Response of exhaled nitric oxide to inhaled corticosteroids in patients with stable COPD: A systematic review and meta‐analysis

To our knowledge, no meta‐analysis has investigated the response of FeNO levels to corticosteroid treatment in ex‐smokers with chronic obstructive pulmonary disease (COPD). Objectives This meta‐analysis assessed the potential role of fraction of exhaled nitric oxide (FeNO) as a biomarker for corticosteroid response in ex‐smokers with stable COPD. Methods Medline, Cochrane, EMBASE, Google Scholar databases were searched until November 5, 2014 using the following terms: corticosteroid, chronic obstructive pulmonary disease, COPD, nitric oxide, NO, exhaled nitric oxide. Only randomized controlled trials (RCT) or two‐arm prospective studies were included. The primary outcome measure was FeNO before and after treatment with inhaled corticosteroids (ICS) in ex‐smokers with COPD. Sensitivity analysis was also performed. Results Five studies were included in the analysis with a total of 171 COPD patients. All five studies included 125 ex‐smokers and two of these also included 46 current smokers. There was a significant decrease of FeNO in ex‐smoking COPD patients following inhaled corticosteroid treatment (−7.51, 95% CI: −11.51 to −3.51; P =0.003); and in a population of subjects that included both smokers and ex‐smokers (−1.99, 95% CI: −3.41 to −0.56; P =0.006). Conclusion Our findings indicate that FeNO levels significantly decreased with corticosteroid treatment in ex‐smokers with COPD. Additional studies are required to evaluate whether concurrent smoking has significant effect on FeNO response to ICS.