title: Measuring respiratory symptoms in clinical trials of COPD: reliability and validity of a daily diary.
abstract: BACKGROUND
  Although respiratory symptoms are characteristic features of COPD, there is no standardised method for quantifying their severity in stable disease.
  
  
  OBJECTIVE
  To evaluate the EXACT-Respiratory Symptom (E-RS) measure, a daily diary comprising 11 of the 14 items in the Exacerbations of Chronic Pulmonary Disease Tool (EXACT).
  
  
  METHODS
  Qualitative: patient focus group and interviews to address content validity. Quantitative: secondary data analyses to test reliability and validity.
  
  
  RESULTS
  Qualitative: n=84; mean (SD) age 65 (10) years, FEV1 1.2(0.4) L; 44% male. Subject descriptions of their respiratory symptoms were consistent with E-RS content and structure. Quantitative: n=188; mean (SD) age 66 (10) years, FEV1 1.2(0.5) L; 50% male. Factor analysis (FA) showed 3 subscales: RS-Breathlessness, RS-Cough & Sputum, and RS-Chest Symptoms; second-order FA supported a general factor and total score. Reliability (total and subscales): 0.88, 0.86, 0.73, 0.81; 2-day test-retest ICC: 0.90, 0.86, 0.87, 0.82, respectively.
  
  
  RESULTS
  Total scores correlated significantly (p < 0.0001) with SGRQ Total (r=0.75), Symptoms (r=0.66), Activity (r=0.57), Impact (r=0.70) scores; subscale correlations were also significant (r=0.26, p < 0.05 (RS-Chest Symptoms with Activity) to r=0.69, p < 0.0001 (RS-Cough & Sputum with Symptoms). RS-Breathlessness correlated with rescue medication use (r=0.32, p < 0.0001), clinician-reported mMRC (r=0.33, p < 0.0001), and FEV1% predicted (r=-0.17, p < 0.05). E-RS scores differentiated groups based on chronic bronchitis diagnosis (p < 0.01-0.001), smoking status (p < 0.05-0.001), and rescue medication use (p < 0.05-0.0001).
  
  
  CONCLUSIONS
  Results suggest the RS-Total is a reliable and valid instrument for evaluating respiratory symptom severity in stable COPD. Further study of sensitivity to change is warranted.
authors.affiliation: Evidera, , Bethesda, Maryland, USA.
authors.forename: N K
authors.initials: NK
authors.lastname: Leidy
authors.forename: C C
authors.initials: CC
authors.lastname: Sexton
authors.forename: P W
authors.initials: PW
authors.lastname: Jones
authors.forename: S M
authors.initials: SM
authors.lastname: Notte
authors.forename: B U
authors.initials: BU
authors.lastname: Monz
authors.forename: L
authors.initials: L
authors.lastname: Nelsen
authors.forename: M
authors.initials: M
authors.lastname: Goldman
authors.forename: L T
authors.initials: LT
authors.lastname: Murray
authors.forename: S
authors.initials: S
authors.lastname: Sethi
mesh_terms: D000368:Aged; D003371:Cough / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D003625:Data Collection / Q000592:standards*; D004417:Dyspnea / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
keywords: COPD Exacerbations