Cholesterol and coronary disease--outstanding questions.

Established facts include the role of raised blood cholesterol in causing coronary atheroma and that a high dietary intake of saturated fat is a leading cause of coronary disease. It is also clear that reduction of hypercholesterolaemia in middle-aged males reduces CHD incidence, mostly that of non-fatal myocardial infarction. But there are many unresolved questions which should lead to a selective and moderate approach to the management of hypercholesterolaemia. These include lack of the exact knowledge of how raised cholesterol levels lead to atheroma; equivocal evidence of whether reduction of hypercholesterolaemia causes regression of atheroma; uncertainty about how far cholesterol levels can safely be reduced and whether the cost-benefit always justifies action; the fact that reduction of hypercholesterolaemia does not reduce total mortality and may increase non-cardiac mortality; and insufficient evidence as to whether the same policies for middle-aged men should be adopted for woman, the elderly and adolescents.