The AHW administrative database provided a unique opportunity to study childhood injury in Alberta since it includes virtually all children in the province and all injuries treated by a physician regardless of the setting. In addition, every child had potentially the same access to the universal healthcare system.
The findings indicate only slightly higher overall rates of child injury between children ages 0–17 years from low SES and higher SES families, but the rates were significantly higher for children of low SES from ages 0 to 9 years. When the three healthcare premium sub-groups were examined an interesting relationship appeared. Children whose family was receiving social services or who were of Treaty status were much more likely to have injuries treated by a physician at all ages than those receiving partial or total healthcare premium subsidy and the latter group actually had similar or lower injury rates when compared to children receiving no premium subsidy.
Further examination of the database provided more insight into the relationship between various types of childhood injury and SES. Children whose families had partial or total subsidised healthcare premiums have a disproportionately increased incidence of all types of injury except for dislocations, sprains and strains, and fractures. When the healthcare premium sub-groups were examined children whose families were on welfare had higher OR's for all types of injury than those receiving partial or total subsidy and most types of injury were also more frequent in those of Treaty status. The differences were especially evident with burns, poisonings, and for those on welfare, internal injuries. Thus, for what might be equivalent low incomes, children on social services or having Treaty status had higher injury rates for most types of injury.
Speculation about the mechanisms underlying these findings could include differences in environments, such as, less safe housing and neighbourhoods, and perhaps reduced use of safety measures at home and in play [18
]. Children from lower socio economic backgrounds tend to live in higher population density neighbourhoods with more traffic and fewer playgrounds. These risks are intensified by the presence of social conditions associated with poverty: single parenthood, teenage parents, lower levels of parental education, large family size, lack of affordable day-care, and drug and alcohol abuse. These factors may add to the stresses of parenting and reduce the knowledge and experience needed to provide a safe environment for the child. Therefore, it is not surprising that children from lower SES families are more at risk for childhood injury.
A possible explanation for the lower rate of dislocations, strains, and sprains, and fractures among children of lower SES is that children of a higher SES may participate in more organised sports, and/or ride on snowmobiles, all terrain vehicles and cars, thereby leading to this type of injury. Interestingly, Lyons et al in Wales looked at fractures in children and concluded that although the rates were similar in both affluent and deprived areas, the causes were different with the more affluent areas having higher rates of sports related fractures and the poorer areas having more assault related injuries [9
]. We can only say that in our study fractures were not significantly associated with SES. An examination of External Cause of Injury Codes (E-codes) would perhaps cast light on our observation, but E-codes were not recorded in this data set.
The findings from this present study appear to have uncovered an important reason for the variation in the literature on the relationship between SES and childhood injury. Most studies examining SES and injury have found a relationship between poverty and injury [12
]. The finding is not universal; others have found no evidence of a relationship. For example, Addor et al demonstrated that socio-economic factors did not influence the occurrence of injury [23
], and Larson et al. also showed no increase in risk of injury from children of lower income [24
]. Our study, examining the type of childhood injury along with the SES of the family and having virtually the entire population of children of the Province of Alberta, presents a clearer picture of the relationship. Children whose parents receive partial or total healthcare subsidies appear to experience fewer injuries than those whose families are on welfare or who have Treaty status. Do the working poor hold different attitudes toward injury and childcare, or do they lack the means or time to take their child to a physician for care? Williamson and Fast reported that social assistance recipients seek medical treatment more frequently than the working poor [25
] and these differences could contribute to the higher rates of childhood injury seen in this study.
Gender was a major factor to the pattern of childhood injury. After the age of one, males consistently presented for a physician consultation more frequently than females for all injuries. Information presented by Health Canada in the 1980's and 1990's indicated that more males were hospitalised and died from injuries than females in all provinces and territories [1
], and Spady et al. also showed boys were more likely to be injured in Alberta [17
]. Further examination of the types of injury and gender, with adjustment for age and SES, showed that males were more prone to all types of injury apart from dislocations, sprains and strains, and poisonings; the latter being more significantly more common in females and supported by Spady et al. [26
]. Further research is required to determine whether males are more prone to injuries because of the different nature of childhood activities or differences in impulsiveness.
The types of injury occurring at differing ages during childhood often reflect various aspects of physical and mental development that influence susceptibility to injury. Several observations were made when rate of injuries in relation to age were examined. Two of the major categories of injury, superficial injury and contusions, and open wounds, demonstrated a dramatic rise in incidence about the age of one. During the infant and toddler period of growth there is a rapid increase in motor development; and there is a drive for autonomy and curiosity about the environment, thereby exposing the child to injury [27
]. Superficial injury then decreased slightly during the four to eight year old age range before peaking during the teenage years. Often, school-age children seek social and peer acceptance and will engage in risk-taking behaviour. This coupled with an inadequate perception of speed, distance and strength may explain the increase in relatively minor injuries for this age range. The incidence of open wounds demonstrated a small increase in numbers but maintained an average rate of about 60–70/1000 children through the remaining years studied. Overall, the rates of childhood injury in Alberta during the fiscal year appear very high (e.g., about 300/1000 in the teenage years). Comparison with other studies and publications has not been possible as this study has captured all injuries treated by a physician and previous studies have only looked at hospitalisations.
When these data were examined in relation to the child's domicile, the analysis showed that injuries were more frequent in urban Alberta and in urban children with lower SES. The latter finding is supported in part by a previous study performed in Manitoba during 1994–1997 which indicated that injury hospitalisation among children living in low income areas of Winnipeg was 2.5 times higher than in the higher income areas[10
]. The present study showed no relationship between SES and injury if the child lived in a rural community in Alberta. However, when the three sub-groups of subsidy were examined separately, children from families receiving partial/total subsidies and living in a rural setting had lower injury rates than other children for reasons that are not clear. Further research is required to determine why this group of children presented less frequently to a physician for an injury.
Limitations to the use of retrospective data depend on what data were collected and how it can be utilised. Unfortunately, there was no means available to determine the mechanisms of the injury with these data. However, these constraints are outnumbered by the advantages of utilising data that includes the individual economic status (healthcare premium payments); utilisation of diagnostic codes (number of times the healthcare system was accessed for injuries); and domicile of the child (rural/urban residence). Therefore, ecological fallacies were negligible in this study due to the individualisation of the data. This study was not able to differentiate between the "very poor", the "near poor" (families that do not qualify for healthcare premium subsidies) and those families with adequate incomes. However, there were distinct differences between children receiving welfare and the non-welfare poor (premium subsidy). It was recognised that Treaty status is not necessarily an indicator of poverty; the federal government pays the healthcare premium regardless of the person's income. First Nation people with Treaty status may be wealthy but often live in an environment where poverty is common. This study only counted one type of injury per episode; clearly, some of the injuries could be multiple. The data used for this study reflects only on children who were treated by a physician for an injury and obviously some injuries were treated at home. Children from lower SES circumstances, who sustain a minor injury, may be less likely to be brought in for physician treatment than their higher SES counterparts. Also, families in rural areas may be less likely to travel long distances to obtain treatment for a suspected minor injury than those of children living in urban domiciles. Therefore we are probably underestimating the true rates of injury. However, the opportunity to examine an individual level indicator of SES, with the possibility of moderate inaccuracies, outweighs the reduced reliability of aggregate data usage. Finally, healthcare services in Canada are universally accessible and because AHW is responsible for reimbursing physicians for consultations, the physician billing information was a reliable data set.