BACKGROUND: Difficult asthma is defined as asthma requiring high dose treatment. However, systematic assessment is required to differentiate severe asthma from difficult-to-treat asthma. Dysfunctional breathing (DB) is a common comorbidity in difficult asthma, which may contribute to symptoms, but how it affects commonly used measures of symptom control is unclear.

METHODS: All adult asthma patients seen in four respiratory clinics over one year were screened prospectively, and patients with possible severe asthma according to ERS/ATS criteria ('Difficult asthma': high-dose inhaled corticosteroids/oral corticosteroids), underwent systematic assessment. Symptoms of DB were assessed utilizing a symptom based subjective tool, Nijmegen questionnaire (NQ), and objective signs of DB with the Breathing Pattern Assessment Tool (BPAT). Asthma control and quality of life were evaluated with the Asthma Control Questionnaire (ACQ) and the mini Asthma Quality of Life Questionnaire (AQLQ).

RESULTS: A total of 117 patients were included. Among these, 29.9% (35/117) had DB according to the NQ. Patients with DB had a poorer asthma control (ACQ: Mean (SD) 2.86 ± 1.05 vs. 1.46 ± 0.93) and lower quality of life (AQLQ score: Mean (SD) 4.2 ± 1.04 vs. 5.49 ± 0.85) compared to patients without DB. Similarly, patients with objective signs of DB according to the BPAT score had worse asthma control: BPAT >4 vs < 4: (ACQ: Mean (SD) 3.15 ± 0.93 vs 2.03 ± 1.15).

CONCLUSION: DB is common among patients with difficult asthma, and is associated with significantly poorer asthma control and lower quality of life. Assessment and treatment of DB is an important part of the management of difficult asthma.