Risk of myocardial infarction in young female smokers

Objectives-To determine the extent of risk of myocardial infarction from ci garette smoking in young women, and to examine the relation of smoking with other putative risk factors. Design-Community based case control study. Setting-England, Scotland, and Wales. Patients-Women (n = 448) between 16 and 44 years old with a diagnosis of in cident myocardial infarction between 1 October 1993 and 16 October 1995. Co ntrols (n = 1728) were age and general practice matched women without a dia gnosis of myocardial infarction. Outcomes measures-Odds ratios for risk of myocardial infarction associated with smoking and other risk factors. Results-Odds ratios for myocardial infarction in smokers versus non-smokers showed a strong dose response, from 2.47 (95% confidence interval (CI) 1.1 2 to 5.45) in smokers of 1-5 cigarettes per day to 74.6 (95% CI 33.0 to 169 ) in smokers of greater than or equal to 40 cigarettes per day. There was n o interaction of smoking with use of oral contraceptives, but there were ad ditive risks with other clinical risk factors such as hypertension and diab etes. It is estimated that if all women aged 16-44 years were able to stop smoking, 400 cases of myocardial infarction per annum (of whom 112 would di e) would be prevented. Conclusions-In young women the risk of myocardial infarction from smoking w as considerable, and heavy smokers with other risk factors were especially at risk.