Clinical risk factors and predictive value of thin-section CT for bronchial mucus plugs in pediatric mycoplasma pneumoniae pneumonia

BACKGROUND: Bronchial mucus plugs in children with Mycoplasma pneumoniae pneumonia (MPP) are often associated with severe clinical presentations, but diagnosing this condition currently depends largely on invasive bronchoscopy. This study aimed to identify clinical risk factors for mucus plug formation and to evaluate the predictive value of chest thin-section CT imaging features in diagnosing bronchial mucus plugs. METHODS: This retrospective study included 186 children (aged 3-15 years) diagnosed with MPP at the Department of Pediatrics, the Hospital of 82nd Group Army PLA, between May 2023 to June 2024. All patients underwent chest thin-section CT and bronchoscopy. Based on bronchoscopic findings, participants were divided into a mucus plug group (n = 54, 29%) and a non-mucus plug group (n = 132, 71%). Clinical characteristics, inflammatory markers (blood counts, C-reactive protein [CRP], lactate dehydrogenase [LDH]), and CT imaging features (bronchial obstruction, bronchiolitis, lung consolidation) were compared. Univariate and multivariate logistic regression analyses were performed to identify risk factors. Patients were further classified into radiological mucus plug (n = 59) and non-mucus plug (n = 127) groups based on CT-detected bronchial obstruction. Consistency between CT and bronchoscopy results was analyzed. Receiver operating characteristic (ROC) curves assessed the diagnostic performance of CT features and D-dimer. RESULTS: Univariate analysis revealed significant differences between the two groups in age, lymphocyte count, lymphocyte percentage, C-reactive protein (CRP), D-dimer, peak body temperature, bronchial obstruction, bronchiolitis, and lung consolidation (all P < 0.05). Multivariate analysis identified elevated D-dimer (P = 0.050, OR = 2.048, 95% CI: 1.000-4.195) as an independent risk factor, and bronchial obstruction on CT(P < 0.001, OR = 31.339, 95% CI: 9.922-98.985) as a strong independent predictor for the presence of bronchial mucus plugs. ROC analysis: Bronchial obstruction: AUC = 0.838 (sensitivity: 79.6%, specificity: 87.9%, PPV: 72.9%, NPV: 91.3%). D-dimer: AUC = 0.692 (sensitivity: 56.6%, specificity: 81.7%). lung Consolidation: AUC = 0.643 (sensitivity: 57.4%, specificity: 73.8%). CONCLUSION: Elevated D-dimer is an independent risk factor, while bronchial obstruction on thin-section CT is a reliable predictive imaging marker for bronchial mucus plugs in pediatric MPP. Bronchial obstruction on CT offers high diagnostic accuracy, especially with its strong specificity and negative predictive value, supporting its role as a non-invasive tool to guide clinical decisions.