Waist circumference-to-height ratio and body mass index for obesity classification in Irish children

Aim
Waist circumference-to-height ratio (WHt) has been proposed as an alternative measure to BMI due to its focus on central weight distribution and its basic threshold for increased cardiometabolic risk. This study aimed to compare prevalence of overweight including obesity using BMI and WHt, and assess 10-year trends of WHt prevalence, in a representative sample of Irish children.

Methods
Children measured during rounds 2–5 of the Childhood Obesity Surveillance Initiative (n = 20037) were classified as healthy weight or overweight including obesity (International Obesity Task Force age and sex BMI cut-offs), and low or high WHt (WHt ≥ 0.5). Differences in prevalence of BMI and WHt classifications were determined for round five in younger (<9 years) and older (≥9 years) children. The prevalence of high WHt was assessed across rounds.

Results
Differences in prevalence between overweight including obesity and high WHt were apparent in younger (BMI: 16.7%, WHt: 8.9%; p < .001) and older (BMI: 21.3%, WHt: 12.1%; p < .001) children. An inverse trend for prevalence of high WHt was identified across rounds (p < .001).

Conclusion
BMI overestimates overweight including obesity prevalence compared to WHt. Given its ease of use, consideration of the WHt as an additional measure in childhood surveillance and screening is warranted.