The age and sex specific percentiles primarily serve to demarcate the categories underweight, normal weight, overweight, and obesity. This definition is based on the statistical distribution of a reference population. The percentiles reflect an orientation along weight development in individuals or trends in a population. They are therefore relevant for estimating and comparing prevalence rates at the population level. If body mass index measurements in a population increase, then the reference data lose their representativeness. Prevalence data for overweight and obesity drop as a result. This has to be taken into consideration when discussing suitable reference values. For adults, the threshold values that apply are based on risk probabilities for morbidity and mortality. Because of the low incidence of obesity dependent disorders and in the absence of appropriate longitudinal studies of the health risk of obesity in children and adolescents, there are no threshold values for the amount of the body fat mass that is associated with health risk for this age group (1). In the guidelines on obesity in childhood and adolescence, it is recommended, with regard to threshold values, to characterize as "noticable" and "very noticable", respectively, if the 90th and 97th percentile are exceeded (1). To determine threshold values for overweight in children, intensive research with clearly defined end points, a long period of observation, and large cohort is required. Internationally, individual epidemiological studies have been conducted in children and adolescents with regard to the association of obesity and morbidity in adulthood. In Germany, current data are available from the KiGGS survey and from the Kiel Adipositas Prevention Study as a long term observational study. Using the results of these studies and expanding on these in the sense of further observation of a KiGGS cohort would enable for more profound questioning of overweight as a risk factor for subsequent disorders (2).
Footnotes
Conflict of interest statement
The authors of both letters declare that no conflict of interest exists according to the guidelines of the International Committee of Medical Journal Editors.
References
- 1. www.a-g-a.de
- 2.Kurth BM, Schaffrath Rosario A. Die Verbreitung von Übergewicht und Adipositas bei Kindern und Jugendlichen in Deutschland. Ergebnisse des bundesweiten Kinder- und Jugendgesundheitssurveys (KIGGS) Bundesgesundheitsbl - Gesundheitsforsch - Gesundheitsschutz. 2007;50:736–743. doi: 10.1007/s00103-007-0235-5. [DOI] [PubMed] [Google Scholar]
- 3.Weber E, Hiebl A, Storr U. Overweight and obesity in children starting school in Augsburg—prevalence and influencing factors. Dtsch Arztebl Int. 2008;105(51-52):883–889. doi: 10.3238/arztebl.2008.0883. [DOI] [PMC free article] [PubMed] [Google Scholar]