The relationship between use of oral contraceptives and myocardial infarction in young women with fatal outcome, compared to those who survive: results from the MICA case-control study

To examine the relationship between use of oral contraceptives and the risk of dying from myocardial infarction, we made a comparison of deceased pati ents and live patients (women aged less than 45) identified for the Myocard ial Infarction Causality case-control study, using data obtained from gener al practice medical notes. There were 422 live patients and 110 deceased pa tients of women with a myocardial infarction with data available. The adjus ted odds ratio for exposure to second generation oral contraceptives and ri sk of death within 28 days of a myocardial infarction compared with no oral contraceptive use was raised (2.88, 95% confidence interval 1.21-6.77), an d this effect was not seen for other types of oral contraceptives including third generation oral contraceptive formulations. In absolute terms, betwe en 47,000 and 71,000 women would have to be exposed to a second generation pill for one year to result in one extra death from myocardial infarction, and this risk applies mainly to smokers. The results suggest a slightly inc reased relative risk of death among those having a myocardial infarction as sociated with exposure to second generation oral contraceptives, but this r epresents a small absolute risk. Further work is required before any change in contraceptive practice should be advocated. (C) 2001 Elsevier Science I nc. All rights reserved.