Abstract
This study examines trends in socioeconomic-related inequalities in obesity risk among Canadian adults (aged 18–65 years) from 2000 to 2010 using five nationally representative Canadian Community Health Surveys (CCHSs). We employed the concentration index (C) to quantify the socioeconomic inequalities in obesity risk across different demographic groups and geographic regions in each survey period. A decomposition analysis of inequality is performed to determine factors that lie behind income-related inequality in obesity risk. Although declining over time, the results show that there exists income-related inequality in obesity risk in Canada. The estimated Cs for men indicate that obesity is concentrated among the rich and its trend is increasing over time. The findings, however, suggest that obesity is more prevalent among economically disadvantaged women. While we found that obesity is mainly concentrated among the poor in the Atlantic Provinces, the degree of socioeconomic related inequality in obesity risk is increasing in these provinces. The results for Alberta showed that obesity is concentrated among the better-off individuals. The decomposition analysis suggests that factors such as demographics, income, immigration, education, drinking habits, and physical activity are the key factors explaining income-related inequality in obesity risk in Canada. Our empirical findings suggest that, in order to combat the obesity epidemic, health policies should focus on poorer females and economically well-off males.
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Notes
We utilized restricted micro-level datasets and employed sampling weights in order to obtain estimates that are representative of the general Canadian population.
Erreygers [44] also proposed a corrected version of the concentration index as: \( \frac{{ 4 {{\upmu}}}}{{{\text{b}} - {\text{a}}}}{\text{C}} \), where, b and a are upper and lower limits of the health variable, respectively. We obtained similar results using the Erreygers’ correction in the calculation of Cs.
Application of the correction factor to the calculation of the C index increased the absolute value of the C, but it did not change the overall trends in socioeconomic inequalities in obesity risk that we found without applying the correction factor.
Similar to other studies in the literature (e.g., [45, 46, 71]), based on large population-based data, the overall explanatory power of our model was low, with R-squared values of 0.0501 (2000/2001) and 0.0616 (2009/2010). This indicates that individual level factors generally explain very small variation in obesity prevalence.
We also performed the decomposition analysis using separate age (continuous variable) and gender (male dummy) variables in the regression. As expected, the results showed that age and being male are both associated with higher probability of being obese in Canada. Also, the total contribution of age and gender factors to income-related inequality in obesity risk was identical in both models.
Detailed decomposition results with the exclusion of behavioral variables are available upon request.
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Acknowledgments
We thank three anonymous reviewers of this journal for their thoughtful comments and suggestion which have substantially improved the manuscript. We would also like to thank comments of participants of the 46th Annual Conference of the Canadian Economics Association held at the University of Calgary, June 7-10, 2012, where a preliminary version of this paper was presented. Funding for this research by the Canadian Institutes of Health Research (CIHR) operating grant (reference number: MOP–97763) is gratefully acknowledged. The views expressed in this paper are the views of the authors and do not necessarily reflect the views of any affiliated organization.
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Hajizadeh, M., Karen Campbell, M. & Sarma, S. Socioeconomic inequalities in adult obesity risk in Canada: trends and decomposition analyses. Eur J Health Econ 15, 203–221 (2014). https://doi.org/10.1007/s10198-013-0469-0
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DOI: https://doi.org/10.1007/s10198-013-0469-0