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  • Pediatric Letter to the Editor
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Reply to Ortega et al.

International Journal of Obesity volume 35, pages 1332–1333 (2011)Cite this article

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Ortega et al.1 raise some interesting prospects for re-analysing our data set,2 which have inspired us to look at our data set again. The question Dr Ortega has asked is whether, in spite of stabilisation in the prevalence of overweight and obesity in 2–18-year-old Australian schoolchildren over the last decade or so, there have been contrary trends in children who are ‘morbidly obese’. He correctly points out that this kind of analysis can be done only with large data sets, because only a small fraction of children would be classified as ‘morbidly obese’.

The initial problem is that, unlike adults, there are no internationally accepted standards to define morbid obesity in children. The solution we have adopted is to look at body mass index (BMI) z-scores using the UK 1990 reference standard.1 About 1.3% of children and adolescents in our data set have BMI z-scores of ⩾3, and 0.3% scores of ⩾3.5; hence we have done some calculations based on both of these thresholds. These correspond reasonably well to the range of 0.1–1.3% suggested by Professor Ortega.

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Figure 1

References

  1. Ortega FB, Ruiz JR, Labayen I . Trends in the prevalence of morbid obesity in Australian children and adolescents from 1985 to 2008: what do we know about? Int J Obes 2011; e-pub ahead of print 28 June 2011; doi:10.1038/ijo.2011.127.

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  2. Olds TS, Tomkinson GR, Ferrar KE, Maher CA . Trends in the prevalence of childhood overweight and obesity in Australia between 1985 and 2008. Int J Obes (Lond) 2010; 34: 57–66.

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  3. Cole TJ, Freeman JV, Preece MA . Body mass index reference curves for the UK, 1990. Arch Dis Child 1995; 73: 25–29.

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Authors and Affiliations

  1. Health and Use of Time (HUT) Group, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia

    T Olds, G Tomkinson, K Ferrar & C Maher

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  1. T Olds
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  2. G Tomkinson
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  3. K Ferrar
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  4. C Maher
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Correspondence to T Olds.

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Olds, T., Tomkinson, G., Ferrar, K. et al. Reply to Ortega et al.. Int J Obes 35, 1332–1333 (2011). https://doi.org/10.1038/ijo.2011.128

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