Risk of Smoking and Metabolic Syndrome for Incidence of Cardiovascular Disease Comparison of Relative Contribution in Urban Japanese Population: The Suita Study

BACKGROUND: Risk factor clustering, the so-called metabolic syndrome (MetS), is an important risk factor for cardiovascular disease (CVD). Smoking is also an important CVD risk factor with still a high prevalence. However, few previous studies have compared the risk for CVD or the population-attributable fraction (PAF) of smoking, MetS, and both. METHODS AND RESULTS: The present study was an 11.9-year cohort study of 1,822 men and 2,089 women, aged 40-74 years, selected randomly from an urban general population in Japan. MetS was defined according to the National Cholesterol Education Program on Adult Treatment Panel III (NCEP-ATPIII) guideline modified by the Asian criteria for waist circumference. The prevalence of smoking was 49.5% in men and 11.1% in women, and that of MetS was 19.8% and 23.5%, respectively. In men, the multivariate-adjusted hazard ratio for CVD incidence, compared with non-smoking participants without MetS, was 2.07 (1.26-3.40) in those who smoked, 2.09 (1.08-4.04) in those with MetS, and 3.56 (1.89-6.72) in those with both. In men the PAF for CVD incidence was 21.8% because of smoking, 7.5% because of MetS, and 11.9% because of both. CONCLUSIONS: Although countermeasures for MetS are important, smoking should continue to be considered an important public health problem and antismoking campaigns should be promoted, especially for men, to prevent CVD.