Demographic changes in the United States have resulted in a growing number of drivers over age 65. It is estimated that by the year 2020, more than 15 percent of drivers will be older than 65.¹ Older adults who drive are able to maintain important links to their communities. Those who stop driving are at risk for isolation and depression,² and often have associated functional impairment.³ Moreover, the societal cost of providing transportation services for older people who cannot drive is considerable.

Because of lack of training in injury prevention or rehabilitation, the fear of losing a patient or, perhaps, legal concerns, family physicians may be reluctant to address the issue of an older person's driving capabilities. Injury prevention and health maintenance are important objectives in family practice. The physician's goal is to identify treatable causes while preserving patients' mobility and independence. Driving should be viewed as an aspect of this independence. Family physicians can play a pivotal role in maintaining or even improving driving skills in their older patients. For patients who can no longer drive, physicians can recommend other transportation resources.

Public safety concerns about the driving performance of older adults have been raised by evidence showing an increased crash rate per mile driven for drivers aged 70 or older compared with other adult age groups.⁴ This increased crash rate has been attributed to age-related changes in driving skills in addition to various medical illnesses.⁵ Older drivers, however, tend to drive less at night, during adverse weather conditions, during rush hours or in congested thoroughfares. These factors, along with a reduction in overall miles driven per year, make public policy decisions on screening older drivers questionable, considering that the number and severity of crashes by younger drivers outweigh those by older people. Nevertheless, these concerns may be important when dealing with individual patients.

Driving Assessment

Driving issues in an older patient may come to the attention of the family physician for various reasons. The patient may question his or her own ability to drive safely. A concerned family member or friend may have observed unsafe driving behavior. The department of motor vehicles may have requested the physician's opinion of a person's driving abilities. Many older adults have jobs, such as driving school buses or company vehicles, and they may be required to have an annual health examination. Finally, the physician may consider driving an important safety or mobility issue when a patient has symptoms such as lightheadedness or diseases such as diabetes mellitus.

DRIVING HISTORY

The comprehensive assessment should begin with the driving history. Important human, environmental and vehicular information can be elicited from the patient, the family members, or both (Table 1). Obtaining additional information from someone who has driven as a passenger with the patient or observed the patient's driving behavior may be useful. Any mention of close calls, mishaps, disorientation or becoming lost in familiar areas should alert the physician to possible problems. If the informant answers no to the question “Do you feel safe riding with the patient?” the interviewer should ask whether this is a change. If the risky behavior has been noted for years, it is unlikely to be due to a new medical illness.

MEDICATION REVIEW

Medications can affect driving skills; for example, an association between the use of long-acting benzodiazepines and crash rates in older adults has recently been reported.⁶ Several other classes of drugs, when assessed by road tests or simulators, are associated with either an increased risk of crashing or impaired driving skills (Table 2). Some cases of physician liability that involve driving are related to medication prescription.⁷ Physicians should warn a patient if a prescription drug may affect tasks such as driving or operating heavy machinery and should document this conversation in the medical record.

Once the issue of driving competency is raised, the patient's medications should be reviewed and an attempt made to discontinue any drugs that could impair driving ability. Alternatively, certain classes of drugs such as nonsedating antidepressants (i.e., selective serotonin reuptake inhibitors) or nonsedating antihistamines may be preferred to others because they are less likely to affect driving.

MEDICAL ILLNESSES THAT IMPAIR DRIVING

Many diseases that are common in older drivers can affect driving ability (Table 3). They include, but are not limited to, musculoskeletal disorders, sensory disorders, dementia, psychiatric disorders, stroke, sleep apnea and alcohol and illicit drug use. Drivers with medical conditions that can change abruptly, such as epilepsy, diabetes or heart disease, are also at increased risk for a crash.⁸ In a recent study in which older drivers injured in crashes were compared with a control group,⁹ the medical illness most predictive of an increased risk for injury in an automobile crash was diabetes, especially in older drivers using insulin or hypoglycemic agents. Adequate detection, diagnosis and treatment of illnesses in these disease categories may assist in reducing crash risk and maintaining driving skills.

PHYSIOLOGIC VARIABLES THAT MAY INCREASE THE RISK OF CRASHING

Assessing patients' level of functioning is another approach to determining the crash risk in older adults.^10,11 Static visual acuity, visual fields, visuospatial skills, complex reaction time, selective attention (the ability to detect stimuli in a complex environment), divided attention (maintaining attention in more than one stimulus location) and hearing all decline with age and may adversely affect driving skills. The functional visual field or “useful field of view” also declines with age. This measure has been correlated with crash data in older drivers.¹² The measurement of many of these physiologic variables is expensive, may require special equipment and training, and is not readily available to most clinicians.

One study found that foot abnormalities, fewer blocks walked and poor design copying on the Mini-Mental State Examination were associated with an increased risk for a crash in older drivers.¹³ Further studies are needed to determine if improvements in these variables will reduce crash risk. Brief physiologic or functional assessments would appear ideal because they can be performed reliably and cost-effectively in the outpatient setting. In many reviews of measures that physicians could include in their office-based assessment of older adult drivers,^14–18 it has been suggested that a thorough history and examination of perception, cognition and motor response are important. Family physicians can measure static (near and far) visual acuity and visual fields (by direct confrontation), hearing (by the whisper test, audiometer or a questionnaire) and cognition (Mini-Mental State Examination). The physician should also assess musculoskeletal function (strength, tone and range of motion of joints and neck), alcohol use (CAGE questionnaire [Table 4]), attention (reciting numbers backwards), visual spatial skills (clock-drawing tasks) and, as discussed previously, medication use.

Physiologic measures that can be assessed by family physicians are summarized in Table 5. Although intervention studies showing that assessment and improvement of these measures will reduce crash risk or improve mobility have not been done, these variables can certainly affect other activities of daily living, and they should be addressed.

Additional Injury Prevention Measures

Family physicians can play an important role in injury prevention in patients of all ages. Physicians should encourage seat-belt use in all drivers and passengers. Factors associated with not wearing seat belts include obesity, inactivity, smoking history, low education level and low socioeconomic status.¹⁹ Articles in Consumer Reports and other lay publications may be helpful in assessing which vehicles are most crashworthy and provide the most comfort and ease of use for older adults.

Alcohol remains an important risk factor for a motor vehicle crash, and alcohol use in older adults is probably underestimated. Three drinks in one hour for a man or in 90 minutes for a woman raise the blood alcohol level to 0.05 mg per dL (0.01 mmol per L), a level where the risk for crash doubles. Physicians should counsel their patients about the “not a drop of alcohol when driving” rule.

In one recent study,²⁰ the use of cellular car telephones while driving was found to double the crash rate, and this practice should be discouraged. These are just some of the issues regarding injury prevention that may be discussed with patients (Table 6).

Referral Sources and Rehabilitation

Most research on older drivers has focused on identifying those at high risk of having a crash while driving.²¹ More effort should go toward improving or maintaining driving skills in older adults.²² A disease or disability may be mild, and the family physician may judge that an older patient's driving skills are not impaired. If the disease is one that could progress, the physician should re-evaluate the patient at regular intervals. For instance, an older driver with diabetes mellitus who is treated with insulin should have periodic examinations to detect new organ impairments (retinopathy or neuropathy) or recurrent hypoglycemic reactions.

Epidemiologic studies have begun to identify conditions in older adults that put them at risk for driving cessation. These medical conditions include stroke, Parkinson's disease, visual impairment, activity limitations, arthritis, hip fracture or memory loss.^2,23 Activity limitation is associated with driving cessation. Difficulty in climbing stairs and inability to walk one-half mile or perform heavy housework also correlated with inability to drive. Although disability in high-level functions limits the time older drivers spend on the road, one study² found that 50 percent of subjects with the previously mentioned disorders continued to drive. Most of the older adults with these disorders who stopped driving did so voluntarily. This indicates that there may be a “window of opportunity” for interventions while maintaining or improving driving skills in frail older patients.

A disease state may be so severe and irreversible that a recommendation to cease driving is obviously appropriate. Often, an increased risk for a crash may not be clear. In these patients, referral to other professionals or organizations may be useful in the evaluation and rehabilitation process.

Many conditions, such as dementia of the Alzheimer's type, cerebrovascular accident or medication use, can affect cognition. Some of the cognitive deficits may be subtle and difficult to detect. Referral to a neuropsychologist may be helpful in determining the presence and severity of cognitive impairment (e.g., hemispatial inattention or neglect) in patients with cerebrovascular accidents or in the early stages of Alzheimer-type dementia. Subspecialty consultations may assist with an opinion about disease stability, such as a neurologist in evaluating the effects of a seizure disorder or a movement disorder on driving competency.

Many occupational therapists specialize in assessing driving skills, and these therapists are often based at university hospitals or rehabilitation centers. They can test visual, cognitive and motor skills before performing a road test.²⁴ The vehicle assessment of driving skill may be conducted on a closed or open course. Despite limitations, road tests have been advocated as the preferred method to assess driving competency,^25,26 and they also play an important role in retraining. The therapist may be able to recommend modifications of the patient's vehicle that could assist in the operation and safety of the automobile.

Physical therapists can be indispensable members of a driving rehabilitation team. A few of the common medical problems that may be amenable to physical rehabilitation are muscle atrophy from lack of use and joint dysfunction from cerebrovascular disease, arthritis or parkinsonism. Also, older drivers often take pain medications for such conditions as back discomfort and arthritis,^27,28 and their use is associated with increased crash rates. Thus, limitations in muscle strength related to pain or disuse, or restrictions in range of motion of joints—frequent causes of driving difficulties in older adults—may be ameliorated through physical therapy so that an older driver can maintain or improve driving skills.

Recommendations on Discontinuing Driving

Older adults stop driving for many reasons. Insight into cognitive or physical deficits, pressure from physicians or family, finances, convenience (if others can provide transportation), loss of insurance or failure to renew a license may result in driving cessation. A health professional may be directly involved in this decision. It is important for the clinician to discuss the issue openly and with sensitivity. The discussion should be documented in the patient's medical record. If the patient accepts the physician's advice to stop driving, the physician should be prepared to offer concrete suggestions about alternative modes of transportation.

Public transportation systems²⁹ are relatively inexpensive and often have reduced fares for elderly persons. However, older adults typically underuse these services. Public mass transit systems may be able to offer special state-funded services. Some of these services provide van transportation for older adults, and many of these vans are equipped with lifts. Retirement centers or local religious groups may have funds or volunteers to provide transportation to medical appointments, grocery shopping and social events.

Patients may refuse to stop driving despite advice from their family or physician. The physician should document these discussions and decisions, and consider referring the patient for further testing or additional opinions. Some states (e.g., California) mandate that physicians report cases of illnesses such as Alzheimer-type dementia to the health department and the department of motor vehicles. Physicians should be aware of the local and state requirements for reporting.¹

Physicians can give their opinions regarding driving, but licensing is determined by the state. The physician may consider writing a letter to the department of motor vehicles stating that, in the physician's opinion, the patient should not drive (and why) or request written or road retesting for a patient. When a patient does not acknowledge diminished driving abilities, the department of motor vehicles and the physician may need to work together to stop the person from driving. Especially in a patient with Alzheimer-type dementia, family members or a spouse may consider filing down the ignition key, removing the car keys or automobile from the premises, disabling the battery cable or having the police or department of revenue confiscate the patient's driver's license.