Epidemiology of severe trauma among status Aboriginal Canadians: a population-based study

Background

Aboriginal Canadians are considered to be at increased risk of major trauma. However, population-based studies characterizing the distribution, determinants and outcomes of major trauma in this group are lacking. We sought to measure the impact of ethnicity, as reflected by Aboriginal status, on the incidence of severe trauma and to broadly define the epidemiologic characteristics of severe trauma among status Aboriginal Canadians in a large health region.

Methods

This population-based, observational study involves all adults (people ≥ 16 years) resident in the Calgary Health Region between Apr. 1, 1999, and Mar. 31, 2002. Stratification of the population into status Aboriginal Canadians and the reference population was performed by Alberta Health and Wellness using an alternate premium arrangement field within the personal health care number. Injury incidence was determined by identifying all injuries with severity scores of 12 or greater in the Alberta Trauma Registry, regional corporate data and the Office of the Medical Examiner.

Results

Aboriginal Canadians were at much higher risk than the reference population in the Calgary Health Region of sustaining severe trauma (257.2 v. 68.8 per 100 000; relative risk RR] 3.7, 95% confidence interval CI] 3.0–4.6). Aboriginal Canadians were found to be at significantly increased risk of injuries resulting from motor vehicle crashes (RR 4.8, 95% CI 3.5–6.5), assault (RR 11.1, 95% CI 6.2–18.6) and traumatic suicide (RR 3.1, 95% CI 1.4–6.1). A trend toward higher median injury severity scores was observed among Aboriginal Canadians (21 v. 18, p = 0.09). Although the case-fatality rate among Aboriginal Canadians was less than half that in the reference population (14/93 15%] v. 531/1686 31%], p < 0.0001), population mortality was almost 2 times greater (RR = 1.8, 95% CI 1.0–3.0, p = 0.046).

Interpretation

Severe trauma disproportionately affects Aboriginal Canadians.In Canada, injury is the leading cause of death among people under the age of 45 and the leading cause of potential years of life lost.¹ Although difficult to quantify, the cost of injury was estimated to be at least $12.7 billion in 1998.² Trauma has been known, even in industrialized countries, to disproportionately affect the most marginalized members of society.³ Aboriginal Canadians are considered to be particularly at risk, and data showing alarming patterns of trauma mortality in this group are beginning to emerge. Unfortunately, the number of studies looking at injury risk among Aboriginal Canadians is small,⁴ and little attention has been paid to quantifying the risk of nonfatal injury. Better understanding of the nature of trauma risk and outcome among Aboriginal Canadians could lead to more effective prevention and treatment strategies.In this study, we used a population-based design in an attempt to quantify the impact of injury, both fatal and nonfatal, on the Aboriginal community in a large, heterogeneous Canadian region with over 1 million urban and rural inhabitants. We sought to measure the impact of ethnicity (defined by registered status within the definition of the Indian Act⁵) on the incidence of severe trauma and to broadly define the epidemiologic characteristics of severe trauma among status Aboriginal Canadians.