Breathlessness burden high despite optimal asthma management


By Geir O'Rourke

25 Jun 2024

One third of people with mild-to-moderate asthma and over half of those with severe asthma experience physically limiting breathlessness despite undergoing optimal treatment, an Australian study has found.

The results highlight the need to treat psychophysiological factors, or traits, associated with breathlessness, with an aim of relieving this distressing symptom, the investigators say.

Some 74 patients with mild-to-moderate and 70 with severe asthma were included in the cross-sectional study, which was led by Professor Vanessa McDonald from the University of Newcastle and Hunter Medical Research Institute.

Multidimensional assessment over two visits found physically limiting breathlessness in 53% of those with severe asthma, defined as modified Medical Research Council (mMRC)  dyspnoea score ≥2.

By contrast, the proportion of those with mild-to-moderate disease reporting mMRC ≥2 was 31%, the researchers reported in The Journal of Allergy and Clinical Immunology: In Practice (link here).

Of note, this high breathlessness burden came despite the fact that study participants were invariably on optimal pharmacotherapy: 46 of the severe asthma patients had been prescribed a monoclonal antibody, 21 of whom still experienced physically limiting breathlessness, the authors said.

Significant predictors of physically limiting breathlessness included BMI and exercise capacity.

These could be targeted with evidence-based approaches such as pulmonary rehabilitation, while pharmacological strategies were available to reduce body mass and BMI and should considered as part of asthma, and potentially breathlessness, management, the authors said.

“For the same average participant of this study, a loss of 2.5 kg would equate to a 1 kg/m2 reduction in BMI and 13% reduced odds of breathlessness,” they wrote.

Other factors identified as correlates of breathlessness in our asthma population included poor asthma control and hyperventilation symptoms, falling under the umbrella of dysfunctional breathing and potentially representing an asthma-specific breathlessness phenotype, according to the team.

“For example, up to two thirds of the asthma population experience dysfunctional breathing, which is higher than in people without asthma,” they wrote.

“Further research is needed to clearly define what constitutes dysfunctional breathing, and then, if dysfunctional breathing diagnosed based on established criteria is a significant driver of breathlessness in people with asthma.”

On the other hand, the asthma super-traits of airflow limitation and type-2 inflammation were poor breathlessness predictors, according to the study.

“Targeting these super-traits alone is likely insufficient to achieve clinically meaningful improvements in breathlessness for people with asthma,” the authors concluded.

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