Asthma, type 1 and type 2 diabetes mellitus, and inflammatory bowel disease amongst South Asian immigrants to Canada and their children: a population-based cohort study

PLoS One. 2015 Apr 7;10(4):e0123599. doi: 10.1371/journal.pone.0123599. eCollection 2015.

Abstract

Background: There is a high and rising rate of immune-mediated diseases in the Western world. Immigrants from South Asia have been reported to be at higher risk upon arrival to the West. We determined the risk of immune-mediated diseases in South Asian and other immigrants to Ontario, Canada, and their Ontario-born children.

Methods: Population-based cohorts of patients with asthma, type 1 diabetes (T1DM), type 2 diabetes (T2DM), and inflammatory bowel disease (IBD) were derived from health administrative data. We determined the standardized incidence, and the adjusted risk of these diseases in immigrants from South Asia, immigrants from other regions, compared with non-immigrant residents of Ontario. The risk of these diseases in the Ontario-born children of immigrants were compared to the children of non-immigrants.

Results: Compared to non-immigrants, adults from South Asia had higher risk of asthma (IRR 1.56, 95%CI 1.51-1.61) and T2DM (IRR 2.59, 95%CI 2.53-2.65). Adults from South Asia had lower incidence of IBD than non-immigrants (IRR 0.32, 95%CI 0.22-0.49), as did immigrants from other regions (IRR 0.29, 95%CI 0.20-0.42). Compared to non-immigrant children, the incidence of asthma (IRR 0.66, 95%CI 0.62-0.71) and IBD (IRR 0.47, 95%CI 0.33-0.67) was low amongst immigrant children from South Asia. However, the risk in Ontario-born children of South Asian immigrants relative to the children of non-immigrants was higher for asthma (IRR 1.75, 95%CI 1.69-1.81) and less attenuated for IBD (IRR 0.90, 95%CI 0.65-1.22).

Conclusion: Early-life environmental exposures may trigger a genetic predisposition to the development of asthma and IBD in South Asian immigrants and their Canada-born children.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Asia / epidemiology
  • Asian People
  • Asthma / epidemiology*
  • Diabetes Mellitus, Type 1 / epidemiology*
  • Diabetes Mellitus, Type 2 / epidemiology*
  • Emigrants and Immigrants / statistics & numerical data*
  • Female
  • Humans
  • Incidence
  • Inflammatory Bowel Diseases / epidemiology*
  • Male
  • Middle Aged
  • Ontario / epidemiology
  • Retrospective Studies
  • Risk Factors
  • Young Adult

Grants and funding

Funding from: (1) Ontario Ministry of Health and Long-Term Care Academic Health Sciences Centre Alternate Funding Plan Innovation Fund. The funders had no role in the study design or conduct, interpretation of the results, or authorship of the manuscript. Researchers were considered independent from the funders. (2) Faculty of Medicine, University of Toronto. The funders had no role in the study design or conduct, interpretation of the results, or authorship of the manuscript. Researchers were considered independent from the funders.