Correction of the self-reported BMI in a teenage population.
OBJECTIVE
To investigate the issue of systematic bias in self-reported weight and height, and produce a simple procedure which can be used to correct reporting bias.


METHODS
Cross-sectional, with self-reported questionnaires.


METHODS
A sub-sample (n = 143) of secondary school students in Siena, Italy, taken from the Food Behaviour Survey (sample size, n = 779).


RESULTS
In the teenage sub-sample, both males and females under-reported their weight and over-reported their height, such that underestimation of the overweight prevalence was in the order of about 8% for both genders. For both weight and height, the correlations between self-reported and measured values were over 0.90. Conversion factors were derived to correct the reported body mass index (BMI) distribution by adjusting the percentages of erroneously classified subjects in the four BMI categories.


CONCLUSIONS
High correlation coefficients (r > or = 0.75), showing a systematic tendency for erroneous self-reporting of a 'slim-body shape', justify the use of conversion factors (measured/self-reported) to correct BMI distributions calculated from self-reported values.
Dpt. Scienze Medico-Legali e Socio-Sanitarie, Università di Siena, Italy.
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Giacchi
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Mattei
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Rossi
D000293:Adolescent; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D003430:Cross-Sectional Studies; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D007558:Italy; D008297:Male; D012649:Self Concept; D011795:Surveys and Questionnaires