Associations Between Cardio-Metabolic Risk Factors and Weight Status Among Canadian Children and Adolescents Using the Canadian Health Measures Survey

Abstract

Objectives: This thesis examines the risks among Canadian children and adolescents for developing cardio-metabolic diseases, extending evidence that is well-established for adults to pediatric populations. As well, novel indicators and cut-offs for the measurements of disease risks are proposed and associations between physical activity, weight status, socio-economic status and cardio-metabolic health are examined. Methodology: Secondary data analysis was conducted using data from three cycles of the Canadian Health Measures Survey (CHMS), a nationally representative data set which includes measured anthropometric characteristics. A population health approach was applied throughout, underpinned by the World Health Organization’s Conceptual Framework for Action on the Social Determinants of Health. The thesis was designed such that a series of four manuscripts successively built on the key findings from each previous research paper: 1. Establishing the prevalence of Metabolic Syndrome and its risk factors for 10-18 year olds using the International Diabetes Federation child, adolescent and adult definitions. 2. Estimating pre-obesity epidemic waist circumference reference values for Canadian children 6-10 years using reference data from the 1981 Canada Fitness Survey, the Third National Health and Nutrition Examination Survey (1988-1994), and the CHMS through regression of linear, logarithmic and quadratic functions. This work facilitated an expanded age range for the subsequent projects as age- and sex-specific cut-offs based on a Canadian population prior to the obesity epidemic had not been available. 3. Cardio-metabolic risk by body mass index (BMI), waist circumference (WC), and a combined BMI-WC indicator quantified the associations between a dichotomous cardio-metabolic risk variable, and obesity, using three indicators of obesity including a novel indicator, for ages 6-18 years. 4. Association between cardio-metabolic risk and inflammation quantified the associations between inflammation, using high-sensitivity c-reactive protein (CRP) as a marker, and cardio-metabolic risk to determine if high CRP was a significant predictor of cardiometabolic risk among 6-18 year olds. Results: For Paper 1 (n=1228), only 2.1% were classified as having the Mets though 38% had at least 1 MetS risk factor. For Paper 2, logarithmic regression predicted WC cut-offs with the lowest degree of error. For Paper 3 (n=2678), 35% were classified as having cardio-metabolic risk with significantly higher levels among those classified as obese and/or having a low level of physical activity. All indicators of obesity had significant associations with cardio-metabolic risk. For Paper 4 (n=1831), 43.6% of children and 62.0% of adolescents with high CRP levels were classified as having cardio-metabolic risk, a significant relationship. Participants from households with moderate to high income and/or education had the lowest prevalence of MetS risk factors and abdominal obesity. Conclusions: High CRP is a useful indicator of cardio-metabolic risk for pediatric populations. With further research, novel combinations of BMI and WC may be shown to be more predictive for cardio-metabolic risk than these indicators individually. The substantial prevalence of multiple risk factors which predict premature onset of chronic disease foreshadows potential years of morbidity in adulthood for Canada’s youth population.