Crash characteristics of older pedestrian fatalities: Dementia pathology may be related to ‘at risk’ traffic situations Authors: Gorrie, C.A. Brown, J. Phil and Waite,M.E.

Introduction  Older people (i.e. those over the age of 65 years) make up less than 13% of the population yet account for about 32% of all pedestrian deaths (ATSB, 2002a).

Introduction  While there has been an overall decrease in pedestrian deaths per capita in recent years, the rate of decline varies by age  For older pedestrians, the decline has been significantly less

Introduction  The mortality rates for people over 65 years exceed those for younger people for comparative injury severity (McCoy et al., 1989).  More older pedestrians die (44.6%) as a result of their injuries compared to 10.4% of younger pedestrians (Sklar et al., 1989).

Introduction  the numbers of older pedestrians killed and injured can only be expected to grow given the rapid ageing of the population  In NSW alone, there will be approximately 1.8 million older people by 2041, which reflects a 144% increase since 1995 (Henderson and Jorm, 1998).

Introduction  Exposure of older pedestrians is also influenced by the fact that walking is the primary mode of transport among many of these road users.  Keall (1995) reported that the percentage of travel time spent walking is highest for people over 65 years.

Introduction  A potential contributory role for cognitive decline in the behaviour of older pedestrians has also been demonstrated in comparisons of road crossing behaviour between older and younger people (Oxley et al., 1997, 2001)

Introduction  Cognitive ability is known to decrease as part of neurodegenerative disease such as Alzheimer’s disease.  In Australia, approximately 6% of people over the age of 65 years and nearly 25% of people over 85 years have diagnosed dementia (Henderson and Jorm, 1998)

Introduction  There are many people diagnosed with mild cognitive impairment (MCI), who are functionally affected but do not meet criteria for dementia (Busse et al., 2003; Fisk et al., 2003; Graham et al., 1997; Ritchie et al., 2001).

Introduction  Mild cognitive impairment and Alzheimer’s disease affect brain functions such as: –complex attentional processes –secondary memory –accessing of word knowledge –visuospatial ability –some forms of abstract reasoning and problem solving, some of which will be vital for safe pedestrian behaviour.

Methods  Subjects  52 pedestrians (24M:28F) aged between 65 and 93 years (mean 77.7±7.3 years)  died following a vehicle–pedestrian crash between 1997 and 2003 in the Sydney metropolitan area  針對到院資料收集研究

Results

Results

Results

Results

Results

Discussion  The majority of older pedestrian crashes occurred on dry fine weekday mornings, on straight sealed urban roads and close to the person’s residence  It is known that road crossing is a high-risk pedestrian activity, for people of all ages (Harruff et al., 1998).

Discussion  42 (80.2%) of the pedestrians in this current study were fatally injured while crossing the road  Of particular concern was the relatively high number (27, 51.9%) of these older pedestrians who were killed on or within 100m of a designated pedestrian crossing while attempting to cross a road.

Discussion  Although older pedestrians often report they do not have enough time to cross at signal- controlled traffic lights (Fildes et al., 1994; Hoxie et al., 1994; Langlois et al., 1997; Sheppard and Pattinson, 1986)  Six of the eight crashes that resulted in a fatality at traffic lights involved the pedestrian crossing incorrectly against a red ‘don’t walk’ signal.

Discussion  Sheppard and Pattinson (1986) have described how some older people with mobility problems have difficulty in walking the extra distance to a designated road crossing facility.

Discussion  Because older people have reduced walking speeds, compared to younger adults (Job et al., 1992)  the time they are exposed to traffic while crossing a road is increased

Discussion  Reduced cognition ability, as a result of ageing or because of a dementing disease, is often cited as a possible contributing factor in older pedestrian crashes (ATSB, 2002b; Fildes, 1998; OECD, 2001; Oxley, 2002; RTA, 2002).

Discussion  a number of different traffic situations were examined to determine whether there were any obvious links between those with moderate to high NFT score and involvement in particular crash situations.

Discussion  Compared to those with no or low NFT, pedestrians with moderate to high NFT scores (III–VI) were more likely to be at least partially responsible for the crash  In other words, these pedestrians were more likely to have behaved unexpectedly e.g. walked into the traffic, disobeyed a traffic signal etc.

Discussion  pedestrians with higher NFTs were also more likely to be impacted by reversing vehicles as compared to pedestrians with lower NFTs

Discussion  It has previously been reported that cognitively normal older people have less ability to accurately judge safe gaps in which to cross the road than younger adults (Oxley et al., 1997)  older adults tend to estimate time of arrival of a vehicle by distance rather than by speed (Oxley, 2002).