title: Development of a conceptual framework and calibrated item banks to measure patient-reported dyspnea severity and related functional limitations.
abstract: OBJECTIVE
  Chronic obstructive pulmonary disease is a major global health problem. Although several patient-reported outcome (PRO) measures of chronic obstructive pulmonary disease exist, none were developed using patient-driven concept development. We developed an item bank for dyspnea severity and related functional limitations on the basis of a PRO conceptual framework derived from patient input.
  
  
  METHODS
  We identified a large pool of existing items based on a conceptual framework and literature review. Using patient and expert review panels and an item refinement/modification process, we developed an item bank aligned with the conceptual framework, which subsequently underwent psychometric testing via an online Internet panel of dyspnea patients (N = 608).
  
  
  RESULTS
  Exploratory factor analysis suggested a dominant first factor accounting for about 78% of the total variance. Confirmatory factor analysis supported a unidimensional model. Item response theory analysis demonstrated good model fit, and differential item functioning analyses indicated that the 33-item scale showed potential for measurement equivalence across sex. A 10-item short form produced comparable scores (r = 0.98) and a computerized adaptive-testing simulation indicated efficient measurement with fewer items (mean 4.65 items).
  
  
  CONCLUSIONS
  An efficient patient-reported measure of dyspnea severity and related functional limitations, based on a patient-driven PRO conceptual framework, is now available for further validation and use.
authors.affiliation: Department of Medical Social Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL 60611,USA. s-choi@northwestern.edu
authors.forename: Seung W
authors.initials: SW
authors.lastname: Choi
authors.forename: David E
authors.initials: DE
authors.lastname: Victorson
authors.forename: Susan
authors.initials: S
authors.lastname: Yount
authors.forename: Susan
authors.initials: S
authors.lastname: Anton
authors.forename: David
authors.initials: D
authors.lastname: Cella
mesh_terms: D000203:Activities of Daily Living; D004417:Dyspnea / Q000503:physiopathology / Q000523:psychology*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D011594:Psychometrics / Q000379:methods*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D015203:Reproducibility of Results; D057566:Self Report; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D014481:United States