Abstract
Introduction: Breathlessness is the main symptom of COPD and should be a key outcome measure in studies of advanced disease. Measures of breathlessness have been poorly researched. There is no gold standard for the assessment of breathlessness in advanced disease. In this study we aimed to identify using existing tools a valid and reliable self-report measure of breathlessness for clinical research in advanced COPD.
Methods: 260 eligible patients with advanced COPD were identified from the disease registers of 72 general practices. Spirometry, MRC dyspnoea scale, mBorg, NRS, CRQ-SAS, Dyspnoea 12, and Hospital Anxiety and Depression Scale, were administered at interview. Distribution of responses, associations and correlations were examined.
Results: 146 (56%) patients were interviewed. Association between the different measures of breathlessness was variable with least correlation between the numerical measures mBorg and NRS and the other measures, and greatest correlation between CRQ-SAS and Dyspnoea 12. Usefulness of tools was limited by ceiling effects (limited room for more severe breathlessness) in MRC Dyspnoea scale and by floor effects (limited room for less severe breathlessness) in mBorg and NRS. Factor analysis of the five measures confirmed that the CRQ-SAS dyspnoea questionnaire (loading -0.74) and Dyspnoea 12 questionnaire (loading 0.73) were closest to the hypothesized latent true value of breathlessness (eigenvalue 2.33, difference 2.21).
Conclusions: Combination of CRQ-SAS dyspnoea and Dyspnoea 12 is the most suitable approach to valid, repeatable, measurement of breathlessness in clinical research in advanced COPD that is sensitive to change. MBorg retains a particular role in standardised exercise testing.
- © 2011 ERS