Predictive value of bronchoalveolar lavage fluid leukotriene C4 for airway hyperresponsiveness in children with

Background: Airway hyperresponsiveness (AHR) is a frequent sequela after acute Methods: We retrospectively studied 158 children with MPP admitted between January 2023 and December 2024; 20 children undergoing bronchoscopy for airway foreign bodies served as controls. BALF LTC4 was measured by enzyme-linked immunosorbent assay (ELISA). AHR was assessed in 87 patients at a 2-week follow-up (positivity 39.1%) using a composite of clinical and spirometric criteria rather than bronchial provocation testing. Features were selected by least absolute shrinkage and selection operator (LASSO) regression and recursive feature elimination (RFE). Nine machine-learning models, including a support vector classifier (SVC), were compared, and predictions were interpreted with SHapley Additive exPlanations (SHAP). Results: In the matched cohort, BALF LTC4 was higher in MPP than in age- and sex-matched controls (46.14 Conclusions: In this retrospective single-center cohort, BALF LTC4 was associated with post-MPP AHR in children and showed greater predictive value than systemic inflammatory markers. A parsimonious SVC based on BALF LTC4 and serum LDH showed encouraging performance, suggesting potential utility for early risk stratification. However, the 55% follow-up rate and selection toward clinically complex patients may have overestimated performance; prospective multicenter validation with more complete follow-up is warranted before clinical implementation.