Physical Function and Frailty Are Associated with Self-Regulation of Driving among Older Adults: A LongROAD Study
This study examined physical function and frailty, and their association with strategic driving self-regulation, using data from the AAA Longitudinal Research on Aging Drivers study.
Many older adults rely on driving a motor vehicle to maintain independence and engage with their environments. However, driving safely can become a concern due to age-related changes in physical, cognitive, and sensory function. To extend the number of years that older adults can drive safely, some self-regulate their driving. Self-regulation refers to modifying driving habits, such as driving less frequently or avoiding challenging situations like driving at night, in bad weather, or during rush hour, due to declining abilities. The goal of this study was to examine physical function and frailty, and their association with strategic driving self-regulation using data from the AAA Longitudinal Research on Aging Drivers (LongROAD) study.
This study used data from in-person assessments and self-report questionnaires across five years of the AAA Longitudinal Research on Older Adult Drivers (LongROAD) study. The LongROAD study was a multisite prospective cohort of 2,990 drivers recruited between July 2015 and March 2017 at ages 65-79 in: Ann Arbor, Michigan; Baltimore, Maryland; Cooperstown, New York; Denver, Colorado; and San Diego, California.
Strategic self-regulation was measured by asking participants whether they tried to avoid specific driving situations (i.e., driving at night, driving in bad weather, driving in unfamiliar areas, driving in rush hour traffic, and driving on the freeway) and reasons for doing so. A count variable was created to identify the number of situations in which each participant self-regulated their driving each year. Physical function was measured using the Short Physical Performance Battery consisting of three timed components of walking speed, repeated chair stands, and standing balance. Summary scores were categorized into three groups: poor, fair, and good physical function. Frailty status was measured using the Fried frailty phenotype which assesses weakness, slowness, low physical activity, exhaustion, and shrinking. Frailty scores were categorized as not frail, pre-frail, and frail.
Analyses were conducted to characterize the sample at baseline, and mixed-effect Poisson models with person-level random intercepts were used to examine frailty and physical function separately in relation to strategic self-regulation of driving behaviors over time. In conjunction with the exposure variable and self-regulation outcome, each model was adjusted for age category, sex, visual perception, contrast sensitivity of both eyes, cognitive health, self-reported miles driven per week, and Rural-Urban Commuting Area codes.
Of the 2,962 participants in the AAA LongROAD cohort who had frailty status data at baseline, 41.2% of participants were classified as non-frail, 55.9% were classified as pre-frail, and 2.9% were classified as frail. Of the 2,945 participants who had physical function data at baseline, 19.4% were classified as having poor physical function, 45.8% had fair physical function, and 34.8% had good physical function. Objectively measured physical function and frailty were both found to be associated with self-reported driving self-regulation. Participants with pre-frail and frail status had rates of self-regulation 1.07 and 1.25 times that of non-frail participants, respectively. Those with fair and poor physical function status had self-regulation rates 1.17 and 1.38 times that of participants with good physical function. These findings are consistent with previous research that suggests that older drivers with worse physical function self-regulate to avoid challenging driving situations due to declining abilities. Although studies have examined the effect of frailty status on other driving-related outcomes, this study was the first to examine frailty and the association with strategic self-regulation among older drivers.