Treatable traits of small airway dysfunction in children with asthma and advances in small airway-targeted therapeutic research: a narrative review

Background and Objective: Small airway dysfunction (SAD) is highly prevalent in children with asthma and is closely associated with adverse outcomes, including poor disease control, frequent exacerbations, and impaired quality of life. However, conventional asthma management has traditionally focused on large-airway assessment, often leading to the oversight of SAD. The maturation of diagnostic techniques and the growing application of therapies with enhanced peripheral lung delivery have rendered targeted intervention increasingly feasible. Concurrently, the emerging "treatable traits" (TTs) paradigm provides a novel framework for personalized asthma management. This review aims to synthesize current evidence on small airway-targeted therapies and, building upon the TT framework, propose a stepwise clinical strategy to operationalize pediatric SAD as a distinct TT, in order to inform future research and guide the evolution of clinical practice. Methods: A narrative review of relevant literature was conducted. We searched PubMed, Embase, the Cochrane Library, and China National Knowledge Infrastructure (CNKI) for English- and Chinese-language publications from 1 January 2015 to 15 March 2025. Search terms covered asthma, children, small airway dysfunction or related small-airway assessment terms, and treatable traits or related precision-management concepts. Original studies, relevant reviews, and consensus/guideline documents concerning the assessment, targeted therapy, and treatable-traits strategy for small airway involvement in pediatric asthma were considered. Key Content and Findings: The review synthesizes evidence supporting SAD as a key modifiable therapeutic target within the TT framework. It details diagnostic approaches, particularly impulse oscillometry, and evaluates therapeutic strategies designed for peripheral lung delivery, such as extrafine-particle inhaled corticosteroids and biologics. Building on this evidence, a practical, stepwise clinical strategy is proposed to systematically identify, assess, and manage SAD as a TT in children with asthma. Conclusions: Integrating SAD into the TTs framework represents a promising pathway towards more precise and individualized management of childhood asthma. Implementing assessment and targeted intervention strategies for SAD has the potential to improve disease control, reduce exacerbations, and enhance the quality of life for affected children. Future research is needed to validate the effectiveness of this proposed strategy and to define the optimal pathways for its implementation in routine clinical care.