Obesity paradox rethinking: Do unequal sample sizes and racial differences matter?

摘要

We recently read the report by Herrmann et al about body mass index (BMI) and its association with patients prognosis after acute myocardial infarction with great interest. According to our knowledge, in most similar previous studies, the study population was divided into 4 groups by standard categories of BMI: lean (< 18.5 or 20 kg/ m2), normal weight (18.5 or 20 to 25 kg/m2), overweight (25 to 30 kg/m2), and obese (>30 kg/m2). This grouping strategy did make sense but led to highly unequal sample sizes between groups. For example, in the report by Li et al,2 among 1,429 patients recruited, only 15 patients (0.98%) were lean and only 189 patients (13.4%) were obese. Similarly in the report by Kaneko et al,3 there were only 92 lean patients (7.6%) and 56 obese patients (4.6%) among the study population of 1,205 patients.