Smoking habits and the risk of non-fatal acute myocardial infarction in Costa Rica

Background: Smoking is a major risk factor for cardiovascular diseases, but there is little information on Latin America. Methods: We used data from a case-control study comprising 2094 cases with a first acute non-fatal myocardial infarction (MI) and 2094 matched controls (by age, sex, and area of residence) living in Costa Rica between 1994 and 2004. Relative risks (RRs) were obtained from conditional logistic regression models. Results: Compared to never smokers, the risk of MI was not higher in ex-smokers, but the RR was 2.71 for current smokers, and increased with the number of cigarettes smoked per day. Smoking ≥25 cigarettes per day was associated with an eight-fold risk of MI. The RR was higher for women (4.39) than for men (2.38). There was no trend in risk with duration and age at starting smoking. RRs were respectively 4.8, 5.6 and 6.1 for smokers of ≥15 cigarettes per day with obesity, diabetes or hypertension compared to non-smokers. Subjects living with a smoker had a 23% higher MI risk. Active and passive smoking accounted for 38% and 8% of MI cases. It explained 25% and 9% of female and 42% and 7% of male cases, 47% and 15% of cases below age 50, and 35% and 5% cases above age 50 years. Stopping smoking reduced the risk of MI already after one year, and after five years the risk approached that of never smokers. Conclusion: In Costa Rica, like elsewhere, inducing smokers to stop is a public health priority.