motor vehicle crashes in older drivers thomas songer, phd university of pittsburgh
TRANSCRIPT
Motor Vehicle Crashesin Older Drivers
Thomas Songer, PhDUniversity of Pittsburgh
Learning Objectives
• Understand the current evidence regarding crash risks in older drivers
• Identify the two concerns that licensing authorities seek to balance in older drivers
• Introduce the study of medical conditions as causal agents in crashes
“Texas police say a 92-year-old driver took a wrong turn on her way to exchange a pair of shoes and ended up on the tarmac of Houston Gulf Airport, where she crashed into a Piper plane taxiing toward the runway. No one was seriously hurt.”
What is the crash risk relatedto older drivers? Howimportant is this risk?
Number of Licensed Drivers
Age
mil
lion
s of
dri
vers
16 25 35 45 55 65 75 85+
0
5
10
15
20
25
NHTSA, FHWA
Crash Involvement Rate
Age
per
1000
lice
nsed
dri
vers
16 25 35 45 55 65 75 85+0
50
100
150
200
NHTSA, FHWA
Total Miles of Travel
Age
mil
lion
s of
mil
es
16 25 35 45 55 65 75 85+0
50
100
150
200
250
300
350
NHTSA,FHWA
Involvement Rate by Mileage
Age
per
100
mil
lion
mil
es V
MT
16 25 35 45 55 65 75 85+0
500
1000
1500
2000
NHTSA, FHWA
Fatality Rate
Age
per
100
mil
lion
mil
es
16 25 35 45 55 65 75 85+0
2
4
6
8
10
12
NHTSA, FHWA
Injuries and Fragility
0
20
40
60
80100
00-0
405
-- 14
15-2
4
25-4
4
45-6
4
65-U
P
Age
Rat
e p
er 1
00,0
00 p
er y
ear
Injury RateMortality Rate
Fatal Accidents of Older Drivers
0
10
20
30
40
50
60
70
80
90
26-40 65+Age Group
Per
cent
age
Rear-endHead-onCrossing
05
101520253035404550
16 20 25 30 35 40 45 50 55 60 65 70 75 80 85
Age
per
cen
t ci
ted
for
infr
acti
on
SpeedingNot Paying AttnFailure to YieldNo proper lane
Violations in Fatal Accidents by Age
Growth of the Elderly Population
Year
num
ber
(mil
lion
s)
1950 1960 1970 1980 1990 2000 2010 2020 20300
5
10
15
20
25
30
35
65-74 yrs75-84 yrs85+ yrs
Car Trouble
Older Drivers Pose Growing Risk on Roads as their Numbers Rise
They Crash More Than Many, Yet Taking Away Wheels Leads to
Isolation, Anger
Wall Street Journal, October 29, 1993
With no standard method to pinpoint dangerous elderly drivers and get them off the roads, perhaps the best that many states can do is to simply encourage people to anonymously report bad drivers. Yet many people are loathe to do so. One such person says she still feels guilty about a woman she turned in a few years ago.
Slide 1 0f 3
The woman, who was in her early 80s, drove poorly and often left her car parked halfway in the street. Her neighbor pointed out the problem, but the woman always said she was too tired to park again. Worried that the woman might kill someone, the neighbor called the police.
Slide 2 of 3
Soon after, state officials retested the woman and revoked her license. Without her wheels, the woman was forced to move into a nursing home, where she subsequently died. “She was crushed” over losing her license,” The neighbor recalls, “I did feel responsible.”
Slide 3 of 3
Relation between Social Activities and Driving Habits in Women
Transportation Mode
56.7*63.6*80.9% club members
96.593.6*99.0% who leave house weekly
52.754.0*61.1% >3 close friends
64.3*85.3*78.5% seeing children
Other ModeOthers DriveDrives SelfSocial Activity
Huntley et al. 1986
"Officials Try to Balance Public SafetyAgainst the Rights of Older Drivers"
Crash Risk
Social Opportunities
New York Times, May 4, 1992
Licensing Older Drivers in the USA
No age provisions More frequentlicense renewals
Require testing(road or vision)
Source: IIHS(June 2001)
Issues for Appropriate Licensing
• Does licensing reduce crash involvement?
• Can high risk drivers be identified by licensing agencies?
• Are screening tests feasible?
• What is an acceptable risk for crashes?
• How many drivers would be affected?
• What are the social costs to the driver of being denied a license?
“legislatures and public agencies are frequently under pressure to
restrict drivers with medical characteristics presumed to be a
hazard to driving”
Haddon, Baker 1981
Relative risk of motor vehicle collision injury by selected cardiovascular conditions
Odds Ratio
% prevalencein
Cases Controls (95% CI)
Coronary heart diseaseMyocardial infarction 7.3 6.1 1.2 (0.6-2.3)Angina pectoris 19.7 14.1 1.5 (0.9-2.2)Coronary-artery bypass 2.6 1.6 1.6 (0.6-5.0)Any of above conditions 21.4 15.5 1.4 (1.0-2.2)
Koepsell 1994
Relative risk of motor vehicle collision injury by selected neurological conditions
Cerebrovascular diseaseStroke 1.7 2.2 0.8 (0.2-2.5)Transient Ischemia 3.0 1.8 1.6 (0.5-4.8)Either of above 4.7 3.8 1.2 (0.5-2.6)
Dementia 1.3 0.4 2.8 (0.4-17.0)Head Injury 0.9 0.2 4.0 (0.4-44.0)
Koepsell 1994
Odds Ratio
% prevalencein
Cases Controls (95% CI)
Relative risk of motor vehicle collisioninjury by selected medical conditions
Condition
Fall in previous year 12.4 9.2 1.4 (0.9-2.4)Alcohol abuse 3.4 5.6 2.1 (0.8-6.0)COPD 9.8 9.9 0.9 (0.5-1.6)
Osteoarthritis 53.8 52.0 1.1 (0.8-1.5)Rheumatoid arthritis 2.1 1.3 1.6 (0.5-5.3)Cancer 18.4 17.9 1.0 (0.6-1.5)Diabetes mellitus 11.1 4.5 2.6 (1.4-4.7)
Koepsell 1994
Odds Ratio
% prevalencein
Cases Controls (95% CI)
Research Issues
• Which population
• Exposures
• Definition of Crashes
• Recall bias
• Reporting bias
Reasons for StoppingDrivng in the Elderly
Advancing Age
Increasing Number of Factors from above
Medical ImpairmentActivity Limitation
Marottoli, 1993
Low Income
Prevalence of Driving Cessation by Age
010203040506070
70-74 75-79 80-84 > 85Age
Pre
vale
nce
%
Future Research - National Agenda
Establish Crash Risk for Medical Conditions
Document consequences of driving cessation
Improve vehicle crashworthiness for elderly
Identify causes of crashes at intersections
Examine physician role in licensing
Examine voluntary reporting of drivers
Examine how older drivers compensate for limitations