Commentary: Obesity and cardiovascular disease risk among the young and old—is BMI the wrong benchmark?

Abstract

The positive relationship between body mass index (BMI) and cardiovascular disease (CVD) mortality has been reported from analyses of data from many large prospective cohort studies.^1–5 There is less agreement, however, as to the shape of the curve¹ and to what degree the risk of mortality from CVD increases with greater BMI. This has also led to a debate on the proper epidemiological methods for analysis and on the optimal BMI range for lowest risk. The reference category of lowest risk should ideally be defined in a population free of existing disease since clinical and pre-clinical disease can cause weight loss and bias rates of CVD upwards in lower BMI categories. The lowest risk group should also be defined among non-smokers because smoking-induced weight loss can again artificially inflate the rates of CVD among lower BMI categories. These methodological issues have been carefully addressed in most prospective studies, including the study by Park et al.⁶ in this issue of the Journal. What has not previously been described as carefully is the extent to which the relationship between BMI and CVD mortality is modified by age.