LAUSR

Exhaled nitric oxide (FENO) is a non-invasive marker of airway inflammation. Smoking decreases FENO. About 15-20% of COPD-patients have asthma, that might increase FENO. The value of FENO in COPD is uncertain and our aim was to study determinants of FENO in COPD subjects with regard to current smoking. Subjects from the Swedish Tools for Identifying Exacerbations (TIE)-study with spirometry-verified COPD were included. Smoking habits, asthma, use of inhaled corticosteroids (ICS) were questionnaire-assessed. Lung function, FENO50 and blood eosinophils (B-Eos) were measured. FENO50 was measured in 533 subjects and lower (geometric mean (95%CI)) levels were found in smokers (n=150) than ex-smokers (n=383): 9.2 (8.4, 10.1) vs 15.0 (14.0, 16.0) ppb, p 300 cells/mm3) related to higher FENO50 in ex-smokers (p FENO50 is markedly reduced by current smoking in COPD subjects. FENO50 in current smokers is related to gender and lung function. FENO50 in ex-smokers with COPD is additionally related to higher levels of eosinophils and to ICS treatment.