A common model for the breathlessness experience

Abstract

Introduction: Chronic breathlessness occurs across many different diseases, independently of severity. Yet, despite being strongly linked to adverse outcomes, chronic breathlessness is generally not considered a stand-alone treatment target. Here we move focus from identifying the "best" measurement tool and use data-driven techniques to identify and confirm the stability of underlying features (factors) driving breathlessness across different cardiorespiratory diseases. Such frameworks could provide an opportunity to address the underlying mechanisms of breathlessness and over-come issues with co-morbidities, particularly when medical therapies have been optimised. Methods: Longitudinal study of questionnaire data on 182 participants with main diagnoses of asthma (21.4%), COPD (24.7%), heart failure (19.2%), idiopathic pulmonary fibrosis (18.7%), other interstitial lung disease (5.5%), and "other diagnoses" (8.8%) were entered into an exploratory factor analysis (EFA). Participants were stratified based on their EFA factor scores, allowing us to examine whether the breathlessness experience differed across disease diagnosis. We then examined model stability after six months and established through an iterative process the most compact, and therefore least burdensome assessment tool. Results: From the 25 input measures, 16 measures were retained for model validation. The resulting model contained four factors to which we assigned the following descriptive labels: 1) body burden, 2) affect/mood, 3) breathing burden and 4) anger/frustration. Stratifying patients by their scores across the four factors revealed two groups corresponding to high and low burden. These were not found to be predictive of primary disease diagnosis and did remain stable after six months. Conclusions: We have identified four stable and disease-independent factors that seem to underlie the experience of breathlessness. We suggest that interventions may target factors within this framework to answer the question of whether they are also driving the experience itself.