Five year study of cardiovascular risk factors in Japanese people: implications concerning new onset of metabolic syndrome.

BACKGROUND: The incidence of metabolic syndrome (MetS) has not been fully studied. METHODS AND RESULTS: The data of 35,534 subjects who underwent a health examination both in 1996 and 2001 were analyzed. Since the waist circumference was not available, modified criteria of MetS was used for those with 3 or more of the following items: 1) body mass index (BMI) >or=25 kg/m(2), 2) blood pressure >or=130 mm Hg in systolic and/or >or=85 mm Hg in diastolic, 3) triglycerides >or=150 mg/dL, 4) high-density lipoprotein (HDL) cholesterol or=100 mg/dL. The subjects who underwent therapy for hypertension, diabetes mellitus, and high TG were considered to have these items. The incidence of MetS over 5 years was determined and its risks were evaluated by Cox proportional-hazards models. During the follow-up of exactly 5 years, MetS developed in 2,853 (9.32%) among 30,623 subjects who had no MetS at baseline. The subjects who developed MetS were older, and had elevated BMI, blood pressure, TG and FBG (p<0.001 for all) and lower HDL (p<0.034 for men and p<0.001 for women). Each item of MetS and their combination was associated with a higher risk to develop MetS. Obesity (BMI >or=25 kg/m(2)) alone or in combination with another item was associated with a higher risk to develop MetS suggesting it plays a key role. CONCLUSION: MetS using BMI developed in 9.32% over 5 years or 1.86%/year. Each item of MetS or their combination showed a high risk to develop MetS. Obesity was associated with a higher hazard ratio to develop MetS.