Predicting safety to drive in people with dementia

1. Predicting safety to drive in people with dementia Nadina B LincolnJenny L TaylorKristina VellaWalter P BoumanKathryn A Radford

2. Background • Driving relies on multiple abilities, (e.g. memory, judgement, psychomotor abilities) which can be affected by dementia. • In the UK “If you have had, or currently suffer from a medical condition or disability that may affect your driving you must tell the Driver and Vehicle Licensing Agency (DVLA).” (http://www.dvla.gov.uk) • Similar procedures apply in other countries • There is currently a lack of consistency in how a person with dementia is declared as safe or unsafe to drive (Donnelly & Karlinsky 1990; BPS 2001)

3. Previous work • Lincoln et al. (2006) developed a cognitive test battery for predicting safety to drive in people with dementia • The predictive equation was 88% accurate

4. Current Study - AIMS • To establish whether assessments found to be predictive of on-road performance in previous study are predictive in an independent sample • To determine whether the predictive validity can be improved by including other measures

5. Procedure • Referral: letter OR phone call • Invitation letter to participant: including consent form and information sheet • Home Visit: discuss the study and deliver assessments (1 or 2 sessions) • Driving Assessment: with specialised driving instructor • Report: to referrer, GP, and participant

6. Assessments • General level of function:MMSE • Attention:SDSA Dot Cancellation; Stroop • Executive abilities:SDSA Square Matrices & Road Sign Recognition; BADS Rule Shift & Key Search; Trail Making • Visuospatial perception:VOSP Incomplete Letters, Position Discrimination & Number Location • Memory:SORT Words Immediate; SORT Words Delayed • Information processing:AMIPB Info Processing A

7. SDSA Square Matrices Directions

8. SDSA Road Sign Recognition

9. SDSA Dot Cancellation

10. Road Assessment 1. Starting Precautions 13. Passing static vehicles 2. Moving Off 14. Merging with traffic stream 3. Observation at Side Junctions 15. Anticipating pedestrians 4. Observations to rear 16. Anticipating beh. of others 5. Use of Signals 17. Use of speed 6. Positioning on Road 18. Obedience of road signs 7. Cornering 19. Observing speed limits 8. Braking 20. Courtesy 9. Accelerating 21. Emergency stop 10. Overtaking 22. Reversing 11. Driving on roundabouts 23. Parking vehicle 12. Driving in traffic lanes 24. Turning right 25. Following too close

11. Road Assessment • Classified: • Definitely Safe • Probably Safe • Probably Unsafe • Definitely Unsafe Recently conducted inter-rater reliability showed 100% agreement in classification between our driving instructor and an independent instructor.

12. Numbers referred (n=122) • Age • Mean = 75.3 years • SD = 7.27 • Gender • Men (n=91), Women (n=31) • Type of dementia • Alzheimer’s: 54 • Vascular: 27 • Mixed Aetiology: 6 • Lewy Body Disease: 3 • Unknown: 32

13. Recruitment

14. Driving Outcome Lower proportion of unsafe drivers than in previous studies 28 24 12 1

15. The AIMS • To establish whether assessments found to be predictive of on-road performance in previous study are predictive in an independent sample • To determine whether the predictive validity can be improved by including other measures

16. The AIMS • To establish whether assessments found to be predictive of on-road performance in previous study are predictive in an independent sample • To determine whether the predictive validity can be improved by including other measures

17. Was the old equation predictive? • 71% correctly classified Predicted group membership (cognitive tests) Unsafe Safe Road Pass841 Assessment Fail310 These individuals are those who are actually unsafe, but would have been missed by the equation Sensitivity for safe drivers=80.4%; Specificity=25.0%; PPV=83.7%; NPV=23.1%

18. The AIMS • To establish whether assessments found to be predictive of on-road performance in previous study are predictive in an independent sample • To determine whether the predictive validity can be improved by including other measures

19. Could we produce a better equation? • From a hierarchical DFA using the original tests, plus VOSP Number Location we developed a new predictive equation

20. Results with new equation? • 83.9% correctly classified Predicted group membership (cognitive tests) Unsafe Safe Road Pass841 Assessment Fail 112 These individuals are less of a concern – we would simply recommend that they are tested on the road These individuals are those who are actually unsafe, but would have been missed by the equation Sensitivity for safe drivers=95.3%; Specificity=57.9%; PPV=83.7%; NPV=84.6%

21. Who did the equation miss? Those who were actually unsafe, but predicted to be safe (n=2) • Often drove an automatic car (whilst in Hungary) but tested in manual which drives in UK • Taking anti-depressants and hypnotics, both proven to hinder driving Two interesting points raised by two individuals: This highlights the importance of clinician involvement

22. Preliminary conclusion • The original equation was only moderately predictive in an independent sample • HOWEVER the battery of tests was still predictive • Further analysis is required to establish how best to combine these tests into a reliable predictive equation.

23. Practical Application Diagnosed with dementia/licence for review Cognitive Screening Assessment Score less than a select cut-off Score more than a select cut-off Referred for on-road assessment at Regional Mobility Centre Continue driving

24. Thank you Any Questions? Lincoln, N. B., Radford, K. A., Lee, E. & Reay, A. C. (2006) The assessment of fitness to drive in people with dementia. Int J Geriatr Psych, 21, 1044-1051.

25. For more information E -mail Jenny.Taylor@nottingham.ac.uk Nadina.Lincoln@nottingham.ac.uk Call 0115 846 7616 Address Institute of Work, Health and Organisations, University of Nottingham, International House, Jubilee Campus, Wollaton Road, Nottingham, NG8 1BB