Childhood obesity in Australia remains a widespread health concern that warrants population-wide prevention programs

To the Editor: We concur wholeheartedly with Gill and colleagues1 in support of recognising obesity as a public health issue, and we dispute claims that the current problem of obesity is being exaggerated.

Gill and colleagues point out that obesity trends have climbed over decades, and state that 6%–8% of Australian school children are affected.1 While this is a substantial burden of over a quarter of a million children, we also consider that restricting definitions of obese to arbitrary cutoff points may underestimate the problem, given that the entire distribution of childhood weight is increasing, not just the extreme group classified as obese. Adiposity is related to cardiovascular outcomes such as myocardial infarction and stroke in a (curvi)linear fashion. Defining obesity by arbitrary cutoff points is vulnerable to differences between sexes, ethnicity and age, and limits our understanding of obesity-related diseases.

It is well known that cardiovascular risk factors cluster, particularly the adiposity-driven components of the so-called metabolic syndrome. In the Western Australian Pregnancy Cohort (Raine) Study, we have used cluster analysis to identify a group of children at risk of future cardiovascular disease with features of the metabolic syndrome.2 The differences in characteristics are shown in the Box. The “high risk” and “low risk” cluster groups differ widely in terms of not only body mass index, the most widely used measure of obesity, but also waist circumference (a measure of central adiposity), insulin resistance, blood pressure, and levels of triglycerides, high-density lipoprotein cholesterol, total cholesterol (data not shown) and low-density lipoprotein cholesterol (data not shown). Not only the conventionally used 95% confidence intervals, but also the 99% confidence intervals do not overlap for any of these intermediate cardiovascular risk factors. We found that 29% of children were in the high-risk cluster at the age of 14 years2 and a similar analysis suggested that even at age 8 years, 25% of children were at increased risk of future obesity, cardiovascular disease and diabetes.3 C-reactive protein (CRP) level is known to be associated with future cardiovascular diseases in adults,4 and with an adverse metabolic profile in children.5 The “high risk” children had significantly higher CRP levels at the age of 14 years than their low-risk counterparts.

Certainly, the magnitude of this problem, affecting up to a third of our youth, needs to be addressed by government and health-planning bodies. We suggest our approach of cluster analysis will help identify earlier those children at substantially increased risk of cardiovascular and other adiposity-related disorders in Australia.

Features of the cluster groups with respect to components of the metabolic syndrome, showing 99% CIs*

BMI = body mass index. HOMA = homeostatic model assessment (for quantifying insulin resistance). SBP = systolic blood pressure. HDL = high-density lipoprotein cholesterol. * From Huang et al.2 Reprinted with permission from the American Diabetes Association.