Assessment

Geriatric Essentials

• Functional assessment involves tests of vision (eg, acuity, useful field of view), physical capacity (eg, strength, range of motion), and cognition; medical assessment involves review of medical conditions and drugs that can impair driving ability.
• State licensing requirements and reporting regulations that pertain to the elderly are available from the National Highway Traffic Safety Administration (NHTSA). (See also Physician's Guide to Assessing and Counseling Older Drivers.)

Health care practitioners become involved in driving decisions when deficits are identified during routine examination, when family members express concern, or when patients solicit advice. The role of practitioners is to perform detailed functional and medical assessments that can contribute to driving safety. (See also Physician's Guide to Assessing and Counseling Older Drivers.) Driving history should be reviewed; details of driving habits and past violations, accidents, close calls, or getting lost may point to general or specific impairments. Some impairments may obligate health care practitioners to refer a patient to the state Department of Motor Vehicles for additional testing or driving restrictions. (See Physician's Guide to Assessing and Counseling Older Drivers for state licensing requirements and reporting regulations.)

Functional Assessment

Functional assessment involves evaluation of a patient's visual, physical, and cognitive functions. Adequate function in these areas is required to drive safely. Health care practitioners should be aware of the coding requirements when evaluating patients for driving safety. See the NHTSA web site for appropriate coding.

Visual function: Visual function is vital to driving. Age-related and pathologic visual changes are common and commonly contribute to driving impairment. With aging, retinal illuminance (amount of light reaching the retina), visual acuity, and peripheral vision decrease. Decreased ability to adapt to changes in light and presbyopia (decreased ability to accommodate) reduce depth perception and heighten sensitivity to glare. Decreased ability to adapt to changes in light and heightened sensitivity to glare are especially likely to impair ability to drive at night. In many states, central visual acuity and peripheral vision are routinely tested by the Department of Motor Vehicles when a license is renewed. Most states still require 20/40 visual acuity in at least one eye for unrestricted licensing, although an on-road test may establish that a patient with 20/70 vision may still be able to drive safely. For horizontal peripheral vision, safe driving thresholds vary widely among states from no requirement to about 140°.

Tests of useful field of view (spatial area from which visual stimuli can be acquired during a single fixed glance), although not yet widely available, provide integrated measures of visual performance (eg, visual-processing speeds, visual-spatial attention). Scores based on these measures decrease with aging and can be used to predict higher risk of collisions. Collisions are 6 times higher when useful field of view is reduced by > 40%.

Physical function: Physical function should also be assessed. Impaired upper body mobility, most often due to osteoarthritis, can limit field of view or ability to steer. Health care practitioners should qualitatively assess neck, shoulder, elbow, and wrist range of motion (full vs less than full); if mobility seems limited, patients are referred to an occupational therapist for quantitative assessment (see The American Occupational Therapy Association, Inc.).

Impaired proprioception may contribute to decreased responsiveness and may warrant referral for on-road testing. Decreased grip strength (in the dominant hand, < 16 kg for men or < 14 kg for women, measured with a dynamometer) can make driving difficult and is cause for concern, but assistive devices can compensate. Feet should be assessed for abnormalities (eg, toenail and toe abnormalities, calluses, bunions) that can increase risk of collisions and moving violations. Because a history of falls in the past 1 to 2 yr increases risk of collisions, general physical function, mobility, and stability should be assessed to identify functional impairments that can increase risk of falls. The "rapid-pace walk" is an easily administered test for assessing general physical function, mobility, and stability. The patient is asked to walk a 10-ft (3 m) path, turn around, and walk back to the starting point as quickly as possible. If the patient normally walks with a walker or cane, it should be used during the test. Time for completion should be < 9 sec. A slower time may indicate an increased risk of a motor vehicle collision.

Cognitive function: Cognition is moderately impaired in about 3% of community-dwelling people age 65 to 74, 14% of those age 75 to 84, and > 20% of those age > 85. Elderly people with cognitive impairment often do not recognize their limitations and are at higher risk of collisions; risk increases with severity of impairment. An easily administered test for cognition is the Trail-Making Test, Part B. The Trail-Making Test, Part B can be found at the NHTSA web site. Drivers with an abnormal score on this test may be candidates for on-road testing. Cognition can also be assessed with a short screening questionnaire such as the Mini-Cog or the Short Orientation-Memory-Concentration Test.

Elderly drivers with mild cognitive impairment should be considered for referral for more precise neuropsychological testing. For example, selective attention (ability to shift focus between competing stimuli) can be evaluated with tests such as the dichotic listening test and Stroop test. Tests for evaluating other measures of attention, such as divided attention (ability to process and respond to >= 2 stimuli simultaneously) and sustained attention (endurance of alertness), are not yet readily available.

Health care practitioners are encouraged (or, in some states, required) by state Departments of Motor Vehicles to report patients with conditions that may affect safe driving, including dementia. More complicated cases can be referred by practitioners directly to most state medical advisory boards for administrative hearings. (See Physician's Guide to Assessing and Counseling Older Drivers.)

Medical Assessment

Medical assessment involves a review of medical conditions and drugs that could impair driving ability. In general, any condition or drug that can impair consciousness should raise concern about driving safety.

Cardiac disorders: Cardiac disorders increase driving risk. General guidelines include refraining from driving for 1 mo after MI, coronary artery bypass surgery, or stabilization of unstable angina symptoms; for 3 mo after arrhythmia with syncope; and for 6 mo after internal cardioverter defibrillator placement or after resuscitation required because of sustained ventricular tachycardia or ventricular fibrillation. Patients with severe heart failure (eg, class IV heart failure, dyspnea at rest or while driving) should refrain from driving until evaluated with on-road testing.

Neurologic disorders: Neurologic disorders also increase driving risk. Drivers with a single transient ischemic attack (TIA) should wait 1 mo before resuming driving; those with recurrent TIAs or stroke should be event-free for at least 3 mo before resuming driving. Physical examination should be done to assess how residual disability due to stroke may affect driving ability. Regulations for drivers who have seizures are state-specific, but most states define a seizure-free interval (often 6 mo) before they reinstate driving privileges. Drugs can adequately control seizures in about 70% of patients, although relapses may occur when anticonvulsants are withdrawn. Many other neurologic disorders (eg, Parkinson's disease) cause disability, which should be monitored by functional assessment.

Diabetes mellitus: Diabetes mellitus poses a risk because patients may become hypoglycemic while driving. Patients who have had a recent hypoglycemic episode affecting awareness should not drive for 3 mo or until factors contributing to the episode (eg, diet, activity, timing and dose of insulin or antihyperglycemic drug) have been assessed and managed.

Sleep disorders: Sleep disorders, most notably obstructive sleep apnea syndrome, can cause drowsiness leading to collisions, and patients should refrain from driving until they are adequately treated.

Drugs: Use of antihistamines, benzodiazepines, opioids, anticholinergics, soporifics (eg, chloral hydrate, zolpidem, zaleplon), antihypertensives, or tricyclic antidepressants increases driving risk because they can cause drowsiness; some can also cause hypotension or arrhythmias. Antiparkinsonian dopamine agonists (eg, pergolide, pramipexole, ropinirole) occasionally cause acute sleep attacks, which pose an especially high risk of accidents. Antiemetics (eg, prochlorperazine), muscle relaxants (eg, cyclobenzaprine), and stimulants (eg, methylphenidate) are also cause for concern because of their potential for altering sensory perception. Instructing patients to bring all drug containers to the office can help identify drugs that increase risk. When beginning treatment with a new drug that could affect visual, physical, or cognitive function, patients should refrain from driving for 1 to 2 days to be sure no adverse effects occur.

Elderly people are involved in fewer alcohol-related fatal collisions. Fewer elderly people consume alcohol, but limiting alcohol consumption is still important because in elderly people, blood alcohol level per amount of alcohol consumed is higher. Also, concurrent use of alcohol and other drugs, particularly multiple drugs, further impairs cognition, increasing the risk of accidents.

This topic was last updated July 2005.