Abstract
Objectives
The aims of this study were to examine (1) the concordance between income measured at the individual and area-based level and (2) the impact of using each measure of income on inequality estimates for three health indicators—the prevalence, respectively, of diabetes, smoking, and obesity.
Methods
Data for the health indicators and individual income among adults came from six cycles of the Canadian Community Health Survey (cycles 2003 through 2013). Area-based income was obtained by linking respondents’ residential postal codes to neighbourhood income quintiles derived from the 2006 Canadian census. Relative and absolute inequality between the lowest and highest income quintiles for each measure was assessed using rate ratios and rate differences, respectively.
Results
Concordance between the two income measures was poor in the overall sample (weighted Kappa estimates ranged from 0.19 to 0.21 for all years), and for the subset of participants reporting diabetes, smoking, or obesity. Despite the poor concordance, both individual and area-based income measures identified generally comparable levels of relative and absolute inequality in the rates of diabetes, smoking, and obesity over the 10-year study period.
Conclusion
The results of this study show that individual and area-based income measures categorize Canadians differently according to income quintile, yet both measures reveal striking income-related inequalities in rates of diabetes and smoking, and obesity among women. This suggests that either individual or area-level measures can be used to monitor income-related health inequalities in Canada; however, whenever possible, it is informative to consider both measures since they likely represent distinct social constructs.
Résumé
Objectifs
Examiner (1) la concordance entre le revenu personnel et régional et (2) l’incidence de l’utilisation de chaque indicateur du revenu sur les estimations des inégalités pour trois indicateurs de la santé, soit la prévalence, respectivement, du diabète, du tabagisme et de l’obésité.
Méthode
Les données des indicateurs de la santé et du revenu personnel chez les adultes proviennent de six cycles (2003 à 2013) de l’Enquête sur la santé dans les collectivités canadiennes. Le revenu régional a été obtenu en maillant les codes postaux de résidence des répondants aux quintiles de revenu selon le quartier dérivés du Recensement du Canada de 2006. Les inégalités relatives et absolues entre les quintiles de revenu inférieur et supérieur pour chaque indicateur ont été évaluées par les rapports de taux et les différences de taux, respectivement.
Résultats
La concordance entre les deux indicateurs du revenu est faible dans l’échantillon global (le coefficient kappa pondéré est de 0,19 à 0,21 pour toutes les années) et pour le sous-ensemble de participants ayant fait état de diabète, de tabagisme ou d’obésité. Malgré cette faible concordance, les indicateurs du revenu personnel et régional révèlent des niveaux généralement comparables d’inégalités relatives et absolues dans les taux de diabète, de tabagisme et d’obésité sur les 10 ans de l’étude.
Conclusion
Les résultats de l’étude montrent que les indicateurs du revenu personnel et régional classent les Canadiens différemment selon le quintile de revenu, mais que les deux indicateurs révèlent des inégalités marquantes liées au revenu dans les taux de diabète et de tabagisme, et chez les femmes, dans les taux d’obésité. L’indicateur personnel ou l’indicateur régional peuvent donc l’un et l’autre être utilisés pour surveiller les inégalités de santé liées au revenu au Canada; dans la mesure du possible, il est toutefois instructif de les utiliser tous les deux, car ils représentent probablement des constructions sociales distinctes.
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Pichora, E., Polsky, J.Y., Catley, C. et al. Comparing individual and area-based income measures: impact on analysis of inequality in smoking, obesity, and diabetes rates in Canadians 2003–2013. Can J Public Health 109, 410–418 (2018). https://doi.org/10.17269/s41997-018-0062-5
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DOI: https://doi.org/10.17269/s41997-018-0062-5