Divergent body mass index trajectories between Aboriginal and non-Aboriginal Canadians 1994-2009--an exploration of age, period, and cohort effects

Am J Hum Biol. Mar-Apr 2012;24(2):170-6. doi: 10.1002/ajhb.22216. Epub 2012 Jan 24.

Abstract

Objectives: Aboriginal Canadians have a high burden of obesity and obesity-related chronic conditions. Body mass index (BMI) trajectories from 1994 to 2009 were estimated for Aboriginal and non-Aboriginal Canadians using self-reported height and weight data from the National Population Health Survey to explore age, period, and cohort effects of BMI change.

Methods: Linear growth curve models were estimated for 311 Aboriginal and 10,967 non-Aboriginal respondents divided into five birth cohorts born in the 1940s, 50s, 60s, 70s, and 80s.

Results: Overall, Aboriginal Canadians experienced higher rates of BMI increase over the 14-year period. Rate of BMI increase was specifically higher for Aboriginal adults born in the 1960s and 1970s when compared with non-Aboriginal adults. At ages 25, 35, and 45, recent-born cohorts had consistently higher BMIs compared with earlier-born cohorts with magnitudes of differences typically larger in the Aboriginal population. Recent-born cohorts also exhibited steeper BMI trajectories.

Conclusions: Cohort effects may be responsible for the divergent BMI trajectories between Aboriginal and non-Aboriginal Canadians born in the 1960s and 1970s. Aboriginal Canadians, particularly of more recent-born cohorts, experienced faster increases in BMI from 1994 to 2009 than non-Aboriginal Canadians, suggesting that prevalence of obesity will continue to rise in this population without intervention.

MeSH terms

  • Adult
  • Body Mass Index*
  • Canada / epidemiology
  • Cohort Effect
  • Cohort Studies
  • Female
  • Humans
  • Linear Models
  • Longitudinal Studies
  • Obesity / ethnology*
  • Population Groups*
  • Prevalence