Investigation of relation between use of oral contraceptives and thromboembolic disease
Vessey, M.P.; Doll, R.
British Medical Journal 2(5599): 199-205
1968
ISSN/ISBN: 0007-1447 PMID: 5653025 DOI: 10.1136/bmj.2.5599.199Document Number: 469378
Married women aged 16 to 40 years with a diagnosis of deep vein thrombosis or pulmonary embolism without evident predisposing cause were identified by means of the hospital diagnostic indexes and interviewed. For comparison, married control patients with acute surgical or medical conditions, or having elective surgery, matched with the affected patients for age, parity, date of admission, and absence of any predisposing cause of thromboembolic disease, were identified and interviewed. Of 58 affected patients 26 (45%) had been using oral contraceptives during the month preceding the onset of their illness while only 10 of the corresponding 116 controls (9%) had done so. The risk of hospital admission for venous thrombo-embollsm is about 9 times greater in women who use oral contraceptives than in those who do not. If national supply data are used for estimating the frequency of use of oral contraceptives in the general population it is calculated that about 1 in every 2000 women using oral contraceptives are admitted to hospital each year with idiopathic venous thrombo-embolism in comparison with about 1 in every 20,000 women not using them. These results are not thought to have been produced by bias or by any common factor responsible both for the use of oral contraceptives and the production of thromboembolism, and it is concluded that oral contraceptives are a cause of the disease. Women suffering from coronary or cerebral thrombosis were also studied. Five of 9 patients who survived an attack of cerebral thrombosis had been using oral contraceptives during the month preceding their illness. Taken in conjunction with other similar findings, it is justifiable to conclude that oral contraceptives can also be a cause of cerebrovascular insufficiency. Of the 13 women who survived an attack of coronary thrombosis without evident predisposing cause none had been using oral contraceptives.