Female sex hormones and thrombosis. Epidemiological aspects.

An epidemiological study of clinical events in wealthy Western countries focused on cardiovascular effects associated with oral contraceptive (OC) use (combination compounds). All published case-control studies reviewed indicate risk of venous thromboembolism in OC users. 2 British cohort studies agreed with case-control results; a Puerto Rican cohort study did not support the British findings but data population was not carefully monitored; and an Australian cohort study indicated that OCs protect against superficial venous thrombosis but this result seemed a function of design and analysis shortcomings. A relationship was drawn between thromboembolic risk and estrogen doses of 50 mcg or greater; this risk increased with time and only while preparations were in use. Case-control reports indicate OC users risk of thrombotic stroke is 6- to 9-fold greater with hemorrhagic stroke 2-fold greater. Cohort studies positively correlated risk of thrombotic stroke with OCs estrogen content. Postmenopausal use generally showed a nonsignificant increase in stroke risk. OCs should be avoided by women with established cardiovascular disease or risk factors regardless of age.