The United States is facing accelerated growth in the number of older citizens due to the aging baby boomer generation. It is expected that this emerging cohort will have more licensed drivers who will drive longer distances more frequently and later into life than preceding generations. What are the risks from elderly drivers and how can we help them drive safely?
November 2005, Vol. XXII, Issue 13
Driven by the aging of the baby boomers, the United States is facing an accelerated growth in the number of older citizens. It is possible that this emerging trendmay be even more marked in some of the nation's sunbeltstates. In California,for example, the senior population (65 and over) will have doubled from 1990 to2020, with those 85 and over constituting the fastest growing segment of thestate's population (State of California, 1998). The coming generation ofseniors will most likely consolidate another trend, which is becoming evidentin the current population of elders. Their greater longevity and better healthover previous generations of elders will translate into a more active andmobile lifestyle than previously experienced by others. Aging baby boomers willneed to rely on more transportation to meet their activity and health needs.Having grown up in a culture of the automobile, they will prefer to drivebefore resorting to any other form of transportation. It is expected that thisnew cohort of elders will have more licensed drivers driving longer distancesmore frequently and later in life than preceding generations (Yanochko, 2002a). This will result in a major increase inthe number of older drivers in the next 20 years.
This anticipated increase in senior drivers has raised some concerns. Froman epidemiologic perspective, drivers over the age of 65, as a whole, are not aserious threat to the safety of other drivers, contrary to media impressionsand popular belief. Rather, they are the ones who are more frequently seriouslyinjured or killed in motor vehicle crashes (California Highway Patrol, 1999).Older adults become more vulnerable to injury from automobile crashes withadvancing age and increasing frailty. The risk of serious injury, resultingeither in incapacity or death, increases almost exponentially after age 60. Thetypes of injuries elders tend to suffer in automobile crashes, such as multiplerib fractures and other severe chest injuries are often associated withfatality (Yanochko, 2002a).
Although seniors do not drive as often as their younger counterparts, theyaccount for a disproportionate number of serious injury or fatal crashes on thenation's roads. Whereas for drivers under 65, the crash death rate has dropped3% since 1995, that death rate for seniors over 65 has risen 15% in the sameperiod, while their population has increased by only 1% (Bowles, 2001).Currently, elders make up about 12% of the U.S. population but they accountfor over 18% of highway fatalities. Seniors accountfor nearly one-third of all deaths occurring at intersection crashes and halfof those elders die attempting left turns. Furthermore, because of theirgenerally cautious and slower driving, the elderly are involved in adisproportionate number of rear-end collisions (Bowles, 2001). Projections bythe National Highway Safety Administration suggest that these trends are likelyto accelerate in the coming decade.
It is worthwhile to examine crash statistics for older drivers more closely.We can, for example, compare the reported yearly crash rates of the youngestdrivers, ages 15 to 19 and 20 to 29, to the normal expectation of crash ratesfor drivers of all ages, set at 1.00. We can then do the same for drivers ages65 and up. In California,the crash expectation for 15- to 19-year-olds is 2.40 or 2.4 times the all-driverfigure, whereas the relative crash rate for 20- to 29-year-olds is 1.43 (Yanochko, 2002b). This is similar to results from otherstates. In contrast, the relative crash rate of drivers 65 and over is 0.85,clearly below the all-drivers figure.
If we examine the 65-and-over population by five-year blocks, we obtain therelative crash rates in the Figure.Even though the younger elders appear to have better-than-average safetyrecords, there does seem to be a relationship between aging and increasing relativecrash risk. After age 80, the trend of older drivers having lower relativecrash rates than the all-driver expectation is reversed.
The aged are characteristically a very heterogeneous group in many regards.Even though they are all seniors, there are likely to be great differencesamong them. Even among elderly people of the same age, great variability innumerous attributes has been described, a fact that has become one of theaxioms of geriatrics. One of the most significant of these variables is stateof health. Health deteriorates exponentially after middle age over a period ofone to three decades. For some, the rate of decline in health will be fairlyrapid, for others it will be slower, with disabilities making a lateappearance. This variability is capital to the task of driving.
It is well established that a number of medical conditions, such as visualimpairments, dementia, stroke or severe arthritis, pose serious obstacles tosafe driving. The likelihood of acquiring these health outcomes increasesdramatically with advancing age. However, even in the very old there are someindividuals who will still be capable of driving safely.
Given their vast driving experience and survivability, the most plausiblereason why seniors might become unsafe drivers would be diminishing facultiesneeded for driving in their otherwise familiar environment. While a rapidlychanging driving environment could possibly also contribute, the greatestimpact on safe driving is likely to come from specific diseases impacting keydriving-relevant organs. These can impair the physical and mental facultiesrequisite for safe driving (Dubinsky et al., 2000; Fitten et al., 1995; Foley et al., 2000). Some of theseage-related diseases, such as dementia, develop insidiously and areparticularly difficult to detect in the earlier stages of development.
Therefore, the focus of our concern should not be the healthy older personwho is a safe driver. Rather, we should worry more about those elderly who nowmay be losing their health in ways that specifically affect their drivingskills. Some evidence concerning drivers with Alzheimer's disease (AD) alreadysupports this concept (Dobbs et al., 1998; Dubinskyet al., 2000; Fitten et al., 1995; Zuin et al., 2002). Furthermore, it is noteworthy that therisk of AD and other common dementias increases exponentially after age 65. Byage 85, more than one-fourth of those individuals suffer from AD or anotherdementia. Seniors age 85 and older represent the most rapidly growing sector ofthe population. Thus, it would seem useful to find the means by which toidentify those health-impaired seniors with conditions likely to negativelyinfluence safe driving.
The screening of elders for driving fitness has been controversial. On theone side, interest in the common good has been championed. On the other, thedesire for protecting the autonomy of the individual has been underscored. Howdo these perspectives stack up against each other? Would reducingthe risk of serious crashes, with their morbidity, mortality and high cost,outweigh the need to allow large numbers of people to drive when no otheradequate means of transportation is available? There are no easy answers.Strong arguments can be offered from both perspectives. In the absence of overwhelmingevidence, weighing in on one side or the other would largely depend on thebalance between the importance of the collective good and the safeguarding ofthe autonomy of individuals (Fitten, 2003).
Most states have enacted laws that address older drivers. At least 32 statesrely on medical review boards to make recommendations about licensing laws ingeneral and about the licensing of individuals on a case-by-case basis whenquestions of driving fitness arise (Yanochko, 2002c).Many states require more frequent testing after a certain age and visiontesting at every renewal. Some states require more frequent road testing ifdrivers have been involved in several crashes, and one state requires everyoneover the age of 75 to take a road test. Other states, such as California, require physicians to reportpeople with dementia or other cognitive impairment, and a few states have lawsthat indemnify from liability anyone who, in good faith, reports an individualwho is believed to be an unsafe driver (Yanochko,2002c).
There is no single screening procedure or test with sufficient technicalefficacy that can reliably and economically separate safe senior drivers fromthose that are clearly more at risk for serious road crashes. Given the natureof driving, the most common disorders with high potential impact on drivingsafety are those of the eye, the brain and the musculoskeletal system. Theseare quite diverse, and it is unlikely that any single test could identify alldeficits in faculties important to driving. Even standard, state-sponsoreddriving tests may be inadequate in identifying many older drivers withimportant cognitive deficits (Dobbs et al., 1998).
Tests of vision and basic neural function have been well established forsome time and are currently applied, whereas tests of cognition relevant todriving are being developed. These have received their main impetus from thestudy of older drivers suffering from dementia, an almost exclusivelyage-related group of maladies. Indeed, several studies have reported anincreased crash risk in mildly demented drivers, as compared to comparably agednon-demented drivers. They have also shown much higher propensities for seriouserrors by drivers with dementia (Dobbs et al., 1998; Fittenet al., 1995; Withaar et al., 2001). In view of thehigh prevalence of dementia in the aged, this has become an important field ofresearch with promising tests having been developed or which are currentlyunder development.
Yet even for cognitive impairment relevant to driving, there is no test thatwill satisfy all the key requisites of a good screening tool: high validity andreliability; good sensitivity and specificity; simplicity and speed ofadministration for large numbers of individuals; low cost; and high tolerability.In time, continued research is likely to produce such tests.
It will be important to determine how such tools should be tested initially.Should they first be applied in state driving regulatory agencies or physicians'offices where health assessment can best take place? The latter approach mightoffer the most desirable rationale on which elder drivers initially to screen.Such a rapid, simple and economic methodology may identify potentiallycognitively impaired drivers, but will need to be subsequently linked to moredetailed screening or more confirmatory road testing of identified, at-riskdrivers.
Of course, such an initial, broad screening methodology will also have todemonstrate that its application would reduce driving-related morbidity andmortality. In view of the relatively low frequency of crashes, this willnecessitate long-term, prospective, randomized, controlled studies that willexamine driving outcomes in screened and non-screened populations. Finally itshould be kept in mind that such screening instruments should not be appliedoutside of a properly developed, comprehensive older-driver program. Thisshould have, as a minimum, well-developed action plans and resources to respondto a variety of relevant issues associated with the testing protocol, results,retesting, redressing false-positive results, confidentiality, post-drivingcessation education and improved transportation options (Fitten,2003).
In conclusion, it may be in the interest of all, including the elderly, toidentify impaired older drivers through scientifically derived andhealth-related screening methods. Preventing impaired seniors from drivingwould lower the crash and morbidity/mortality rates of this population.However, it would be inadvisable to undertake this identification task in theabsence of well-developed screening instruments and a well-organized managementand support program.
Dr. Fitten is professor of psychiatry and biobehavioralsciences at the University of California, Los Angeles.He is also director of geriatric psychiatry at the Greater Los Angeles Veterans Affairs HealthcareSystem, Sepulveda Campus.
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