Issue 170 Item 13 Metabolic Syndrome Predicts Coronary Heart Disease And Type 2

New defintion for metabolic syndrome consists of five easily measured variables linked to insulin reststance.

The definition of metabolic syndrome recently proposed by the National Cholesterol Education Program (NCEP) incorporates thresholds for five easily measured variables linked to insulin resistance. Individuals with values exceeding the predefined thresholds for any three variables are considered to be at increased risk for CHD and type 2 diabetes.

Naveed Sattar, MD, and colleagues, the Glasgow Royal Infirmary, Glasgow, evaluated the predictive power of the NCEP definition using data from the West of Scotland Coronary Prevention Study. The original study analysed the efficacy of pravastatin in preventing coronary morbidity and mortality in 6,595 moderately hypercholesterolemic men over the course of 4.9 years.

Using baseline data, the researchers classified the men on the basis of whether or not they had metabolic syndrome USING the NCEP-defined criteria, excepting waist circumference, which was substituted with body mass index (BMI). Threshold values were as follows: triglycerides 150 mg/dL or greater; high-density lipoprotein cholesterol 40 mg/dL or less; fasting plasma glucose concentration 110 mg/dL or greater, systolic blood pressure 130 mm Hg or greater; or diastolic blood pressure 85 mm Hg or greater; BMI greater than 28.8 kg/m2.

The CHD risk analyses were performed with a subgroup of 6,447 men who did not have diabetes at baseline (blood glucose 126mg/dL or less). Diabetes risk analyses included a subgroup of 5,974 men with at least two or more post-randomization fasting glucose measurements.

At baseline, 26.2% of men had the metabolic syndrome as defined by the modified NCEP criteria (mean age 52.2 years). Metabolic syndrome increased the risk for both CHD (hazard ratio [HR], 1.76; 95% CI] and new-onset diabetes (HR, 3.51; 95% CI) by univariate analysis. The syndrome continued to predict CHD in multivariate analysis that included conventional risk factors such as age, smoking status and blood pressure [HR, 1.30; 95% CI].

Risk for CHD and new-onset diabetes increased as the number of metabolic abnormalities rose. Men with four or more baseline abnormalities had a 3.7-fold increased risk for CHD and a 24-fold increased risk for diabetes.

Mean age and low-density lipoprotein cholesterol concentration were similar between the two groups, but C-reactive protein (CRP) level was significantly elevated in those with metabolic syndrome (with syndrome 2.36 mg/L, without syndrome 1.56 mg/L, P<.0001). CRP measurement enhanced the prediction of both CHD and diabetes in men with metabolic syndrome, and it remained a significant predictor in multivariate analyses (P<.001).

Pravastatin produced a similar relative risk reduction in those with the syndrome (0.73) and those without (0.69) the syndrome, although the absolute risk reduction was the greatest in those with the metabolic syndrome.

The researchers conclude, "a modified version of the NCEP definition of the metabolic syndrome prospectively identifies risk for CHD and even more strongly predicts new-onset diabetes." They also suggest, "minor modifications of the current definition as achieved by adding CRP or lowering the glucose cut-off may enhance prediction of CHD and diabetes." Circulation 2003 July;108:4:414-419

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FACT: Diabetic Kidney Disease Reversible: A study has found that a high level of albuminuria is a marker of dynamic, rather than fixed kidney damage. (N Engl J Med 2003 June 5; 348: 2285-93). The researchers found that microalbuminuria may progress to diabetic kidney disease (nephropathy), remain static, or, as in almost 60% of people in the study group, regress toward normal levels. Regression was associated with low blood pressure and low cholesterol. This suggests that otherwise healthy people with Type 1 Diabetes might benefit from taking blood pressure or cholesterol-lowering drugs. The study heightens the importance of screening for microalbuminuria to permit aggressive early intervention. Researchers understand that special repair mechanisms exist in the kidney that enable the organ to repair itself in the rarly stages.