The authors take issue with an article by Dr. K.D. MacRae claiming there is no association between estrogen dose and the risk of thrombosis. Dr. MacRae concentrated on 4 epidemiological studies, ignoring papers published prior to 1977. A comprehensive review of the literature shows that, with only 2 or 3 exceptions, all the 20 or so studies that have been reported point to an association between pill use and certain types of cardiovascular events. Dr. MacRae has not cited any of the studies on possible mechanisms for the thrombotic effects of the pill; that is, effects on hemostatic function, blood flow, the vessel wall, blood pressure, blood lipids, glucose metabolism, and so on. The studies in question are generally consistent in suggesting that the pil is likely to have a thrombogenic effect, and they provide strong support for the epidemiological investigations. Ideally, the effects of oral contraceptives should be evaluated in a large-scale randomized controlled trial. Unfortunately, the opportunity to carry out a satisfactory study of this type has now passed. Accordingly, we must rely on the findings in observational studies. Thus far, these studies do not suggest that use of the pill need much be curtailed. They do, however, indicate that caution is required in prescribing oral contraceptives for older women, especially those who have risk factors for cardiovascular disease such as cigarette smoking. Dr. MacRae's review should not be given serious attention.

作者：M P, Vessey；J I, Mann；T W, Meade

来源：British journal of hospital medicine 1981 年 25卷 2期