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Quality of Life Questionnaire-Bronchiectasis: final psychometric analyses and determination of minimal important difference scores
  1. Alexandra L Quittner1,
  2. Anne E O'Donnell2,
  3. Matthias A Salathe3,
  4. Sandra A Lewis4,
  5. Xiaoming Li4,
  6. A Bruce Montgomery5,
  7. Thomas G O'Riordan4,
  8. Alan F Barker6
  1. 1Department of Psychology & Pediatrics, University of Miami, and Behavioral Health Sciences Research, Coral Gables, Florida, USA
  2. 2Division of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine, Georgetown University, Washington, District of Columbia, USA
  3. 3Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami, Miami, Florida, USA
  4. 4Gilead Sciences Inc., Seattle, Washington, USA
  5. 5Cardeas Pharma Corp., Seattle, Washington, USA
  6. 6Department of Medicine, Division of Pulmonary and Critical Care, Oregon Health & Science University, Portland, Oregon, USA
  1. Correspondence to Dr Alexandra L Quittner, University of Miami, 5665 Ponce de Leon Blvd., Coral Gables, FL 33146, USA; AQuittner{at}Miami.edu

Abstract

Background The Quality of Life-Bronchiectasis (QOL-B), a self-administered, patient-reported outcome measure assessing symptoms, functioning and health-related quality of life for patients with non-cystic fibrosis (CF) bronchiectasis, contains 37 items on 8 scales (Respiratory Symptoms, Physical, Role, Emotional and Social Functioning, Vitality, Health Perceptions and Treatment Burden).

Methods Psychometric analyses of QOL-B V.3.0 used data from two double-blind, multicentre, randomised, placebo-controlled, phase III trials of aztreonam for inhalation solution (AZLI) in 542 patients with non-CF bronchiectasis and Gram-negative endobronchial infection.

Results Excellent internal consistency (Cronbach's α ≥0.70) and 2-week test–retest reliability (intraclass correlation coefficients ≥0.72) were demonstrated for each scale. Convergent validity with 6 min walk test was observed for Physical and Role Functioning scores. No floor or ceiling effects (baseline scores of 0 or 100) were found for the Respiratory Symptoms scale (primary endpoint of trials). Baseline Respiratory Symptoms scores discriminated between patients based on baseline FEV1% predicted in only one trial. The minimal important difference score for the Respiratory Symptoms scale was 8.0 points. AZLI did not show efficacy in the two phase III trials. QOL-B responsivity to treatment was assessed by examining changes from baseline QOL-B scores at study visits at which protocol-defined pulmonary exacerbations were reported. Mean Respiratory Symptoms scores decreased 14.0 and 14.2 points from baseline for placebo-treated and AZLI-treated patients with exacerbations, indicating that worsening respiratory symptoms were reflected in clinically meaningful changes in QOL-B scores.

Conclusions Previously established content validity, reliability and responsivity of the QOL-B are confirmed by this final validation study. The QOL-B is available for use in clinical trials and routine clinical practice.

  • Respiratory Measurement
  • Respiratory Infection
  • Perception of Asthma/Breathlessness
  • Bronchiectasis

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