title: Development and validation of the Dyspnea Index (DI): a severity index for upper airway-related dyspnea.
abstract: OBJECTIVE
  To (1) develop and validate the Dyspnea Index (DI); (2) quantify severity of symptoms in upper airway dyspnea; and (3) validate the DI as an outcome measure.
  
  
  METHODS
  Survey development and validation.
  
  
  METHODS
  Three hundred sixty-nine participants were recruited for different phases of the study. Two hundred participants with chief complaints of dyspnea were given a 41-item questionnaire addressing common symptoms of dyspnea related to the upper airway. The questions were then reduced based on principal component analysis (PCA) and internal consistency resulting in a 10-item questionnaire. Cognitive interviews were conducted with 15 participants. Test-retest reliability and discriminant validity were measured from 51 participants. The DI was further validated by administering the index to 57 healthy controls (HC). Validation of the DI as a treatment outcome tool occurred with 46 participants' pre- and post-treatment scores.
  
  
  RESULTS
  PCA revealed that only a single factor was being measured in both the original 41- and 10-item questionnaires. Additional cognitive interviewing suggested that no modification was needed to the DI. Test-retest reliability was r = 0.83. Discriminant validity was r = 0.62. The Mann-Whitney test demonstrated significant differences between healthy/symptomatic participants. Scores from the HC cohort resulted in a mean of 3.12 (SEM = 0.484; SD = 3.65) for the normative values.
  
  
  CONCLUSIONS
  The DI is an effective and efficient instrument to quantify patients' symptoms of upper airway dyspnea. It is a statistically robust index, with significant reliability and validity, and can be dependably used as a treatment outcome measure.
authors.affiliation: Department of Otolaryngology, University of Pittsburgh Voice Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania. Electronic address: jgs@pitt.edu.
authors.forename: Jackie L
authors.initials: JL
authors.lastname: Gartner-Schmidt
authors.affiliation: Department of Otolaryngology, University of Pittsburgh Voice Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Adrianna C
authors.initials: AC
authors.lastname: Shembel
authors.affiliation: Department of Dental Public Health, University of Pittsburgh Voice Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Zullo
authors.affiliation: Department of Otolaryngology, University of Pittsburgh Voice Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Clark A
authors.initials: CA
authors.lastname: Rosen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003071:Cognition; D004417:Dyspnea / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology / Q000628:therapy; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D025341:Principal Component Analysis; D011379:Prognosis; D015203:Reproducibility of Results; D012119:Respiration; D012137:Respiratory System / Q000503:physiopathology*; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Dyspnea; Glottal stenosis; Laryngeal stenosis; Outcomes; Paradoxical Vocal Fold Motion Disorder (PVFMD); Questionnaire; Shortness of breath; Symptom severity; Vocal Cord Dysfunction (VCD)