title: Classifying the severity of COPD: are the new severity scales better than the old?
abstract: BACKGROUND
  Forced expiratory volume in 1 second cut-off points establish the severity of chronic obstructive pulmonary disease (COPD).
  
  
  OBJECTIVE
  To compare how the American Thoracic Society (ATS), the British Thoracic Society (BTS), the Global Initiative for COPD (GOLD) and the ATS-European Respiratory Society (ATS-ERS) guidelines for rating COPD severity predict several significant outcomes.
  
  
  METHODS
  Five-year prospective cohort study. Spirometry was performed and health-related quality of life (HRQoL) assessed using the Short Form 36 Health Survey and the Saint George's Respiratory Questionnaire. Hospital admissions resulting from COPD exacerbation and mortality during a 5-year follow-up period were recorded.
  
  
  RESULTS
  In all guidelines, the number of admissions was directly associated with COPD severity. The sensitivity and specificity for 5-year respiratory mortality were respectively 0.21 and 0.97 for the GOLD/ATS-ERS, 0.51 and 0.79 for the BTS, and 0.37 and 0.89 for the ATS guidelines. A similar pattern was seen for all-cause mortality. For HRQoL, statistically significant differences between guidelines were seen only for the BTS and ATS scales.
  
  
  CONCLUSIONS
  These guidelines did not consistently stratify patients with regard to 5-year mortality and HRQoL. Although the BTS system was slightly superior, none of the guidelines were closely related to these outcomes. Other instruments are needed for a better determination of the severity of COPD.
authors.affiliation: Pneumology Department, Hospital de Galdakao-Usansolo, Galdakao, Vizcaya, Spain. cristolbal_esteban@yahoo.es
authors.forename: Cristóbal
authors.initials: C
authors.lastname: Esteban
authors.forename: J M
authors.initials: JM
authors.lastname: Quintana
authors.forename: M
authors.initials: M
authors.lastname: Egurrola
authors.forename: J
authors.initials: J
authors.lastname: Moraza
authors.forename: M
authors.initials: M
authors.lastname: Aburto
authors.forename: J
authors.initials: J
authors.lastname: Pérez-Izquierdo
authors.forename: L V
authors.initials: LV
authors.lastname: Basualdo
authors.forename: A
authors.initials: A
authors.lastname: Capelastegui
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification* / Q000175:diagnosis* / Q000401:mortality; D011788:Quality of Life; D012720:Severity of Illness Index; D013030:Spain / Q000453:epidemiology; D011795:Surveys and Questionnaires