Asthma diagnosis in adults and children: challenges, future directions, and a call to action

Asthma is the most common chronic airway disease worldwide, imposing substantial clinical, societal, and economic burden. Asthma is generally defined as a heterogeneous clinical syndrome characterised by fluctuating respiratory symptoms and variable expiratory airflow limitation. Despite this definition, asthma misdiagnosis remains high; 20-70% of individuals with asthma remain undiagnosed and untreated, and approximately 30% of those labelled as having asthma do not have the disease. Objective evidence, alongside variability of symptoms, is essential to support a diagnosis of asthma. However, international guidelines vary in the selection, sequencing, and interpretation of diagnostic tests, reflecting differences in methodology, health-care infrastructure, test availability, and health-economic considerations. Demonstration of variable expiratory airflow remains central to most pathways, whereas guidance on type 2 inflammatory biomarkers is inconsistent. No single test reliably confirms or excludes asthma, necessitating multi-test diagnostic approaches. Implementing guideline recommendations in routine practice is challenging. Barriers include temporal variability of symptoms and physiology, insufficient patient symptom recognition, restricted access to objective testing, and the presence of multimorbidity. This Personal View summarises the similarities and differences in diagnostic pathways across major guidelines, examines the challenges of applying these recommendations, and looks to future developments and potential solutions. We call for a coordinated international effort to advance diagnostic innovation and generate the high-quality evidence needed to transform asthma diagnosis.