Premium
Is oral contraceptive use still associated with an increased risk of fatal myocardial infarction? Report of a case‐control study
Author(s) -
THOROGOOD MARGARET,
MANN JIM,
MURPHY MICHAEL,
VESSEY MARTIN
Publication year - 1991
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/j.1471-0528.1991.tb15397.x
Subject(s) - medicine , confounding , myocardial infarction , relative risk , family planning , sterilization (economics) , demography , risk factor , case control study , epidemiology , population , gynecology , obstetrics , environmental health , confidence interval , research methodology , foreign exchange market , foreign exchange , sociology , monetary economics , economics
Objective— To investigate the association between fatal myocardial infarction and use of modern low‐dose oral contraceptives. Design— A case‐control study. Setting— General practices throughout England and Wales. Subjects— 161 women aged under 40 dying from myocardial infarction during 1986–1988. Living controls (2 per case), matched for age and marital status, were chosen from general practice lists. Information was collected during structured interviews with general practitioners, and from postal questionnaires sent to surviving partners of the cases and to control women. Main outcome measures— Mortality from myocardial infarction in relation to many risk factors, notably oral contraception, as measured by relative risk. Results— After allowing for the confounding effects of medical risk factors and for surgical sterilization, the overall relative risk associated with both current and past use of oral contraceptives was estimated to be 1–9 (95% CI 0–7 to 4–9, and 1–0 to 3–5 respectively). The relative risk associated with current use of preparations containing 50 μg of oestrogen, however, was estimated to be 4–2 (0–5 to 39.2). At least some of the relative risk associated with oral contraceptive use is likely to be attributable to the confounding effect of cigarette smoking, but it is impossible to estimate how much from the available data. Conclusions— If there was an increased risk of fatal myocardial infarction associated with oral contraceptive use in 1986–1988 it is likely to have been less than two‐fold; in this study risks were slightly, but not significantly, elevated with both current and previous use. It may be that any increase in risk is associated solely with the older combined preparations containing 50 μg of oestrogen.