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Canadian Journal of Public Health

, Volume 95, Issue 2, pp 90–94 | Cite as

Ecologic Proxies for Household Income

How Well Do They Work for the Analysis of Health and Health Care Utilization?
  • Murray M. Finkelstein
Article

Abstract

Background

Researchers often use census-derived measures of socioeconomic status (SES) when personal information is not available. Theory predicts that the resulting misclassification will blunt associations between outcomes and SES and that control for confounding by SES will be less effective. The purpose of this paper was to examine the magnitude of this problem using data from the National Population Health Survey (NPHS).

Methods

Subjects were 4,037 respondents to the NPHS who were linked to the Ontario Health Insurance Plan. An ecologic measure of income was obtained by linkage of subjects’ postal codes to the Census.

Results

The relationships between the ecologic-level measure and health outcomes or health services utilization were attenuated in comparison to the relationships relative to the direct measure of household income. The ecologic measure also produced poorer control for confounding by income in the analysis of other health relationships.

Conclusions

Many interesting public health and health services questions can be addressed only with the use of ecologic level socioeconomic information. While most of the results were qualitatively similar when the direct and ecologic measures were compared, researchers and users of research findings should be aware that attenuated or potentially misleading findings may result from the use of these methods.

Résumé

Contexte

En l’absence de données d’identification, les chercheurs utilisent souvent des mesures du statut socio-économique (SSE) dérivées du recensement. En théorie, les erreurs de classement qui pourraient en résulter devraient émousser les associations entre les résultats et le SSE, et il devrait être plus difficile de tenir compte du facteur confusionnel que représente le SSE. Nous avons donc voulu étudier l’ampleur du problème à l’aide des données de l’Enquête nationale sur la santé de la population (ENSP).

Méthode

Nos sujets étaient les 4 037 répondants de l’ENSP reliés au Régime d’assurance-maladie de l’Ontario. Nous avons obtenu une mesure „écologique” [liée au milieu de vie] du revenu des sujets en reliant leurs codes postaux aux données du recensement.

Résultats

Les relations entre la mesure écologique et les résultats sanitaires ou le recours aux services de santé étaient atténuées par rapport aux relations obtenues par la mesure directe du revenu des ménages. En outre, la mesure écologique a moins bien permis de tenir compte du facteur confusionnel que représente le revenu dans l’analyse des autres relations touchant la santé.

Conclusions

Beaucoup de questions intéressantes sur la santé publique et les services de santé ne peuvent être étudiées qu’en employant une information socio-économique à l’échelle écologique. Bien que l’on obtienne des résultats semblables, du point de vue qualitatif, que l’on utilise des mesures directes ou écologiques, il est bon que les chercheurs et les utilisateurs des résultats de recherche sachent que ces méthodes peuvent mener à des constatations atténuées ou potentiellement trompeuses.

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Copyright information

© The Canadian Public Health Association 2004

Authors and Affiliations

  1. 1.Family Medicine CentreMt Sinai HospitalTorontoCanada
  2. 2.Department of Family MedicineMcMaster UniversityHamiltonCanada
  3. 3.Department of Family and Community MedicineUniversity of TorontoCanada

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