Abstract
Background: Dyspnoea consists of multiple dimensions: intensity, quality, and affective. In clinical practice and research, measurement focuses on intensity; in part because there is no tool available that measures the multidimensionality of dyspnoea. Aim: To develop a tool that captures multiple dimensions of clinical dyspnoea. Methods: Items suitable for inclusion in a multi-dimension dyspnoea instrument were identified following an extensive literature review. After removal of duplicates, 81 were assembled into a list and administered to 123 patients with COPD (mean (SD) age 69 (8) years, 62 male, mean (SD) FEV1/FVC 55 (12)%pred, mean (SD) MRC grade 3.0 (1.0)); 129 patients with interstitial lung disease (age 50 (12) years, 47 male, FEV1/FVC 72 (22)%pred, MRC grade 3.1 (2.0)) and 106 patients with chronic heart failure (age 68 (11) years, 72 male, mean (SD) ejection fraction 35 (15)%, MRC grade 2.6 (1)). Patients were asked to respond to each item using: none, mild, moderate, or severe. A hierarchical method of item reduction was used to exclude items if more than 60% of patients from each group rated them as “none” or if they were influenced by age or gender. Principal components analysis (PCA) was used to test for the presence of different domains and test internal consistency. Results: 24 items were removed because of low response rate or gender or age bias. Of the remaining 57 items, 30 were experienced by all three patient groups, and 14 items were specific to a single disease. PCA of these 57 items produced a 3-component solution (Cronbach’s α = 0.974). Component 1 (n = 25) related to various qualities of dyspnoea, eg, “work/effort”, “air hunger”; Component 2 (n = 12) related to affect, eg, “panicky”, “frightening”; Component 3 (n = 6) related to a mixed item collection including “constricted breathing”, “light-headedness”. Fifteen items did not reach the pre-specified >0.5 factor loading threshold onto any of the 3 components, eg, “puffed”, “gasping”. Conclusion: This is the largest analysis of dyspnoea descriptors yet performed. The experience of dyspnoea among patients with cardiopulmonary disease includes separate qualitative and affective domains, demonstrating that dyspnoea is multi-dimensional. The identified dyspnoea descriptors will form the basis of a new instrument Multi-Dimensional Dyspnoea Questionnaire for the evaluation and quantification of dyspnoea.