The 13th World Conference on Tobacco OR Health

Objective: The prevalence of cigarette smoking is frequently estimated by self-reported behavior that can lead to misclassification rates of smoking, since part of current cigarette smokers may report themselves as nonsmokers. Carbon monoxide in exhaled air (Coe) and Urinary Cotinine (UN) can be used as a biologic marker of smoking habit. The purpose of this study was to detect the level of deception among self-reported nonsmoking patients with Asthma and COPD.

Methods: 247 patients either having Asthma or COPD recruited from our outpatients clinic and not aware that the study as intended to certify their smoking behavior were interviewed to determine their self-reported smoking status which was confirmed by measurements of Coe and UN.

Results: 236 patients denied smoking: 27 had Coe levels > 10 ppm and UN > 400 ng/ml and were considered misclassified smokers (estimated proportion 12%). Conclusions: A considerable proportion of patients with Asthma and COPD don't tell the truth about their smoking behavior. The measurements of Coe and Urinary Cotinine can be helpful in accessing these patients real smoking behavior and allow a better clinical management and counseling.