Tar yield and risk of acute myocardial infarction: pooled analysis from three case-control studies

BACKGROUND: Controversial information is available with reference to the role of type or yield of cigarettes on the risk of cardiovascular disease. DESIGN: We considered the issue in a combined dataset of three case-control studies of acute myocardial infarction conducted in Italy between 1983 and 2003. METHODS: Cases were 1990 subjects with a first episode of non-fatal acute myocardial infarction, and controls were 2521 patients in hospital for acute diseases unrelated to smoking or other recognized risk factors for myocardial infarction. The odds ratio and the corresponding 95% confidence interval (CI) were derived by unconditional multiple logistic regression models, including terms for age, sex, and several major risk factors for myocardial infarction. RESULTS: As compared to never smokers, the multivariate odds ratio was 2.70 (95% CI 2.01-3.63) for smokers of low tar cigarettes (<10 mg), 3.06 (95% CI 2.53-3.70) for intermediate (10-19 mg) and 3.14 (95% CI 2.12-4.64) for high tar yield (> or =20 mg). After further allowance for duration of smoking and number of cigarettes per day, as compared to low tar yield cigarettes, the odds ratio was 1.14 (95% CI 0.85-1.53) for intermediate, and 1.28 (95% CI 0.81-2.02) for high tar yield. CONCLUSION: Our study confirms that no substantial reduction in acute myocardial infarction risk resulted from the decrease of cigarette tar yield.