Factors related to driving difficulty and habits in older drivers

Abstract

Objectives: To evaluate the association between chronic medical conditions, functional, cognitive, and visual impairments and driving difficulty and habits among older drivers. Design: Cross-sectional study. Setting: Mobile County, Alabama. Participants: A total of 901 residents of Mobile County, Alabama aged 65 or older who possessed a driver's license in 1996. Measurements: Information on demographic characteristics, functional limitations, chronic medical conditions, driving habits, and visual and cognitive function were collected via telephone. The three dependent variables in this study were difficulty with driving, defined as any reported difficulty in ≥3 driving situations (e.g. at night), low annual estimated mileage, defined as driving less than 3000 miles in 1996, and low number of days (≤3) driven per week. Results: A history of falls, kidney disease or stroke was associated with difficulty driving. Older drivers with a history of kidney disease were more likely to report a low annual mileage than subjects without kidney disease. Low annual mileage was also associated with cognitive impairment. In general, older drivers with a functional impairment were more likely to drive less than 4 days per week. Older drivers with a history of cataracts or high blood pressure were more likely to report a low number of days driven per week, while subjects with visual impairment were at increased risk of experiencing difficulty driving as well as low number of days driven per week. Conclusions: The results underscore the need to further understand the factors negatively affecting driving independence and mobility in older drivers, as well as the importance of improved communication between older adults and health care professionals regarding driving.

Introduction

In the US, the most common method of travel for elderly people is driving an automobile (Federal Highway Administration, 1995). As this segment of the population continues to increase, so does the concern for the safety of these drivers. Older drivers have one of the highest automobile crash rates per mile traveled as compared with most other groups (Williams and Carsten, 1989); they also drive fewer miles, make fewer trips, and drive less in certain situations (e.g. nighttime, during rush hour) (Chu, 1990). This reduction in driving and changes in driving behavior patterns has been attributed to the absence of work related mileage, other lifestyle changes, and the recognition of decreased driving performance (Rosenbloom, 1988, Bly, 1993, Stutts, 1998, Burns, 1999). The effect of these factors on the elderly population is a reduction in mobility, which is a major contributor to their well-being (Carp, 1988).

The primary focus of research on driving decisions made by older persons has been the cessation of driving (Stutts, 1998). The reasons behind the decision to stop driving most commonly given by older persons are a lack of comfort driving or loss of confidence in their driving abilities, vision problems, or health problems other than vision (Wallace and Colsher, 1991, Persson, 1993, Kington et al., 1994). However, driving cessation lies at the end of a continuum leading from complete driving independence to driving cessation. Few studies to date have evaluated the characteristics that propel the older driver along this continuum. There is increasing attention on the influence of different medical conditions on driving, performance. Dementia (Fitten et al., 1995, Trobe et al., 1996, Lundberg et al., 1997), visual impairment (Johnson and Keltner, 1983, Owsley et al., 1998a, Owsley et al., 1998b), and chronic medical conditions (Gresset and Meyer, 1994, Koepsell et al., 1994, Marottoli et al., 1994, Hemmelgarn et al., 1997, Sims et al., 1998) have been found to be associated with automobile crashes in the elderly. The effect of medical conditions on an older driver's current driving patterns (e.g. driving frequency and avoidance strategies) is also of great interest. Prior research suggests that medical and functional impairment may be associated with driving, patterns in older adults (Forrest et al., 1997, Stutts, 1998), however, the specific effects of certain conditions remain to be evaluated.

The objective of this study was to evaluate the association between specific chronic medical conditions and functional, cognitive, and visual impairments and reduced mobility and driving difficulty among older drivers.