Accident Analysis and Prevention 37 (2005) 613–618

Self-rated driving performance among elderly drivers referredfor driving evaluation

Barbara Freunda,∗, LeighAnna A. Colgrovea, Bonnie L. Burkeb, Rebecca McLeoda

a The Glennan Center for Geriatrics and Gerontology, Eastern Virginia Medical School, 825 Fairfax Avenue, Norfolk, VA 23507, USAb Epidemiology and Biometry Core, Graduate Program in Public Health, Eastern Virginia Medical School, 700 West Olney Road, Norfolk, VA, USA

Received 4 January 2005; received in revised form 14 March 2005; accepted 14 March 2005

Abstract

Purpose:To explore whether elderly drivers of varying driving skill levels (1) differ in their perception of their driving evaluation performanceand (2) determine if self-rated driving evaluation performance is related to cognitive ability.Methods:One hundred and fifty-two drivers aged 65 years or older and referred for a driving evaluation were enrolled into the study. Subjectswere asked the question, “how well do you think you will perform today on your driving evaluation compared to others your own age?” Subjectsa TM ne,CR felt theyw % of thosec there was as ter thano to or worset ng groups(C ive abilityw©

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lso completed the Mini-Mental State Exam and a 30-min drive on a STISIM Drivesimulation (Systems Technology, Inc., HawthorA). Only 47 subjects completed both the simulated drive and self-rated item.esults:Sixty-five percent of drivers rated themselves as performing better on a driving test than others of their age. Another 31.9%ould perform the same as others of their age on a driving test. A 50.0% of those considering themselves “a little better” and 52.9onsidering themselves “a lot better” had an unsafe driving performance. As self-rated driving evaluation performance increased,ignificantly increased risk of unsafe driving (p= 0.02) in the study population. Drivers who considered themselves at least a little betthers of their age were over four times more likely to be unsafe drivers compared to others who believed they were comparable

han other drivers of their age (RR = 4.13, 95% CI = 1.08–15.78). There was no significant difference in MMSE between self-ratip= 0.76).onclusion:Older drivers assign high ratings to their driving performance, even in the presence of suspected skill decline. Cognitas not related to self-rated driving evaluation performance.2005 Elsevier Ltd. All rights reserved.

eywords: Insight; Older drivers; Driving performance; Driving evaluation

. Introduction

Older drivers generally perceive their driving ability to beetter than or equal to that of their peers (Holland, 1993;arottoli and Richardson, 1998) and better than that of

ounger drivers (Groeger and Brown, 1989). However, olderriver involvement in fatal crashes is projected to increase55% by 2030 and account for 54% of the total projected in-rease in fatal crashes among all drivers (Lyman et al., 2002).eclining driving competence is associated with impairments

n vision, functional abilities and cognition, all of which have

∗ Corresponding author. Tel.: +1 757 446 7040; fax: +1 757 446 7049.E-mail address:freundbm@evms.edu (B. Freund).

been linked to increased crash risk (Owsley et al., 1998Sims et al., 1998; Wallace, 1997). While many older driverrestrict or stop driving voluntarily, a large number continudrive. Taken together, these findings suggest that manydrivers either lack or deny awareness of their limitationsmay not restrict or curtail their driving. Declining drivinability is a cause for concern as these drivers may encodriving situations known to be difficult for the older driv(e.g., unprotected left turns, stop sign controlled intersec(Preusser et al., 1998)), and in which they are less capableresponding to safely.

While studies have explored self-rated driving abilityolder adults in general, little is known about how older drivreferred for driving evaluation would rate their expected d

001-4575/$ – see front matter © 2005 Elsevier Ltd. All rights reserved.oi:10.1016/j.aap.2005.03.002

614 B. Freund et al. / Accident Analysis and Prevention 37 (2005) 613–618

ing performance. One might expect that these drivers wouldbe cognizant of skill decline because they have been referredor self-selected for an evaluation. According to the HealthBelief Model (HBM), older drivers take cues from their envi-ronment and social contacts regarding suspected driving skilldecline (Janz et al., 2002). The model predicts an expectedincrease in both perceived susceptibility and perceived seri-ousness of hazardous driving. The combination of perceivedsusceptibility and severity forms perceived threat. If the cuesare sufficient to alter the health belief, here fitness to performwell on a driving evaluation, older drivers should perceivea greater driving skill threat and report more conservativeself-ratings of driving evaluation performance prior to thesimulated drive.

The aims of this study were to explore (1) whether un-safe elderly drivers differ in their perception of their drivingevaluation performance than safe or restricted elderly driversand (2) determine whether self-rated driving performance atthe time of evaluation is related to cognitive ability overalland within driving groups. It is hoped that increased under-standing of older drivers’ self-ratings will lead to efforts toenhance safety and assist clinicians who counsel them aboutcontinued and restricted driving as well as driving cessation.

2. Methods

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2.3. Measures

2.3.1. Self-rated driving evaluation performanceSelf-rated driving evaluation performance was measured

by asking the question, “how well do you think you will per-form today on your driving evaluation compared to othersyour own age?” The response to the question was collectedon a patient information form completed by the patient imme-diately before the evaluation. Responses were a ranked on a5-point Likert-style scale, as follows: 5—“a lot better;” 4—“alittle better;” 3—“the same;” 2—“a little worse;” 1—“a lotworse.”

2.3.2. CognitionThe Folstein Mini-Mental State Examination (MMSE;

Folstein et al., 1975) was administered to all subjects. TheMMSE is a popular clinical screening tool for cognitive im-pairment and is used to document intellectual changes thatoccur over time. It is relatively brief and easily scored, requir-ing 5–15 min to administer depending on the patient’s levelof impairment. The MMSE is comprised of items assessingorientation to time and place, attention and concentration,immediate and delayed recall, language, and constructionalability. Possible scores range from 0 to 30. The age/education-appropriate MMSE is a binary variable that denotes whetherthe MMSE score was appropriate for the patient’s age ande et ore .,1

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.1. Participants

One hundred and fifty-two community dwelling, oldctive drivers with valid drivers’ licenses in the Hampoads metropolitan statistical area (six cities and nine c

ies in eastern Virginia) were physician, family membeelf-referred for driving evaluation. Subjects presentedecutively to the clinic over the course of 36 months. Subjects had repeated evaluations over time (e.g., newation added to regime or after treatment for depressionvoid confounding a “learning effect” with self-concept, ohe first driving evaluation for each patient was used. All sects provided informed consent according to the guidef the Institutional Review Board (IRB) for human subjerotection at Eastern Virginia Medical School who appro

he study.

.2. Procedure

After providing a patient history and informed conseubjects completed the self-rated appraisal of driving peance evaluation, the Mini-Mental State Exam (MMSE),

he driving performance evaluation. The self-rated apprnd MMSE were administered first and scored by an exnced research associate. The driving performance evalas administered and simultaneously assessed by the pal investigator. The principal investigator was blinded toubjects’ self-rating and MMSE results to reduce measent bias.

ducation level, based on whether the MMSE score mxceeded the published population norms (Tangalos et al996).

.3.3. Driving evaluation performanceDriving evaluation performance was tested utilizin

TISIM DriveTM simulator (Systems Technology, Inawthorne, CA). Driving simulation, across a range of teological sophistication, has been shown to be a senethod to evaluate actual driving performance (Cox et al.998, 1999; Freund et al., 2001; Ponds et al., 1988; Qu

et al., 1999; Rizzo et al., 1997, 2001) and directly correlateith on-road testing (Freund et al., 2002; Lee et al., 2003).The system responds to driver inputs (e.g., steering, t

le, brake) and generates roadway images in real-timexed base driving cab consists of an adjustable car seat,rator and brake pedals, and dash with standard size stheel. Three ceiling mounted Epson 700c projectors dis

oadway images on three contiguous 4 ft× 8 ft screens, proiding a 135◦ field of view.

A 10 min practice session preceded the evaluation anowed participants to become familiar with the simulator.he test situation, subjects were required to drive on bothnd high traffic rural, suburban, and urban roads for appately 30 min. The course required execution of maneuhich demonstrate a range of abilities, such as mainta

ane position, lane changes, directional turns, observingnd changing traffic signals, interacting with other trafficicular and pedestrian), monitoring speed, and hazard ance. Performance measures included hazardous error

B. Freund et al. / Accident Analysis and Prevention 37 (2005) 613–618 615

crashes, running red lights, etc.) and traffic violations (e.g.,speeding 10 mile/h or more above the posted speed limit).In our clinic, subjects are judged as safe (pass), conditionalsafe (restricted) or unsafe (failure) based on the number andtype of driving errors committed. To be considered safe, thedriver may not commit any hazardous errors. Restricted andunsafe determinations are based on the presence and qualityof hazardous errors and traffic or rule violations. While thereis some overlap in number and types of errors, considerationis given to the severity of the errors, the length of time drivingbefore any errors occurred, and the patients’ ability to learnfrom the error (i.e. that particular error was not repeated).This three-tiered classification system is described in detailelsewhere (Freund et al., 2005).

2.4. Analyses

Distributions of continuous variables were evaluated fornormality using the Shapiro–Wilk test. Normally distributeddata are described using the mean and standard error. Non-normally distributed data are described using the median and25th and 75th percentiles (interquartile range, IQR) and min-imum and maximum values (range). Differences in demo-graphic and self-rated characteristics between safe/restrictedand unsafe driving groups were tested using eitherχ2-testor Fisher’s exact test for categorical variables, and eithert-t les,a werem ta toa werep 8.01( de-c

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Table 1Descriptive statistics on demographic and study variables.

Characteristic Included(N= 47)

Excluded(N= 105)

p-Value

Mean age 77.0 77.4Percentiles (25th, 75th) (72, 82) (73, 81)[Min, Max] [66, 91] [66, 96] 0.76

Gender,n (%)Male 27 (57.5) 31 (42.5)Female 20 (42.5) 42 (57.5)Not noted 0 32 0.11

Age/education appropriate MMSE,n (%)Yes 28 (68.3) 60 (75.0)No 13 (31.7) 20 (25.0)Not noted 6 25 0.43

Median MMSE 27 27Percentiles (25th, 75th) (24, 29) (25, 29)[Min, Max] [15, 30] [18, 30] 0.62

Outcome,n (%)Safe/restricted 29 (61.7) 26 (57.8)Unsafe 18 (38.3) 19 (42.2)Not noted 0 60 0.70

Self-rated driving evaluation performance,n (%)A lot better 17 (36.2) 4 (28.6)A little better 14 (29.8) 4 (28.6)The same 15 (31.9) 6 (42.9)A little worse 1 (2.1) 0 (0)A lot worse 0 (0) 0 (0)Not noted 0 91 0.85

levels increased, there was a significantly increased risk of un-safe driving (p= 0.02) in the study population. Drivers whoconsidered themselves at least a little better than others oftheir age were more than four times more likely to be unsafedrivers compared to others who believed they were compa-rable to or worse than other drivers of their age (RR = 4.13,95% CI = 1.08–15.78).

Median MMSE score for the sample was 27 (range:15–30), indicating normal cognitive functioning overall. Me-dian MMSE for 28 safe/restricted drivers (1 subject had noMMSE) was 29 (range: 21–30) compared to 25.5 (range:21–30) among the 18 unsafe drivers. The single driver consid-ering him/herself “a little worse” compared to others his/herage had an MMSE of 23, four points below the Mayo Clinicage and education cut-point for patients diagnosed with de-mentia (Tangalos et al., 1996). There was no significant dif-ference in MMSE between self-rated driving evaluation per-formance groups (p= 0.76), nor was there an association be-tween self-rated performance and the categorical assessmentof whether the patient scored above or below the age andeducation appropriate MMSE norms (p= 0.51), demonstrat-ing that neither a general nor age and education adjusteddifference exists between the MMSE and self-rated drivingevaluation performance.

Table 2presents a comparison of drivers based on age-education appropriate MMSE norms and self-rated drivinge there

est or Wilcoxon Rank Sum test for continuous variabs appropriate. Demographic and clinical comparisonsade between patients with and without complete dassess generalizability of results. Statistical analyseserformed using the SAS System for Windows, ReleaseSAS Institute, Cary, NC). Statistical significance waslared at an alpha level of 0.05.

. Results

A total of 152 patients were enrolled into the study andescribed inTable 1. Sixty-one patients (40.1%) complet

he self-rated driving evaluation performance measure aatients (60.5%) completed the 30-min drive. Forty perf all drivers were considered unsafe by driving simula37/92) and 66% (31/47) of all drivers who completedelf-rated item felt their driving ability was better than othf their age. Only 47 subjects completed both the driimulation and answered the question regarding self-riving evaluation performance; all subsequent resultse provided only for these 47 subjects. No differenceemographic or study variables were noted between sub

ncluded in the analysis and those excluded for missing vaps > 0.11; seeTable 1).

Fig. 1 presents the distribution of driving evaluaterformance outcome by self-rated driving evaluation

ormance. Only one driver considered himself “a liorse” than others his age, and this driver was found tafe/restricted. As self-rated driving evaluation performa

valuation performance. Among safe/restricted drivers

616 B. Freund et al. / Accident Analysis and Prevention 37 (2005) 613–618

Fig. 1. Distribution of driving evaluation performance outcome by self-rated driving evaluation performance.

was a marginal association between self-rated driving eval-uation performance and cognitive ability as indicated by theage/education MMSE (p= 0.06), where those with better cog-nitive ability expected their driving evaluation performanceto be better compared to other drivers of their age. How-ever, among unsafe drivers no such association was apparent(p= 0.64).

Controlling for driving evaluation performance on thesimulator, there was no significant association betweenage/education normal MMSE and self-rated driving evalua-tion performance (χ2 p= 0.40), indicating that cognitive sta-tus as established by the MMSE is not coloring this inflatedappraisal. Significant differences did result, however, for theactual driving performance evaluation; drivers not meetingage and education-expected MMSE were significantly morelikely to be unsafe drivers (RR = 2.42, 95% CI = 1.22–4.82).

4. Discussion

Our results are consistent with the findings of othersin that older drivers assign high ratings to their perceiveddriving ability (Groeger and Brown, 1989; Holland, 1993;Marottoli and Richardson, 1998). In those studies where driv-ing performance was tested, all subjects who failed either con-

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sidered themselves safe drivers (Hunt et al., 1993) or ratedthemselves as at least as good or better than same age peers(Marottoli and Richardson, 1998).

Our findings further demonstrate that these ratings persisteven in the presence of suspected skill decline, as evidencedby referral for driving evaluation. According to HBM, olderdrivers who understand they have been referred for a driv-ing evaluation because their current driving skills are suspectshould appraise their perceived driving performance moreconservatively. Because we found no association between theself-rated driving evaluation performance and standard or ageand education adjusted MMSE, the high self-appraisals arenot merely an artifact of cognitive impairment. The resultsindicate either (1) actual health beliefs regarding driving eval-uation performance and/or (2) a reticence to candidly discloseactual self-ratings.

Indeed, while 38% of the drivers tested were found to beunsafe, all unsafe drivers rated their expected driving perfor-mance as the same or better than other drivers of their age(Fig. 1). While the discrepancy between self-rated and actualdriving evaluation performance may suggest a lack of aware-ness or unwillingness to report deficits, the importance givento the privilege of driving in meeting mobility needs, remain-ing independent, and maintaining self-esteem may confoundthe issue. Driving is so socially desirable that patients beingformally evaluated may wish to put themselves in a positivel er ata Evenm c-o vings orec r nor thanl

withl SE( inM jectsw ts ford ers.

lua-t lated

able 2omparison of drivers by age/education MMSE norms and self-rated dvaluation performance level

elf-rated drivingvaluation performance

Below age/educationMMSE norms

Above age/educatioMMSE norms

afe/restricted driversA little worse 1 (25) 0 (0)The same 2 (50) 8 (40)A little better 1 (25) 5 (25)A lot better 0 (0) 7 (35)

nsafe driversA little worse 0 (0) 0 (0)The same 1 (11) 1 (13)A little better 2 (22) 4 (50)A lot better 6 (66) 3 (37)

ote:Six of 47 subjects were missing data on education level and ancluded. Values in parentheses are percentages.

ight and thus assign a high rating. Reluctance to answll may have been a factor in the low response rate.ildly cognitively impaired drivers with insight should regnize that referral for a driving evaluation suggests drikills that are in question and should prompt them to be monservative in their self-ratings. Thus, higher ratings (oesponse) may be indicative of conscious denial ratherack of awareness.

Lack of awareness, or insight, has been associatedevel of cognitive impairment as measured by the MMHarwood et al., 2000). We found no significant differencesMSE scores between self-rated groups, although subho scored below age and education adjusted cut poinementia were significantly more likely to be unsafe driv

A secondary concern in the self-rated driving evaion performance measure is the effect of technology-re

B. Freund et al. / Accident Analysis and Prevention 37 (2005) 613–618 617

bias. Many people assume older adults are slower to adopttechnology-based innovations, such as computer use, com-pared to other age groups. Yet, research suggests older adultsare increasingly willing and able to develop computer skills,especially for accessing health information (Kressig andEcht, 2002; Lawhorn et al., 1996; Morrell et al., 2000). Evenso, technological challenges were minimized. The drivingcab of the simulator is designed and proportioned like anactual car, reducing unfamiliarity with the setup. A 10 minwarm-up drive is conducted to allow acclimation to the pro-jected roadway. However, if older drivers expected perceivedtechnology limitations prior the simulated drive, older driversshould also be more conservative in their appraisal of driv-ing performance. The self-rated item was asked before thesimulator practice and test drive. If technology-related appre-hension was introduced, it should bias the self-rated drivingevaluation performance toward the null. The high self-ratingspersist in spite of these potential factors.

The use of a cohort of drivers referred for driving eval-uation, and thus whose skills are in question, distinguishesthis work from other studies of this kind. The selection ofthis cohort was expected to have altered self-appraisals dueto the referral. The primary limitation of the study is thesmall number who completed both the driving simulationtest and assigned a rating of driving ability. The small sam-ple size may have affected our ability to detect an associa-t andc ral-i ofc liza-t d in-f didn erral( ianr

of ad allyd ulatedd nsa ;L m-p is as vingfi s areg am-p g oro thes roadd ofc

dingt ase ng thep mald d tob find

a means for distinguishing persons who are not competent todrive from those who are competent, since nearly all believethey are good drivers.

Acknowledgements

This research was supported in part by a grant from theVirginia Center on Aging Alzheimer’s and Related DiseasesResearch Award Fund. The authors wish to thank Robert Fre-und for assistance with simulator programming.

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