The strength of the multivariable associations of major risk factors predicting coronary heart disease mortality is homogeneous across different areas of the Seven Countries Study during 50-year follow-up

OBJECTIVES: To compare the magnitude of multivariable coefficients and hazard ratios of four cardiovascular risk factors across five worldwide regions of the Seven Countries Study in predicting 50-year coronary deaths. MATERIAL AND METHODS: A total of 13 cohorts of middle-aged men at entry (40-59 years old) were enrolled in the mid-1900s from five relatively homogeneous groups of cohorts (areas): USA, Finland and Zutphen - the Netherlands, Italy and Greece, Serbia, Japan for a total of 10,368 middle-aged men. The major risk factors measured at baseline were age, number of cigarettes smoked, systolic blood pressure and serum cholesterol. Cox proportional hazards models were solved for 50-year (45 years for Serbia) deaths from coronary heart disease (CHD), and the multivariable coefficients were compared for heterogeneity. RESULTS: The highest levels of risk factors and CHD death rates were found in Finland and Zutphen - the Netherlands and the lowest in Japan. All four risk factors were predictive for long-term CHD mortality in all regions, except serum cholesterol in Japan where the mean levels and CHD events were lowest. Tests of heterogeneity of coefficients for single risk factors in predicting CHD mortality were non-significant across the five areas. The same analyses for the first 25 years of follow-up produced similar findings. CONCLUSIONS: The strength of the multivariable associations of four major traditional CHD risk factors with long-term CHD mortality appears to be relatively homogeneous across areas, pending needed further evidence.