title: Shortness of Breath with Daily Activities questionnaire: validation and responder thresholds in patients with chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  To test the reliability, validity and responsiveness of the 13-item Shortness of Breath with Daily Activities (SOBDA) questionnaire, and determine the threshold for response and minimal important difference (MID).
  
  
  METHODS
  6 week, randomised, double-blind, placebo-controlled study.
  
  
  METHODS
  40 centres in the USA between 29 October 2009 and 1 July 2010.
  
  
  METHODS
  547 patients with chronic obstructive pulmonary disease (COPD) were enrolled and 418 entered the 2-week run-in period. Data from the run-in period were collected to test internal consistency, test-retest reliability, convergent validity and known-groups validity of the SOBDA. Three hundred and sixty six patients were randomised 2:2:1 to fluticasone propionate/salmeterol 250/50 µg, salmeterol 50 µg or placebo, twice daily. Results from the SOBDA questionnaire, Patient Global Assessment of Change Question, modified Medical Research Council Dyspnoea Scale (mMRC), Clinician Global Impression of Dysponea Severity (CGI-S), Clinician Global Impression of Change Question and Chronic Respiratory Disease Questionnaire self-administered standardised version (CRQ-SAS) were evaluated; spirometry and safety parameters were measured. Study endpoints were selected to investigate the cross-sectional and longitudinal validity of the SOBDA questionnaire in relation to the clinical criteria.
  
  
  RESULTS
  Internal consistency of the SOBDA questionnaire (Cronbach α) was 0.89. Test-retest reliability (intraclass correlation) was 0.94. The SOBDA weekly scores correlated with the patient-reported and clinician-reported mMRC, CGI-S and CRQ-SAS dyspnoea domain scores (0.29, 0.24, 0.24 and -0.68, respectively). The SOBDA weekly scores differentiated between the responders and the non-responders as rated by the patients and the clinicians. Anchor-based and supportive distribution-based analyses produced a range of the potential values for the threshold for the responders and MID.
  
  
  CONCLUSIONS
  The 13-item SOBDA questionnaire is reliable, valid and responsive to change in patients with COPD. On using anchor-based methods, the proposed responder threshold shows a -0.1 to -0.2 score change. A specific threshold value will be identified as more data are generated from future clinical trials.
  
  
  BACKGROUND
  NCT00984659; GlaxoSmithKline study number: ASQ112989.
authors.affiliation: Respiratory Medicines Development Center, GlaxoSmithKline, Research Triangle Park, North Carolina, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Watkins
authors.forename: Teresa K
authors.initials: TK
authors.lastname: Wilcox
authors.forename: Maggie
authors.initials: M
authors.lastname: Tabberer
authors.forename: Jean M
authors.initials: JM
authors.lastname: Brooks
authors.forename: James F
authors.initials: JF
authors.lastname: Donohue
authors.forename: Antonio
authors.initials: A
authors.lastname: Anzueto
authors.forename: Wen-Hung
authors.initials: WH
authors.lastname: Chen
authors.forename: Courtney
authors.initials: C
authors.lastname: Crim
keywords: RESPIRATORY MEDICINE (see Thoracic Medicine); THORACIC MEDICINE