Tuesday, August 30, 2005

ADA statement- metabolic syndrome not a useful concept any longer

In what will be to many a surprising comment,The American Diabetes Association issued a statement challenging the value of the metabolic syndrome label. Their chief scientific and medical officer was quoted in USA-Today as saying "We don't believe there 's a syndrome"
The ADA is quoted as saying that each of the conditions that make up the syndrome are potentially life threatening but there is no evidence to suggest that someone with multiple factors is any sicker . Headlines aside, the ADA position is put forth in an ADA Statement published in Diabetes Care 28:2289-2304, 2005. It is a length and scholarly review of the subject and is worth plowing through because this clustering of cardiovascular disease (CVD) risk factors has reached "disease equivalent" status replete with a ICD-9 code and has become part of the medical vocabulary of patients as well as physicians. Here are some of the key points of the statement.
Although certain CVD risk factors are prone to cluster, there is considerable doubt as to the predictive value of the syndrome, i.e. does the syndrome impart any risk greater than its individual components.
In regard to whether metabolic syndrome is a coronary risk equivalent, the authors quote a study by Wilson et. al. which showed that when an elevated blood sugar is taken out of the definition, the 10 yr. Framingham risk does not reach the ATP III's threshold for risk
equivalent. So using the NCEP definition of Metabolic Syndrome, it matters which of the 3 out 5 criteria are present as data suggest that all combination of factors leading to the syndrome diagnosis do not convey equal risk.
There is considerable uncertainty regarding the syndrome's pathogenesis, i.e.everyone with the label-and there are various definitions proposed-may not have the putative underlying mechanism which is thought to be insulin resistance.
In short, the syndrome lacks a precise definition, is of doubtful value as a CVD marker and its underlying pathophysiology is dubious.
The ADA therefore recommends for physicians to treated all CVD risk factors per se and not label patients with the term metabolic syndrome because that may give the impression that the syndrome denotes a greater risk than its components which is a conclusion for which the evidence is not convincing. The term has been a useful paradigm to the extent that atttention was drawn to the fact that some CVD risk factors cluster in patients so predisposed and doctors need to evaluate a patient who has one major CVD risk factor for other risk factors.
The statement is likely to have wide impact as ADA is well respected and their European cohorts (European Association for the study of Diabetes) published the same statment in the journal Diabetologia.
One of the news reports mentioned the term "disease mongering" referring to drug companies' promotion of the syndrome to develop markets for its treatment. This is a concept that has received considerable interest in Australia and in the pages of the BMJ and that deserves a posting of its own at a later date.

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