[An epidemiological approach to the metabolic syndrome]

To investigate four risk factors for the metabolic syndrome.

Using the health examination database of a Japanese company, 8,194 middle-aged male workers were assessed for the metabolic syndrome with reference to: (1) obesity (body mass index > or = 25 kg/m2); (2) hypertension (> or = 140/90 mmHg or taking antihypertensive drugs); (3) diabetes (fasting blood glucose > or = 110 mg/dl); and (4) hyperlipidemia (total cholesterol > or = 220 mg/dl or triglyceride > or = 150 mg/dl). (1) Those who had developed the metabolic syndrome (n = 148) were retrospectively followed for 5 years. Persistence rates for the four risk factors were calculated. (2) Those who had three risk factors (n = 1,100) were followed for 5 years to observe the development of metabolic syndrome. The incidence rates from Kaplan-Mayer analysis were compared among four different patterns for three risk factors. Adjusted hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) were calculated using the Cox's proportional hazard

(1) The highest persistence rate was found for obesity, followed by hyperlipidemia, hypertension, and diabetes. (2) After adjusting for age, smoking, drinking, and exercise, significantly higher HRs (95%CIs) were found for those with obesity, hypertension, and diabetes (4.4; 2.9 to approximately 6.9), those with obesity, diabetes, and hyperlipidemia (3.2; 2.1 to approximately 4.9), and those with obesity, hypertension, and hyperlipidemia (2.1; 1.4 to approximately 3.0), compared with those with hypertension, diabetes, and hyperlipidemia.

Obesity may be the key to developing the metabolic syndrome in those who demonstrate three risk factors.