Quantification of breathlessness using descriptors in cardiopulmonary disease

Yorke, J

Abstract

Rationale: Breathlessness is a multidimensional construct reflected in different verbal descriptors. It is a perceptual experience that is complex and highly subjective. In cardiopulmonary disease breathlessness can be extremely debilitating and distressing. It is usually measured using scales such as visual analogue and Borg scales; or indirectly through report of activity limitation or quality of life. This thesis presents the development and validation of an instrument that measures overall breathlessness magnitude using descriptors that reflect its different aspects.
Methods: Eighty-one breathlessness descriptors were administered to 123 patients with chronic obstructive pulmonary disease (COPD), 129 with interstitial lung
disease (ILD) and 106 with chronic heart failure. These were reduced to 34 items using hierarchical methods. Rasch analysis was then applied to inform decisions regarding further item removal and overall fit to the Rasch unidimensional model.
Principal components analysis (PCA) tested whether items separated into discrete components. Validity and reliability of the new instrument was further assessed in a
separate group of 53 patients with COPD, 46 with ILD and 65 with asthma.
Results: After removal of items with hierarchical methods (n=47) and items that failed to fit the Rasch model (n=22), 12 items were retained. The 12-item set had good internal-reliability (Cronbach's alpha=0.9) and fit to the model (x2 p=0.08). PCA identified two sub-components: 'physical' (n=7) and 'affective' (n=5). 'Affective' items represented more severe breathlessness. In the separate validation study, Dyspnoea-12 correlated with six-minute walk distance, St George's Respiratory Questionnaire, MRC dyspnea grade, and had good stability over time (ICCC=0.9,
p<0.001).
Conclusion: Dyspnoea-12 fulfills modern psychometric requirements for measurement. It provides a global score of breathlessness that incorporates both 'physical' and 'affective' aspects. It addresses the need for a comprehensive breathlessness instrument and is based on the language used by patients. It can measure breathlessness across several disease groups.

Citation

Yorke, J. Quantification of breathlessness using descriptors in cardiopulmonary disease. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Oct 3, 2012
• Award Date: Jan 1, 2009