Oral contraceptives and thrombosis. From risk estimates to health impact.

OBJECTIVE The scientific debate on oral contraceptives (OCs) and thrombotic diseases continues unabated. The aim of this survey was to evaluate available scientific data on OCs and thrombotic diseases and to make tentative prescription recommendations of OCs to women with and without various thrombotic risk factors. CONSENSUS In women 15-29 years old, venous thromboembolism is about twice as common as arterial complications. In women between 30 and 44 years, the number of arterial complications exceeds venous diseases by about 50%. The mortality from arterial diseases is 3.5 times higher than the number of deaths from venous diseases in women below 30 years, and 8.5 times higher in women 30-44 years old. A significant disability is more frequent in women suffering and surviving an arterial complication than in women with venous thromboembolism. Although many important scientific issues still have to be addressed, the available scientific data suggests a differential influence of OCs with second and third generation progestagens on the risk of venous and arterial diseases. OCs with second generation progestagens seem to confer a smaller increase in the risk of venous diseases and a higher increase in risk of arterial complications, compared with OCs containing third generation progestagens. The possible difference on the venous side seems to be smaller than primarily anticipated. RESULTS Young women without any known risk factor for thrombotic diseases may use any low-dose OC. If OCs are prescribed to women with known risk factors for arterial thrombotic disease; e.g. smoking, diabetes, controlled hypertension, migraine without aura, family disposition of acute myocardial infarction (AMI) or thrombotic stroke, a low-dose pill with a third generation progestagen may have an advantage. If OCs are considered for women with risk factors for venous disease such as severe obesity, varicose veins, family history of VTE or with factor V Leiden mutation, a low-dose combined pill with a second generation progestagen may be preferable. In women above 30 years, OCs with third generation progestagens generally seem to confer less overall thrombotic morbidity, mortality and disability than OCs with second generation progestagens. These women should reconsider, however, the indication of combined OCs in the presence of significant risk factors of thrombotic diseases.