Validity of Self-Reported Anthropometric Values Used to Assess Body Mass Index and Estimate Obesity in Greek School Children

Department of Physical Education and Sport Science, Democritus University of Thrace, Komotini, Greece. <>
Journal of Adolescent Health (Impact Factor: 3.61). 05/2007; 40(4):305-10. DOI: 10.1016/j.jadohealth.2006.10.001
Source: PubMed


To examine the validity of self-reported values of body height and weight, used for the estimation of body mass index (BMI), as a diagnostic method for the evaluation of overweight and obesity in Greek school children.
Self-reported height and weight was recorded and then measured in 378 primary (mean age 11.4 +/- .4 years) and 298 high school students (mean age 12.5 +/- .3 years). The BMI cutoff points adopted by the International Obesity Task Force were used to compare prevalence estimates of overweight and obesity obtained from self-reported and actual measures.
Significant differences were found between self-reported and measured anthropometric indices in all subgroups, except for height in elementary school girls. The degree of self-report bias did not differ between genders; however, it was higher for high school students and heavier children, compared to elementary school pupils and lighter children, respectively. Based on self-reports, prevalence estimates were 23.1% for overweight and 4.3% for obesity, but according to measured data the corresponding rates were 28.8% and 9.5%, respectively.
The present findings imply that the observed discrepancy between self-reported and measured anthropometric data in Greek children and adolescents might lead to erroneous estimating rates of overweight and obesity. Although self-reported data are easy to obtain, health surveys of overweight and obesity in youth need valid and accurate procedures.

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    • "On the basis of the HBSC study in Wales, in which measurements were made in parallel with the questionnaire [5], the authors point out that measured data are definitely needed in order to assess the magnitude of misclassification. A study of Greek school students came to the same conclusion [10]. It is recommended that the degree of misclassification in subgroups of children and adolescents be examined more closely by a validation study. "
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    ABSTRACT: Prevalence rates for overweight and obesity based on self-reported height and weight are underestimated, whereas the prevalence rate for underweight is slightly overestimated. Therefore a correction is needed. Aim of this study is to apply correction procedures to the prevalence rates developed on basis of (self-reported and measured) data from the representative German National Health Interview and Examination Survey for Children and Adolescents (KiGGS) to (self-reported) data from the German Health Behaviour in School Aged Children (HBSC) study to determine whether correction leads to higher prevalence estimates of overweight and obesity as well as lower prevalence rates for underweight. BMI classifications based on self-reported and measured height and weight from a subsample of the KiGGS study (2,565 adolescents aged 11-15) were used to estimate two different correction formulas. The first and the second correction function are described. Furthermore, the both formulas were applied to the prevalence rates from the HBSC study (7,274 adolescents aged 11-15) which are based on self-reports collected via self-administered questionnaires. After applying the first correction function to self-reported data of the HBSC study, the prevalence rates of overweight and obesity increased from 5.5% to 7.8% (compared to 10.4% in the KiGGS study) and 2.7% to 3.8% (compared to 7.8% in the KiGGS study), respectively, whereas the corrected prevalence rates of underweight and severe underweight decreased from 8.0% to 6.7% (compared to 5.7% in the KiGGS study) and from 5.5% to 3.3% (compared to 2.4% in the KiGGS study), respectively. Application of the second correction function, which additionally considers body image, led to further slight corrections with an increase of the prevalence rates for overweight to 7.9% and for obese to 3.9%. Subjective BMI can be used to determine the prevalence of overweight and obesity among children and adolescents. Where there is evidence of bias, the prevalence estimates should be corrected using conditional probabilities that link measured and subjectively assessed BMI from a representative validation study. These corrections may be improved further by considering body image as an additional influential factor.
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    • "Third, using self-reported height and weight data may result in some inaccuracies. As shown in other studies, the use of self-reported weight and BMI tends to underestimate actual values, particularly in overweight women [48]. In addition, the self-reported weight at age 20 years relied on the mother's and the grandmother's memories, thereby increasing the risk of inaccuracy. "
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    • "Study populations of adolescents are often characterised by a substantial proportion of missing values on height and weight [2-4]. Further, weight is often under-reported [5-13] while height tends to be over-reported [5,6,8,10,12,13]. Consequently, BMI is frequently underestimated leading to misclassification as some overweight individuals are classified as being normal weight. "
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