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Open Access Research article

Association of vitamin D status with socio-demographic factors in Calgary, Alberta: an ecological study using Census Canada data

Christopher Naugler1234*, Jianguo Zhang5, Dan Henne3, Paul Woods2 and Brenda R Hemmelgarn5

Author Affiliations

1 Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada

2 Department of Family Medicine, University of Calgary, Calgary, Alberta, Canada

3 Calgary Laboratory Services, Calgary, Alberta, Canada

4 C414, Diagnostic and Scientific Centre, 9, 3535 Research Road NW, Calgary, AB T2L 2K8, Canada

5 Department of Medicine, University of Calgary, Calgary, Alberta, Canada

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BMC Public Health 2013, 13:316  doi:10.1186/1471-2458-13-316

Published: 8 April 2013

Abstract

Background

Low 25-hydroxyvitamin D levels are a global health problem with northern countries such as Canada at particular risk. A number of sociodemographic factors have been reported to be associated with low vitamin D levels but prior studies have been limited by the ability of the researchers to gather this data directly from clinical trial participants. The purpose of this study was to use a novel methodology of inferring sociodemographic variables to evaluate the correlates of vitamin D levels in individuals dwelling in the City of Calgary, Alberta, Canada.

Methods

We utilized data on vitamin D test results from Calgary Laboratory Services between January 1 2010 and August 31 2011. In addition to vitamin D level, we recorded age, sex, and vitamin D testing month as individual-level variables. We inferred sociodemographic variables by associating results with census dissemination areas and using Census Canada data to determine immigration status, education, median household income and first nations status as clustered variables. Associations between vitamin D status and the individual- and dissemination area-specific variables were examined using the population-averaged regression model by a generalized estimating equations approach to account for the clustering in the data.

Results

158,327 individuals were included. Age, sex, month of vitamin D testing (at an individual level), and education, immigrant status, first nations status and income (at an aggregate level) were all statistically significant predictors of vitamin D status.

Conclusions

Vitamin D status was associated with a number of sociodemographic variables. Knowledge of these variables may improve targeted education and public health initiatives.

Keywords:
Vitamin D; Ecological study; Sociodemographic factors