LAUSR

Exhaled NO (F E NO) is affected by airway inflammation, smoking and inhaled corticosteroid treatment, conditions common in COPD. In addition, about 15-20% of COPD-patients have features of asthma that may affect F E NO. At the inclusion of the 2-year prospective COPD-study patients performed F E NO 50 , exhaled CO and spirometry. CRP and blood cells were assessed. Exacerbations and symptoms were assessed by questionnaire, COPD Assessment Tool (CAT) and COPD Clinical Questionnaire (CCQ). Patients (n=533), 58% female, age 68±8 years, 34% reported asthma and 25% frequent exacerbations (≥ 2 or 1 exacerbation with hospital admission). F E NO 50 correlated with FEV 1 (r=0.17, p E NO 50 was 17 (11,20) ppb (geometrical mean and CI95%), higher than stage 2: 13 (12,14); stage 3: 12 (11,14) and stage 4:11 (9,15) ppb (all p-values E NO 50 correlated to eosinophils (r=0.18, p E NO 50 in those with frequent exacerbations 12 (11,14) vs. non frequent exacerbations 13 (12,14) ppb or those with asthma diagnose 13 (12,14) vs. without asthma 13 (12,14) ppb. F E NO 50 decreased with smoking (p E NO 50 of 15 (14,16) ppb, smokers (eCO between 6-10 ppm) 10 (8,12) ppb and heavy smokers (eCO >10ppm) 8 (7,9) ppb. F E NO 50 did not correlate to CAT or CCQ. ICS-treated patients (60%) had similar F E NO 50 as subjects without ICS. In conclusion, there is a relation between F E NO 50 and eosinophilic inflammation in COPD. Patients in GOLD stage 1 have normal F E NO levels. Further studies are needed in order to understand the value of F E NO 50 in acute exacerbation or as predictor for future events /-or lung function decline.