Book Description

Evaluates the strength and significance of evidence linking use of combined oral contraceptives to an increased risk of cardiovascular disease in women. Recommendations and conclusions reflect the consensus reached by a group of scientists, including researchers directly involved in several recent large-scale investigations of cardiovascular disease and hormone contraception. The experts also considered evidence that other factors, such as smoking, hypertension, diabetes, age, and family history, might influence the risk of cardiovascular disease in users of combined oral contraceptives. In view of major recent changes in the hormonal content of these contraceptives and the prescribing patterns of providers, the assessment concentrates on data collected after 1980. The experts also aimed to determine whether the risk of disease is influenced by the estrogen or progestogen content of different preparations. To facilitate the comparison and interpretation of study results, the report opens with a discussion of the strengths and weaknesses of the different epidemiological approaches used to assess the safety of steroid contraceptives. Also discussed is the important distinction between the use of relative risk to examine epidemiological associations and the use of absolute risk to examine clinical importance. Against this background, the main part of the report examines the strength of evidence linking steroid contraceptives to an increased risk of acute myocardial infarction, ischaemic stroke, haemorrhagic stroke, and venous thromboembolism. Studies of combined oral contraceptives and progestogen-only contraceptives are considered separately for each disease. An effort is also made to determine whether conclusions, based on studies conducted in industrialized countries, are also valid for women living in the developing world. The assessment of findings from epidemiological studies is complemented by a review of possible biological explanations for the effects of combined oral contraceptives on cardiovascular functions. On the basis of all available evidence, the report concludes that mortality rates from cardiovascular disease are extremely low among women of reproductive age and that the added risk of using steroid contraceptives is also very low in users who do not smoke or have other risk factors for cardiovascular disease. A final section places these risks in perspective and offers balanced advice useful to providers of family planning when helping women to make informed choices about the use of hormonal contraceptives.