Fractionated exhaled nitric oxide in COPD patients

<b>Introduction:</b> Nearly one-third of patients with chronic obstructive pulmonary disease (COPD) have eosinophilic airway inflammation yet data on FeNO in COPD are inconsistent. <b>Methods Data:</b> of 450 patients included in the PREVENT study receiving standardized low-dose therapy with LABA/ICS (Budesonide 400ug/Formoterol 12 ug daily) with scheduled visits half-yearly at stable state and unscheduled visits for exacerbations and upper respiratory tract infections (URTI) were analyzed. Follow-up occurred 21 days after exacerbation and 10 and 21 days after a URTI. FeNO measurements and multiplex viral PCR for 18 viruses in nasopharyngeal swabs were performed at each visit. <b>Results:</b> 2664 visits (2063 at stable state, 196 at exacerbation and 405 at the follow-up to an URTI) were analysed. FeNO significantly increased from stable state to exacerbations (p&lt;0.0001; median 17 [11.5 to 26.0] to 26 [16 to 44] ppb, respectively). Adjusted analyses included smoking status, MMRC score, CAT score, SGRQ total score and post-bronchodilator FEV1 showed significantly higher FeNO levels in patients with viral infection at exacerbation compared with no viral infection (24.6 vs 15.6 ppb; p=0.041). Differences in FeNO between patients with and without virus detection at stable state did not reach statistical significance (22.0 vs 20.9 ppb, p=0.069). There was no difference in FeNO between patients with and without growth of potential pathogenic bacteria in sputum in the crude or adjusted multivariate analysis. <b>Conclusion:</b> In a large COPD cohort on standardized low-dose ICS/LABA, COPD exacerbations, particularly the ones caused by a viral infection, are associated with increased FeNO levels. FeNO decreases to stable state values after convalescence.