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Oral Contraceptives, Smoking, and the Risk for Myocardial Infarction

This study provides more evidence that women aged 35 and older who smoke and use oral contraceptives increase their risk for myocardial infarction.

Studies that assessed the risk for myocardial infarction (MI) in women who use combination oral contraceptives (OCs) have yielded inconsistent results. The authors of this nationwide, population-based, case-control, Dutch study examined OC use and cigarette smoking among 245 reproductive-aged women (72% aged 40 or older) who had had an MI and 916 age-matched controls who had not had an MI.

Compared with nonuse, OC use was associated with an overall odds ratio for MI of 2.0 (95% CI, 1.5-2.8). When nonsmokers who did not use OCs were used as the comparison group, the OR for MI was 7.9 among nonusers who smoked and 13.6 among users who smoked.

Comment: In this study and other recent European studies, a modest elevation in the risk for MI has been noted with OC use. Several recent, large U.S. studies have not observed this association, however (see JWWH Nov 1998, p. 85, accession number 981101014; Circulation 1998; 98:1058; and Arch Intern Med 2001; 161:1065). What might explain the difference? About 85% of the women in this study were aged 35 or older, and overall, 84% were current smokers. U.S. clinicians have been trained not to prescribe OCs to women aged 35 or older who smoke. A slightly more permissive approach to prescribing OCs to high-risk women in Europe, where smoking is more prevalent than in the U.S., could explain why these investigators have found an elevated risk for MI with OC use.

As editorialists note, in contrast to the modest association between OC use and MI, the association between smoking and MI in reproductive-aged women is robust and consistently observed, with three quarters of all MIs among these women attributed to smoking. Clinicians should discourage smoking in all patients. For patients who continue to smoke, OC use should be discontinued at age 35; intrauterine or progestin-only methods represent sound contraceptive choices for these women.

— Andrew M. Kaunitz, MD

Published in Journal Watch Women's Health February 19, 2002

Citation(s):

Tanis BC et al. Oral contraceptives and the risk of myocardial infarction. N Engl J Med 2001 Dec 20; 345:1787-93.

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• Medline abstract (Free)

Chasan-Taber L and Stampfer M. Oral contraceptives and myocardial infarction -- The search for the smoking gun. N Engl J Med 2001 Dec 20; 345:1841-2.

• Original article (Subscription may be required)
• Medline abstract (Free)