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

IntroductionTo our knowledge, no meta-analysis has investigated the response of FeNO levels to corticosteroid treatment in ex-smokers with chronic obstructive pulmonary disease (COPD). ObjectivesThis 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. MethodsMedline, 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. ResultsFive 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). ConclusionOur 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.