Change in body mass index in Australian primary school children, 1985–1997

Abstract

BACKGROUND: Childhood obesity is an important, potentially modi®able risk factor for a range of concurrent and later morbidities. Despite concerns about recent increases in children's body mass index (BMI), supporting data in Australia (as elsewhere) are scant. OBJECTIVE: To seek anthropometric evidence of a recent secular increase in BMI in primary school children in Victoria, Australia. DESIGN: Data from two cross-sectional population-based surveys of primary school children (the Victorian subsample of the 1985 Australian Health and Fitness Survey and the 1997 Health of Young Victorians Study) were compared. Similar strati®ed random sampling and standardized measurement methods were employed in the two studies. Subjects were all children aged 7 ± 12 y with complete height and weight data. Body mass index (BMI (weightaheight 2 )) was used as the index of relative adiposity. Non-parametric and parametric methods were used to examine the pattern and magnitude of change in BMI over the 12 y interval. RESULTS: Data for 1421 children (50% male, 68% response) from the 1985 survey and 2277 children (51% male, 75% response) from the 1997 survey were analysed. At all ages, mean height and median weight were greater in 1997 than 1985 for both boys and girls. Median BMI was signi®cantly higher in the 1997 sample for all but 12 y-old girls and for boys aged 7, 8 and 10 y (Mann ± Whitney U test). The magnitude of the overall increase in BMI was estimated using analysis of covariance for log-transformed BMI adjusted for exact age, which indicated an increase of 1.03 kgam 2 for boys and 1.04 kgam 2 for girls (both P`0.001). Plots of BMI against BMI percentile clearly showed a pattern of higher BMI at any given percentile, especially at the upper percentiles, for all ages and both genders. CONCLUSIONS: Primary school children in Victoria have become more obese over the last decade. Increases in BMI are most marked at the heavier end of the distribution. Lesser increases in median and mean BMI (con®rmed by both parametric and non-parametric statistical models) may also have major public health implications.

The development of waist circumference percentiles in British children aged 5.0–16.9 y

“…This trend is also being observed in other countries (Troiano et al, 1995;Hanley et al, 2000;Lazarus et al, 2000;Moreno et al, 2000) and childhood obesity has also been linked with increased risk of obesity in adulthood (Parsons et al, 1999) and morbidity and mortality in adults (Power et al, 1997).…”

Family and early life factors associated with changes in overweight status between ages 5 and 14 years: findings from the Mater University Study of Pregnancy and its outcomes

“…Overweight or obesity in one or both parents probably affects the risk of overweight or obesity in their offspring due to the collective effect of genetic and environmental factors within families. 11 A direct comparison of our results with those of other studies 1,23 is difficult because of differences in the birth years of the cohorts, the ages at which examinations were performed and the definition of overweight or obesity. However, our prevalence estimate of childhood and adolescence overweight or obesity using standard definitions derived from international surveys 18 is of the same magnitude as the prevalence of children and adolescents overweight or obese, estimated at 20-25%, reported by the National Health and Medical Research Council (NHMRC) 24 and, in a prospective study of Australian children, proportions of overweight including obesity in boys and girls were 13 and 18% at 5 y 25 and in the age group 7-15 y, 20% boys Changes in overweight status between ages 5 and 14 years AA Mamun et al and 20.5% girls 23 were overweight or obese.…”

Outcome data from the LEAP (Live, Eat and Play) trial: a randomized controlled trial of a primary care intervention for childhood overweight/mild obesity

“…1 In Australia, the prevalence trebled between 1985 and 1997 2,3 and has since continued to rise. 4 Concerningly, increases since the late 1990s appear greater among children of lower socioeconomic status.…”

“…Improve child nutrition and increase physical activity. 3. Quantify any harm to child functional health status, body image and/or global self-worth resulting from the intervention.…”