Heterogeneity of cardiovascular risk among smokers is related to degree of carbon monoxide exposure

Background: Between smokers matched for daily tobacco consumption there are marked variations of the cardiovascular risk. This follow up of the population based cohort "Men born in 1914" from Malmo, Sweden, explored whether this is accounted for by the levels of carbon monoxide (CO). Methods: Three hundred and sixty-five men without history of cardiovascular disease (CVD) were followed over 27 years. Leg artery disease was defined as a systolic ankle-arm pressure ratio (ABPI) below 0.9 in either leg. Incidence of myocardial infarction (MI), stroke and deaths is based on linkage with regional and national registers. The distribution of CO in blood and expired air, respectively, was divided into quartiles. Results: There was a significant inverse relation between ABPI and CO in blood and expired air. Incidence of CVD events and deaths increased progressively with degree of CO exposure. Men with CO in the top quartile had significantly increased risks of CVD events (RR: 2.2; 95% CL 1.00-4.6) and cardiovascular deaths (RR: 3.2, CL 1.2-8.3), adjusted for daily tobacco consumption and other potential confounders. Conclusions: In smokers, the prevalence of leg atherosclerosis and incidence of cardiovascular disease is related to the amount of carbon monoxide in blood or expired air. (c) 2004 Published by Elsevier Ireland Ltd.