title: Severity staging of chronic obstructive pulmonary disease: differences in pre- and post-bronchodilator spirometry.
abstract: OBJECTIVE
  The Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines for chronic obstructive pulmonary disease (COPD) uses the post-bronchodilator spirometry for diagnosis and severity staging. We evaluated differences in the severity classification of COPD, based on pre- and post-bronchodilator spirometry.
  
  
  METHODS
  From 2000 to 2004, 207 COPD patients who underwent spirometry before and after inhalation of 400 microg of fenoterol were analyzed. A responder to the bronchodilator test (BDT) was defined by the American Thoracic Society (ATS) as an increase in forced expiratory volume in one second (FEV(1)) or forced vital capacity > or = 12% and > or = 200 mL, and by the European Respiratory Society (ERS) as an increase in FEV(1) > or = 10% of the predicted value. COPD severity was classified according to the 2008 GOLD guidelines.
  
  
  RESULTS
  For the entire study population, the FEV(1) increased by 11.8 +/- 12.5% of baseline after BDT and 41.1% and 27.1% of subjects were classified as responders using the ATS and ERS criteria, respectively. Based on pre-BDT spirometry, 55, 85, 58, and 9 patients were classified as Stage I-IV COPD, respectively. Sixty-seven (32.4%) patients changed severity staging after BDT, including 20.0%, 28.2%, 44.8%, and 66.7% of pre-BDT patients Stages I through IV, respectively. More ATS or ERS BDT-responders had a change in severity staging than non-responders (52.9% vs. 18.9% and 62.5% vs. 21.2%, both p < 0.001).
  
  
  CONCLUSIONS
  Our data suggest that the severity staging of COPD using pre-BDT spirometry might lead to significant differences as compared to staging, based on post-BDT spirometry, as recommended by the current GOLD guidelines.
authors.affiliation: Department of Internal Medicine, Taipei County Hospital, Taipei County, Taiwan.
authors.forename: Sheng-Hsiang
authors.initials: SH
authors.lastname: Lin
authors.forename: Ping-Hung
authors.initials: PH
authors.lastname: Kuo
authors.forename: Sow-Hsong
authors.initials: SH
authors.lastname: Kuo
authors.forename: Pan-Chyr
authors.initials: PC
authors.lastname: Yang
mesh_terms: D001993:Bronchodilator Agents; D005280:Fenoterol; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D017410:Practice Guidelines as Topic; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis*; D013147:Spirometry / Q000379:methods
chemical_list: D001993:Bronchodilator Agents; D005280:Fenoterol