The pill and thrombosis
Thranov, I.; Obel, E.B.
Ugeskrift for Laeger 146(36): 2709-2711
1984
ISSN/ISBN: 0041-5782 PMID: 6515890 Document Number: 231307
The risk of thromboembolism in oral contraceptive (OC) users is evaluated based on findings of major cohort studies conducted in England, the US, and Denmark. Since approximately 25% of Danish Women aged 15-45 use OCs, such an assessment is timely and critical. A study by the Royal College of General Practitioners (RCGP) found a slightly higher risk of venous thrombosis and pulmonary embolism, especially postoperatively (deep venous thrombosis). Major risk was found only with the use of high estrogen-content pills. No connection between OC use and subarachnoidal bleeding could be established according to the latest studies. In a US study examining 182 cases of apoplexy cerebri of thrombotic origin in comparison with 98 controls, the risk was 9.5 times higher on OC users. However, 74% of the patients with cerebral thrombosis were smokers vs. 43% of controls. The high gestagen component of pills was implicated in the increased risk. In a case control study, the risk of myocardial infarct was found 4 times higher in OC users and 20 times higher in smokers who used OCs. Another study of the RCGP supported these findings: myocardial infarct was .3/1000 women per year in pill users vs. .15 in nonusers, and the risk of death from ischemic heart disease was 6.4 times higher among users. These risk factors were also borne out by Danish data: the number of women aged 35-39 and 40-45 dying of ischemic heart disease between 1951-1981 rose slightly, but there was no significant increase after 1967, when low-dose OCs were introduced; in recent years there has been a decline. To establish a firm link between the use of the estrogen and gestagen components of OCs and thromboembolic disease, further investigations must be conducted in view of recently introduced low-dose pills.