BMI-related errors in the measurement of obesity

Body mass index (BMI) has various deficiencies as a measure of obesity, especially when the BMI measure is based on self-reported height and weight. BMI is an indirect measure of body fat compared with more direct approaches such as bioelectrical impedance. Moreover, BMI does not necessarily reflect...

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Bibliographic Details
Published in:International Journal of Obesity 2008-08, Vol.32 (S3), p.S56-S59
Main Author: Rothman, K.J
Format: Article
Language:English
Subjects:
accuracy
Adipose tissues
Age
Age Factors
Bias
body composition
Body fat
Body Mass Index
body weight
Cohort analysis
Cross-sectional studies
Diagnosis
Diagnosis, Differential
disease diagnosis
Epidemiology
Female
gender differences
Health aspects
Health Promotion and Disease Prevention
height
Humans
Impedance
Internal Medicine
literature reviews
Male
measurement
Medicine
Medicine & Public Health
men
Metabolic Diseases
Middle Aged
Obesity
Obesity - diagnosis
Obesity - mortality
original-article
Physiological aspects
Properties
Public Health
reliability
Self Disclosure
Self report
Sensitivity and Specificity
Sex Factors
temporal variation
test sensitivity
test specificity
Women
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Description
Summary:Body mass index (BMI) has various deficiencies as a measure of obesity, especially when the BMI measure is based on self-reported height and weight. BMI is an indirect measure of body fat compared with more direct approaches such as bioelectrical impedance. Moreover, BMI does not necessarily reflect the changes that occur with age. The proportion of body fat increases with age, whereas muscle mass decreases, but corresponding changes in height, weight and BMI may not reflect changes in body fat and muscle mass. Both the sensitivity and specificity of BMI have been shown to be poor. Additionally, the relation between BMI and percentage of body fat is not linear and differs for men and women. The consequences of the errors in the measurement of obesity with BMI depend on whether they are differential or nondifferential. Differential misclassification, a potentially greater problem in case-control and cross-sectional studies than in prospective cohort studies, can produce a bias toward or away from the null. Nondifferential misclassification produces a bias toward the null for a dichotomous exposure; for measures of exposure that are not dichotomous, the bias may be away from the null. In short, the use of BMI as a measure of obesity can introduce misclassification problems that may result in important bias in estimating the effects related to obesity.
ISSN:0307-0565
1476-5497
DOI:10.1038/ijo.2008.87