Abstract

PIP: Information on the association between combined oral contraceptives (OCs) and cardiovascular disease risks has been derived almost exclusively from studies in developed countries. To assess this relationship in developing countries, where the risk factors for cardiovascular disease may be different, a case-control study of venous thromboembolism, stroke, and myocardial infarction was carried out in 21 centers in 17 countries in Africa, Asia, Europe, and Latin America. The World Health Organization Collaborative Study of Cardiovascular Disease and Steroid Hormone Contraception enrolled 3800 cases of stroke, venous thromboembolism, and myocardial infarction and 11,200 matched controls. Studies in the UK had suggested that OCs containing desogestrel and gestodene doubled the risk of venous thromboembolism compared with levonorgestrel and norethindrone-containing OCs. The multi-center study identified an overall risk of venous thromboembolism in the lower range of that reported in developed countries, an increased risk soon after starting OC use but elimination of such risk within a few months after pill discontinuation, and slightly increased risk among obese women and those with a history of high blood pressure during pregnancy. Unexpected was the finding that women who use OCs containing desogestrel or gestodene may be at double the risk of blood clotting in the veins compared with users of OCs containing levonorgestrel or norethindrone. Although these findings remain controversial, several countries have modified OC prescribing practices to eliminate women at high risk of cardiovascular disease.