ELEVATED SERUM-CHOLESTEROL IS A RISK FACTOR FOR BOTH CORONARY HEART-DISEASE AND THROMBOEMBOLIC STROKE IN HAWAIIAN JAPANESE MEN - IMPLICATIONS OF SHARED RISK

Background and Purpose The relation between total serum cholesterol le vel and thromboembolic or nonhemorrhagic stroke is controversial. The Honolulu Heart Program cohort of Japanese-American men provides data w hich show that elevated serum cholesterol is an independent predictor of thromboembolic stroke as well as coronary heart disease (CHD). The data are presented to suggest that the association of elevated cholest erol with stroke is sometimes underestimated or underreported partly b ecause of competing or shared risk with CHD, the other major atheroscl erotic end point. Methods The data are based on 6352 men (aged 51 to 7 4 years) at baseline examination (1971 to 1974) who were free of clini cal CHD and stroke and were followed an average of 15 years for new ca ses of both end points. Relative risks of serum cholesterol for CHD an d thromboembolic stroke were calculated, controlling for other major c ardiovascular covariates. Results There was a continuous and progressi ve increase in both CHD and thromboembolic stroke rates with increasin g levels of serum cholesterol. The relative risk between the highest a nd lowest quartiles of serum cholesterol was 1.7 (95% confidence inter val, 1.4 to 2.0) for CHD and 1.4 (95% confidence interval, 1.1 to 1.9) for thromboembolic stroke. There was a decline in the difference in r elative risks between CHD and thromboembolic stroke in older men (aged 60 years and older) compared with younger men (aged younger than 60 y ears). Conclusions These data provide additional evidence that elevate d serum cholesterol should be considered a primary risk factor for thr omboembolic stroke, presumably through its effect on both coronary and cerebrovascular atherosclerosis. It is suggested that this associatio n is sometimes underestimated or underreported partly because of share d or competing risk with CHD, the clinical manifestation of atheroscle rosis that generally occurs earlier in life and with greater frequency than thromboembolic stroke.