Metabolic Syndrome Increases Cardiovascular Disease Risk

Source: Tufts University
January 17, 2003 (Reviewed: January 21, 2005)

Recent research has associated "metabolic syndrome" - a set of concurrent and interrelated symptoms including dyslipidemia, insulin resistance, hypertension, and abdominal obesity - with increased risk for cardiovascular disease (CVD) and type 2 diabetes. Now a new study finds that middle-aged men with the syndrome are more likely to develop CVD or coronary heart disease (CHD) or to die from any cause compared with men without the syndrome. The results are published in the Journal of the American Medical Association.

Measuring health indicators

Researchers studied a cohort of 1209 Finnish men who, at baseline, were between the ages of 42 and 60 and had no history of CVD, cancer, or diabetes. They obtained data on potential cardiovascular risk factors, including age, BMI, waist circumference and waist-to-hip ratio, smoking status, blood pressure, blood lipids, blood glucose, and insulin metabolism. They then tracked the cases of CVD, CHD, and death that occurred during approximately 11 years of follow up.

Defining the metabolic syndrome

The researchers made associations between the presence of the metabolic syndrome and the CVD risk using two different (but similar) definitions of metabolic syndrome.

The National Cholesterol Education Program's (NCEP) definition of metabolic syndrome includes the presence of three or more of the following criteria:

• Fasting plasma glucose >/= 110 mg/dL (6.1 mmol/L)
• Serum triglycerides >/= 150 mg/dL (1.7 mmol/L)
• Serum HDL cholesterol < 40 mg/dL (1.04 mmol/L)
• Blood pressure >/= 130/85 mm Hg
• Waist girth > 102 cm (40 inches), or >94 cm (37 inches) in men genetically susceptible to insulin resistance

The definition of the World Health Organization (WHO) includes hyperinsulinemia or elevated fasting blood sugar (defined as a fasting blood glucose of 101-109 mg/dL [5.6-6.0 mmol/L]), along with two or more of the following criteria:

• Abdominal obesity
• Dyslipidemia
• Hypertension

Associating the syndrome with CVD risk

At the end of an 11-year follow-up period, there had been 109 deaths (46 from CVD and 27 from coronary heart disease).

After adjustment for potential confounders, both the NCEP- and WHO-defined metabolic syndrome were associated with an almost 3-fold greater risk of death from CHD (relative risk, or RR=2.9; 95% CI, 1.2-7.2 by NCEP standards; RR=2.9; 95% CI, 1.2-6.8 by WHO standards).

Men with metabolic syndrome (WHO-defined) had a 2.6 (95% CI, 1.4-5.1) to 3.0 (95% CI, 1.5-5.7) times higher risk of CVD mortality and a 1.9 (95% CI, 1.2-3.0) to 2.1 (95% CI, 1.3-3.3) times higher risk of all-cause mortality than men without metabolic syndrome.

While the prospective design of this study is one of its strengths, it is limited by the relatively small, homogeneous study population, so the results are not necessarily applicable to other gender, age, or ethnic groups.

Practical implications

As the causes and effects of the metabolic syndrome continue to be investigated, this study adds to a growing body of evidence that the cluster of symptoms that comprise the syndrome increases the risk of CVD as well as mortality. Based on prior research, the authors suggest that even "modest lifestyle modifications", including weight loss and regular physical activity, may "favorably affect components of the metabolic syndrome", and they say that randomized controlled trials of the effects of such lifestyle interventions on the metabolic syndrome are necessary.

They also point out that early intervention may be particularly important, because the men in this study with the metabolic syndrome and its associated increased risk for CVD, CHD, and mortality did not have baseline CVD or diabetes.

With obesity and heart disease remaining major public health problems in many developed as well as developing countries, individual and community-wide efforts to change health behaviors are vital. Perhaps the most important message for patients is that even small reductions in body weight and increases in physical activity may have significant benefits in both the short term and the long run.

Source

• The metabolic syndrome and total and cardiovascular disease mortality in middle-aged men. H-M. Lakka, DE. Laaksonen, TA. Lakka,  et al., JAMA, 2002, vol. 288, pp. 2709--2716

Related Links
Is There a Syndrome X Epidemic?
The Metabolic Syndrome: Time for Action!
Exercise: How Much and What Type to Prevent Heart Disease?
Excess Weight Adds Health Problems
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