Time for proper physiological assessment: the role of cardiopulmonary exercise testing in helping step-up therapy in difficult-to-treat and severe asthma

CPET may represent a valuable physiological adjunct in selected patients with difficult-to-treat or severe asthma and persistent exertional dyspnea insufficiently explained by resting assessments. Its integration into the assessment pathway may help contextualize symptoms, distinguish asthma-driven exercise limitation from non-inflammatory or non-asthmatic causes of dyspnea, and support more mechanism-based management. However, current evidence supports CPET primarily as a tool for physiological phenotyping and trait reclassification rather than as a prospectively validated guide to treatment escalation, biologic stewardship, or long-term outcome improvement.