Despite your encouragement, Mr. Phillips declines to take ADReS because “I don’t see the need for it.” You reiterate your concerns for his safety, and give him a copy of the Am I A Safe Driver? worksheet to complete at home. In addition, you counsel Mr. Phillips on the Successful Aging Tips and Tips for Safe Driving. Mr. Phillips agrees to allow his son to observe his driving, and you give his son the How to Help the Older Driver resource sheet. You document all of this in Mr. Phillips’ chart.
At Mr. Phillips’ next visit, you ask him if he has tried putting any of the Tips into practice. He admits that he had another near-miss, and the son states he observed several driving errors. These motivated Mr. Phillips to complete the Am I A Safe Driver worksheet. He claims that this was an eye-opening experience, and he is now willing to undergo ADReS.
On ADReS, Mr. Phillips completes the rapid pace walk in 9.5 seconds. His visual acuity is 20/70 OU. His motor strength is 4-/5 in both lower extremities, and 4/5 in both upper extremities. He has limited range of motion on the finger curl and neck rotation; ankle plantar flexion and dorsiflexion are within normal limits. It takes him 82 seconds to complete the Trail-Making Test, Part B, and his clock drawing is scored as ‘normal’ for all eight criteria.
Now that your patient has undergone ADReS, what does his/her performance indicate? In this chapter, we will help you interpret your patient’s test performance by providing you with scoring cut-offs. We also provide examples of interventions to help you manage and treat any functional deficits that are identified through ADReS.
As you review the recommended interventions,* remember that the goal of physician intervention is to identify and correct any functional deficits that may impair the patient’s driving performance.
Although many states currently require far visual acuity of 20/40 for an unrestricted license, current research indicates that there is no scientific basis for this cut-off. In fact, studies undertaken in some states have demonstrated that there is no increase crash risk between 20/40 and 20/70, resulting in several new state requirements.1
General recommendations regarding visual acuity and driving are stated below. Please note that these recommendations are subject to each state’s licensing requirements.
For visual acuity less than 20/40, the physician should:
For visual acuity less than 20/70, the physician should follow the recommendations stated above, and:
For visual acuity less than 20/100, the physician should follow the recommendations stated above, and:
Research indicates that visual field loss can significantly impact driving safety. In an examination of 10,000 volunteer California license applicants, significant deterioration in visual fields was found among drivers over 60 years old. In addition, drivers with binocular visual field loss had driving accident and conviction rates more than twice as high as age- and gender-matched drivers with normal fields.2
While it is known that adequate visual fields are important for safe driving, there is no conclusive evidence to define what is meant by “adequate.” Most likely, this varies widely from patient to patient. For example, a driver with limited peripheral vision but excellent scanning ability may drive as safely as a driver with unrestricted peripheral vision but poor neck rotation.1
General recommendations regarding visual fields and driving are stated below. Physicians should be aware of their state’s visual field requirements, if any, and adhere to them.
For visual field deficits noted on clinical exam, the physician should:
Although the following cognitive tests are scored separately, interventions are recommended if the patient reaches designated cut-off values (as described below) on either of them.
Trail-Making Test, Part B
A time for completion of greater than 180 seconds signals a need for intervention.3
Numerous studies have demonstrated an association between performance on the Trail-Making Test, Part B (TMT-B) and cognitive function and/or driving performance. In a study of 1,700 drivers aged 65 and older applying for renewal of their North Carolina driver’s license, TMT-B test results were strongly associated with recent prior crash involvement.4 A study of 105 drivers in Nebraska aged 65-88 indicated that on-road driving performance significantly correlated with TMT-B performance (correlation coefficient -0.42).5 Most recently, data from the Maryland Pilot Older Driver Study†a study of 2,508 drivers aged 55 and older, including license renewal applicants, medically referred drivers, and older drivers in a residential communitydemonstrated a significant correlation between TMT-B performance and future at-fault crash in the license renewal sample (odds ratio 2.21).3
Clock Drawing Test, Freund Clock Scoring for Driving Competency
Any incorrect element in the Freund Clock Scoring signals a need for intervention.
Clock drawing tests (CDT) have been found to correlate significantly with traditional cognitive measures, and to discriminate healthy older patients from ones with dementia.6 Several versions of the CDT are available, each varying slightly in the method of administration and scoring.7 The Freund Clock Scoring is based on eight ‘principal components’ (as outlined on the ADReS Score Sheet), which were derived by analyzing the clock drawings of 88 drivers aged 65 and older against their performance on a driving simulator. Errors on these principal components were found to correlate significantly with specific hazardous driving errors, signaling the need for formal driving evaluation.8, 9
If the patient’s performance signals the need for interventions, the physician should:
Although the following tests are scored separately, interventions are recommended if the patient reaches designated cut-off values (as described below) on any of them.
Rapid Pace Walk
A time for completion of greater than 9.0 seconds signals a need for intervention.3
The rapid pace walk assesses lower limb mobility, trunk stability, and balance. In a prospective cohort study of 283 drivers aged 72 years and older, subjects who took longer than 7 seconds to complete the test were twice as likely to experience an adverse traffic event (traffic crash, violation, or being stopped by the police) in the year following the test.14 More recently, data from the Maryland Pilot Older Driver Studya study of 2,508 drivers aged 55 and older, including license renewal applicants, medically referred drivers, and older drivers in a residential communitydemonstrated a correlation between performance on the rapid pace walk and future at-fault crash in the license renewal sample (odds ratio 1.70).3
Manual Test of Motor Strength
Less than grade 4/5 strength in either upper extremity or the right lower extremity signals a need for intervention. (If the patient drives a vehicle with manual transmission, or if the patient reports using both feet to operate the brake and accelerator pedals,†† this applies to the left lower extremity as well.)
The manual test of motor strength evaluates separate muscle groups in both the upper and lower limbs. The United States Public Health Service guidelines regarding musculoskeletal ability and driving state that a driver should have at least grade 4/5 strength in the right lower extremity and both upper extremities.15 The physician should also be aware that the amount of strength required for safe driving may depend on the vehicle driven by the patient. For example, a patient who drives an older car that does not have power steering may require greater strength to safely drive this vehicle.
Manual Test of Range of Motion
If the patient’s range of motion is not within normal limits (ie, if the patient has a good range of motion with excessive hesitation/pain or a very limited range of motion), this signals the need for intervention.
The scoring for range of motion is vague, and this is due to several reasons: (1) Range of motion requirements vary with automobile design, and so it is difficult to specify exact requirements; (2) as discussed earlier in the visual fields section, the impact of limited range of motion on driving safety also depends on other functions; and (3) as with all the other tests in ADReS, a patient’s poor performance should act as a stimulus for optimization of function, rather than for immediate driving restrictions.
If the patient’s performance on this test is not within normal limits, the physician should be certain to elicit the reason: Do these movements cause muscle or joint pain? Does the patient complain of tight muscles or stiff joints? Do these movements cause a loss of balance? Knowing the answers to these questions will help in the management of the patient’s physical limitations.
If the patient’s performance warrants interventions, the physician should:
After administering ADReS, you can follow one of three courses of action. (See also Physician’s Plan for Older Drivers’ Safety in Chapter 1.)
ADReS is useful as an in-office assessment, but it does not evaluate the patient’s performance in the actual driving task. For this, an on-road assessment performed by a driver rehabilitation specialist (DRS) is needed. The DRS can more specifically determine the patient’s level of driving safety and help correct the patient’s functional impairments, if possible, through adaptive techniques or devices. We will discuss the role of the DRS in the next chapter.
We encourage all physicians to pursue a diagnosis of dementia where appropriate. Dementia is one of the most serious disorders in the older population, and it affects 4 to 5 million persons in the United States.12 However, it is frequently unrecognized and undocumented by primary care physicians13a situation that is particularly unfortunate since early treatment and planning may slow the course of the disease and improve the safety and comfort of the patient.
With regards to driving, patients with progressive dementia ultimately become unsafe to drive, yet often lack the cognitive abilities to be aware of this. When it becomes unsafe for these patients to drive, it frequently falls upon family members and caregivers to enforce driving cessation and arrange alternative forms of transportation. With early diagnosis, patients and their families have the opportunity to plan early for a smooth transition from ‘driving’ to ‘non-driving’ status. (For a more detailed discussion of driving cessation and the dementia patient, see Chapter 6.)
Co-piloting refers to a situation in which an individual drives with the assistance of a passenger who provides navigational directions and instructions on how to drive. In contrast to passengers who lend the driver company and provide simple navigational aid (eg, reading a map or finding an address), co-pilots participate more actively in the driving task. For example, patients with dementia may rely on co-pilots to tell them where to drive and how to respond to driving situations, while patients with vision deficits may require passengers to alert them to traffic signs and signals.
The use of co-pilots is not rare. In a study of the prevalence and cessation of driving among older men with dementia, about 10% of the 59 subjects still driving relied on co-pilots.16 It has even been recommended that individuals with mild to moderate cognitive decline (Global Deterioration Score 2, 3, 4) drive only with a co-pilot,17 and that state driver licensing agencies accommodate these individuals by permitting on-road assessment with co-pilots.18
Nonetheless, patients should not continue driving unless they are capable of driving safely without the use of a co-pilot. In many traffic situations, there is insufficient time for the co-pilot to detect a hazard and alert the driver, and for the driver to then respond quickly enough to avoid a crash. In such situations, the driver places not only himself/herself in danger, but also the co-pilot and other road users. Furthermore, the use of co-pilots to meet standards for licensure raises questions of who, exactly, is licensed to drive, how the presence of the co-pilot can be ensured, and what standards for medical fitness-to-drive should be applied to the co-pilot.19
Patients who are not safe to drive should be recommended to retire from driving, regardless of the use of a co-pilot. Co-pilots should never be recommended to unsafe drivers as a means to continue driving. Instead, efforts should focus on helping the patient find safe transportation for himself/herself and the co-pilot.
1 American Academy of Ophthalmology. Policy statement: vision requirements for driving. Approved by Board of Trustees, October 2001. Available at: http://www.aao.org/age/member/policy/driving.cfm. Accessed January 9, 2003.
2 Johnson CA, Keltner JL. Incidence of visual field loss in 20,000 eyes and its relationship to driving performance. Archives of Ophthalmology. 1983;101:371-375.
3 Staplin L, Lococo K, Gish K, Decina L. Model Driver Screening and Evaluation Program Final Technical Report, Volume 2: Maryland Pilot Older Driver Study. Washington, DC: National Highway Traffic Safety Administration. In Press.
4 Stutts JC, Stewart JR, Martell C. Cognitive test performance and crash risk in an older driver population. Accident Analysis and Prevention. 1998;30(3):337-346.
5 Tarawneh MS, McCoy PT, Bishu RR, Ballard JL. Factors associated with driving performance of older drivers. Transportation Research Record. 1993;1405:64-71.
6 Royall DR, Cordes JA, Polk MJ. Clox: An executive clock drawing task. Journal of Neurology, Neurosurgery, and Psychiatry. 1998;64:588-594.
7 Royall DR, Mulroy AR, Chiodo LK, Polk MJ. Clock drawing is sensitive to executive control: A comparison of six methods. Journal of Gerontology: Psychological Sciences. 1999;54B(5):328-333.
8 Freund B, Gravenstein S, Ferris R. Use of the clock drawing test as a screen for driving competency in older adults. Presented at: Annual Meeting of the American Geriatrics Society; May 9, 2002; Washington, DC,
9 E-mail correspondence from Barbara Freund, PhD, dated 9/16/02, 9/17/02, and 9/19/02.
10 Messinger-Rapport BJ, Rader E. High risk on the highway: How to identify and treat the impaired older driver. Geriatrics. 2000;55:32-45.
11 Knopman DS. Practice parameter: Diagnosis of dementia (an evidence-based review). Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2001;56(9):1143-1153.
12 Marcantonio E. Dementia. In: Beers MH, Berkow R. The Merck Manual of Geriatrics. Merck & Co., Inc. 2000. Available at: http://www.merck.com/pubs/mm-gereatrics/home.html. Accessed January 24, 2003.
13 Valcour CG, Masaki KH, Curb JD, Blanchette PL. The detection of dementia in the primary care setting. Archives of Internal Medicine. 2000;160:2964-2968.
14 Marottoli RA, Cooney LM, Wagner R, Doucette J, Tinetti ME. Predictors of automobile crashes and moving violations among elderly drivers. Annals of Internal Medicine. 1994;121(11):842-846.
15 As described in: Marottoli RA, Drickamer MA. Psychomotor mobility and the elderly driver. Clinics in Geriatric Medicine. 1993;9(2):403-411.
16 Foley DJ, Masaki KH, Ross GW, White LR. Driving cessation in older men with dementia. Journal of the American Geriatrics Society. 2000;48(8):928-930.
17 Freedman ML, Freeman DL. Should Alzheimers disease patients be allowed to drive? A medical, legal, and ethical dilemma. Journal of the American Geriatrics Society. 1996;44(7):876-877.
18 Shua-Haim JR, Gross JS. The “co-pilot” driver syndrome. Journal of the American Geriatrics Society. 1996;44(7):815-817.
19 Fox GF, Bashford GM. Dementia and driving: balancing personal independence and public safety. Medical Journal of Australia. 1997;167:406-407.
* Please be aware that the recommendations stated in this chapter are subject to your state’s reporting laws and driver licensing requirements.
† Among the tests used in the Maryland Pilot Older Driver study, performance on the Motor Free Visual Perception Test, Visual Closure Subtest was most predictive of at-fault crash involvement by drivers in the license renewal sample. However, this test was not included in ADReS because it is not readily accessible to physicians.
†† Although this is not the recommended way of driving, many older drivers initially learned to drive using both feet to operate the pedals.