PROSPECTIVE-STUDY OF EXOGENOUS HORMONES AND RISK OF PULMONARY-EMBOLISM IN WOMEN

Background Current use of oral contraceptives (OCs) is a well-recognis ed risk factor for venous thrombosis and consequent pulmonary embolism (PE). Little is known about residual effects of past OC use. Furtherm ore, few epidemiological studies have assessed the relation between po stmenopausal use of hormones and thrombotic disease. Methods in this p rospective study information was obtained through questionnaires sent every 2 years (1976-92) to 112 593 women aged 30-55 in 1976, We exclud ed women with previously diagnosed cardiovascular disease or cancer in 1976 and at the beginning of each subsequent 2-year follow-up period. Findings From self-reports and medical records, we documented 123 cas es of primary PE (no identified antecedent cancer, trauma, surgery, or immobilisation). Current users of postmenopausal hormones had an incr eased risk of primary PE (relative risk adjusted for multiple risk fac tors 2 . 1 [95% CI 1 . 2-3 . 8]). However, past use showed no relation to PE (1 . 3[0 . 7-2 . 4]). In current users of OCs the risk of prima ry PE was about twice that in non-users (2 . 2[0 . 8-5 . 9]), but this finding was based on only five cases who were current OC users. Users of OCs in the past had no increase in risk of PE (0 . 8[0 . 5-1 . 2]) . These relations were consistent irrespective of cigarette-smoking st atus. Interpretation Primary PE was uncommon in this cohort. The risk was increased by current though not past use of postmenopausal hormone s or OCs.