Earlier epidemiologic studies have indicated an increase in mortality from certain cardiovascular diseases in young women associated with the use of oral contraceptives. However, since these studies were conducted, newer oral contraceptives containing less estrogen and progestogen have been widely adopted. In addition, an increasing majority of oral contraceptive use is by women under the age of 30 years. Early results from a new case-control study suggest the possibility that the risk of myocardial infarction associated with oral contraceptive use is now lower than in the past, although the previously observed small increase in the risk of subarachnoid hemorrhage appears to be unchanged.
PIP: Epidemiologic studies carried out in the UK in the late 1960s and 1970s suggested a strong link between oral contraceptive (OC) use and certain cardiovascular diseases. Most striking was the increased risk (2-4 times) of myocardial infarction in OC users compared to nonusers. OC use was also associated with a greater than average risk of subarachnoid hemorrhage, thrombotic stroke, and fatal pulmonary embolism. It is important, however, to reassess these risks in light of changes that have occurred since these early studies. Most notably, the OCs currently being marketed contain lower estrogen/progestin dosages than earlier formulations and the majority of OC use is concentrated in the under 30 year age group. In fact, preliminary results from a case- control study begun in 1968 suggest that the risk of OC-related myocardial infarction has dropped in recent years as a result of these changes. At present, data have been analyzed for 130 cases 16-39 years of age who died of myocardial infarction and an additional 237 women who died of subarachnoid hemorrhage. 24% of the myocardial infarction cases were OC users at the time of death compared to 19% of matched controls. This produces a relative risk of 1.8 for OC users, which is statistically significant yet lower than that identified in earlier studies. The data confirm that cigarette smoking is another important risk factor for myocardial infarction; the risk increased nearly 12-fold in smokers compared to nonsmokers. The risk of myocardial infarction in women who both smoked and used OCs was increased over 50-fold. The risk of subarachnoid hemorrhage was 1.4 in the current study, which is similar to that found in earlier research; again, the risk was greater among OC users who smoked.