Tobacco smoking and acute myocardial infarction in young adults: a population-based case-control study

Abstract

Objective: To evaluate the effect of tobacco smoking on the risk of non-fatal acute myocardial infarction in young adults (< or = 45 years), and whether there is modification of this effect by sex.

Methods: We conducted a population-based case-control study with 329 incident acute myocardial infarction cases (42 women; 287 men), consecutively admitted to the Cardiology department of hospitals in Porto, Portugal, and 778 controls (486 women; 292 men), selected within the non-institutionalized Porto population, during 2001-2003. Odds ratios and 95% confidence intervals (OR, 95%CI) were calculated using unconditional logistic regression.

Results: The prevalence of current smoking was 80.8% in male cases and 53.8% in male controls (OR=3.63, 95%CI: 2.50, 5.27) and 59.5% of female cases were smokers compared to 35.8% of controls (OR=2.64, 95%CI: 1.39, 5.02). No interaction was found between current smoking and sex on myocardial infarction risk (p=0.401). A dose-effect response was present, the odds favoring myocardial infarction reaching an eight-fold increase for those that smoked > 25 cigarettes/day compared to never smokers. The risk estimate for former smokers was similar to never smokers.

Conclusions: Tobacco smoking is an important independent risk factor for acute myocardial infarction in young adults, with similar strength of association for both sexes.