More Evidence Against Concept of Metabolic Syndrome

[Guest guest]

Patients with metabolic syndrome are no more at risk of future MI than those

with diabetes or hypertension alone, a new study suggests [1].

The study, published in the May 25, 2010 issue of the *Journal of the

American College of Cardiology*, was conducted by a group led by *Dr

Mente* (McMaster University, Hamilton, ON).

Mente commented to *heartwire *: " Our study examined whether we need to look

at metabolic syndrome as a distinct entity or whether we should instead be

focusing on the individual risk factors, and we found that the individual

risk-factor approach is probably best. The results strongly suggest that we

should be treating the individual risk factors rather than metabolic

syndrome. "

n the paper, the researchers explain that the common clustering of metabolic

abnormalities, including abdominal obesity, elevated glucose, abnormal

lipids, and elevated blood pressure is often referred to as the metabolic

syndrome. While metabolic syndrome is associated with an increased risk of

coronary heart disease, it is not known whether this risk is greater than

that conferred by its constituent components, and the value of classifying

subjects with metabolic syndrome has recently been called into question.

To investigate this issue, Mente et al analyzed data from the

*INTERHEART*study, a case-control study of incident acute MI that

involved 12 297 cases

and 14 606 controls from 52 countries. They classified the study

participants using the *World Health Organization* (WHO) and *International

Diabetes Federation* (IDF) criteria for metabolic syndrome, and their risks

for MI were compared with the individual metabolic-syndrome component

factors. Results showed that metabolic syndrome was associated with a two-

to three-times increased risk of MI, but the same risk was conferred by

having either hypertension or diabetes alone.

*Adjusted Odds Ratio for MI Associated With Metabolic Syndrome or Its

Component Factors*

*Risk factor * *OR (95% CI) * *Metabolic syndrome (WHO definition)* 2.69

(2.45–2.95) *Metabolic syndrome (IDF definition)* 2.20 (2.03-2.38) *Diabetes

* 2.72 (2.53–2.92) *Hypertension * 2.60 (2.46–2.76) *Abdominal obesity

(WHO definition)* 1.64 (1.55–1.74) *Abdominal obesity (IDF definition)* 1.32

(1.25–1.39) *Low HDL * 1.30 (1.22–1.37)

Mente noted: " People who advocate for the metabolic syndrome concept believe

that when the component risk factors occur together this would have an

additive or greater effect on risk, and therefore it is important to

identify these individuals. But we didn't find that. So our study adds to

the evidence that a diagnosis of metabolic syndrome is not useful. It is

better just to treat the actual risk factors. "

The researchers also looked at subthreshold values for the risk factors

making up the metabolic syndrome--ie, levels higher than normal but below

the levels that define diabetes, hypertension, low HDL or abdominal obesity.

They found that there appeared to be a dose-response relationship between MI

and risk-factor measures, and an aggregation of risk factors with values

below their threshold was associated with a significantly greater risk of

MI, compared with having component factors with normal values (OR 1.5), but

lower than the risk conferred by an aggregation of risk factors with values

above the threshold points.

They write: " These findings of a dose-response relationship between

risk-factor severity and MI risk suggest that a standard definition of

metabolic syndrome loses information when continuous variables are converted

to categorical variables and provide support for calls to replace the

categorical definition of metabolic syndrome with a scoring system that may

involve each risk factor being assigned a weight based on its level and a

regression formula developed to estimate risk. "

To *heartwire *, Mente added: " This is another knock against the diagnosis

of metabolic syndrome. It is not a case of 'Yes, you are at increased risk'

or " No, you are not at increased risk.' Risk increases incrementally, and if

we use the definition of metabolic syndrome, we would not catch any of the

patients with these subthreshold increases in risk factors. "

Asked whether there is now enough evidence to do away with the concept of

metabolic syndrome, Mente replied: " We are seeing a little more evidence

with each study. It gets to a point where the evidence becomes overwhelming.

It is hard to say if we are there yet. Our findings are consistent with at

least a couple of other studies, and, yes, in my opinion this should be the

end of the metabolic syndrome. But there might be some who disagree. "

*This study was supported by the Canadian Institutes of Health Research, the

Heart and Stroke Foundation of Ontario, the International Clinical

Epidemiology Network, and unrestricted grants from several pharmaceutical

companies (with major contributions from AstraZeneca, Novartis, Hoechst

n Roussel [now Sanofi-Aventis], Knoll Pharmaceuticals [now Abbott],

Bristol-Myers Squibb, and Sanofi-Synthélabo). The authors do not report any

other disclosures.*

--

Ortiz, MS, RD

" I plan on living forever - so far so good "

" Cause of obesity, heart disease and cancer: Look at the end of your fork "