Using routine growth data to determine overweight and obesity prevalence estimates in preschool children in the capital health region of Alberta

Background: Overweight and obesity prevalence is increasing in Canadian children. In the Capital Health region of Alberta, there is a need to examine this public health issue and implement strategies to overcome it. Two growth references, one provided by the US Centers for Disease Control and Prevention (CDC), and the other by the International Obesity Task Force (IOTF), are available to assess individuals and screen populations for overweight and obesity. The prevalence can vary as a function of the reference used. The primary objective of this study is to determine prevalence estimates of overweight and obesity in 4-6 year olds in the Capital Health region. The secondary objective is to explore differences in estimates using both classification systems. Methods: Anthropometric measurements were incorporated into regular preschool immunization visits. Body Mass Index (BMI), defined as the bodyweight in kilograms divided by height in metres squared was calculated for each record and percentiles for age and sex were determined using cut-offs from the IOTF and CDC. The prevalence estimates of overweight and obesity using both classification systems were determined and compared. Results: Out of 7,369 children, 13.8% were overweight and 11.4% were obese according to the CDC reference. The IOTF reference classified 11.5% as overweight and 6.8% as obese. The two reference systems had moderate agreement (kappa 0.69, p<0.01). Conclusion: The results indicate a lower prevalence estimate of overweight and obesity among young children in the Capital Health region compared to other parts of Canada. The IOTF reference provides more conservative estimates than the CDC reference, accounted for more by the difference in estimates of obesity than by the difference in estimates for overweight.