High-density lipoproteins in the prevention of atherosclerotic heart disease. Part I. Epidemiological and family studies.

It has recently been proposed that the concentration of the high-density lipoprotein (HDL) fraction in plasma bears a negative relationship to the incidence of atherosclerotic heart disease. The biological and environmental factors affecting plasma HDL levels and the evidence pertaining to the proposed 'negative risk potential' of this lipoprotein are reviewed. HDL concentrations are low at birth, but rise rapidly in early infancy to adult or above-normal adult levels. This trend is influenced by biological factors such as sex and ethnicity and by a host of environmental variables. Despite methodological inadequacies in some studies, the epidemiological evidence consistently reflects an inverse relationship between the level of HDL in the plasma and the risk of ischaemic heart disease. Investigations on families suffering from genetic dyslipoproteinaemias, characterized by reduced levels of low-density lipoprotein (LDL) relative to HDL, suggest that the LDL:HDL ratio is itself an important determinant of atherosclerotic heart disease. The practical application of this information is limited by the lack of reliable reference ranges in various population groups and the absence of quantitative data regarding the 'negative risk potential' of any given concentration of plasma HDL in the presence of other positive and negative risk factors.