The Upper Airway as a Treatable Trait: A United-Airway Framework for Biologic Selection in Asthma

The treatable traits approach reframes asthma management around measurable and modifiable factors rather than diagnostic labels, and it has become a cornerstone of the precision medicine model in chronic airway disease. Among the traits that shape asthma control, corticosteroid burden and treatment response, upper airway comorbidity is both prevalent and frequently under-recognised. Allergic rhinitis, chronic rhinosinusitis with and without nasal polyps, and olfactory dysfunction share anatomical, immunological and clinical links with the lower airway, and upper-airway comorbidities are increasingly considered in the management of severe asthma. However, their systematic characterisation as measurable, discrete treatable traits and their formal integration with lower-airway biomarkers at the point of biologic selection remain heterogeneous across clinical practice. In this narrative review, we propose a conceptual united-airway framework for the integrated assessment of upper- and lower-airway treatable traits in patients with asthma. The framework combines clinical phenotyping, validated assessment tools and local and systemic inflammatory biomarkers to characterise upper-airway disease and to support, rather than prescribe, biologic selection. We argue that type 2-high traits align with approved, biomarker-guided monoclonal antibodies, while upstream epithelial alarmin blockade has further expanded the therapeutic landscape. Tezepelumab, an anti-TSLP monoclonal antibody, is now approved for CRSwNP and does not require biomarker-based evidence of type 2 inflammation for treatment eligibility. We further consider how a treatable traits strategy helps disentangle uncontrolled from difficult-to-treat and severe asthma, how it supports corticosteroid-sparing, and how it can be operationalised within an integrated pulmonology-allergy-otolaryngology care pathway. Prospective studies are required to determine whether this conceptual approach improves biologic selection and patient-relevant outcomes across the united airway.