Acutemyocardial infarction: association with timesince stopping smoking inItaly

Studyobjective - The studyaimedto investigate the relationship between yearssincestopping smoking andtherisk ofacutemyocardial infarction. Design-Thiswasahospital based, multicentre, case-control studyconducted in ItalybetweenSeptember1988andJune 1989withintheframework oftheGISSI-2 clinical trial. Setting -Over80coronarycareunitsin various Italian regions participated. Subjects -A total of916incident casesof acutemyocardial infarction, belowage 75years, andwithnohistory ofischaemic heartdisease, and1106control subjects admitted tothesamehospitals foracute, non-neoplastic, cardiovascular or cerebrovascular conditions thatwere not knownorsuspected toberelated tocigarettesmokingtookpartinthestudy. Main outcomemeasuresandresults Measureswererelative risk(RR)estimatesof acutemyocardialinfarction according to thetimesincestopping smokingand adjusted foridentified potential confounding factors. Comparedwithneversmokers, themultivariateRRswere1-6(95%confidence interval(CI)0-8,3 2)forsubjects who had givenupsmokingforoneyear;1-4(95% CI0-9,2-1) forthosewhohadstopped for twotofiveyears; 1-2(95%CI0-7,2-1) for sixto10years; and11(95%CI0-8,1-8) for thosewho hadnotsmokedforover10 years.The estimated RR forcurrent smokerswas 2-9(95%CI22,3-9). The risks ofquitters werehigherforheavier smokersandthosebelowage50years, whilenodifference emergedinrelation to theduration ofsmoking, sex,andother riskfactors formyocardial infarction. Conclusions -Theseresults indicate that thereisalready asubstantial dropinthe riskofacutemyocardial infarction one yearafterstopping. The riskin ex