Validity of self-reported weight and height and the body mass index within the "Pró-saúde" study

Abstract

OBJECTIVE: Evaluate the validity of self-reported weight and height and the body mass index (BMI). METHODS: A study was made of 3,713 employees of a public university in Rio de Janeiro, in which they were participants in Phase 1 of a longitudinal study. Information was obtained through a self-administered questionnaire, and measurements were carried out after its application. Student's paired t-test, Bland & Altman's graphs and the intraclass correlation coefficient (ICC) were utilized to evaluate the differences between the measured and the reported parameters. The sensitivity and specificity of the various BMI categories were estimated. RESULTS: There was high agreement between the measured and reported weights (ICC=0.977) and heights (ICC=0.943). The BMI sensitivity, in its various categories, was around 80%, and the specificity was close to 92%. There was a slight and uniform tendency toward self-reported weight underestimation and self-reported height overestimation in both sexes. CONCLUSIONS: Self-reported and measured weight and height information had good agreement and validity. In similar populations, when few resources are available, it is possible to use self-reported data instead of actual measurements.