Diagnosis of Dysfunctional Breathing in Severe Asthma.

BACKGROUND

Dysfunctional breathing (DB) is common in severe asthma and is associated with poor asthma control. Diagnosing DB remains challenging owing to the lack of a gold standard.

OBJECTIVE

To investigate the characteristics of patients with severe asthma identified with DB using 2 distinct diagnostic modalities: the Nijmegen Questionnaire (NQ) combined with the hyperventilation provocation test (HVPT) and cardiopulmonary exercise testing (CPET).

METHODS

Patients with severe asthma were prospectively recruited from 3 asthma expert centers. The diagnosis of DB using NQ-HVPT was confirmed by a panel of 4 chest physicians based on the results of the NQ and HVPT. A CPET-based diagnosis was performed independently by 2 blinded physiologists, with erratic breathing patterns evaluated by visual inspection and objective criteria.

RESULTS

Among 138 patients with severe asthma, 44% were diagnosed with DB using NQ-HVPT. These patients were predominantly female and had poorer asthma control, lower quality of life, and more comorbidities such as depression. Similar findings were noted when DB was defined by an NQ greater than 23. The NQ was independently linked to anxiety, depression, and quality of life regardless of DB diagnosis. Using CPET, 45% of patients were diagnosed with DB, but agreement between NQ-HVPT and CPET for DB diagnosis was poor (κ = 0.16). Patients diagnosed via CPET showed less impaired lung function and higher partial pressure of oxygen (PaO2), possibly indicating a DB pattern more consistent with typical DB presentation.

CONCLUSIONS

The diagnostic agreement between NQ-HVPT and CPET is poor and both modalities may identify different DB patterns. The combination of NQ and HVPT seems to reflect the global burden of asthma rather than DB. The CPET may be a more reliable tool for diagnosing DB, but further studies are needed to confirm its role.