Hormone replacement therapy: II. A pharmacoeconomic appraisal of its role in the prevention of postmenopausal osteoporosis and ischaemic heart disease.

The reduction in estrogen production that occurs at menopause is associated with several long term sequelae. There is an accelerated decrease in bone mineral density leading to an increased risk of osteoporotic fracture. Furthermore, changes in plasma lipid profiles and other cardiovascular parameters increase the risk of cardiovascular and cerebrovascular pathology. These effects are additional to the menopausal symptoms experienced by many women. The effectiveness of estrogen-based hormone replacement therapy (HRT) is well established in preventing bone mineral loss and also in ameliorating menopausal symptoms, with the addition of progestogen maintaining or possibly enhancing the bone-conserving effects. However, prolonged therapy appears to be necessary to conserve bone mineral density and prevent osteoporotic fracture, particularly in women aged greater than or equal to 75 years, and compliance with long term therapy is likely to be poor. Estrogen favourably alters plasma lipid profiles, improves coronary blood flow and inhibits the central distribution of body fat. Effects on haemostatic mechanisms and coronary vasomotor response to acetylcholine have also been suggested as mechanisms for the beneficial effects of estrogen on ischaemic heart disease. The effects of concomitant progestogens on plasma lipids are variable, and may depend on the type, dosage regimen and duration of therapy. Pharmacoeconomic analyses of HRT have used a variety of risk assumptions. Relative risk rates of osteoporotic fracture and mortality from myocardial infarction are assumed to reduce to 0.5 after greater than 5 years' therapy. Long term HRT is associated with a relative risk of approximately 1.3 for breast cancer, whereas the relative risk of endometrial cancer is 4.0 to 8.0 in women with intact uteri receiving prolonged unopposed estrogen therapy. HRT that includes progestogens is assumed to incur no added risk of endometrial cancer, and this treatment is generally recommended for women with intact uteri. Data concerning the effect of HRT on quality of life are limited and utility values for hip fracture of 0.95 to 0.36 have been assigned, depending on assumptions of disability. Cost-benefit, cost-effectiveness and cost-utility studies evaluating HRT in the prevention of osteoporotic fracture have differed widely in methodology, making comparison of results difficult. HRT appears to be most economically useful in the prevention of fracture if used in women who have undergone hysterectomy, in women with high risk of osteoporotic fracture or ischaemic heart disease, and/or in women with menopausal symptoms.(ABSTRACT TRUNCATED AT 400 WORDS)