30-year cross-sectional trends in waist-to-height ratio in Australian school age children; 1985 to 2015

Abstract

Aim: To report 30-year changes in the proportion of children with abdominal obesity measured by waist-to-height ratio (WHtR) ≥ 0.5.

Methods: Secondary analysis of WHtR ≥ 0.5 data on Australian children age 7 to 15 years from five national cross-sectional population surveys conducted in 1985, 1995, 2007, 2012 and 2015. Changes in the proportions of children with a WHtR ≥ 0.5 across survey years, by age and sex were assessed using chi-squared tests.

Results: Between 1985 and 2012, the proportion of children with WHtR ≥ 0.5 increased from 8.6% [95%CI: 8.0, 9.2] to 25.1% [95%CI: 23.5, 26.7]. An increase of ~5% each decade was observed between 1985 and 2007, and a 6.6% increase was observed between 2007 and 2012. Overall, there was a non-significant decrease in the proportion of children with WHtR ≥ 0.5 between 2012 (25.1% [95%CI: 23.5, 26.7] and 2015 (23.3% [95%CI: 21.6, 25.2].

Conclusion: Abdominal obesity has increased over the last 30 years in Australian children. In 2015, one in five children had WHtR ≥ 0.5, a marker of cardiometabolic risk in children. Our finding highlights the importance of including WHtR as a routine measurement in primary health care and population health surveys. This information is needed to guide policy and practice to manage long-term cardiovascular risk in children.

Keywords: Child health; Childhood obesity; Cross-sectional survey; Prevalence; Surveillance; Waist-to-height ratio.