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BMI or Metabolic Syndrome Which Is More Important?
Abstract & Commentary
By Harold L. Karpman, MD, FACC, FACP, Clinical Professor of Medicine, UCLA School of Medicine. Dr. Karpman reports no financial relationship to this field of study.
Synopsis: Middle-aged men who are overweight or obese, with or without the metabolic syndrome, are at increased risk for cardiovascular events and total death.
Source: Arnlov J, et al. Impact of body mass index and the metabolic syndrome on the risk of cardiovascular disease and death in middle-aged men. Circulation 2010;121:230-236.
One of the main reasons behind the major impact of obesity on the development of cardiovascular disease (CVD) is that it is often accompanied by the metabolic syndrome (MetS), a cluster of comorbid illnesses including dyslipidemia, hyperglycemia, and hypertension.1-5 MetS is a strong predictor of future CVD and death and it should be noted that the increase in risk occurs even if only one MetS component is present.3,4 Obese individuals without MetS are sometimes referred to as the metabolically healthy obese because in two previous prospective studies the data did not appear to demonstrate an increased risk of CVD in this group;6,7 however, it is well known that an increased CV risk is present even in normal weight individuals if they are afflicted with MetS.4,6-8
Arnlov and colleagues questioned reports suggesting that overweight/obesity without MetS was not associated with a higher CV risk and they therefore decided to investigate the risk of CVD and death in middle-aged men and the associations with various combinations of body mass index (BMI) and MetS. Cardiovascular risk factors were assessed in 1758 participants without diabetes. During a median follow-up period of 30 years, 788 participants died and 681 others developed CVD (i.e., a composite of CV death or hospitalization for myocardial infarction, stroke, and/or heart failure). Participants with MetS had increased risk for CV events and total deaths regardless of BMI status during the more than 30 years of follow-up and overweight and obese individuals without MetS also had an increased risk. The data in essence refuted the notion that overweight and obesity without MetS are benign conditions.
It has been suggested that the differentiation of medically healthy obese (MHO) from metabolically impaired obese (i.e., MetS) individuals is important in determining therapeutic medical decision-making9 and, in fact, some investigators have even suggested that weight loss in MHO patients could be potentially harmful.10 However, because the data in the Arnlov study clearly demonstrate that overweight and obese individuals are at higher cardiovascular risk regardless of their metabolic status, the potential benefits of labeling overweight or obese patients as MHO in clinical practice appears to be of limited or no value. The finding that men with MetS are at higher risk for cardiovascular events regardless of their BMI status compared with normal-weight men without MetS and/or insulin resistance is in accordance with previously published longitudinal community-based data.4,6,7
In summary, the present study data did not support the suggestion that cardiovascular risk is low in the healthy obese phenotype (i.e., defined as the absence of the MetS and/or insulin resistance) and, therefore, there seems to be little question that all overweight and obese individuals are at increased cardiovascular risk and that weight reduction is desirable for all of these patients whether or not they have an associated MetS.
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