Early Risk Stratification for Subsequent Small Airway Dysfunction in Hospitalized Children with Mycoplasma Pneumoniae...

Background/Objectives: Small airway dysfunction (SAD) may occur early in children with Mycoplasma pneumoniae pneumonia (MPP), but pulmonary function testing is often deferred until clinical stabilization and may be limited by poor cooperation. Early risk stratification may therefore help identify children who warrant further testing. We aimed to identify early predictors of subsequent spirometry-defined SAD and to develop an internally validated risk-stratification model in hospitalized children with MPP. Methods: In this single-center retrospective cohort study conducted between July 2022 and July 2024, 172 hospitalized children with confirmed MPP were included. Clinical characteristics, immune-inflammatory indices, and chest computed tomography (CT) findings were collected during early hospitalization. Pulmonary function testing was performed after clinical stabilization, and SAD was defined as at least two of forced expiratory flow at 25%, 50%, and 75% of forced vital capacity being <65% of predicted values. Multiple imputation, LASSO selection, and multivariable logistic regression were used for model development and bootstrap internal validation. Results: SAD was identified in 76/172 children (44.2%). Wheezing, CT evidence of small airway involvement, and higher soluble interleukin-2 receptor levels were more common in children with SAD; wheezing remained independently associated with SAD. A model based on routine clinical and chest CT variables showed good discrimination (AUC, 0.885; optimism-corrected AUC, 0.869). Adding interleukin-17 provided limited incremental value. Conclusions: SAD was common in hospitalized children with MPP. An internally validated model based on readily available clinical and chest CT variables may help prioritize children for pulmonary function testing after clinical stabilization, whereas interleukin-17 added limited predictive value. External validation is required before broader clinical application.