Anthropometric measurements and body silhouette of women: validity and perception.

International audienceOBJECTIVE: To examine the validity of self-reported values for current anthropometric measurements and factors related to misreporting. DESIGN: E3N, a prospective cohort study of cancer risk factors, conducted in France and part of the European Prospective Investigation on Cancer. E3N comprises 100,000 women, born between 1925 and 1950, followed with self-administered questionnaires sent every 18 to 24 months starting in 1990. SUBJECTS: 152 women for the validation study of self-reported anthropometric measurements, and 91,815 women selected to evaluate factors affecting misreporting of body silhouette. STATISTICAL ANALYSIS: Paired t tests, Pearson and Spearman correlations were applied to evaluate the validity of self-reported measures, and analysis of variance and logistic regression were used to assess the factors influencing misreporting of silhouette. RESULTS: The correlation coefficients between self- and external measurements were high. All but sitting height (r = 0.56) were more than 0.80, with weight and bust (nipples) measurement correlation coefficients attaining 0.94. The correlation between body mass index (BMI), measured by the technician and the self-reported silhouette, was 0.78. Small height was always associated with misclassification. Specific factors related to a more favorable perception of body silhouette were: being overweight, small height, younger age, and a lower level of education. These women were also more frequently unmarried, more physically active, and had had a slender body shape during adolescence. Results denoting a less favorable perception of body shape were reversed. CONCLUSION/APPLICATIONS: Self-reported measurements (made with or without help) are valid measures in epidemiological studies. Body silhouettes are simple and useful indicators of body mass index. However they should be interpreted with caution in certain instances, especially for overweight subjects

[Adjustment for energy intake in the assessment of dietary risk factors]

Epidemiologic studies assessing the association between health status and nutritional factors raise the issue of adjusting for energy intake. Indeed, as most nutrients are highly correlated with energy intake which can itself be associated with disease risk, energy intake needs to be adjusted for upon assessing the effect of a specific nutrient. To avoid problems of estimation and interpretation incurred by the use of the standard method which rests on directly adjusting for energy intake, several other methods have been suggested. Namely, the density method uses the ratio of nutrient intake over total energy intake, the residual method relies on the residuals from the regression of nutrient intake on total energy intake, and the partition method fits energy from the nutrient and energy from other sources. These methods yield estimates of different effects but do not allow direct estimation of specific nutrient effects. Estimated effects combine specific and generic energy effects of nutrients and reflect effects of adding or substituting one nutrient for another. We review and apply these methods to the assessment of the association between protein intake and colorectal adenoma occurrence in the E3N-EPIC cohort. This example illustrates how considering findings from all of these methods rather than one single method can lead to a more in-depth understanding of such associations and provide useful guidance for nutritional recommendations