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Incidence and patterns of spinal cord injury in Australia
Accident Analysis and Prevention 34 (2002) 405– 415 www.elsevier.com/locate/aap
Incidence and patterns of spinal cord injury in Australia Peter O’Connor * AIHW National Injury Sur6eillance Unit, Research Centre for Injury Studies, Flinders Uni6ersity, Mark Oliphant Building, Laffer Dri6e, Bedford Park, SA 5042, Australia Received 20 July 2000; received in revised form 25 January 2001; accepted 28 February 2001
Abstract The objective of this paper is to report on the epidemiology of spinal cord injury (SCI) based on the Australian SCI register and to discuss the implications for prevention. All adult cases of SCI are reported to the registry. The case reports for 1998/1999 were aggregated and described. The age adjusted rate of persisting SCI was 14.5 per million of population. Rates were highest in young adults and in males. The vast majority of cases (93%) were due to unintentional injury. Forty-three percent were due to motor vehicle crashes, principally from motor vehicle rollover. Cases of SCI from falls, aquatic activities, and working for income are also described. Incomplete cervical cord injuries were most common (38%), particularly as a result of motor vehicle crashes and low falls. The study indicates that the surveillance of SCI needs to be improved internationally so that comparative studies can be undertaken. It is recommended that the Centers for Disease Control case definition be adopted. Australia is one of the few countries that have a register based on that case definition, and the only one that has a register covering a full national adult population. The results presented on the basis of this data source provide some hitherto unavailable information on the incidence rates and patterns of SCI. National population based surveillance is fundamental to an understanding of the epidemiology, and hence the prevention, of this severe and costly health and welfare problem. © 2002 Elsevier Science Ltd. All rights reserved. Keywords: Spinal cord injury; Epidemiology; Surveillance; International comparisons; Prevention
1. Introduction The health and welfare burden due to spinal cord injury (SCI) is substantial. Despite decreasing length of stay brought about by the introduction of case management in specialist facilities (DeVivo et al., 1992a,b; Tator et al., 1995; Eastwood et al., 1999), hospital costs are increasing (DeVivo et al., 1992a,b). As survival from SCI is increasing due to improvements in resuscitation and long-term care (Geisler et al., 1983; DeVivo et al., 1992a,b,c; Whiteneck et al., 1992; Samsa et al., 1993; Hartkopp et al., 1997a,b; McColl et al., 1997; Tyroch et al., 1997), and the incidence rate is not falling (Go et al., 1995, p. 24; O’Connor and Cripps, 1998), the size of the prevalent population is increasing in Australia and elsewhere (Ditunno and Formal, 1994; Blumer and Quine, 1995; Lasfargues et al., 1995; Tyroch et al., 1997). Those who suffer an SCI due to * Corresponding author. Tel.: + 61-8-83740970; fax: + 61-883740702. E-mail address: [email protected] (P. O’Connor).
trauma are generally young people in the prime of their lives, working and contributing to the wealth of the country through the taxation system, consumption and the investment of discretionary income. After injury between 60 and 70% do not return to work (Athanasou et al., 1996; Murphy et al., 1997), increasing the community cost through unemployment and welfare payments. When it is considered that a large proportion of cases do not receive insurance compensation for their injury (O’Connor, 2000a), the increasing prevalence of SCI signals the potential for escalating costs to the community through the public health and welfare system. Concern has been expressed that a disproportionate share of the cost of caring for trauma victim is placed on the public (Mackersie et al., 1995; Tyroch et al., 1997). Given the potential for escalating health and welfare costs, and the fact that there is no cure for SCI, prevention should be emphasised. The information required for the prevention and control of SCI and the monitoring of the health and welfare of the prevalent population indicates the need for surveillance. The de-
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velopment of appropriate interventions requires information on causal factors as well as on the characteristics of the SCI population. The Australian SCI register (ASCIR), established in 1995, enables the incidence and patterns of SCI to be monitored. The ASCIR is the only SCI register covering a full national adult population. The ASCIR is now in its fifth year of operation and has nearly 9000 cases registered. This article presents statistical information on new cases of SCI from traumatic causes that occurred during the financial year 1998/1999 in Australia to Australian residents. The purpose of the article is to highlight the characteristics of SCI and to focus preventive efforts. 2. Method
2.1. Co6erage of the Australian spinal cord injury register In Australia it is possible to identify each hospitalised adult who has suffered an SCI from trauma because there are a small number of specialist treatment units nationally and referral of cases with SCI to one of these units is a well established hospital protocol. However, the coverage of children is not complete as some cases will be treated in paediatric hospitals rather than spinal units. Based on routine hospital separations data 1986– 1998, it is estimated that about half of the new cases of SCI that occur each year amongst 0– 14-year-olds nationally, are covered by ASCIR. For 1998/1999, in addition to the three reported paediatric cases, there could be an additional three non-reported cases, indicating that this group could constitute about 2% of new incident cases; 3% if 15-year-olds are included in the group, which is comparable with North American figures (Nobunaga et al., 1999, Fig. 1, p. 1375).
2.2. Case definition In order to facilitate national and international comparisons, the case definition that has been adopted for the registration of traumatic cases of SCI in Australia is USA Centers for Disease Control (CDC) clinical definition: ‘‘a case of SCI is defined as the occurrence of an acute, traumatic lesion of neural elements in the spinal canal (spinal cord and cauda equina) resulting in temporary or permanent sensory deficit, motor deficit, or bladder/bowel dysfunction’’ (Thurman et al., 1995b). For the purposes of the current article, the case selection excluded cases that had suffered no neurological deficit at admission or discharge, in order to focus the analysis on those with permanent rather than transient deficit. Cases suffering persisting neurological deficit at discharge from hospital accounted for 88% of all cases.
2.3. Data dictionary The ASCIR data dictionary (Research Centre for Injury Studies, 1997) was developed on the basis of relevant international data standards (Hamilton and Fuhrer, 1987; World Health Organisation, 1996), including the American Spinal Injury Association International Standards for Neurological and Functional Classification of SCI (Maynard et al., 1997). Other items conformed to the Australian National Health Data Dictionary (Australian Institute of Health and Welfare, 1997). The items are more fully described in an article by O’Connor (2000b).
3. Results
3.1. Incidence There were 265 new persisting cases of SCI from traumatic causes in 1998/1999 reported to the ASCIR. The age adjusted incidence rate of persisting SCI, based on reported cases, was 14.5 per million of population. There were no statistically significant differences in the Australian State rates in 1998/1999. The age distribution of SCI from traumatic causes is presented in Fig. 1. The age group of 0–14 years was excluded from the figure, and other figures showing age group breakdowns, as case numbers were small and coverage of ASCIR was not complete for this group. The highest case count and rate occurred in the age group 15–24 years (73 cases). With increasing age, the case count and rate declined substantially to the age group 45–54 years (23 cases), after which the count remained fairly constant. The increasing rate from age 55 years reflects a progressive decline, with age, in the number of elderly people in the population. The wide confidence intervals on the rates (95% confidence intervals based on the Poisson distribution) reflect the small case count for individual age groups. The rate for age group 15–44 years (21.5 per million of population) was significantly higher, statistically, than the rate for the older combined age group of 45 years and above (13.1 per million of population). Of the cases of SCI from traumatic causes aged 15 years and above, 76% were male and 24% were female. There was a higher rate of SCI for males at all ages and the differences were statistically significant for those under 45 years of age and also for 55–64-year-olds (Fig. 2).
3.2. Intent Ninety-three percent of the cases resulted from unintentional injury. Three percent resulted from intentional self-harm. Two percent were due to assault. The re-
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mainder was due to legal intervention, medical care and events of undetermined intent.
3.3. External cause of injury The external cause classification for injury surveillance (Australian Institute of Health and Welfare, 1997), based on ICD-9-CM, enabled a simple classification (Fig. 3). More than two-thirds of cases involved transport crashes and falls. Transport related injury accounted for 43% of the cases of SCI (n=113). Twenty-eight percent were motor vehicle occupants (n =74) and 15% were unprotected road users i.e. pedestrians, pedal cyclists and motor cycle riders (n =39). Eighty-five percent (n = 96) of the cases of transport related SCI were aged 15– 44 years. Further assessment of the crash types of motor vehicle occupants (n =74), using the structured text description of the injury event provided on the ASCIR registration form, revealed that 40% were due to vehicle rollover, 23% were due to collision with a roadside hazard (i.e. tree, pole or other fixed object) and the remainder were due to other crash types. Only 11% of cases were ejected from the motor vehicle in all crash types. Twenty-three percent (n =61) of the cases of SCI involved high falls (drop of 1 m or more) and 8% (n = 22) involved low falls. Of all falls related SCIs (n= 83), a third involved elderly persons (aged 65 years and above). Of low falls, more than two-thirds were elderly (n= 16).
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3.4. Place of injury The road environment was the primary place of SCI for those aged 15–44 years (Fig. 4). 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 above. Further assessment of the cases that suffered their SCI in an aquatic environment (n= 23), using the structured text description of the injury event, 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 or a sand-bar; and one case had an other specified event.
3.5. Type of acti6ity 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, mainly involving motorbike riding (five cases), but also field sports: rugby league and rugby union (two cases in New South Wales and two cases in other States), Australian rules football (two cases) and horse-riding (one case). Of the remaining 123 cases, most of whom
Fig. 1. Incidence of SCI from traumatic causes by age group, Australia 1998/1999 (counts and age specific rates).
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Fig. 2. Incidence of SCI from traumatic causes by age group and sex, Australia 1998/1999 (age specific rates).
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 structured text description of the injury event, 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.
3.6. Workers compensation At admission, only 27 of the 48 people injured at work (i.e. 56%) were reported to be eligible for some form of compensation payment through an insurance scheme. Of the 11 people injured in a motor vehicle while working, all of whom 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.
3.7. Clinical information The neurological level of SCI at admission is presented in Fig. 5. The most commonly injured spinal cord segments were: the cervical segments, particularly C4 (18%, n=47), C5 (17%, n =45), and C6 (9%,
n= 25); the lumbar segment L1 (11%, n = 30); and the lower thoracic segment T12 (6%, n = 17). The overall severity of SCI is usually measured by a combination of the neurological level and extent of injury into four neurologic categories: complete tetraplegia, incomplete tetraplegia, complete paraplegia and incomplete paraplegia. The most common neurologic category (Table 1) was incomplete tetraplegia (38% of total, n= 101), followed by incomplete paraplegia (24% of total, n= 64), complete paraplegia (18% of total, n= 48), and complete tetraplegia (19% of total, n = 51). Complete injury was most common in the thoracic spinal segments. Table 2 presents information on the neurological level of SCI by external cause of injury. Motor vehicle occupants most often suffered from injury to the cervical segments of the spine, resulting in tetraplegia, with incomplete damage to the cord being most common at this level (63%, n= 33). Unprotected road users most often suffered thoracic level injuries, which generally involved complete damage to the cord (60%, n=12). Low falls primarily resulted in cervical level injury and most of these involved incomplete damage to the cord (84%, n = 16). Fifty-seven percent (n= 16) of the high falls tetraplegia cases suffered complete damage to the cord whereas 64% (n= 21) of the high falls paraplegia cases suffered incomplete cord damage. There was a higher frequency of complete cord damage in high falls compared to low falls. Motor vehicle occupants and high falls cases made up the largest proportion of the most severely injured i.e. those with complete tetraplegia (35 and 31%, respectively; n = 18 and 16, respectively).
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4. Discussion International comparisons can assist in the identification of potential SCI prevention measures. Unfortunately, there is a paucity of comparative information on the incidence of SCI outside USA. The information that is available shows some substantial differences within and between countries, which may be due to different methods of case ascertainment, differing case definitions and the different populations studied. It is interesting to note the lack of any substantial State to State differences in Australia, compared to the substantial State differences reported for USA (Go et al., 1995, pp. 22–24). Notwithstanding that the population of the Australian States may well be more homogeneous than for USA, this result may also reflect the fact that in Australia there is a single surveillance system, national in scope, with fully standardised definitions and procedures, and common case selection criteria, auditing and quality control measures. Other countries should adopt the CDC clinical case definition (Thurman et al., 1995b) and work toward the development of national registers of SCI so that international comparative studies can be undertaken. Studies from the mid-1970s to 1990s, in USA, have estimated the incidence rate of acute care hospital admissions for SCI to be 30– 53 cases per million of population (Kraus et al., 1975; Kalsbeek et al., 1982; Price et al., 1994; Thurman et al., 1994; Go et al., 1995; Carroll, 1997; Johnson et al., 1997). In Canada, the incidence rate has been estimated to be 35 cases per million (Canadian Paraplegia Association, 2000). In Russia, the rate has been estimated to be about 30 cases per million (Silberstein and Rabinovich, 1995). Rates of between 17 and 21 per million have been reported for Jordan, Taiwan and Fiji (Chen and Lien, 1985; Chiu et
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al., 1991; Maharaj, 1996; Chen et al., 1997; Karamehmetoglu et al., 1997; Otom et al., 1997). In Portugal, the incidence rate, excluding deaths, was reported to be about 25 per million (Martins et al., 1998). In Australia, the rate of SCI in 1998/1999 was less than 15 per million of population based on new persisting cases, lower than the rates of other countries in the region and less than half the North American rates. The lowest reported rate was for Denmark (Biering-Sorensen et al., 1990), which at 9.2 per million was 37% lower than the Australian rate. The highest reported rate was for the Plovdiv area of Bulgaria, with a rate of 130 per million (Stavrev et al., 1994). One reason for the difference in the Australian rate from those of other countries is that the Australian rate is based on persisting cases (i.e. those who continued to have neurological deficit at discharge). If those who resolved neurologically or died after admission were included, the rate would have been : 2 cases per million higher. However, this accounts for only a very small component of the difference from USA rate. While no definitive conclusions can be made, a number of plausible explanations for the differences in rates between Australia and USA can be offered. Australia has a very low rate of SCI due to violence. Less than 2% of SCI cases in 1998/1999 were due to inter-personal violence, with a rate of less than 0.3 cases per million of population. In USA, 15– 17% of cases were due to inter-personal violence (Go et al., 1995), suggesting an incidence rate of between 6 and 9 per million of population. Carroll (1997) found a slightly lower rate in Arkansas in 1989 (5 per million of population). Whereas SCI from violence related penetrating injury is rising in USA (Carroll, 1997), there has been no such increase in Australasia (Sidhu et al., 1996; Civil et al., 1998). There
Fig. 3. Incidence of SCI from traumatic causes by external cause of injury (major groupings) and age group, Australia 1998/1999 (counts). Note: Excludes 3 cases where age was 0 –14 years.
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Fig. 4. Incidence of SCI from traumatic causes by place of injury (major groupings) and age group, Australia 1998/1999 (counts).
are strong legislative controls restricting the availability of guns in Australia (Chapman, 1998). Semi-automatic weapons and pump-action shotguns are prohibited. If gun control measures were effectively introduced in USA, and the nature of the social problems that lead to violence was also addressed effectively, the SCI rate in USA could be up to 17% lower than at present. The rate of motor vehicle related SCI is low in Australia (:4 cases per million for motor vehicle occupants). In USA, 44.5% of cases of SCI are due to motor vehicle crashes (Go et al., 1995), suggesting a rate of 18–24 cases per million of population. Kraus et al. (1982) reported 21 cases per million for motor vehicle occupants. The difference in the rates of Australia and USA could reflect differences in seat belt wearing rates, drink driving and other factors. In Australia, seat belt wearing has been required by law since the 1970s. As a consequence of the law and active enforcement and publicity, seat belt wearing rates in the general population of drivers have been over 90% for many years (Rungie and Trembath, 1988; Roads and Traffic Authority, 1998; Trembath and Furse, 1998; Vic Roads, 1998). Seat belt wearing rates are however lower in those that suffer SCI. In a study of SCI crashes in Australia in the early 1980s, Toscano (1986) found that 46% of cases were not wearing a seat belt. In USA, Tyroch et al. (1997) reported that 80% of SCI patients involved in motor vehicle crashes in the early to mid 1990s were not wearing restraint devices. Another indicator of the impact of seat belt wearing on the SCI incidence rate is the difference between the two countries in the incidence of ejection from the vehicle. In Australia, in 1998/1999 only 11% of occupant SCI cases were ejected from the vehicle, compared with 40% in USA (Thurman et al., 1995a).
There may be a difference in the contribution of alcohol to SCI crashes in Australia and USA. Recently, a study based on the linkage of SCI medical reports and Police crash reports in South Australia (O’Connor, unpublished data), found that 26% of SCI cases in South Australia over the period 1988–1995 had a blood alcohol concentration of more than 50 g per 100 ml. In one of the few studies in USA to report evidence on the basis of the analysis of blood rather than self-reports or clinical evidence, Heinemann et al. (1988) found that 40% of SCI cases had a blood alcohol concentration of more than 50 g per 100 ml. Australia has been at the forefront of controls on drink-driving; introducing random breath testing in the late 1970s and maintaining high intensity enforcement and publicity programs (Homel, 1983; McDermott, 1983; McCaul and McLean, 1990; South, 1991; Loxley et al., 1992; Homel, 1994). Legislative controls have been toughened progressively, including the introduction of zero BAC for novice drivers and 0.05 BAC for other drivers (South, 1991). McDermott (1983) comments that a considerably smaller reduction in our road toll would have occurred if Australians had been unwilling to accept countermeasures opposed by civil libertarians. Tougher drink-driving legislation and enforcement could further reduce incidence rates of SCI in USA. Recently, Tyroch et al. (1997) have estimated that 72% of SCI in USA could be prevented by the prevention of drink-driving and the enforcement of seat belt wearing and gun controls laws. While this may seem to be an unrealistically large percentage, it is to be noted that the Australian rate of SCI (B 15 cases per million) is between 50 and 72% lower than USA rate (30–53 cases per million). This may lend some support to the authors’ general contention.
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While Australia does not have as high a rate of SCI as most other countries, the rate is higher than in Denmark (Biering-Sorensen et al., 1990), suggesting Australia still has some way to go with prevention. The results of studies such as the present one, based on national population based surveillance, can assist in focussing attention on the priority areas for prevention in Australia. However, more detailed information about the causes of injury, based on in-depth investigation, is required. Also, the coverage of ASCIR in relation to paediatric SCI needs to be improved. Although this group is small (about 2% of new persisting cases), it is an important one to register and monitor for at least two reasons: (1) these cases will have the most prolonged years of life with SCI; and (2) it seems that the biomechanical properties, mechanisms, and thus preventative interventions differ for this group compared with adults (Yoganadan et al., 1999; Kumaresan et al., 2000). Arguably, prevention should be focussed on reducing the incidence of SCI due to motor vehicle crashes and falls as these causes are responsible for the largest proportion of the most severely injured (i.e. those with complete tetraplegia). The principal cause of SCI in motor vehicle crashes was vehicle rollover and collision with a roadside hazard. Among the measures which could reduce the frequency of these causes are: the sealing of road shoulders on country roads (Ryan et al., 1988; Digges and Klisch, 1991; Kloeden et al., 1999), removal of trees in close proximity to rural roads (Corben, 1997; Kloeden et al., 1999); modification of vehicle roof strength (Rechnitzer and Lane, 1994; Henderson and Paine, 1998); and the raising of seat belt wearing rates
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in rural areas (Trembath and Furse, 1998). The increasing popularity of four wheel drive vehicles, and other high centre of gravity vehicles, in Australia (Federal Office of Road Safety, 2000) and also in USA (National Highway Traffic Safety Administration, 1998), is a factor that has the potential to increase the incidence of vehicle related SCI as these vehicles have a greater propensity for rollover (Henderson and Paine, 1998; National Highway Traffic Safety Administration, 1998). Engineering measures to reduce the rollover propensity of these vehicles are required. Falls, particularly those involving the elderly, are a leading external cause of SCI. With increasing age, there is a deterioration in the capacity of the spine and its supporting structures to withstand a mechanical insult (Bartley et al., 1966; Atkinson, 1967; Bell et al., 1967; Tkaczuk, 1968; Rockoff et al., 1969; Hanson and Roos, 1980; White and Punjabi, 1990, pp. 21–42; Myers and Wilson, 1997; Pintar et al., 1998). This might explain the particularly high incidence of SCI from low falls in the elderly. Tetraplegia was the principal outcome of low falls suggesting that head impacts were involved. Fall prevention program for the elderly mostly focus on the prevention of lower limb and hip fractures (Fildes 1994) with little attention to the prevention of head impacts and SCI. Different mechanisms are probably involved, suggesting the need for different prevention measures. There is a paucity of information on work-related SCI in the medical and occupational health and safety literature internationally. Rosenberg et al. (1993) reported that 13% of SCIs in Colorado were work-related. In Australia, 18% of SCI cases were working for income at the time of injury. The incidence of work
Fig. 5. Incidence of SCI from traumatic causes by neurological level of injury at admission, Australia 1998/1999 (percentages).
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Table 1 Incidence of SCI from traumatic causes by neurological level (major grouping) and extent of injury at admission, Australia 1998/1999 (counts and column percentages) Extent of injury
Tetraplegia
Paraplegia
Total count (%)
Cervical count (%)
Thoracic count (%)
Lumbar count (%)
Sacral count (%)
Complete Incomplete Not specified
51 (33) 101 (66) 1 (1)
40 (61) 26 (39) 0 (0)
8 (18) 36 (82) 0 (0)
0 (0) 2 (100) 0 (0)
48 (43) 64 (57) 0 (0)
99 (37) 165 (62) 1 (1)
Total
153 (100)
66 (100)
44 (100)
2 (100)
112 (100)
265 (100)
related SCI is best considered in relationship to the size of the labour force. No published reports have presented incidence data on the basis of this denominator. In Australia, which had a labour force of : 8.7 million in 1999 (Australian Bureau of Statistics, 1999), the labour force based rate of SCI was about 5.5 cases per million in 1998/1999. Twenty-three percent of the workrelated cases of SCI were driving a motor vehicle at the time of injury. Nineteen percent were tree felling. Nineteen percent were working on a roof, ladder or scaffolding. Seventeen percent were engaged in some other activity and suffered a fall. Fifteen percent were unloading. The remainder was engaged in some other activity. There is no information available on the exposure of different occupational activities to provide the basis for an assessment of comparative risk. However, 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). The fact that these occupational activities accounted for a similar proportion of cases suggests that tree felling is particularly hazardous for SCI. Rosenberg et al. (1993) have suggested that workers in at-risk occupations should be educated about the risks and prevention of SCI. Work practises should also be assessed to minimise the hazardous components of work activities. In the present study, 44% of the work-related cases of SCI were not considered to be eligible for compensation for their injuries. This was based on assessment at admission to hospital. While compensation status may become clearer with time, it is nevertheless a cause for concern and warrants further investigation. The general public may not appreciate that in the event of an injury at work, they may not be fully covered, or covered at all, if personal negligence is proven or the nature of the event does not fit within the specific technical terms of the insurance policy. The average cost of the long-term care (medical and non-medical care) of a person with SCI in Australia has been estimated to range from $600 000, for a paraplegic, to $4 000 000 for a ventilator dependent tetraplegic (Walsh and DeRavin, 1995).
All paraplegia count (%)
Those who have no insurance cover obviously face a more challenging future financially. In addition, it has been shown on numerous measures, that SCI patients who are not eligible for compensation payments have worse outcomes (DeVivo et al., 1989; Tate et al., 1994). In Australia, 9% of the cases of SCI occurred in an aquatic environment, with an incidence rate of about 1.3 per million. Approximately 3% were surfing or swimming and were dumped by waves. Two percent fell or dived into a river or lake. Two percent were diving into a swimming pool. One percent was entering the surf and hit their head on a sand bar. Go et al. (1995) indicated that 9.1% of SCI cases in USA occurred in water sports, almost exclusively from diving (8.5%) with only 0.4% of cases due to surf related activities. The higher relative frequency of SCI from surf related activities in Australia, is probably explained by the greater participation in these activities, facilitated by climate and proximity; 84% of Australians live on 1% of the continent at the coastal margin (Australian Bureau of Statistics, 2000). It has been estimated that in 1993, 1.4 million people in Australia used a surfboard, or a surf mat popularly referred to as a ‘boogie board’ (Office for Recreation and Sport, 1998). On the basis that three of the SCI cases in 1998/1999 were using surf craft, it can be estimated that the rate of SCI was about 2 cases per million surf craft users. A review of the international literature suggests a number of prevention issues that should be addressed. It has been shown that most swimming pool SCIs occur in less than 1.5 m of water (Blanksby et al., 1997). However, warning signs about shallow water are rarely present (DeVivo and Sekar, 1997). As there were cases of SCI in Australia in 1998/1999 that could be attributed directly to the presence of sandbars, with impact upon first entry to the water, there is a need to post signs on affected beaches. Diving technique has been shown to affect the likelihood of a head contact with the bottom (Blanksby et al., 1997). The results of studies based on trained divers have frequently been used to determine the required depth of swimming pools. However, the definition of an optimal depth of water, including the standards for
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Table 2 Incidence of SCI from traumatic causes by external cause (major groupings), and neurological level, of injury at admission, Australia, 1998/1999 (counts and column percentages) External cause of injury
Motor vehicle occupant Unprotected road user Low fall (B1 m) High fall (1 m+) Struck by object Other cause Total
Tetraplegia
Paraplegia
Cervical count (%)
Thoracic count (%)
Lumbar count (%)
Sacral count (%)
11 20 1 17 12 5
10 4 2 16 9 3
1 1 0 0 0 0
52 14 19 28 28 12
(34) (9) (12) (18) (18) (8)
153 (100)
(17) (30) (2) (26) (18) (8)
66 (100)
Total count (%)
(23) (9) (5) (36) (20) (7)
44 (100)
swimming pool design and use, needs to consider the range of diving techniques and behaviours 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 and affected by alcohol (DeVivo and Sekar, 1997) that is injured rather than the trained diver. A review of the scientific literature failed to reveal any studies of the actual diving behaviour and SCI risk factors of the untrained public in swimming pools. Amongst the field sports played in Australia, rugby stands out as the most frequent cause of SCI. A twofold increase in the incidence of spinal injuries from rugby was reported during the 1970s and 1980s in Australia and the United Kingdom (Silver, 1984; Taylor and Coolican, 1987; Silver and Stewart, 1994), a trend that was reported to be due to changes in the strength and intensity of tackles and scrums. As a consequence of the increasing SCI trend, changes were reportedly made in Australia to the rules of the game and to player exercise programs and position play, resulting in a small reduction in incidence (Rotem et al., 1998). This result contrasts with the increasing trend reported in New Zealand (Armour et al., 1997) and South Africa (Scher, 1998) over a similar period, despite rule changes, suggesting that the changes required to prevent SCI either are not well known or have not been effectively introduced in some places. In conclusion, the present study indicates that the surveillance of SCI needs to be improved internationally so that comparative studies can be undertaken. While the CDC have recommended a case definition for SCI (Thurman et al., 1995b), few incidence studies have used it. Australia is one of the few countries that have a register of SCI following the CDC case definition, and the only one that has a register covering a full national adult population. It is clear from the results presented that national population based surveillance
(50) (50) (0) (0) (0) (0)
2 (100)
All paraplegia count (%) 22 25 3 33 21 8
(20) (22) (3) (29) (19) (7)
112 (100)
74 39 22 61 49 20
(28) (15) (8) (23) (18) (8)
265 (100)
provides some hitherto unavailable information on the incidence rates and patterns of SCI. This is fundamental to an understanding of the epidemiology of SCI and hence the prevention of this severe and costly health and welfare problem. More detailed information about the causes of SCI should be sought, based on in-depth investigation, as it might lead to more targeted intervention. Acknowledgements The ASCIR is a cooperative arrangement of the six Australian spinal units and the National Injury Surveillance Unit of the Flinders University Research Centre for Injury Studies (RCIS), funded by the Australian Institute of Health and Welfare. The assistance of the Directors and staff of the spinal units is gratefully acknowledged, as is the assistance of Dr Raymond Cripps of RCIS who is involved with unit liaison and quality assurance. References Armour, K.S., Clatworthy, B.J., Bean, A.R., et al., 1997. Spinal injuries in New Zealand rugby and rugby league – a twenty year survey. New Zealand Medical Journal 110 (1057), 462 –465. Athanasou, J., Brown, D., Murphy, G., 1996. Vocational achievements following spinal cord injury in Australia. Disability and Rehabilitation 18 (4), 191 – 196. Atkinson, P.J., 1967. Variation in trabecular structure of vertebrae with age. Calcified Tissue Research 1, 24. Australian Bureau of Statistics, 1999. Labour force, Australia 1999. ABS Catalogue no. 6203.0, Canberra. Australian Bureau of Statistics, 2000. Australia now – a statistical profile of Australia, Canberra (www.abs.gov.au). Australian Institute of Health and Welfare, 1997. National health data dictionary: version 6.0. AIHW, Canberra. Bartley, M.H., Arnold, J.S., Haslam, R.K., et al., 1966. The relationship of bone strength and bone quantity in health, disease and aging. Journal of Gerontology 21, 517.
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Incidence and patterns of spinal cord injury in Australia Peter O’Connor * AIHW National Injury Sur6eillance Unit, Research Centre for Injury Studies, Flinders Uni6ersity, Mark Oliphant Building, Laffer Dri6e, Bedford Park, SA 5042, Australia Received 20 July 2000; received in revised form 25 January 2001; accepted 28 February 2001
Abstract The objective of this paper is to report on the epidemiology of spinal cord injury (SCI) based on the Australian SCI register and to discuss the implications for prevention. All adult cases of SCI are reported to the registry. The case reports for 1998/1999 were aggregated and described. The age adjusted rate of persisting SCI was 14.5 per million of population. Rates were highest in young adults and in males. The vast majority of cases (93%) were due to unintentional injury. Forty-three percent were due to motor vehicle crashes, principally from motor vehicle rollover. Cases of SCI from falls, aquatic activities, and working for income are also described. Incomplete cervical cord injuries were most common (38%), particularly as a result of motor vehicle crashes and low falls. The study indicates that the surveillance of SCI needs to be improved internationally so that comparative studies can be undertaken. It is recommended that the Centers for Disease Control case definition be adopted. Australia is one of the few countries that have a register based on that case definition, and the only one that has a register covering a full national adult population. The results presented on the basis of this data source provide some hitherto unavailable information on the incidence rates and patterns of SCI. National population based surveillance is fundamental to an understanding of the epidemiology, and hence the prevention, of this severe and costly health and welfare problem. © 2002 Elsevier Science Ltd. All rights reserved. Keywords: Spinal cord injury; Epidemiology; Surveillance; International comparisons; Prevention
1. Introduction The health and welfare burden due to spinal cord injury (SCI) is substantial. Despite decreasing length of stay brought about by the introduction of case management in specialist facilities (DeVivo et al., 1992a,b; Tator et al., 1995; Eastwood et al., 1999), hospital costs are increasing (DeVivo et al., 1992a,b). As survival from SCI is increasing due to improvements in resuscitation and long-term care (Geisler et al., 1983; DeVivo et al., 1992a,b,c; Whiteneck et al., 1992; Samsa et al., 1993; Hartkopp et al., 1997a,b; McColl et al., 1997; Tyroch et al., 1997), and the incidence rate is not falling (Go et al., 1995, p. 24; O’Connor and Cripps, 1998), the size of the prevalent population is increasing in Australia and elsewhere (Ditunno and Formal, 1994; Blumer and Quine, 1995; Lasfargues et al., 1995; Tyroch et al., 1997). Those who suffer an SCI due to * Corresponding author. Tel.: + 61-8-83740970; fax: + 61-883740702. E-mail address: [email protected] (P. O’Connor).
trauma are generally young people in the prime of their lives, working and contributing to the wealth of the country through the taxation system, consumption and the investment of discretionary income. After injury between 60 and 70% do not return to work (Athanasou et al., 1996; Murphy et al., 1997), increasing the community cost through unemployment and welfare payments. When it is considered that a large proportion of cases do not receive insurance compensation for their injury (O’Connor, 2000a), the increasing prevalence of SCI signals the potential for escalating costs to the community through the public health and welfare system. Concern has been expressed that a disproportionate share of the cost of caring for trauma victim is placed on the public (Mackersie et al., 1995; Tyroch et al., 1997). Given the potential for escalating health and welfare costs, and the fact that there is no cure for SCI, prevention should be emphasised. The information required for the prevention and control of SCI and the monitoring of the health and welfare of the prevalent population indicates the need for surveillance. The de-
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velopment of appropriate interventions requires information on causal factors as well as on the characteristics of the SCI population. The Australian SCI register (ASCIR), established in 1995, enables the incidence and patterns of SCI to be monitored. The ASCIR is the only SCI register covering a full national adult population. The ASCIR is now in its fifth year of operation and has nearly 9000 cases registered. This article presents statistical information on new cases of SCI from traumatic causes that occurred during the financial year 1998/1999 in Australia to Australian residents. The purpose of the article is to highlight the characteristics of SCI and to focus preventive efforts. 2. Method
2.1. Co6erage of the Australian spinal cord injury register In Australia it is possible to identify each hospitalised adult who has suffered an SCI from trauma because there are a small number of specialist treatment units nationally and referral of cases with SCI to one of these units is a well established hospital protocol. However, the coverage of children is not complete as some cases will be treated in paediatric hospitals rather than spinal units. Based on routine hospital separations data 1986– 1998, it is estimated that about half of the new cases of SCI that occur each year amongst 0– 14-year-olds nationally, are covered by ASCIR. For 1998/1999, in addition to the three reported paediatric cases, there could be an additional three non-reported cases, indicating that this group could constitute about 2% of new incident cases; 3% if 15-year-olds are included in the group, which is comparable with North American figures (Nobunaga et al., 1999, Fig. 1, p. 1375).
2.2. Case definition In order to facilitate national and international comparisons, the case definition that has been adopted for the registration of traumatic cases of SCI in Australia is USA Centers for Disease Control (CDC) clinical definition: ‘‘a case of SCI is defined as the occurrence of an acute, traumatic lesion of neural elements in the spinal canal (spinal cord and cauda equina) resulting in temporary or permanent sensory deficit, motor deficit, or bladder/bowel dysfunction’’ (Thurman et al., 1995b). For the purposes of the current article, the case selection excluded cases that had suffered no neurological deficit at admission or discharge, in order to focus the analysis on those with permanent rather than transient deficit. Cases suffering persisting neurological deficit at discharge from hospital accounted for 88% of all cases.
2.3. Data dictionary The ASCIR data dictionary (Research Centre for Injury Studies, 1997) was developed on the basis of relevant international data standards (Hamilton and Fuhrer, 1987; World Health Organisation, 1996), including the American Spinal Injury Association International Standards for Neurological and Functional Classification of SCI (Maynard et al., 1997). Other items conformed to the Australian National Health Data Dictionary (Australian Institute of Health and Welfare, 1997). The items are more fully described in an article by O’Connor (2000b).
3. Results
3.1. Incidence There were 265 new persisting cases of SCI from traumatic causes in 1998/1999 reported to the ASCIR. The age adjusted incidence rate of persisting SCI, based on reported cases, was 14.5 per million of population. There were no statistically significant differences in the Australian State rates in 1998/1999. The age distribution of SCI from traumatic causes is presented in Fig. 1. The age group of 0–14 years was excluded from the figure, and other figures showing age group breakdowns, as case numbers were small and coverage of ASCIR was not complete for this group. The highest case count and rate occurred in the age group 15–24 years (73 cases). With increasing age, the case count and rate declined substantially to the age group 45–54 years (23 cases), after which the count remained fairly constant. The increasing rate from age 55 years reflects a progressive decline, with age, in the number of elderly people in the population. The wide confidence intervals on the rates (95% confidence intervals based on the Poisson distribution) reflect the small case count for individual age groups. The rate for age group 15–44 years (21.5 per million of population) was significantly higher, statistically, than the rate for the older combined age group of 45 years and above (13.1 per million of population). Of the cases of SCI from traumatic causes aged 15 years and above, 76% were male and 24% were female. There was a higher rate of SCI for males at all ages and the differences were statistically significant for those under 45 years of age and also for 55–64-year-olds (Fig. 2).
3.2. Intent Ninety-three percent of the cases resulted from unintentional injury. Three percent resulted from intentional self-harm. Two percent were due to assault. The re-
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mainder was due to legal intervention, medical care and events of undetermined intent.
3.3. External cause of injury The external cause classification for injury surveillance (Australian Institute of Health and Welfare, 1997), based on ICD-9-CM, enabled a simple classification (Fig. 3). More than two-thirds of cases involved transport crashes and falls. Transport related injury accounted for 43% of the cases of SCI (n=113). Twenty-eight percent were motor vehicle occupants (n =74) and 15% were unprotected road users i.e. pedestrians, pedal cyclists and motor cycle riders (n =39). Eighty-five percent (n = 96) of the cases of transport related SCI were aged 15– 44 years. Further assessment of the crash types of motor vehicle occupants (n =74), using the structured text description of the injury event provided on the ASCIR registration form, revealed that 40% were due to vehicle rollover, 23% were due to collision with a roadside hazard (i.e. tree, pole or other fixed object) and the remainder were due to other crash types. Only 11% of cases were ejected from the motor vehicle in all crash types. Twenty-three percent (n =61) of the cases of SCI involved high falls (drop of 1 m or more) and 8% (n = 22) involved low falls. Of all falls related SCIs (n= 83), a third involved elderly persons (aged 65 years and above). Of low falls, more than two-thirds were elderly (n= 16).
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3.4. Place of injury The road environment was the primary place of SCI for those aged 15–44 years (Fig. 4). 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 above. Further assessment of the cases that suffered their SCI in an aquatic environment (n= 23), using the structured text description of the injury event, 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 or a sand-bar; and one case had an other specified event.
3.5. Type of acti6ity 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, mainly involving motorbike riding (five cases), but also field sports: rugby league and rugby union (two cases in New South Wales and two cases in other States), Australian rules football (two cases) and horse-riding (one case). Of the remaining 123 cases, most of whom
Fig. 1. Incidence of SCI from traumatic causes by age group, Australia 1998/1999 (counts and age specific rates).
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Fig. 2. Incidence of SCI from traumatic causes by age group and sex, Australia 1998/1999 (age specific rates).
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 structured text description of the injury event, 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.
3.6. Workers compensation At admission, only 27 of the 48 people injured at work (i.e. 56%) were reported to be eligible for some form of compensation payment through an insurance scheme. Of the 11 people injured in a motor vehicle while working, all of whom 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.
3.7. Clinical information The neurological level of SCI at admission is presented in Fig. 5. The most commonly injured spinal cord segments were: the cervical segments, particularly C4 (18%, n=47), C5 (17%, n =45), and C6 (9%,
n= 25); the lumbar segment L1 (11%, n = 30); and the lower thoracic segment T12 (6%, n = 17). The overall severity of SCI is usually measured by a combination of the neurological level and extent of injury into four neurologic categories: complete tetraplegia, incomplete tetraplegia, complete paraplegia and incomplete paraplegia. The most common neurologic category (Table 1) was incomplete tetraplegia (38% of total, n= 101), followed by incomplete paraplegia (24% of total, n= 64), complete paraplegia (18% of total, n= 48), and complete tetraplegia (19% of total, n = 51). Complete injury was most common in the thoracic spinal segments. Table 2 presents information on the neurological level of SCI by external cause of injury. Motor vehicle occupants most often suffered from injury to the cervical segments of the spine, resulting in tetraplegia, with incomplete damage to the cord being most common at this level (63%, n= 33). Unprotected road users most often suffered thoracic level injuries, which generally involved complete damage to the cord (60%, n=12). Low falls primarily resulted in cervical level injury and most of these involved incomplete damage to the cord (84%, n = 16). Fifty-seven percent (n= 16) of the high falls tetraplegia cases suffered complete damage to the cord whereas 64% (n= 21) of the high falls paraplegia cases suffered incomplete cord damage. There was a higher frequency of complete cord damage in high falls compared to low falls. Motor vehicle occupants and high falls cases made up the largest proportion of the most severely injured i.e. those with complete tetraplegia (35 and 31%, respectively; n = 18 and 16, respectively).
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4. Discussion International comparisons can assist in the identification of potential SCI prevention measures. Unfortunately, there is a paucity of comparative information on the incidence of SCI outside USA. The information that is available shows some substantial differences within and between countries, which may be due to different methods of case ascertainment, differing case definitions and the different populations studied. It is interesting to note the lack of any substantial State to State differences in Australia, compared to the substantial State differences reported for USA (Go et al., 1995, pp. 22–24). Notwithstanding that the population of the Australian States may well be more homogeneous than for USA, this result may also reflect the fact that in Australia there is a single surveillance system, national in scope, with fully standardised definitions and procedures, and common case selection criteria, auditing and quality control measures. Other countries should adopt the CDC clinical case definition (Thurman et al., 1995b) and work toward the development of national registers of SCI so that international comparative studies can be undertaken. Studies from the mid-1970s to 1990s, in USA, have estimated the incidence rate of acute care hospital admissions for SCI to be 30– 53 cases per million of population (Kraus et al., 1975; Kalsbeek et al., 1982; Price et al., 1994; Thurman et al., 1994; Go et al., 1995; Carroll, 1997; Johnson et al., 1997). In Canada, the incidence rate has been estimated to be 35 cases per million (Canadian Paraplegia Association, 2000). In Russia, the rate has been estimated to be about 30 cases per million (Silberstein and Rabinovich, 1995). Rates of between 17 and 21 per million have been reported for Jordan, Taiwan and Fiji (Chen and Lien, 1985; Chiu et
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al., 1991; Maharaj, 1996; Chen et al., 1997; Karamehmetoglu et al., 1997; Otom et al., 1997). In Portugal, the incidence rate, excluding deaths, was reported to be about 25 per million (Martins et al., 1998). In Australia, the rate of SCI in 1998/1999 was less than 15 per million of population based on new persisting cases, lower than the rates of other countries in the region and less than half the North American rates. The lowest reported rate was for Denmark (Biering-Sorensen et al., 1990), which at 9.2 per million was 37% lower than the Australian rate. The highest reported rate was for the Plovdiv area of Bulgaria, with a rate of 130 per million (Stavrev et al., 1994). One reason for the difference in the Australian rate from those of other countries is that the Australian rate is based on persisting cases (i.e. those who continued to have neurological deficit at discharge). If those who resolved neurologically or died after admission were included, the rate would have been : 2 cases per million higher. However, this accounts for only a very small component of the difference from USA rate. While no definitive conclusions can be made, a number of plausible explanations for the differences in rates between Australia and USA can be offered. Australia has a very low rate of SCI due to violence. Less than 2% of SCI cases in 1998/1999 were due to inter-personal violence, with a rate of less than 0.3 cases per million of population. In USA, 15– 17% of cases were due to inter-personal violence (Go et al., 1995), suggesting an incidence rate of between 6 and 9 per million of population. Carroll (1997) found a slightly lower rate in Arkansas in 1989 (5 per million of population). Whereas SCI from violence related penetrating injury is rising in USA (Carroll, 1997), there has been no such increase in Australasia (Sidhu et al., 1996; Civil et al., 1998). There
Fig. 3. Incidence of SCI from traumatic causes by external cause of injury (major groupings) and age group, Australia 1998/1999 (counts). Note: Excludes 3 cases where age was 0 –14 years.
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Fig. 4. Incidence of SCI from traumatic causes by place of injury (major groupings) and age group, Australia 1998/1999 (counts).
are strong legislative controls restricting the availability of guns in Australia (Chapman, 1998). Semi-automatic weapons and pump-action shotguns are prohibited. If gun control measures were effectively introduced in USA, and the nature of the social problems that lead to violence was also addressed effectively, the SCI rate in USA could be up to 17% lower than at present. The rate of motor vehicle related SCI is low in Australia (:4 cases per million for motor vehicle occupants). In USA, 44.5% of cases of SCI are due to motor vehicle crashes (Go et al., 1995), suggesting a rate of 18–24 cases per million of population. Kraus et al. (1982) reported 21 cases per million for motor vehicle occupants. The difference in the rates of Australia and USA could reflect differences in seat belt wearing rates, drink driving and other factors. In Australia, seat belt wearing has been required by law since the 1970s. As a consequence of the law and active enforcement and publicity, seat belt wearing rates in the general population of drivers have been over 90% for many years (Rungie and Trembath, 1988; Roads and Traffic Authority, 1998; Trembath and Furse, 1998; Vic Roads, 1998). Seat belt wearing rates are however lower in those that suffer SCI. In a study of SCI crashes in Australia in the early 1980s, Toscano (1986) found that 46% of cases were not wearing a seat belt. In USA, Tyroch et al. (1997) reported that 80% of SCI patients involved in motor vehicle crashes in the early to mid 1990s were not wearing restraint devices. Another indicator of the impact of seat belt wearing on the SCI incidence rate is the difference between the two countries in the incidence of ejection from the vehicle. In Australia, in 1998/1999 only 11% of occupant SCI cases were ejected from the vehicle, compared with 40% in USA (Thurman et al., 1995a).
There may be a difference in the contribution of alcohol to SCI crashes in Australia and USA. Recently, a study based on the linkage of SCI medical reports and Police crash reports in South Australia (O’Connor, unpublished data), found that 26% of SCI cases in South Australia over the period 1988–1995 had a blood alcohol concentration of more than 50 g per 100 ml. In one of the few studies in USA to report evidence on the basis of the analysis of blood rather than self-reports or clinical evidence, Heinemann et al. (1988) found that 40% of SCI cases had a blood alcohol concentration of more than 50 g per 100 ml. Australia has been at the forefront of controls on drink-driving; introducing random breath testing in the late 1970s and maintaining high intensity enforcement and publicity programs (Homel, 1983; McDermott, 1983; McCaul and McLean, 1990; South, 1991; Loxley et al., 1992; Homel, 1994). Legislative controls have been toughened progressively, including the introduction of zero BAC for novice drivers and 0.05 BAC for other drivers (South, 1991). McDermott (1983) comments that a considerably smaller reduction in our road toll would have occurred if Australians had been unwilling to accept countermeasures opposed by civil libertarians. Tougher drink-driving legislation and enforcement could further reduce incidence rates of SCI in USA. Recently, Tyroch et al. (1997) have estimated that 72% of SCI in USA could be prevented by the prevention of drink-driving and the enforcement of seat belt wearing and gun controls laws. While this may seem to be an unrealistically large percentage, it is to be noted that the Australian rate of SCI (B 15 cases per million) is between 50 and 72% lower than USA rate (30–53 cases per million). This may lend some support to the authors’ general contention.
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While Australia does not have as high a rate of SCI as most other countries, the rate is higher than in Denmark (Biering-Sorensen et al., 1990), suggesting Australia still has some way to go with prevention. The results of studies such as the present one, based on national population based surveillance, can assist in focussing attention on the priority areas for prevention in Australia. However, more detailed information about the causes of injury, based on in-depth investigation, is required. Also, the coverage of ASCIR in relation to paediatric SCI needs to be improved. Although this group is small (about 2% of new persisting cases), it is an important one to register and monitor for at least two reasons: (1) these cases will have the most prolonged years of life with SCI; and (2) it seems that the biomechanical properties, mechanisms, and thus preventative interventions differ for this group compared with adults (Yoganadan et al., 1999; Kumaresan et al., 2000). Arguably, prevention should be focussed on reducing the incidence of SCI due to motor vehicle crashes and falls as these causes are responsible for the largest proportion of the most severely injured (i.e. those with complete tetraplegia). The principal cause of SCI in motor vehicle crashes was vehicle rollover and collision with a roadside hazard. Among the measures which could reduce the frequency of these causes are: the sealing of road shoulders on country roads (Ryan et al., 1988; Digges and Klisch, 1991; Kloeden et al., 1999), removal of trees in close proximity to rural roads (Corben, 1997; Kloeden et al., 1999); modification of vehicle roof strength (Rechnitzer and Lane, 1994; Henderson and Paine, 1998); and the raising of seat belt wearing rates
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in rural areas (Trembath and Furse, 1998). The increasing popularity of four wheel drive vehicles, and other high centre of gravity vehicles, in Australia (Federal Office of Road Safety, 2000) and also in USA (National Highway Traffic Safety Administration, 1998), is a factor that has the potential to increase the incidence of vehicle related SCI as these vehicles have a greater propensity for rollover (Henderson and Paine, 1998; National Highway Traffic Safety Administration, 1998). Engineering measures to reduce the rollover propensity of these vehicles are required. Falls, particularly those involving the elderly, are a leading external cause of SCI. With increasing age, there is a deterioration in the capacity of the spine and its supporting structures to withstand a mechanical insult (Bartley et al., 1966; Atkinson, 1967; Bell et al., 1967; Tkaczuk, 1968; Rockoff et al., 1969; Hanson and Roos, 1980; White and Punjabi, 1990, pp. 21–42; Myers and Wilson, 1997; Pintar et al., 1998). This might explain the particularly high incidence of SCI from low falls in the elderly. Tetraplegia was the principal outcome of low falls suggesting that head impacts were involved. Fall prevention program for the elderly mostly focus on the prevention of lower limb and hip fractures (Fildes 1994) with little attention to the prevention of head impacts and SCI. Different mechanisms are probably involved, suggesting the need for different prevention measures. There is a paucity of information on work-related SCI in the medical and occupational health and safety literature internationally. Rosenberg et al. (1993) reported that 13% of SCIs in Colorado were work-related. In Australia, 18% of SCI cases were working for income at the time of injury. The incidence of work
Fig. 5. Incidence of SCI from traumatic causes by neurological level of injury at admission, Australia 1998/1999 (percentages).
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Table 1 Incidence of SCI from traumatic causes by neurological level (major grouping) and extent of injury at admission, Australia 1998/1999 (counts and column percentages) Extent of injury
Tetraplegia
Paraplegia
Total count (%)
Cervical count (%)
Thoracic count (%)
Lumbar count (%)
Sacral count (%)
Complete Incomplete Not specified
51 (33) 101 (66) 1 (1)
40 (61) 26 (39) 0 (0)
8 (18) 36 (82) 0 (0)
0 (0) 2 (100) 0 (0)
48 (43) 64 (57) 0 (0)
99 (37) 165 (62) 1 (1)
Total
153 (100)
66 (100)
44 (100)
2 (100)
112 (100)
265 (100)
related SCI is best considered in relationship to the size of the labour force. No published reports have presented incidence data on the basis of this denominator. In Australia, which had a labour force of : 8.7 million in 1999 (Australian Bureau of Statistics, 1999), the labour force based rate of SCI was about 5.5 cases per million in 1998/1999. Twenty-three percent of the workrelated cases of SCI were driving a motor vehicle at the time of injury. Nineteen percent were tree felling. Nineteen percent were working on a roof, ladder or scaffolding. Seventeen percent were engaged in some other activity and suffered a fall. Fifteen percent were unloading. The remainder was engaged in some other activity. There is no information available on the exposure of different occupational activities to provide the basis for an assessment of comparative risk. However, 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). The fact that these occupational activities accounted for a similar proportion of cases suggests that tree felling is particularly hazardous for SCI. Rosenberg et al. (1993) have suggested that workers in at-risk occupations should be educated about the risks and prevention of SCI. Work practises should also be assessed to minimise the hazardous components of work activities. In the present study, 44% of the work-related cases of SCI were not considered to be eligible for compensation for their injuries. This was based on assessment at admission to hospital. While compensation status may become clearer with time, it is nevertheless a cause for concern and warrants further investigation. The general public may not appreciate that in the event of an injury at work, they may not be fully covered, or covered at all, if personal negligence is proven or the nature of the event does not fit within the specific technical terms of the insurance policy. The average cost of the long-term care (medical and non-medical care) of a person with SCI in Australia has been estimated to range from $600 000, for a paraplegic, to $4 000 000 for a ventilator dependent tetraplegic (Walsh and DeRavin, 1995).
All paraplegia count (%)
Those who have no insurance cover obviously face a more challenging future financially. In addition, it has been shown on numerous measures, that SCI patients who are not eligible for compensation payments have worse outcomes (DeVivo et al., 1989; Tate et al., 1994). In Australia, 9% of the cases of SCI occurred in an aquatic environment, with an incidence rate of about 1.3 per million. Approximately 3% were surfing or swimming and were dumped by waves. Two percent fell or dived into a river or lake. Two percent were diving into a swimming pool. One percent was entering the surf and hit their head on a sand bar. Go et al. (1995) indicated that 9.1% of SCI cases in USA occurred in water sports, almost exclusively from diving (8.5%) with only 0.4% of cases due to surf related activities. The higher relative frequency of SCI from surf related activities in Australia, is probably explained by the greater participation in these activities, facilitated by climate and proximity; 84% of Australians live on 1% of the continent at the coastal margin (Australian Bureau of Statistics, 2000). It has been estimated that in 1993, 1.4 million people in Australia used a surfboard, or a surf mat popularly referred to as a ‘boogie board’ (Office for Recreation and Sport, 1998). On the basis that three of the SCI cases in 1998/1999 were using surf craft, it can be estimated that the rate of SCI was about 2 cases per million surf craft users. A review of the international literature suggests a number of prevention issues that should be addressed. It has been shown that most swimming pool SCIs occur in less than 1.5 m of water (Blanksby et al., 1997). However, warning signs about shallow water are rarely present (DeVivo and Sekar, 1997). As there were cases of SCI in Australia in 1998/1999 that could be attributed directly to the presence of sandbars, with impact upon first entry to the water, there is a need to post signs on affected beaches. Diving technique has been shown to affect the likelihood of a head contact with the bottom (Blanksby et al., 1997). The results of studies based on trained divers have frequently been used to determine the required depth of swimming pools. However, the definition of an optimal depth of water, including the standards for
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Table 2 Incidence of SCI from traumatic causes by external cause (major groupings), and neurological level, of injury at admission, Australia, 1998/1999 (counts and column percentages) External cause of injury
Motor vehicle occupant Unprotected road user Low fall (B1 m) High fall (1 m+) Struck by object Other cause Total
Tetraplegia
Paraplegia
Cervical count (%)
Thoracic count (%)
Lumbar count (%)
Sacral count (%)
11 20 1 17 12 5
10 4 2 16 9 3
1 1 0 0 0 0
52 14 19 28 28 12
(34) (9) (12) (18) (18) (8)
153 (100)
(17) (30) (2) (26) (18) (8)
66 (100)
Total count (%)
(23) (9) (5) (36) (20) (7)
44 (100)
swimming pool design and use, needs to consider the range of diving techniques and behaviours 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 and affected by alcohol (DeVivo and Sekar, 1997) that is injured rather than the trained diver. A review of the scientific literature failed to reveal any studies of the actual diving behaviour and SCI risk factors of the untrained public in swimming pools. Amongst the field sports played in Australia, rugby stands out as the most frequent cause of SCI. A twofold increase in the incidence of spinal injuries from rugby was reported during the 1970s and 1980s in Australia and the United Kingdom (Silver, 1984; Taylor and Coolican, 1987; Silver and Stewart, 1994), a trend that was reported to be due to changes in the strength and intensity of tackles and scrums. As a consequence of the increasing SCI trend, changes were reportedly made in Australia to the rules of the game and to player exercise programs and position play, resulting in a small reduction in incidence (Rotem et al., 1998). This result contrasts with the increasing trend reported in New Zealand (Armour et al., 1997) and South Africa (Scher, 1998) over a similar period, despite rule changes, suggesting that the changes required to prevent SCI either are not well known or have not been effectively introduced in some places. In conclusion, the present study indicates that the surveillance of SCI needs to be improved internationally so that comparative studies can be undertaken. While the CDC have recommended a case definition for SCI (Thurman et al., 1995b), few incidence studies have used it. Australia is one of the few countries that have a register of SCI following the CDC case definition, and the only one that has a register covering a full national adult population. It is clear from the results presented that national population based surveillance
(50) (50) (0) (0) (0) (0)
2 (100)
All paraplegia count (%) 22 25 3 33 21 8
(20) (22) (3) (29) (19) (7)
112 (100)
74 39 22 61 49 20
(28) (15) (8) (23) (18) (8)
265 (100)
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