Factors associated with the SCI event

• External cause of injury
• Place of injury
• Type of activity when injured

In addition to collecting information on the demographic features of cases of SCI, the ASCIR also collected information about factors associated with the injury event such as external cause of injury, role of human intent, type of place of injury, and type of activity at the time of injury. These factors, which were coded in ASCIR according to the National Injury Surveillance Unit (NISU) National Data Standards for Injury Surveillance (NDS-IS), provide useful information for understanding the causes and prevention of SCI (NISU, 1995). Supplementation of this data with other information from special in-depth investigations and data linkage is often required to gain a more detailed account of these injuries (O'Connor, 1999a).

External cause of injury

The external cause of injury for cases of SCI from traumatic causes is presented in Figure 5. It was evident that: Transport related injury accounted for forty three percent of the cases of SCI (n=113). Twenty-eight percent were motor vehicle occupants (n=74) and fifteen percent were unprotected road users (n=39). Eighty-five percent (n=96) of the cases of transport related SCI were aged 15-44 years. Twenty-three percent (n=61) were from high falls (drop of 1 metre or more) and eight percent (n=22) were from low falls. Eighty-two percent (n=18) of the low falls cases were aged 55 years or older.

Figure 5: Incidence of SCI from traumatic causes by external cause of injury (major groupings) and age group, Australia 1998/99 (counts)

Motor vehicle occupants

Further assessment of the cases that were occupants of motor vehicles (n=74), using the text description of the injury event provided on the ASCIR registration form, revealed that: 42 percent were due to vehicle rollover; 23% were due to collision with a roadside hazard (ie. tree, pole or other fixed object); 7% were due to ejection from the motor vehicle; and 30% were due to other collisions (Figure 6).

Figure 6: Description of the injury event for cases suffering their SCI as occupants of vehicles, Australia 1998/99 (percentages)

These results are generally consistent with others reported in the scientific literature (Cushman et al 1991; Huelke et al 1977, 1981, 1985; Huelke & Compton, 1983; Kraus et al 1982; Thurman et al 1995b; Toscano, 1987). The prevention measures that have been emphasised in the literature include improvement of road engineering and vehicle design (eg. sealing of road shoulders and improvement of roof crush strength and window strength), to prevent vehicle rollover and ejection, and removal of roadside hazards (Corben 1997; Kloeden et al 1999).

The information available in the ASCIR concerning SCI in road crashes can be substantially extended by linking it with Police data on crash circumstances, as was recently undertaken for South Australia (O'Connor et al, 1999). This enables crash factors (eg. vehicle, environmental and human factors) to be assessed in relationship to injury and outcome type (eg. neurological level and extent of SCI). A better understanding of the causes of SCI, through research such as this, leads to better prevention. The study by O'Connor et al (1999) showed that SCI from vehicle rollover was much less likely in sedan type vehicles than other vehicles, such as four wheel drive vehicles, vans and utilities. Further research is required to focus in on the specific vehicle characteristics that raise the likelihood of SCI.

Falls in the elderly

The leading cause of injury death and hospitalisation in the elderly (ie. those aged 65 years or older) is falls (Harrison & Dolinis, 1995; Fildes, 1994). In 1998/99 a third of all falls related SCIs, and more than two thirds of low falls SCIs, occurred to elderly persons (ie. those aged 65 years or older).

Fracture of the lower limbs and hip is a frequent outcome of a fall (Fildes, 1994). It would appear that different mechanisms are involved in these types of injuries and falls related SCIs. In the elderly in 1998/99, 15 of the 16 low falls SCIs involved tetraplegia. Involvement of the cervical segments of the cord suggests that a head impact was involved (specific mention of a head impact was made on the registration form for more than half the cases). While considerable attention has been directed at the prevention of lower limb and hip fractures due to falls (Fildes 1994), little attention has been directed at the specific prevention of SCI. Different prevention strategies may be required to prevent falls related SCIs. Unfortunately, little is known about the circumstances of fall related SCI. The information in the text description of the injury event provided on the ASCIR registration form is insufficient for this purpose. Considering the high cost of SCI in personal and economic terms, there is ample justification for a detailed study of the causes and prevention of these events.

Place of injury

The road environment was the primary place of SCI for those aged 15-34 years (Figure 7). In this age group aquatic environments also featured prominently. A similar number of cases of SCI occurred at commercial and industrial sites in each of the age groups up to age 74 years. The home was the principal place of SCI for those aged 55 years and older.

Further assessment of the cases that suffered their SCI in an aquatic environment (n=23), using the text description of the injury event provided on the ASCIR registration form, revealed that: seven were surfing or swimming and were dumped by waves; six were diving into swimming pools; six were diving, or fell, into a river or lake; three were entering the surf, dived into the water and hit their head on the sand/sand-bar; and one case had another specified event (Figure 8).

Figure 7: Incidence of SCI from traumatic causes by place of injury (major groupings) and age group, Australia 1998/99 (counts)

Over the last four years, an average of 21 new cases of SCI have occurred each year in aquatic environments. The information available on the circumstances of these injuries is limited in ASCIR, but could be extended through supplementary in-depth investigation of the registered cases, for example, by using data available to Surf Life Saving Australia which investigates the circumstances of injury on beaches patrolled by their members.

Figure 8: Description of the injury event for cases suffering their SCI in aquatic environments, Australia 1998/99 (percentages)

A review of the international literature suggests that: bodysurfing is particularly hazardous for healthy middle aged men, especially those endowed with a narrow spinal canal (Cheng et al, 1992); the mechanism of SCI from bodysurfing is primarily one of forced hyperextension of the head and neck from contact of the head with the ocean floor (Scher, 1995); the consumption of alcohol is a contributing factor in half the cases of swimming pool related SCIs (DeVivo & Sekar, 1997); most of the swimming pool SCIs occur in less that one and a half metres of water (Blanksby et al, 1997); and warning signs about shallow water or sand-bars are rarely present (DeVivo & Sekar, 1997). As there are two to three cases of SCI each year in Australia that can be attributed to the presence of sand bars, with impact upon first entry to the water, there may be a need to post signs on affected beaches and to consider the potential for such an injury when determining the location of flags on beaches to delineate the area patrolled by surf lifesavers.

Diving technique has been shown to affect impact velocity and the angle of entry to the water, both of which affect the rate of deceleration upon entry to the water and the likelihood of the head contact with the bottom (Blanksby et al, 1997). However, consideration of the optimal depth of water for diving needs to be based on the range of diving techniques of members of the general public, most of whom have never been taught how to dive properly. It is generally the untrained member of the public, often in a party situation (DeVivo & Sekar, 1997) that is injured in a diving accidents rather than the trained diver. A review of the scientific literature failed to reveal any studies of the actual diving behaviour and other risk factors of the untrained public. Such a study might have implications for the design and use of swimming pools and other aquatic environments. As there are underwater viewing portals at many pools the frequency of near misses and head contacts could be studied by videotaping natural behaviour and taking supplementary measurements to determine human and environmental risk factors.

Type of activity when injured

Most of the cases were undertaking some form of leisure activity (n=108, 41%) or domestic activity (n=22, 8%) when they suffered their SCI. Twelve of the cases (5%) were engaged in a sporting activity. Of the remaining 123 cases, most of whom were engaged in 'other and unspecified' activities, 48 (18%) were working for income.

Further assessment of the cases that suffered their SCI while working for income (n=48), using the text description of the injury event provided on the ASCIR registration form, revealed that: 23% were driving a motor vehicle; 19% were felling trees, and either fell from a tree or were crushed by falling branches or the tree itself; 19% fell from a roof, ladder or scaffolding; 17% fell whilst engaged in some other work activity; 15% were unloading and were crushed by a falling load; and the remaining 8% were engaged in some other type of work activity (Figure 9).

Figure 9: Description of the injury event for cases suffering their SCI while working for income, Australia 1998/99 (percentages)

At admission, only 27 of the 48 people injured at work (ie. 56%) were reported to be eligible for some form of compensation payment through an insurance scheme. Of the 11 people involved in a motor vehicle accident while working, all of whom were vehicle occupants and would normally be expected to be covered by motor vehicle third party insurance, two were considered to be non-compensable (one was not wearing a seat belt and the other was shot in the back in an act of violence rather than in a vehicle collision) and one was considered to have an unclear compensation status due to the fact that alcohol was involved. The general public may not appreciate that in the event of an injury while at work or in a motor vehicle crash, where insurance cover is expected, they may not be fully covered or covered at all if personal negligence is involved or the nature of the event does not fit within the specific terms of the insurance cover. Those who have no insurance cover obviously face a more challenging future financially. Some jurisdiction have addressed this need by implementing no-fault compensation schemes, where all are covered (eg. the Victorian Transport Accident Commission compensation scheme). For those who are insured, there has been concern expressed that lump sum payments are often spent within a short period leaving people to rely on the welfare system. Insurers are actively lobbying for changes to the tax treatment of structured settlements to encourage people to opt for a periodic payment for the life of a claimant as an alternative to lump sum payments (MAA, 1999).

Tree felling would appear to be a hazardous occupation for SCI. It would be expected that the time exposure of tree felling (or the population of tree fellers) would be substantially lower than the time exposure of motor vehicle driving (or the population of drivers) and yet these occupational activities account for a similar proportion of the annual cases of SCI. A review of the circumstances of these events could reveal work practices that could be improved.

In order to determine the preventable factors of work-related SCI, data further to that already collected by the ASCIR would be required. For those who are insured, much of the data required might already be collected for the purposes of the insurance claim, and this could be analysed in the first instance. The need to contain insurance costs has encouraged insurers to invest in injury research and prevention.