Pravastatin. A pharmacoeconomic review of its use in primary and secondary prevention of coronary heart disease.

Abstract

Coronary heart disease (CHD) is a major cause of death and illness in industrialised countries. Like other hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, pravastatin reduces total and low density lipoprotein (LDL)-cholesterol levels and increases high density lipoprotein (HDL)-cholesterol levels. Cholesterol modification with pravastatin in middle-aged hypercholesterolaemic men without CHD (i.e. primary prevention) was shown in the West of Scotland Coronary Prevention Study (WOSCOPS) to reduce the incidence of fatal and nonfatal coronary events. In several other large studies, pravastatin reduced the incidence of CHD events in patients with prior CHD (secondary prevention). Large, long term studies of the relationship between cholesterol modification and CHD event rate have been conducted for some, but not all, other HMG-CoA reductase inhibitors. A UK pharmacoeconomic analysis of the WOSCOPS data indicated that primary prevention with pravastatin was associated with a cost of 20,375 Pounds per year of life gained (YLG) [discounted]. Treatment of men at high risk for CHD resulted in a lower cost estimate (13,995 Pounds/YLG). A US economic analysis based on secondary prevention with pravastatin in large plaque regression studies suggested a net cost of drug therapy of $US7124 to $US12,665 per YLG. A number of projected-risk models have attempted to calculate the cost effectiveness of primary or secondary prevention with pravastatin compared with other lipid-modifying interventions. These comparisons indicated that pravastatin was economically superior to intensive lifestyle counselling without drug therapy. Pravastatin generally appeared to be less cost effective than other HMG-CoA reductase inhibitors, although the relative effectiveness of the various drugs depended on the model considered. Risk-projection economic models are subject to methodological limitations, principally the necessity of estimating clinical effectiveness from epidemiological data (often derived from the Framingham Heart Study). An increased absolute risk of CHD improves the cost effectiveness of lipid-lowering therapy. Thus, the cost per YLG of pravastatin in secondary prevention is, in general, lower than that of primary prevention, reflecting the higher absolute risk of second versus first CHD events. However, it is important to note that individual absolute risk rates may overlap between patients receiving primary and secondary prevention. Similarly, treatment of selected individual patients at high risk for CHD events is associated with a lower cost per YLG than unselected treatment. In large clinical studies, pravastatin effectively reduced the risk of primary and secondary CHD events. These benefits come at a substantial economic cost, but one that is in line with accepted costs for other medical interventions. Selective treatment of patients or populations at high risk of CHD events improves the cost effectiveness of pravastatin therapy.