affects about 1% of men and women between 70 and 80 increasing to about 6% in those aged 85 years and older

• Findings broadly in line with others in Europe, Asia, and the USA

Matthews et al. The incidence of dementia in England and Wales: findings from the five

identical sites of the MRC CFA study. PLoS Medicine 2005 2: e193.

Increases with ageIncreases with age

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Numbers of drivers with dementia

• Estimated prevalence of drivers with dementia in Ontario

Hopkins et alCan J Psych 2004, 49(7)434-8

0

10

20

30

40

50

60

70

80

90

100

1986 2000 2028

Driverswithdementia

1000’s

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• In 2005, it is estimated that 73% of men and 35% of women aged 70 and over held a full car driving licence, compared to 81% of all men and 63% of all women.

Transport Statistics of Great Britain, Department for Transport 2006

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Estimate: drivers with dementia in UK

0

50

100

150

200

250

300

350

2005 2026

Driverswithdementia

1000’s

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Summary justification

• Screening - to identify who needs further assessment • Road assessments for everybody are expensive and

time consuming, therefore an objective screening test would be useful

• Decisions by doctors subjective and not based on any standard scale – introduces some standardisation to decision making

• To identify underlying impairments which may impact on driving performance and behaviours– Because driving is a complex task

• Because it’s a growing problem

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What do cognitive tests do?

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Uses of cognitive tests

• Screening

• Diagnosis Is there evidence of organic brain

dysfunction?

• Monitoring Does cognitive performance change over

time?

• Evaluation What is the nature and extent of cognitive

impairment?

Psychometric properties determine use

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Interpreting Tests

• Comparison with test norms• Scaled scores

• Percentiles

• z scores

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Normative sample• Scores of a reference group• Sample size• Age • How and where sample were

selected• Education • Ethnicity• How recent?

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Interpreting Tests

• Comparison with test norms• Scaled scores

• Percentiles

• z scores

• Comparison with premorbid ability

• Comparison with cut-off score

• Criterion referenced testing

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Normal curve

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Percentiles

• Normal distribution

• % of scores that fall at or below that score

• Mid-point 50% percentile

e.g. VOSP

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Why standardise scores?

• Compare against norms

• Compare tests with different scales of

measurement

• Different forms – all based on mean and

SD

• SD = spread of scores around the mean

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Compare with premorbid ability

• Depends on accuracy of estimation of premorbid level

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Comparison with cut-off

• Cut-off may be set for

– Sensitivity – the proportion of positives correctly

identified by the test (presence of condition)

– Specificity – the proportion of negatives (absence

of condition)

– Trade-off between sensitivity and specificity

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No. of Cases Predicted Group Membership

Actual Group Pass Fail

Pass 37 36 295% 5%

Fail 15 5 935.7% 64%

Percent of grouped cases correctly classified: 86.5%Positive Predictive Value: 60%Negative Predictive Value: 97.3%

Classification results by Discriminant Equation (TBI)

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Criterion referenced testing

• Does test performance predict behaviour?

• Is ability at a level that would enable someone to carry out particular task?– Drive a car

e.g. Stroke Drivers Screening Assessment

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Interpreting Scores

• Interpret in context of range of tests

• Scores don’t prove or disprove anything

• Performance normal for that individual?

• Other reasons for performance

• Background information

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Summary

• Tests for different purposes

• Test interpretation depends on development

purpose; how it is scored and on the standardisation

sample

• Interpretation requires

– Estimate of previous ability

– Understanding of behavioural factors and mood

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Points to Consider

• Are we using tests as they were designed?

• Are we comparing like with like?

• Do we know what value the patient places on the tests and their results?

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Inaccurate performance and other issues

• Concurrent psychological distress

• Fatigue

• Concurrent physical illness or injury

• Pre-existing low capacity

• Malingering

• Age, education, culture and language

• Compensatory strategies

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Formulation

• Cognitive assessment is just one part of the assessment formula; other information derived from the patient and other sources (background information, semi-structured interview, relative/carer input, observation, brain imaging, multi-disciplinary reports), together with cognitive assessment

• Any of these methods in isolation (especially cognitive assessment) will be much less meaningful and more prone to misinterpretation

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Cognitive assessment Vs Functional Assessment

• Cognitive tests are just one part of a complete neuropsychological assessment– Also addresses practical and functional

consequences of impairment e.g. affect on ADL. Work, leisure, driving• (usually done via interviews and observation)

– and how mood and behaviour might be affected by brain dysfunction• E.g. depression negatively impacts on performance

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Relevance Vs functional assessment

• Part of the same overall process

• Interviews with patients/ family members

• Functional on road testing procedures are arguably the observational parts of a comprehensive neurological assessment

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Introduction to some commonly used tests:

– Mini Mental State Examination (MMSE)– Trail Making Test– Stroke Drivers Screening Assessment

–Star cancellation

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Trail Making Test• Army Individual Test Battery (1944) • Test of visuomotor tracking, complex visual scanning an

attention with a motor component - it tests how effectively the patient responds to a complex visual array, mental sequencing ability and shifting attention

• Different forms and scoring instructions –Reitan (undated)• Advantages• 5-10 mins, simple, transportable, little specialist training• in public domain • a number of studies found a significant relationship

between performance on the TMT and on road driving performance.

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PART A PART B

Time in Seconds Credits Time in Seconds Credits

0 - 38 10 0 - 43 10

39 - 44 9 44 - 50 9

45 - 49 8 51 - 56 8

50 - 58 7 57 - 63 7

59 - 65 6 64 - 71 6

66 - 72 5 72 - 78 5

73 - 82 4 79 - 88 4

83 - 97 3 89 - 99 3

98 - 110 2 100 - 145 2

111 and over 1 146 and over 1

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Star cancellation

• Halligan, Cockburn and Wilson, (1991)• Behavioural Inattention Test

• Un-timed test of visual inattention• Available in 2 versions (allow retesting)

• Mean score of misses for 50 norms = 0.28 (at most 2 missed)

• Cut of score of 3 or more = failure (inattention present)

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Mini Mental State Examination

• Folstein Folstein & McHugh, (1975)• Mot widely used brief screening instrument

for dementia• Tests a restricted set of cognitive functions

quickley and simply• Scores <24 abnormal for dementia but

higher cut offs for specific conditions and people of different ages. E.g 27 for MS, 25 for educated people with dementia, 29 (ages 40-49; 28 – 50-59; 26- 80-89)

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• Advantages– 5-10 mins to administer– No specialist training– Minor cultural or language modifications– Scores not related to depression severity– High test retest and inter -rater reliability

• Disadvantages– False negatives (high scores in dementia

patients) hence diff to interpret indiv. scores

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MMSE Instructions

• Orientation – – e.g. Can you tell me todays date– Which season is it?

– Registration and recall – naming three common objects and recalling after a delay

– Attention and calculation –subtracting seven’s from 100– Spell world backwards– Language – naming objects– Repeating “No iffs ands or buts”– Reading ‘CLOSE YOUR EYES”– Following a three stage command– Construction – copying a drawing

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MMSE?Mini mental state examination * pass or fail on the driving

assessment Crosstabulation

Count

1 1

1 1

2 1 3

2 2

1 2 3

4 4

1 1 2

3 3

1 1

2 2 4

5 5

1 1 2

1 1 2

2 2

2 2

10 27 37

8.00

9.00

18.00

19.00

20.00

21.00

22.00

23.00

24.00

25.00

26.00

27.00

28.00

29.00

30.00

Mini mentalstateexamination

Total

fail pass

pass or fail on thedriving assessment

Total

Lincoln NB, Radford KA, et al, 2006

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The Stroke Drivers Screening Assessment

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Development of Stroke DriversScreening Assessment

+

•SDSA

Nouri & Lincoln Clin Rehabil 1992; 6: 275-281

79 stroke patients79 stroke patientsCognitive Cognitive AssessmentAssessment

BSMBSMRoad TestRoad Test

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Construct Validity

Radford 2000• 93 Stroke patients• SDSA• Cognitive Tests

– RMT– Stroop– Trail Making– Cognitive Estimates– VOSP Cube Analysis

• Measures executive abilities and attention

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BackgroundBackground

SDSA - Predicts ‘on the road’ performance in stroke patients (Nouri, Tinson and Lincoln, 1987, Nouri and Lincoln, 1992)

- Found to be a more accurate predictor than the advice of the GP or the DVLA (Nouri and Lincoln, 1993)

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How does SDSA compare with usual practice?

SDSA GroupRoad Test

Control GroupRoad Test

Pass Fail Pass Fail

Predicted Pass

6 (75%)

3 10 10

Predicted Fail

2 16 ( 84%)

1 4

Accuracy 81% 56%

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Dot cancellationDot cancellation

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SDSA -Square Matrices SDSA -Square Matrices DirectionsDirections

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Square Matrices Compass

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SDSA - SDSA - Road Sign Recognition TestRoad Sign Recognition Test

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Intended use

Stroke

Stroke Drivers Screening

Pass Borderline Fail

GP fit Repeat SDSA Repeat SDSA

Specialist Driving not fit GP

Centre e.g. Derby

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Use of SDSA

• Screening procedure to decide who to refer for ‘on road’ assessment

• Pass – May need physical adaptations

• Borderline (-0.5 - + 0.5) (Lundberg et al 2003) – referral to assessment centre which involves

cognitive assessment• Fail

– if early wait and retest (Lincoln & Fanthome 1994)– If late not fit to drive

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Diagnosis Specific Equations• Radford KA et al Validation of the Stroke Drivers Screening

Assessment for people with Traumatic Brain Injury. Brain Injury 2004; 18: 775-786.

• KA Radford et al The Effects of Cognitive Abilities on Driving in People with Parkinson’s Disease. Disability & Rehabilitation 2004; 26: 65-70.

• Lincoln NB et al The Assessment of Fitness to Drive in People with Dementia Int J Geriatric Psychiatry 2006; 21:1044-1051

• LINCOLN, N.B. and RADFORD, K.A., 2007. Cognitive abilities as predictors of safety to drive in people with multiple sclerosis. Multiple Sclerosis 2008, 14(1)

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Conclusions

• SDSA on its own good for stroke drivers• Extra assessments needed for other

client groups• Predictive equations need validation• Information can be used to guide

clinical practice

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SDSASDSA

Advantages•Short test Battery, < 30 minutes to administer•Accurate at identifying safe drivers with TBI and Stroke and those needing additional on-road testing.•Criterion Validity, ecological validity•Helps inform decisions about driving and adding standardised assessment where currently little exists.

DisadvantagesInstructions and interpretation complex for clinicians?• Tests still needed to identify unsafe drivers with TBI• Further validation needed.

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Fitness to Drive and Cognition

• Multi-disciplinary Working Party Report, British Psychological Society, Jan 2001, ISBN:1 85433 324 0

• Reviews suggest the need for a battery of Neuropsychological tests (Lundberg 1997, McKenna 1998)

• It’s a complex issue (Mazer et al, 2004, Brooks and Hawley

2005, Heikkila and Tampani 2005)

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Opportunity to take part

• Implementation research

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References• Crawford J.R, Parker, D.M., & McKinlay, W.W. (1992) A

Handbook of Neuropsychological Assessment. Hove: Lawrence Erlbaum.

• Evans, J.J. (2003). Basic concepts and principles of neuropsychological assessment. In P. Halligan, U. Kischka, and Marshall, J.C. (Eds.) Handbook of Clinical Neuropsychology (pp.15-26). Oxford: Oxford University Press.

• Lezak, M.D., Howieson, D.B., Loring, D.W., Hannay, H.J., & Fischer, J.S. (2004). Neuropsychological Assessment (4th Edition). Oxford: Oxford University Press.

• Miller, E. (1992). Some basic principles of neuropsychological assessment. In J.R. Crawford, D.M. Parker, and W.W. McKinlay (Eds.) A Handbook of Neuropsychological Assessment (pp.10-11). Hove: Lawrence Erlbaum.

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References• Chaytor, N. & Schmitter-Edgecombe, M. (2003) The

ecological validity of neuropsychological tests: a review of the literature on everyday cognitive skills. Neuropsychology Review, 13, 181-197.

• Evans, J.J. (1996) Selecting, administering and interpreting cognitive tests. Bury St Edmunds: Thames Valley Test Company.

• Lezak, M.D. (2004) Neuropsychological Assessment. Oxford: Oxford University Press.

• Spreen, O. & Strauss, E. (1998) A compendium of neuropsychological tests. Administration norms, and commentary. New York: Oxford University Press.

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References

• Brooke MM, Questad KA, Patterson DR, Valois TA (1992) Driving Evaluation after traumatic brain injury. American Journal of Physical Medicine and Rehabilitation, 71, 177-182.

• Ranney TA (1994) Models of driving behaviour: A review of their evolution. Accident Analysis and Prevention, 26(6), 733-750.

• Korteling JE and Kaptein MA (1996) Neuropsychological driving fitness tests for brain damaged subjects. Archives of Physical Medicine and Rehabilitation, 77, 138-146.

• Mazer BL, Korner-Bitensky NA, Softer S (1998) Predicting ability to drive after stroke. Archives of Physical Medicine and Rehabilitation, 79, 743-750.

• Lundqvist A, (2001), Neuropsychological aspects of driving characteristics, Brain Injury, 15(11) 981-994.

• Lundqvist A and Rönnberg J, (2001) Driving problems and adaptive driving behaviour after brain injury: a qualitative assessment. Neuropsychological Rehabilitation, 11, 171- 185.

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References• SDSA Development • Nouri FM and Lincoln NB (1994) The Stroke Drivers Screening Assessment. Nottingham

Rehab. UK.• Nouri FM and Lincoln NB (1992) Validation of a cognitive assessment: Predicting driving

performance after stroke. Clinical Rehabilitation, 6, 275-281.• Nouri FM and Lincoln NB (1993) Predicting driving performance after stroke. British

Medical Journal, 307, 482-483.• Nouri FM, Tinson DJ, Lincoln NB (1987) Cognitive ability and driving after stroke.

International Disability Studies, 9, 110-115.• Lincoln NB. Fanthome Y, (1994) Reliability of the Stroke Drivers Screening Assessment,

Clinical Rehabilitation. Vol 8(2), 157-160 • Radford KA Validation of the Stroke Drivers Screening assessment for patients with an

acquired neurological disability, 2000, Phd Thesis University of Nottingham• Dementia• Lincoln NB, Radford KA, Lee E, Reay AC, The Assessment of Fitness to Drive in People with Dementia,

International Journal of Geriatric Psychiatry 2006;21:1044-1051• TBI/Stoke• Radford KA, Lincoln NB, Murray-Leslie C. 2004c. Validation of the Stroke Drivers

Screening Assessment for people with Traumatic Brain Injury. Brain Injury 18: 775-786.• Radford KA, Lincoln NB. 2004. Concurrent validity of the Stroke Drivers Screening

Assessment. Arch Phys Med Rehabil 85:324–8. • PD• Radford KA, Lincoln NB. The Effects Of Cognitive Abilities On Driving In People With Parkinson's

Disease, Disability and Rehabilitation, 2004, 26 (2) 65 - 70. • MS• LINCOLN, N.B. and RADFORD, K.A., 2007. Cognitive abilities as predictors of safety to drive in people

with multiple sclerosis. Multiple Sclerosis 2008, 14(1) 123-128.

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Stroop

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Stroop