Serum total cholesterol levels and risk of mortality from stroke and coronary heart disease in Japanese: The JACC study

Abstract

The relation between serum total cholesterol and coronary heart disease is well established, but the relations with total stroke and stroke subtypes are controversial. We conducted a nested case–control study as part of the JACC study. A total of 39,242 subjects, 40–79 years of age, provided serum samples at baseline between 1988 and 1990. During the 10-year follow-up, 345 deaths from total strokes (including 76 intraparenchymal hemorrhages) and 150 deaths from coronary heart diseases were recorded. The control subjects were matched for sex, age, community, and year of serum storage, and further adjusted for systolic blood pressure, high density lipoprotein (HDL)-cholesterol, ethanol intake category, smoking status, and diabetes. Serum total cholesterol levels were measured using an enzymatic method. Cases with total stroke and more specifically intraparenchymal hemorrhage had lower mean values of serum total cholesterol levels compared with control subjects. The risk of mortality from intraparenchymal hemorrhage was significantly higher for persons with low total cholesterol levels [less than 4.14 mmol/l (160 mg/dl)] than with those with higher levels. The risk of mortality from coronary heart disease for persons with serum total cholesterol levels more than or equal to 6.72 mmol/l (260 mg/dl) was significantly higher than those with levels less than 4.14 mmol/l (160 mg/dl). Low serum total cholesterol levels are associated with high mortality from intraparenchymal hemorrhage while high levels are associated with high mortality from coronary heart disease among Japanese.

Introduction

It is well known that high serum total cholesterol levels correlate positively with increased risk of coronary heart disease [1], [2]. However, the relations with stroke and stroke subtypes are controversial. Prospective studies of Americans [3], Europeans [4], and Japanese-American men [5] indicate a positive association between serum cholesterol concentration and risk of ischemic stroke. While a study of Japanese showed no association of serum total cholesterol with risk of ischemic or total stroke [6]. On the other hand, prospective studies of Japanese men and women [7], Japanese-American men [8], American men [3], elderly American men [9], Swedish women [10], and Scottish men and women [11], but not all [12] showed that serum total cholesterol levels was inversely associated with risk of intraparenchymal hemorrhage.

The aim of present study was to examine comprehensively the relationships between serum cholesterol levels and mortality from total stroke, stroke subtypes, and coronary heart disease among Japanese men and women. We conducted a nested control-study in a large prospective cohort study.