Sex hormones and cardiovascular risk

Inspection of the age-incidence curve of ischaemic heart disease in both sexes shows an increase in slope for women around the menopause, approaching that of men at older ages. Although the increase is likely to be related to the menopause, epidemiological evidence is not defined. Likewise, there is some suggestion that reproductive factors may be related to the subsequent risk of cardiovascular diseases, since a few studies found an elevated risk in women with an earlier first birth. In terms of prevention and public health considerations, treatments via exogenous hormones are, however, much more important. A systematic overview of the available epidemiological evidence indicates that oestrogen replacement treatment is protective against ischaemic heart disease. The overall relative risks based on 18 studies and > 3300 cases was 0.81, with a narrow 95% confidence interval (0.76-0.85), thus suggesting a protective effect of 15-25%. This protection has a plausible biological interpretation in terms of increased high density lipoprotein (HDL) levels. The serum lipoprotein pattern can be unfavourably influenced by progestin supplementation. With reference to oral contraceptives, the relative risk for cardiovascular mortality was increased about twofold in current users. There appears now to be convincing evidence that the elevated risk is restricted to current users. In terms of practical implications for use on prescription, however, the avoidance of oral contraceptive use in women aged > 35 or 40 years and/or those at high risk of ischaemic heart disease for other reasons has reduced most of the excess risk of cardiovascular diseases associated with oral contraceptives. These indications for selective prescription, based on earlier epidemiological findings, have probably been even more important for reducing the vascular risk than the changes in composition of newer 'pills'.