New England Journal of Medicine · 1981 · 183 citations · 11 references
MedicineCardiologyContraceptionReproductive EpidemiologyReproductive HealthCardiovascular RiskContraceptive DiscontinuationContraceptive EpidemiologyContraceptive UseIschemic Heart DiseaseCase-control Study DesignOral Contraceptive Discontinuation
The study assessed myocardial infarction risk associated with current and discontinued oral contraceptive use in a hospital‑based case‑control design. The analysis compared 556 women aged 25–49 who had myocardial infarction with 2,036 age‑matched controls. Current users had a 3.5‑fold higher risk, while past users showed a duration‑dependent increase up to 2.5‑fold, indicating that the elevated risk persists after stopping long‑term use.
In a hospital-based case-control study, we evaluated the rate of myocardial infarction in relation to discontinued as well as current use of oral contraceptives. We compared 556 women with infarction, 25 to 49 years old, with 2036 age-matched control subjects. For current users, the rate-ratio estimate was 3.5 (95 per cent confidence limits, 2.2 to 5.5). For past users 40 to 49 years of age, the magnitude of the rate ratio was related to the duration of use: for total durations of past use of less than five years, five to nine years, and 10 or more years, respectively, the rate-ratio estimates (with 95 per cent confidence limits) were 1.0 (0.8 and 1.4), 1.6 (1.1 and 2.5), and 2.5 (1.5 and 4.1). This trend was statistically significant (P less than 0.01). The findings suggest that an effect on the risk of myocardial infarction persists after the discontinuation of long-term use of oral contraceptives.
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