title: The language of breathlessness differentiates between patients with COPD and age-matched adults.
abstract: BACKGROUND
  If descriptors of the sensation of breathlessness are able to differentiate between medical conditions, the language of breathlessness could potentially have a role in differential diagnosis. This study investigated whether the language used to describe the sensation of breathlessness accurately categorized older individuals with and without a prior diagnosis of COPD.
  
  
  METHODS
  Using a parallel-group design, participants with and without a prior diagnosis of COPD volunteered words and phrases and endorsed up to three statements to describe their sensation of breathlessness. Cluster analysis (v-fold cross-validation) was applied, and subjects were clustered by their choice of words. Cluster membership was then compared to original group membership (COPD vs non-COPD), and predictive power was assessed.
  
  
  RESULTS
  Groups were similar for age and gender (COPD, n = 94; 48 men; mean age, 70 +/- 10 years [+/- SD]; vs non-COPD, n = 55; 21 men; mean age, 69 +/- 13 years) but differed significantly in breathlessness-related impairment, intensity, and quality of life (p < 0.0001). Cluster membership corresponded accurately with original group classifications (volunteered, 85%; and up to three statements, 68% agreement). Classification based on a single best descriptor (volunteered [62%] or endorsed [55%]) was less accurate for group membership.
  
  
  CONCLUSIONS
  Language used to describe the sensation of breathlessness differentiated people with and without a prior diagnosis of COPD when descriptors were not limited to a single best word or statement.
authors.affiliation: School of Health Sciences, University of South Australia, City East Campus, Adelaide. Electronic address: marie.williams@unisa.edu.au.
authors.forename: Marie
authors.initials: M
authors.lastname: Williams
authors.affiliation: Department of Respiratory Medicine, Repatriation General Hospital, Daw Park, Adelaide.
authors.forename: Paul
authors.initials: P
authors.lastname: Cafarella
authors.affiliation: School of Health Sciences, University of South Australia, City East Campus, Adelaide.
authors.forename: Timothy
authors.initials: T
authors.lastname: Olds
authors.affiliation: Applied Statistics Unit, University of South Australia, Whyalla Campus, Whyalla.
authors.forename: John
authors.initials: J
authors.lastname: Petkov
authors.affiliation: Respiratory Services, Repatriation General Hospital and Flinders Medical Centre, Repatriation General Hospital, Daw Park, Adelaide, SA, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Frith
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D016000:Cluster Analysis; D003142:Communication; D004417:Dyspnea / Q000145:classification* / Q000209:etiology / Q000523:psychology; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology; D007802:Language; D008297:Male; D008875:Middle Aged; D010817:Physician-Patient Relations; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D012132:Respiratory Muscles / Q000503:physiopathology; D009626:Terminology as Topic