Canadian Childhood Obesity Estimates Based on WHO, IOTF and CDC Cut-points

Objective: This article compares prevalence estimates of excess weight among Canadian children and youth according to three sets of body mass index (BMI) reference cut-points. The cut-points are based on growth curves generated by the World Health Organization (WHO), the International Obesity Task Force (IOTF), and the US Centers for Disease Control (CDC). A secondary objective is to compare estimates by method of data collection.

Methods: Prevalence estimates of overweight and obesity were produced for 2- to 17-year-olds using the three sets of BMI cut-points. Estimates are based on data from 8 661 respondents from the 2004 Canadian Community Health Survey and 1 840 respondents from the 1978/79 Canada Health Survey. In both surveys, the height and weight of children were measured.

Results: The 2004 prevalence estimate for the combined overweight/obese category is higher (35%) when based on the WHO cut-points compared with the IOTF (26%) or CDC (28%) cut-points. Estimates of the prevalence of obesity are similar based on WHO and CDC cut-points (13%), but lower when based on IOTF cut-points (8%). Absolute differences in excess weight estimates between 1978/79 and 2004 are similar based on the three sets of cut-points, but the relative increase is greater when based on the IOTF cut-points. Estimates vary substantially by method of data collection.

Conclusion: When interpreting prevalence estimates of overweight and obesity for children and youth, it is important to consider the definitions used and the method of data collection.