The most recent FARS data indicate that older driver involvement in fatal crashes varies with the road type and occurs most often on arterials (through traffic), where traffic densities tend to be higher, information processing demands and the potential for distraction because of roadside development are greater, and posted speeds of 45 miles per hour and higher are common. Fatal crashes on such roads are even more prevalent among drivers ages 75 and older than among those ages 65 to 74 (see Tables 4 and 5).3 Older driver involvement in such crashes is relatively rare on interstate highways or expressways, possibly because of driver self-restriction on these roadways as well as superior design that reduces the potential for conflict.
A research study sponsored by the NHTSA sought to determine which age groups, vehicles, roadways, and environmental characteristics were most strongly associated with increased crash involvement for drivers ages 60 to 69, 70 to 79, and 80 or older.4 Using 2002 through 2006 data from FARS and the National Automotive Sampling System–General Estimates System, this study found that the following activities were most problematic for older drivers:
- making left turns
- negotiating stop sign–controlled intersections
- driving on high-speed, two-lane roadways and multilane roads with speed limits of 40 to 45 miles per hour
Drivers ages 60 to 69 managed most traffic situations nearly as well as their middle-aged counterparts, but both these drivers and older drivers were more prone than drivers under age 60 to err at intersections with flashing signals. Drivers in their 70s demonstrated greater difficulty than those in their 60s in navigating high-speed, multilane roadways, particularly at junctions; in terms of safety, however, their driving was more like that of the 60 to 69 cohort than the 80 or older one. For drivers ages 80 and older, errors negotiating yield sign–controlled intersections were responsible for 26 of 27 fatal crashes.4
Certain driving situations, such as navigating intersections that require complex visual searches, rapid processing of information from multiple sources, and divided attention, create problems for older drivers. Under such conditions, a driver cannot rely exclusively on formal or informal rules, but rather must resort to judgment or executive function.
AGE-RELATED FUNCTIONAL DECLINE
It must be emphasized that the decline in driving abilities is related to functional status, not chronological age. Furthermore, with increasing age, populations become more heterogeneous regarding functional status. Many older adults—including those who are 75 and older—demonstrate no impairments serious enough to compromise driving. Nevertheless, a host of visual, cognitive, and psychomotor functional abilities reliably decline with advancing age.
Vision. Contrast sensitivity, which is the ability to process differences in brightness between an object and its background, has been shown to decrease with age.5 Reduced contrast sensitivity may impair a driver's ability to detect road hazards, pavement markings, curbs, and road signs, increasing the likelihood of lane boundary crossings and slowing driver reaction times. Likewise, static visual acuity (the ability to distinguish details on a stationary target, such as the letters on an eye chart) and dynamic visual acuity (the ability to distinguish details on a moving target or on a stationary target while in motion—for example, the ability to read road signs while in a moving car) have been shown to decline with age, even in adults with healthy eyes.6
In addition to the visual deterioration that occurs with normal aging, several medical conditions associated with advanced age can also diminish vision. For example, it's well established that
- cataracts impair acuity, contrast sensitivity, color discrimination, and depth perception.
- glaucoma constricts the peripheral visual field.
- stroke, trauma, tumors, infections, and surgery can cause hemianopia, a partial loss of the visual field in one or both eyes.
- macular degeneration often causes deficits in both spatial and temporal contrast sensitivity.
Some of these visual deficits can be mitigated by medication or surgery, greatly improving driving performance. For example, a study by Wood and Carberry found that bilateral cataract surgery significantly improved binocular visual acuity and binocular contrast sensitivity, resulting in marked improvement in sign recognition, ability to detect and avoid hazards, and overall driving performance, with improved contrast sensitivity being most predictive of improved driving performance.7 According to one analysis—which considered the number and cost of motor vehicle accidents, the probability of fatalities, the probability of having cataract surgery, and the age at which cataract surgery occurs and its cost—relaxing the reimbursement standards to allow for early cataract surgery (before significant vision problems develop) would lower the number of motor vehicle accidents and related expenses for 2% to 6% of U.S. drivers ages 60 to 89, resulting in substantial societal cost savings, such as reducing the average number of motor vehicle accidents, fatalities, and per-person crash-related costs by about 21%.8
Cognition. Some cognitive disabilities associated with advanced age are predictive of diminished driving performance and risk of crash involvement. Most often cited is a decline in executive function—that is, in the processes that guide behavior incorporating attention, working memory, planning, organization, problem solving, set shifting (moving back and forth between tasks), abstract thinking, judgment, decision making, and the inhibition of inappropriate responses.
Executive function deficits have been identified in adults as young as 45 years of age9 and have been shown to worsen with age.10-12 Deficits in the areas of response inhibition (the aspect of executive function that enables a person to suppress behaviors that are inappropriate to the immediate situation, even if they are habitual or were appropriate at another time) and divided attention (the ability to divide attention between two or more simultaneous tasks) predict diminished driving performance11, 13 and greater crash risk.14, 15 Task-switching ability may be determined by performance on the Trail Making Test, Part B, which requires test takers to sequence two sets of stimuli (letters and numbers) in alternating order as quickly as possible.
Working memory deficits are similarly linked to a significant increase in crashes.16, 17 This ability allows a driver to remember, and apply when needed, navigational directions and rules for traffic operations, while processing and responding to the real-time demands of steering, anticipating and avoiding conflicts, and performing other moment-to-moment vehicle control tasks.
Visual cognitive functions that degrade with age and are known to affect driving performance include visual information processing speed, selective visual attention, and visuospatial ability. The following three tests can significantly predict driving performance and crash risk:
- the Useful Field of View measure for speed of processing and selective (as well as divided) visual attention18-20
- the Motor-Free Visual Perception Test, Visual Closure subtest, which measures the ability to visualize spatial relationships among objects21
- various maze tests that track the time required to draw a path through a maze either on paper or on a computer screen22
Medical conditions that can impair various aspects of cognitive function, with adverse effects on driving performance, include the following:
- multiple sclerosis24, 25
- type 1 and type 2 diabetes26, 27
- hepatic encephalopathy28
- obstructive sleep apnea29
- Parkinson's disease30, 31
Physical function and psychomotor response must be intact for drivers to carry out vehicle maneuvers. Both normal, healthy aging and such conditions as arthritis can reduce flexibility, range of motion, and muscular strength, compromising driving performance.
Increased crash risk has been associated with poor upper-extremity range of motion32, 33 as well as poor lower-extremity strength and range of motion.17, 34 Sims and colleagues found that older drivers who had fallen in the previous two years were at elevated crash risk compared with older drivers who had experienced no falls.33 Any deficiency in head and neck flexibility, which allows a driver to effectively scan the vehicle and surrounding environment, can predict driving impairment and has been found to significantly degrade driving performance, particularly at intersections.17, 35
Improving physical function. Physical activities that increase strength, flexibility, and range of motion in older adults may improve driving performance. These include yoga,36 dance,37-39 tai chi,40-42 and various multicomponent exercise programs.43-45 NHTSA research is currently under way to determine whether there is a direct correlation between better driving performance and greater fitness among older adults.
STARTING A CONVERSATION ABOUT AGING AND SAFE DRIVING
When assessing an older patient, particularly one at high risk for motor vehicle accidents, nurses might introduce the topic of safe driving by simply asking if the patient has experienced any difficulties while driving. An affirmative response opens the door to a discussion of risks associated with the patient's medical or functional status. A negative response presents an opportunity to raise the patient's awareness of “driving health”—that is, to remind the patient that staying safe behind the wheel depends on the ability to see, pay attention, understand, remember, decide, and react quickly and appropriately to ever-changing traffic conditions and that normal aging, as well as disease and medications, can compromise these abilities.
Nurses who work in home health care or in a senior residential setting enjoy the benefit of building long-term relationships with their older patients and can assess subtle and incremental changes over time. They should inquire about any problems the patients experience while performing activities of daily living, such as getting to the grocery store, the pharmacy, or medical appointments. Any concerns should be documented and reported to the primary care provider.
Ideally, nurses should spend a minute or two talking about aging and safe driving during each patient visit; however, such talks are a priority for patients who
- present with signs or symptoms of cognitive impairment.
- have progressive medical conditions.
- will soon be discharged from a hospital following surgery or treatment for traumatic injury.
- have fallen in the past two years.
- have had a recent change in their medication regimen.
- show a marked change from baseline on an annual wellness visit, particularly with respect to functional abilities.
After undergoing knee or hip surgery, particularly of the right leg, some patients may worry that they will be unable to resume driving for an extended period, as these surgeries can slow brake reaction time. Others may underestimate the length of postsurgical recovery and expect to resume driving too soon. Although patients should discuss with their orthopedist the return to driving after knee or hip surgery, two studies have shown that many patients can drive safely after a postoperative period as brief as two to four weeks.46, 47
Formal driving evaluations. Assessment and clinical data may be used to determine the need for a formal driving evaluation. Several reliable, standardized tools that have been validated as statistically significant predictors of crash risk for older drivers can be used to detect loss of cognitive function, including the following21, 22:
- the Trail Making Test, Part B
- the Motor-Free Visual Perception Test, Visual Closure subtest
- a maze test
- the Useful Field of View test
All are available in both paper-and-pencil and computer-based form except for the Useful Field of View test, which can be administered by computer only. The paper-and-pencil forms of these tools may not be feasible for in-office screening as they require 10 to 15 minutes with an active test administrator and are more susceptible to measurement error. However, the computer-based screens can be self-administered using, for example, a touchscreen tablet in a waiting room. One such screening tool is currently being pilot tested by the Iowa Department of Transportation under an NHTSA cooperative agreement.
Patients’ visual health should be monitored during annual eye examinations. Other important measures of diminished physical capability that significantly increase crash risk may be quickly checked during a patient visit. These include
- being unable to walk from a starting point to a point 10 feet away, turn, and walk back in less than 10 seconds.48
- having insufficient head or neck flexibility to look over the shoulder to identify an object (for example, the time on a clockface) 10 feet behind.17
Using validated screening instruments for crash involvement risk is key. For patients with no diagnosis of cognitive impairment, it should be noted that such screens as the Mini-Mental State Exam and the Montreal Cognitive Assessment, which do not focus primarily on the abilities associated with driving, cannot be used in isolation as reliable indicators of crash risk. However, for patients with an established diagnosis of cognitive impairment, a score of 18 or lower on the Montreal Cognitive Assessment should raise concerns about their ability to drive safely.49
If additional time and available human resources permit a more in-depth patient interaction, nurses may wish to consult the following publications, which are available online at no cost:
- the American Geriatrics Society's Clinician's Guide to Assessing and Counseling Older Drivers (http://geriatricscareonline.org/ProductAbstract/clinician's-guide-to-assessing-and-counseling-older-drivers/B022)
- the Driving Decisions Workbook from the University of Michigan Transportation Research Institute (http://hdl.handle.net/2027.42/1321)
For computer-savvy older patients, consider recommending the home educational program, Roadwise Rx (www.roadwiserx.com), which instructs older adults on the effects of medications on driving and is available online for free.
Health care providers may not be comfortable making recommendations about if, when, or how much patients should drive, but referring patients to professionals who can evaluate or rehabilitate their driving can help keep older patients—and others who use the road—safe.
In North America and throughout the world, there is a wide spectrum of driver programs that can determine a person's risk of unsafe driving and, depending on the type and severity of that person's impairment, intervene to help her or him drive safely for longer. For example, patients with little impairment may benefit from an educational driver improvement program or a commercial driving school, which can provide refresher training, help them improve their driving skills, and raise awareness of age-related deficits for which they can compensate through self-regulation (by avoiding driving at night, during rush hour, or on highways). Patients with cognitive, motor, visual, or perceptual deficits following stroke, or those recovering from traumatic brain injury who become easily frustrated, may require referral to a professional who can apply medical knowledge to safe driving ability and assess the effects of cognitive, visual, perceptual, behavioral, and physical limitations on driving performance. Such professionals include
- driver rehabilitation specialists, who can perform in-office clinical evaluations and determine whether an on-road evaluation is needed.
- certified driver rehabilitation specialists, who can perform on-road driving performance evaluations (possibly in a vehicle with adaptive equipment).
- occupational therapists certified in driving and community services.
There are three levels of driver rehabilitation programs, all of which provide comprehensive driving evaluation, training, and education, though they differ in the type of services they provide. The NHTSA, in collaboration with the Association for Driver Rehabilitative Specialists and the American Occupational Therapy Association, has described the various services in two very helpful documents50:
- “Spectrum of Driver Services: Right Services for the Right People at the Right Time,” which describes and differentiates between community-based education; medically based assessment, education, and referral; and specialized evaluation and training services
- “Spectrum of Driver Rehabilitation Program Services,” which describes the various levels of driver rehabilitation programs (basic, low tech, and high tech)
Both documents are available online at www.aota.org/-/media/Corporate/Files/Practice/Aging/Spectrum-of-Driving-Services-2014.pdf. The information contained in these documents can guide nurses in providing advice to patients about the most appropriate level of driver services for their particular needs.
Of course, not all drivers need the services of a driver rehabilitation program. A patient who recovers quickly from a stroke and demonstrates no difficulty with other instrumental activities of daily living may require only a clinical assessment by a physician, an occupational therapist, or a social worker to confirm that any impairments are below the threshold of driving risk and to receive appropriate risk counseling. And a patient recovering from a severe stroke with significant impairments would not benefit from the expensive services provided by a driver rehabilitation program until substantial recovery had occurred. If, however, a patient failed to recognize her or his limitations, a driving performance evaluation might be necessary, if only to convince the patient to stay off the road.
REFERRAL TO THE STATE MOTOR VEHICLE DEPARTMENT
Only six states require health care providers to report patients with impairments that could affect their ability to drive safely: California, Delaware, Nevada, New Jersey, Oregon, and Pennsylvania. The states differ in terms of the conditions each specifies as reportable. Health care providers should familiarize themselves with their state's reporting laws and the procedures to follow when required by law to report a patient to their state's driver licensing agency. Although 44 states do not currently require health care providers to report patients with impairments that could affect their driving, all states accept such reports when provided in good faith to protect the safety of the patient and the public, and some provide health care practitioners with immunity from civil liability.
For some patients, loss of licensure will lead to feelings of depression and isolation. In states with no mandatory reporting law, clinicians will need to weigh these concerns against the risk the patient's driving poses to personal and public safety. Discussing your concern for safety with your patient and recommending driving cessation when you believe she or he is no longer fit to drive (and cannot be helped with medical treatment or other therapies) is an important first step. You may only need to report the patient to the state if the patient is unwilling to comply with your recommendation to stop driving. The American Geriatrics Society's Clinician's Guide to Assessing and Counseling Older Drivers includes a chapter on ethical and legal issues surrounding health care practitioner reporting of patients to a state's driver licensing agency and provides case studies illustrating how and when to discuss this topic with patients.
When patients can no longer drive safely, providing information about transportation alternatives and offering emotional support can help them navigate their retirement from driving. This is a time to encourage and applaud the patient's good decision making.
ACCESSING ALTERNATIVE TRANSPORTATION
When a nurse and a patient determine that it is temporarily unsafe for that patient to drive—or in certain cases, that it may be time for the patient to consider permanently retiring from driving—it's essential to discuss alternative transportation options. You could begin this conversation by asking whether the patient has family members or friends close by who are willing or able to assist with transportation. It would also be useful to have a list on hand of community resources that can work with patients to find appropriate local transportation. Occupational therapists in your community may have a transportation resource guide, and the nonprofit Independent Transportation Network of America (ITNAmerica) maintains a current, national database of transportation services for aging and visually impaired people called Rides in Sight (www.ridesinsight.org). Other helpful links and information may be found on the website of the National Association of Area Agencies on Aging at www.n4a.org.
Be sure to know the most valuable resources in your community for providing mobility counseling and local transportation alternatives. Your referral to this person or group can provide the appropriate pathway for patients to obtain services for community mobility, which is essential for maintaining independence and quality of life.
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For 59 additional continuing nursing education activities on topics related to older adults, go to www.nursingcenter.com/ce.
Keywords:Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
age-related functional decline; driver rehabilitation; driving health; driving safety; injury prevention; motor vehicle accidents; older drivers; preventive medicine