コレステロール神話の崩壊―疫学調査から―

Abstract

The health risk from hypercholesterolemia in Japan has been overemphasized for years. When discussing the risk of hypercholesterolemia, the famous figure is often cited that shows an exponential relationship between serum cholesterol levels and the risk of coronary heart disease (Guideline for Diagnosis and Treatment of Hyperlipidemias in Adults, 1997, Japan Atherosclerosis Society). This figure, consisting of several sets of epidemiological data, recently turned out to be based on unreliable data and data manipulation. One of the misleading epidemiological studies in that figure incorporated a surprisingly large number of familial hypercholesterolemic subjects. Familial hypercholesterolemia should be excluded from this kind of epidemiological studies, because the disease is rare (0.2%), and the incidence of coronary heart disease is exceptionally high. Almost all the recently performed large-scale epidemiological studies in Japan showed that higher cholesterol levels, like 240-260 mg/dL (6.2-6.7 mmol/L) or 240-280 mg/dL (6.2-7.3 mmol/L), are safer than lower cholesterol levels in terms of all-cause mortality. This is partly due to a very low coronary heart disease incidence in Japan. Prescribing lipid-lowering medicines to subjects with 240 to 260 mg/dL of cholesterol, which is recommended by the newest guideline (2004) of Japan Atherosclerosis Society, faces the paradox of treating those who are least likely to die. The guideline for hypercholesterolemia must be set by those researchers who have not received any assistance from cholesterol-lowering drugs makers.