Case-control Study of Passive Smoking at Home and Risk of Acute Myocardial Infarction. Argentine FRICAS Investigators. Factores De Riesgo Coronario En América Del Sur

Objectives: We sought to study the relation between passive smoking at home and the risk of acute myocardial infarction (AMI).

Background: Previous epidemiologic studies have linked environmental tobacco smoke to an increased risk of coronary heart disease, but the evidence to support this view is not strong enough. To study this issue further, we analyzed the data from a case-control study conducted in Argentina between 1991 and 1994.

Methods: Case patients included 336 never-smokers with AMI. Control patients were 446 never-smokers admitted to the same network of hospitals with a wide spectrum of acute disorders unrelated to smoking or to known or suspected risk factors for AMI. Data on the smoking habits of the participants' close relatives (spouse and children) were collected by trained interviewers using a structured questionnaire.

Results: Compared with subjects whose relatives had never smoked, the multivariate odds ratios for passive smokers, according to the smoking status of their relatives, were 1.68 (95% confidence interval [CI] 1.20 to 2.37) for one or more relatives who smoked; 1.59 (95% CI 0.85 to 2.96) for a spouse who smoked; 1.24 (95% CI 0.61 to 2.52) for a spouse who smoked 1 to 20 cigarettes/day; 4.03 (95% CI 0.99 to 16.32) for a spouse who smoked >20 cigarettes/day; and 1.80 (95% CI 1.20 to 2.68) for one or more children who smoked. There was a significant interaction between passive smoking and hypercholesterolemia (> or = 240 mg/dl), hypertension, diabetes and family history of MI.

Conclusions: In never-smokers, passive smoking at home appeared to be associated with the risk of AMI, and approximately 14% of cases in men and 18% of cases in women in this Argentinian cohort are attributable to passive smoking.