Elsevier

Accident Analysis & Prevention

Volume 45, March 2012, Pages 99-106
Accident Analysis & Prevention

Individual and area socioeconomic inequalities in cause-specific unintentional injury mortality: 11-Year follow-up study of 2.7 million Canadians

https://doi.org/10.1016/j.aap.2011.11.010Get rights and content

Abstract

This study investigated the association between individual and area socioeconomic status (SES) and leading causes of unintentional injury mortality in Canadian adults. Using the 1991–2001 Canadian Census Mortality Follow-up Study cohort (N = 2,735,152), Cox proportional hazard regression was used to calculate hazard ratios and 95% confidence intervals for all-cause unintentional injury, motor vehicle collision (MVC), fall, poisoning, suffocation, fire/burn, and drowning deaths. Results indicated that associations with SES differed by cause of injury, and were generally more pronounced for males. Low education was associated with an elevated risk of mortality from all-cause unintentional injury and MVC (males only) and poisoning and drowning (both sexes). Low income was strongly associated with most causes of injury mortality, particularly fire/burn and poisoning. Having no occupation or low occupational status was associated with higher risks of all-cause injury, fall, poisoning and suffocation (both sexes) and MVC deaths among men. Associations with area deprivation were weak, and only areas with high deprivation had elevated risk of all-cause injury, MVC (males only), poisoning and drowning (both sexes). This study reveals the importance of examining SES differentials by cause of death from a multilevel perspective. Future research is needed to clarify the mechanisms underlying these differences to implement equity-oriented approaches for reducing differential exposures, vulnerability or consequences of injury mortality.

Highlights

► The association between individual and area socioeconomic status and unintentional injury mortality in Canadian adults depended on cause of death. ► Associations were generally stronger for low income and no occupation than for low education and area deprivation. ► Motor vehicle and fall deaths were more strongly associated with socioeconomic status for males than females. ► Equity-oriented approaches to reduce differential exposures, vulnerability and consequences of injury mortality are needed to address the safety gap.

Introduction

Unintentional injury is the sixth leading cause of death for Canadians of all ages, with motor vehicle collisions (MVCs), falls, poisoning, suffocations, drowning and burns accounting for three-quarters of cases, or approximately 7000 deaths per year (Public Health Agency of Canada, 2008). Besides being a major cause of premature death, unintentional injury typically has a steep socioeconomic gradient (Laflamme et al., 2009a). Although a goal of Canadian health policy is to reduce or eliminate socioeconomic inequalities in health, relatively little work has been done to document socioeconomic inequalities in injury mortality. Canadian studies tend to only include children/youth or examine disadvantage from an area-level perspective (Joly et al., 1989, Joly et al., 1991, Dougherty et al., 1990, Bagley, 1992, Faelker et al., 2000, Birken et al., 2006, Gilbride et al., 2006, Oliver and Kohen, 2010). Multilevel studies that disentangle the influence of adult socioeconomic status (SES) from their living areas are absent in Canada and rare elsewhere (Cubbin et al., 2000a, Borrell et al., 2002). Moreover, injuries such as fall, poisoning or drowning contribute substantially to injury burden, but their associations with SES are seldom investigated. Knowledge of the safety divide for different injury causes can deepen our understanding of underlying mechanisms and pathways for prevention, thereby facilitating targeted prevention activities (Boland et al., 2005). The aim of this study was therefore to examine the association between individual and area SES and leading causes of unintentional injury mortality in Canadian adults.

Section snippets

Data

Data came from the 1991–2001 Canadian Census Mortality Follow-up Study, which linked 1991 census data to mortality data over a follow-up period of 10.6 years for 15% of the Canadian non-institutionalized population aged 25+ years at baseline (N = 2,735,152) (Wilkins et al., 2008). Ethical approval for the follow-up study was obtained from the Statistics Canada Policy Committee and the research ethics committee of the University of Toronto.

Unintentional injury deaths were identified using

Results

The cohort experienced 260,820 deaths during the study period, of which 8316 (3%) were due to unintentional injuries. Of these, 2660 involved a MVC (32%), 2993 resulted from falls (36%), 666 from poisoning (8%), 410 from drowning (5%), 372 from suffocation (4.5%) and 277 from fire/burn (3.3%). For both males and females, mortality rates for unintentional injury were higher for individuals with lower socioeconomic status or living in more deprived areas, although a clear gradient was not always

Discussion

This study showed that the association with SES differed by type of injury and indicator of SES. Associations were generally more pronounced for males. Low education was associated with an elevated risk of mortality from all-cause unintentional injury and MVC (males only) and poisoning and drowning (both sexes). Except for MVCs among males and falls among females, low income was strongly associated with injury mortality, particularly for fire/burn and poisoning. No occupation was the category

Conclusion

This study provides important information on the nature and extent of socioeconomic inequalities for unintentional injury mortality in Canadian adults. In particular, it reveals the importance of examining SES differentials by cause of death from a multilevel perspective. MVC and fall deaths were more strongly associated with SES for males than females. Poisoning, drowning, suffocation and fire/burn deaths, not commonly investigated in the literature, were found to be associated with SES in

Conflict of interest

None.

Funding

Funding for the creation of the Census Mortality Follow-up Study was provided by the Canadian Population Health Initiative.

Acknowledgement

The researchers would like to thank the Health Analysis Division of Statistics Canada for facilitating access to the Canadian Mortality Database.

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