Objective: The aim of this study was to examine whether LDL cholesterol raises the risk of coronary heart disease in a dose-response fashion in a population with low LDL-cholesterol levels.
Design: Population-based prospective cohort study in Japan.
Subjects and main outcome measures: A total of 30,802 men and 60,417 women, aged 40 to 79 years with no history of stroke or coronary heart disease, completed a baseline risk factor survey in 1993. Systematic mortality surveillance was performed through 2003 and 539 coronary heart disease deaths were identified.
Results: The mean values for LDL-cholesterol were 110.5 mg dL(-1) (2.86 mmol L(-1)) for men and 123.9 mg dL(-1) (3.20 mmol L(-1)) for women. Men with LDL-cholesterol > or =140 mg dL(-1) (> or =3.62 mmol L(-1)) had two-fold higher age-adjusted risk of mortality from coronary heart disease than did those with LDL-cholesterol <80 mg dL(-1) (<2.06 mmol L(-1)), whereas no such association for women was found. The multivariable hazard ratio for the highest versus lowest categories of LDL-cholesterol was 2.06 (95 percent confidence interval: 1.34 to 3.17) for men and 1.16 (0.64 to 2.12) for women.
Conclusion: Higher concentrations of LDL-cholesterol were associated with an increased risk of mortality from coronary heart disease for men, but not for women, in a low cholesterol population.