Excess mortality estimates may be too high

Abstract

For a modeling study of excess mortality associated with higher body weight in the USA, Ward et al1 used direct standardisation to measured body-mass index (BMI) as adjustment for bias in “self-reported” BMI (calculated from self-reported weight and height). This method does not reduce systematic error in self-reported BMI and changes neither the overall misclassification rate nor the variance of the differences between self-reported and measured BMI.2 It can overestimate the prevalence of the highest BMI category.