title: Effects of inhaled corticosteroids on sputum cell counts in stable chronic obstructive pulmonary disease: a systematic review and a meta-analysis.
abstract: BACKGROUND
  Whether inhaled corticosteroids suppress airway inflammation in chronic obstructive pulmonary disease (COPD) remains controversial. We sought to determine the effects of inhaled corticosteroids on sputum indices of inflammation in stable COPD.
  
  
  METHODS
  We searched MEDLINE, EMBASE, CINAHL, and the Cochrane Databases for randomized, controlled clinical trials that used induced sputum to evaluate the effect of inhaled corticosteroids in stable COPD. For each chosen study, we calculated the mean differences in the concentrations of sputum cells before and after treatment in both intervention and control groups. These values were then converted into standardized mean differences to accommodate the differences in patient selection, clinical treatment, and biochemical procedures that were employed across original studies. If significant heterogeneity was present (p < 0.10), then a random effects model was used to pool the original data. In the absence of significant heterogeneity, a fixed effects model was used.
  
  
  RESULTS
  We identified six original studies that met the inclusion criteria (N = 162 participants). In studies with higher cumulative dose (>or= 60 mg) or longer duration of therapy (>or= 6 weeks), inhaled corticosteroids were uniformly effective in reducing the total cell, neutrophil, and lymphocyte counts. In contrast, studies with lower cumulative dose (< 60 mg) or shorter duration of therapy (< 6 weeks) did not demonstrate a favorable effect of inhaled corticosteroids on these sputum indices.
  
  
  CONCLUSIONS
  Our study suggests that prolonged therapy with inhaled corticosteroids is effective in reducing airway inflammation in stable COPD.
authors.affiliation: James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research, St, Paul's Hospital and the Department of Medicine (Pulmonary Division), University of British Columbia, Vancouver, Canada. wgan@mrl.ubc.ca <wgan@mrl.ubc.ca>
authors.forename: Wen Qi
authors.initials: WQ
authors.lastname: Gan
authors.forename: S F Paul
authors.initials: SF
authors.lastname: Man
authors.forename: Don D
authors.initials: DD
authors.lastname: Sin
mesh_terms: D000280:Administration, Inhalation; D000305:Adrenal Cortex Hormones / Q000276:immunology / Q000494:pharmacology* / Q000627:therapeutic use*; D006801:Humans; D007249:Inflammation; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000473:pathology; D016032:Randomized Controlled Trials as Topic; D013183:Sputum / Q000166:cytology; D016896:Treatment Outcome
chemical_list: D000305:Adrenal Cortex Hormones