title: Comparison between an alternative and the classic definition of chronic bronchitis in COPDGene.
abstract: BACKGROUND
  Previous studies on chronic bronchitis (CB) have used varying definitions.
  
  
  OBJECTIVE
  We sought to compare an alternative CB definition, using the St. George's Respiratory Questionnaire (SGRQ), a commonly used assessment tool, with the classic definition and to investigate if it had independent or additive value.
  
  
  METHODS
  We analyzed data from 4,513 subjects from Global Initiative for Chronic Obstructive Lung Disease groups 1 to 4 in the COPDGene cohort. We compared the classic definition of CB with the SGRQ definition, defined by their answers to the questions about both cough and phlegm. We compared the Classic CB+ versus CB- groups, and the SGRQ CB+ and CB- groups. We also analyzed the cohort split into four groups: Classic CB+/SGRQ CB+, Classic CB+/SGRQ CB-, Classic CB-/SGRQ CB+, Classic CB-/SGRQ CB-.
  
  
  RESULTS
  A total of 26.1% subjects were Classic CB+, whereas 39.9% were SGRQ CB+. When the SGRQ definition was compared with the Classic CB definition, using this as the gold standard, the SGRQ CB definition had a sensitivity and specificity of 0.87 and 0.77, respectively. The SGRQ CB+ and Classic CB+ groups were strikingly similar, with more respiratory symptoms and exacerbations, worse lung function, and greater airway wall thickness. In addition, the Classic CB+/SGRQ CB+, Classic CB+/SGRQ CB-, and Classic CB-/SGRQ CB+ groups shared similar characteristics as well.
  
  
  CONCLUSIONS
  The SGRQ CB definition identifies more subjects with chronic cough and sputum who share a similar phenotype identified by the Classic CB definition. The addition of the SGRQ CB definition to the classic one can be used to identify more patients with chronic obstructive pulmonary disease at risk for poor outcomes.
authors.affiliation: 1 Department of Pulmonary and Critical Care Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania.
authors.forename: Victor
authors.initials: V
authors.lastname: Kim
authors.forename: James
authors.initials: J
authors.lastname: Crapo
authors.forename: Huaqing
authors.initials: H
authors.lastname: Zhao
authors.forename: Paul W
authors.initials: PW
authors.lastname: Jones
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Silverman
authors.forename: Alejandro
authors.initials: A
authors.lastname: Comellas
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Make
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Criner
mesh_terms: D000328:Adult; D000368:Aged; D029481:Bronchitis, Chronic / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology; D011788:Quality of Life; D013902:Radiography, Thoracic; D012720:Severity of Illness Index; D013147:Spirometry
keywords: Saint George’s Respiratory Questionnaire; chronic bronchitis; chronic obstructive pulmonary disease