title: Retrospective characterization of airway reversibility in patients with asthma responsive to bronchodilators.
abstract: BACKGROUND
  National and international asthma guidelines recommend the use of reversibility to assist in the diagnosis of asthma.
  
  
  METHODS
  This retrospective pooled analysis assessed the reversibility characteristics of a large cohort of patients (n = 30 816) selected from 106 clinical trials conducted by GlaxoSmithKline in which bronchodilator reversibility (> or = 12%) was required for participation in the trials.
  
  
  RESULTS
  Patients (n = 1434) with a baseline forced expiratory volume in 1 second (FEV1) between 40% and < 50% at screening had a mean reversibility of 42% and those (n = 550) with a baseline FEV1 between 90% and < 100% had a mean reversibility of 18%. In general, the lower the patient's baseline lung function, the higher the reversibility. Further, in a subset of studies (n = 7; 1477 patients) that provided reversibility data at study baseline and endpoint, the mean reversibility for patients receiving placebo or fluticasone propionate (FP) was 26%. At study completion, nearly 30% fewer patients receiving placebo were shown to be reversible and approximately half of the patients receiving fluticasone propionate were no longer reversible.
  
  
  CONCLUSIONS
  This analysis shows that airway reversibility is affected by asthma severity as measured cross-sectionally by spirometry, pharmacotherapeutic interventions, including placebo, and time. Additional studies are needed to confirm this finding in broader populations as studies in this analysis were limited to those conducted in the US by GlaxoSmithKline.
authors.affiliation: GlaxoSmithKline, Research Triangle Park, NC 27709, USA. steve.w.yancey@gsk.com
authors.forename: Steven W
authors.initials: SW
authors.lastname: Yancey
authors.forename: Hector G
authors.initials: HG
authors.lastname: Ortega
mesh_terms: D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy*; D001980:Bronchi / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D001993:Bronchodilator Agents