Safe Mobility for Older Americans (2005)

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2Research History Historically, research on older drivers has followed three distinct periods andareas of inquiry. First, in the 1970s, research focused on whether older driversrepresented a problem. Results showed that older drivers have fewer crashes per capita but more per mile driven (Sirén et al. 2001; see Hakamies-Blomqvist and Wahlstrom 1998 for a comprehensive review). The second period began in the 1980s and focused on identifying what in the aging process contributed to the increased risk for older drivers. The following findings were documented during this period (Hakamies-Blomqvist 2004): • Older drivers have more crash fatalities and injuries per mile driven than middle- aged drivers, as is shown in Figure 2. • Older drivers are more likely than middle-aged drivers to be at least partly at fault in their crashes (McGwin and Brown 1999; Stewart et al. 1999). • Intersection incidents are overrepresented in older-driver crashes. • The increased crash risk in older drivers, which begins after age 75, is generally attributed to age-related functional deficits. • Older-driver crashes are less likely to be reported as involving alcohol and speed- ing, and the occupants are more likely to wear safety belts than would be expected in other age cohorts. Subsequent to the publication of Special Report 218, “the field of cognition and aging brought deeper understanding to the discourse” (Hakamies-Blomqvist and Wahlstrom 1998). It was also during this period that crash propensity was questioned, and it was shown that older drivers’ high injury and fatal crash rates could be explained at least in part by their greater physical frailty (Sirén et al. 2001; Li et al. 2001). Therefore, to understand more clearly the safety implications of the aging pop- ulation, one needs to examine not only the fatality rate but also the crash rate. Figure 3 shows that, while older drivers and passengers may be more likely to die in a crash, their crash involvement rate compares favorably with that of middle-aged driv- ers at least until age 75. While the perceived problem is that older drivers constitute a highway hazard and a major cause of crashes, research suggests that there is no marked increase in crashes until drivers are 80 or older, and even then the increase is relatively small. Data also indicate that older adults are more likely to bring death and injury to themselves than to other vehicle occupants or pedestrians. Moreover, it is also important to bear in mind that the absolute number of deaths from crashes falls steadily with age. 6

RESEARCH HISTORY 7 FIGURE 2 Driver fatalities and injuries by age, related to population, number of driver licenses, and mileage driven, 1997. Killed and injured drivers per 10,000 population Killed and injured drivers per 10,000 licensed drivers Killed and injured drivers per 100 million miles driven Number 14 12 10 8 6 4 2 0 16–19 20–24 25–29 30–34 35–39 40–44 44–49 Age group 50–54 55–59 60–64 65–69 70–74 75–79 80–84 85+ FIGURE 3 Crash involvement rate per 100 million vehicle miles traveled. 0 500 1000 1500 2000 2500 3000 3500 4000 4500 16 17 18 19 20–24 25–29 30–34 35–39 40–44 45–49 50–54 55–59 60–64 65–69 70–74 75–79 80–84 85+ Driver Age Crash Involvement Rate

While safety is and will continue to be a concern, researchers coming of age in the 1990s have been more likely to balance the traditional focus on safety with a broader discussion of transportation and mobility needs. In 1986, the Transportation Research Board (TRB) “initiated a study on the mobili- ty and safety needs of older persons. It convened a panel of experts to review the design and operation of the surface transportation system and to recommend improve- ments that would better serve an aging population” (TRB 1988, 2). Subsequently, “Congress asked for ‘a comprehensive study and investigations of (1) problems which may inhibit the safety and mobility of older drivers using the Nation’s roads and (2) means of addressing these problems’” (TRB 1988, 2). The results were published in 1988, and the original committee’s findings are worth summarizing and reviewing for an understanding of the research activities implemented over the following decade and beyond: • Mobility1 is essential to the quality of life of older persons, and the automobile is the primary means of meeting that mobility need. • Most older drivers have good driving records. • Older persons are among the most vulnerable to injury in motor vehicle crashes. • In general, visual and cognitive performance on driving-related tasks diminishes with age. At the same time, there is a great deal of variability in performance among individuals. • Because, for any individual, age is a poor predictor of performance, age alone should not be the basis for restricting or withholding driver’s licenses. • Sign visibility and maintenance standards, assumptions about performance used in intersection design and traffic operations, and vehicle crashworthiness standards fail to account for the needs and capabilities of older persons using the roadway system. • The population of older persons who are able to live in their own homes but who are unable to drive is growing. Better and more efficient specialized transportation service will be needed for this group to allow them to maintain their mobility and independence. • Too little research is under way that could improve the mobility and safety of older persons, and research responsibilities are scattered across several different feder- al agencies. TRB’s Special Report 218 was a milestone in the history of transportation research and served as a blueprint for a decade of research. That report summarized knowledge SAFE MOBILITY FOR OLDER AMERICANS 8 1 Mobility, in this context, refers to more than simply moving from one place to another. It even goes beyond access to life’s necessities, such as medical appointments and food. Mobility for older people encompasses quality-of-life issues, such as access to social and cultural experiences.

about the special needs of older persons and speculated on how those emerging needs might affect future mobility and safety (Schieber 2004). The interval between the issuance of Special Report 218 and the present has seen a shift in emphasis from describing the “older-driver issue” to investigating the factors that underlie elevated crash risk for some older persons. To this end, research has focused on the physical, health, and cognitive changes known to accompany aging and their impact on mobility. There have been four recurring themes in the research since the issuance of Special Report 218: (a) understanding changes in mobility with age and factors affecting such behavior changes, (b) understanding the functional impair- ments that place some older drivers at risk for crashing as they age, (c) identifying methods for the early detection of these functional changes, and (d) discovering how the transportation system might be altered in response to these functional changes. CHANGES IN MOBILITY WITH AGE In 1988, “fundamental gaps exist[ed] in our understanding of how human perform- ance changes across the life cycle and how those changes affect the driving task” (TRB 1988, 76). Since that time a great deal of research has been conducted on the driving habits of older adults and factors that affect such behaviors. Results indicate that older drivers limit their driving in specific contexts. For example, older drivers are less likely to drive alone, in fog, in rain, in high traffic, or at night (Chu 1994; Hennessy 1995). Overall, older adults tend to limit their driving to particular times and places in which they feel safe (Ball et al. 1998; Chu 1994; Hennessy 1995; Janke 1994). [Although some persons with dementia or a related disorder may not make prudent choices about driving, older drivers, in general, tend to limit driving on their own (Ball and Owsley 2000).] AGING-RELATED IMPAIRMENT AND MOBILITY “Vision” is obviously a prerequisite for driving, but the term encompasses a wide range of functional abilities. While many licensing agencies continue to test high contrast static visual acuity (ability to see detail), other functional aspects of vision have been found to be more strongly related to crashing, most notably contrast sensitivity (ability to detect objects against their background) (Owsley et al. 2001; Owsley et al. 2002). Reliable indices of contrast sensitivity are readily available and can be easily administered. Similarly, over the past 15 years the role of age-related diseases of the eye and their treat- ment (e.g., cataracts, glaucoma) in crash risk has been investigated. Glaucoma and cataracts, accompanied by visual function impairment, have both been associated with increased crash risk (Owsley et al. 2001; Owsley, McGwin et al. 1998), and cataract removal has been associated with decreased crash risk (Owsley et al. 2003). The associa- tion between visual function and driving safety is now much clearer than it was a decade ago and is well summarized in Conference Proceedings 27 (see Owsley 2004). RESEARCH HISTORY 9

Overall health conditions have also been explored in relation to their impact on the driving ability of older adults. For example, Campbell et al. (1993) compared drivers and nondrivers 70 years of age and older and found that 32 percent of the nondrivers cited health or medical reasons as influencing their decision to cease driving. Similarly, Forrest and Hunter (1997) compared female drivers and nondrivers and found that some specific medical conditions (e.g., diabetes, angina, self-reported vision) were associated with driving cessation. From a sample of 404 very old drivers (84 or over), Brayne et al. (2000) reported that the reason provided most frequently for driving cessation was general health problems. Furthermore, compared with older drivers, older individuals who have ceased driving have a higher number of medical conditions (e.g., Parkinson’s disease, stroke, cataracts, macular degeneration), as well as poorer self-ratings of health (Campbell et al. 1993; Marottoli et al. 1993). Research since 1988 has also elucidated the impact of medications on crash risk. Ray et al. (1992) found an increased injurious crash risk associated with benzodi- azepine and cyclic antidepressant use in drivers 65 and older. Leveille et al. (1994) also found an increased risk of crashes associated with antidepressant use. Similarly, Foley et al. (1995) found that the use of nonsteroidal anti-inflammatory drugs (NSAIDs) was associated with a twofold increase in the likelihood of crashing. McGwin et al. (2000) found that after adjusting for age, gender, race, and annual mileage, use of NSAIDs, angiotensin converting enzyme (ACE) inhibitors, anticoagu- lants, and benzodiazepine was associated with involvement in at-fault crashes. Interactions between drugs were also explored, and results indicated that individuals taking both NSAIDs and ACE inhibitors were 3.4 times more likely to be involved in a crash than were individuals taking neither of the drugs. Whether medication usage actually contributes to crash risk may depend on other factors. For instance, Hemmelgarn et al. (1997) determined that the probability of vehicle crashes for elders taking benzodiazepines varies on the basis of length of time and type (i.e., duration of action) of medication taken. Also, the increase in crashes correlated with the use of certain drugs may be related to the underlying disorder as much as to the treatment. For example, an untreated or undertreated depressed indi- vidual may be as likely to crash as or more likely to crash than one who is adequately treated. Overtreatment, or medication doses that are too high for an individual, can also increase the risk of crash involvement. Declines in physical functioning can also affect driving behavior. For example, Sims et al. (2001) found that crash-involved drivers were more likely to have experi- enced at least one fall in the past year than were noncrash controls. In fact, many researchers have found similar risk factors for falls and vehicle crashes (Foley et al. 1995; Koepsell et al. 1994). Physical factors other than falls that have been shown to affect driving safety include head and neck rotation, lower limb strength, and upper limb strength. Marottoli et al. (1998) determined that limited neck rotation was linked significantly to self-reported crashes spanning a prior 5-year period. Investigating the effects of such physical limitations, Hunter-Zaworski (1990) found that when head SAFE MOBILITY FOR OLDER AMERICANS 10

movements were restricted, older drivers failed to compensate as compared with younger drivers, who successfully offset the physical limitation. In a study of lower limb strength, Marottoli et al. (1994) found that individuals with three or more foot abnormalities or impaired knee flexion as well as poor performance on the rapid walk test had more self-reported crashes and citations. Hu et al. (1998) determined that reaching ability is associated with increased crash risk. Similarly, in a study of upper limb strength, Retchin et al. (1988) discovered that older adults who had quit driving had worse grip strength and reaction time than older adult drivers. Declines in physical and cognitive skills have been linked to mobility restrictions such as increased driving avoidance, decreased driving exposure, and driving cessa- tion. For example, Stutts (1998) found that poorer cognitive abilities—as measured by the Trail Making Test, a measure of visual attention and executive function, and the Short Blessed Test, a measure of mental status—were associated with decreased driv- ing exposure (miles driven per year). Similarly, Ball et al. (1998) found that older drivers who were cognitively impaired, as indicated by the Mattis Mental Status Screening Examination, tended to report more avoidance of certain driving situations and fewer days of driving per week. Reduced speed of cognitive processing, as meas- ured by useful field of view (UFOV) performance, was also associated with the avoid- ance of several types of driving situations (Ball et al. 1998). While adequate vision and physical functioning are important, the past decade again highlighted the importance of impairments in certain critical cognitive domains to driving safety. Impaired memory has been implicated as a contributing factor in crash involvement (Foley et al. 1995; Johansson et al. 1996; Hu et al. 1998). Furthermore, visual attention and visuospatial ability have been found to be signifi- cantly associated with self-reported crashes (Marottoli et al. 1994; Marottoli et al. 1998). A consistently strong predictor of both retrospective and prospective crashes across a number of studies has been impairment in visual processing speed, particu- larly as measured by the UFOV test (U.S. Department of Transportation 2003a). EARLY DETECTION Since the discovery of the relationship between functional measures and driving com- petence, research has focused on determining the usefulness and feasibility of such measures as screening tools. The early identification of at-risk older drivers, and per- haps their remediation, has been a central theme since the publication of Special Report 218 (see Staplin 2004). Short screening batteries of both physical and cogni- tive measures have been field tested at licensing bureaus. The Older Driver Program, initiated in Maryland in the late 1990s, is of particular interest with respect to an over- all programmatic approach (see Box 1). The Model Driver Screening and Evaluation Program (U.S. Department of Transportation 2003a) recommends validated screening practices that can assist in retaining mobility and enhancing safety. RESEARCH HISTORY 11

SAFE MOBILITY FOR OLDER AMERICANS 12 Box 1 OLDER DRIVER PROGRAM The Maryland Motor Vehicle Administration (MVA) Older Driver Program encourages a commonsense approach to understanding the needs of citizens, regardless of age, and recognizes the benefits of safe mobility for life. The pro- gram recognizes that although functional abilities are jeopardized by conditions related to advancing age, the stereotype equating older age with loss of driving ability threatens the independence of older drivers, underestimates the financial costs to communities, and fails to acknowledge that public transportation and mobility alternatives for older adults are woefully inadequate for most. With National Highway Traffic Safety Administration (NHTSA) and National Institutes of Health support and many collaborators, Maryland developed a sci- entifically sound approach for proactively identifying, assessing, and remediating drivers for personal and public safety. The effort included a statewide multidisci- plinary consortium concerned with (a) older-driver issues and safe mobility for life and (b) research on functional capacity testing to determine the level of training, counseling, and remediation needed for safe, independent mobility. Of particular note, the research program focused on keeping older drivers on the road by using screening tests of vision, physical ability, and a variety of cog- nitive skills. The tests were designed to be administered quickly and efficiently in office settings to detect emerging threats to driving safety and to make deter- minations about driving remediation and training needs. Subsequent evaluation found them to yield scientifically valid predictions of driving risk (U.S. Department of Transportation 2003a). The results of these screening tests are not used to take away driver’s licenses. Instead, they can be used at license renewal for early prevention and intervention to prolong independent, safe mobility. In addition, they are being used by MVA’s Medical Advisory Board physicians to determine the appropriate course of action for a given individual for that individ- ual to achieve safe mobility. The results of the Maryland pilot program are incor- porated in the Model Driver Screening and Evaluation Program offered by NHTSA (U.S. Department of Transportation 2003a).

CHANGES IN THE TRANSPORTATION SYSTEM The functional changes that accompany the aging process have become better under- stood over the past decade, and a movement is under way to adjust the traffic environ- ment to these changes. The recent publication of two Federal Highway Administration (FHWA) handbooks (Highway Design Handbook for Older Drivers and Pedestrians and Guidelines and Recommendations to Accommodate Older Drivers and Pedes- trians) is a first step in the process of implementing this knowledge. Some practices recommended in the Design Handbook include modification of pavement markings and curb edgings for nighttime driving, geometric enhancements to intersections, improved directional signing and enhanced use of portable changeable message signs at freeways, modifications of signal timing at pedestrian crossings, and signage and channelization enhancements designed to reduce information-processing demands placed on drivers approaching work zones (Staplin 2004). Many of these improve- ments have been called for by older drivers themselves (Iowa Safety Management System 2002). As the recent publication Safe Mobility for a Maturing Society: Challenges and Opportunities (U.S. Department of Transportation 2003b) points out, the next step in this process is to inform highway engineers of these guidelines, develop training pro- grams for traffic and highway engineers to ensure understanding of the issues, and encourage use of the guidelines in future highway design. REFERENCES Ball, K., C. Owsley, B. Stalvey, D. L. Roenker, M. E. Sloane, and M. Graves. 1998. Driving Avoidance and Functional Impairment in Older Drivers. Accident Analysis and Prevention, Vol. 30, No. 3, pp. 313–322. Ball, K., and C. Owsley. 2000. Increasing Mobility and Reducing Accidents of Older Drivers. In Mobility and Transportation in the Elderly (K. W. Schaie and M. Pietrucha, eds.), New York, Springer, pp. 213–251. Brayne, C., C. Dufouil, A. Ahmed, T. R. Dening, L.-Y. Chi, M. McGee, and F. A. Huppert. 2000. Very Old Drivers: Findings from a Population Cohort of People Aged 84 and Over. International Journal of Epidemiology, Vol. 29, No. 4, pp. 704–707. Campbell, M. K., T. L. Bush, and W. E. Hale. 1993. Medical Conditions Associated with Driving Cessation in Community-Dwelling, Ambulatory Elders. Journal of Gerontology: Social Sciences, Vol. 48, pp. S230–S234. Chu, X. 1994. The Effects of Age on the Driving Habits of the Elderly. U.S. Department of Transportation, Washington, D.C. Foley, D. J., R. B. Wallace, and J. Eberhard. 1995. Risk Factors for Motor Vehicle Crashes Among Older Drivers in a Rural Community. Journal of the American Geriatrics Society, Vol. 43, No. 7, pp. 776–781. RESEARCH HISTORY 13

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