# Pulmonary lesion volume ratio and laboratory parameters as risk factors for plastic bronchitis in pediatric refractory Mycoplasma pneumoniae pneumonia

## TL;DR

The study identifies risk factors for plastic bronchitis in children with a severe form of Mycoplasma pneumoniae pneumonia.

## Contribution

The study introduces a scoring system using clinical and laboratory parameters to predict plastic bronchitis risk in pediatric patients with refractory Mycoplasma pneumoniae pneumonia.

## Key findings

- Elevated NLR, LDH, ALT, pulmonary lesion volume ratio, and reduced APTT are independent predictors of plastic bronchitis in pediatric RMPP.
- A scoring system based on these predictors achieved high sensitivity and specificity in identifying PB cases.
- The high-risk group had a significantly higher incidence of plastic bronchitis compared to lower-risk groups.

## Abstract

Refractory Mycoplasma pneumoniae pneumonia (RMPP) frequently leads to complications, including plastic bronchitis (PB). This study aimed to identify clinical risk factors for PB development in pediatric RMPP.

A total of 361 pediatric patients with RMPP underwent bronchoscopy intervention were divided into a PB group and a non-PB group. Clinical characteristics, laboratory parameters, and chest CT findings were evaluated. Univariate analysis was initially performed to identify potential risk factors of PB, followed by multivariate logistic regression analysis to determine independent predictors, with receiver operating characteristic (ROC) analysis assessing their predictive value. A scoring system for PB risk assessment was developed based on odds ratio (OR) values.

PB patients showed significantly higher rates of extrapulmonary lesions (48.98% vs. 18.59%, p < 0.001), pleural effusion (59.18% vs. 25.64%, p < 0.001), and treatment resistance. Furthermore, PB patients demonstrated significantly elevated levels of neutrophil-to-lymphocyte ratio (NLR), C-reactive protein (CRP), procalcitonin (PCT), erythrocyte sedimentation rate (ESR), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), D-dimer (DD), and pulmonary lesion volume ratio. Conversely, platelet count (PLT), prealbumin (PA), albumin (ALB), complement 3 (C3), complement 4 (C4), activated partial thromboplastin time (APTT), and the proportion of neutrophils in bronchial alveolar lavage fluid (BALF) were significantly lower compared to non-PB group (all P-values < 0.05). Multivariate analysis identified five independent predictors: NLR ≥ 3.30 (OR 2.92), LDH ≥ 451.0 U/L (OR 4.91), ALT ≥ 21.75 U/L (OR 5.68), pulmonary lesion volume ratio ≥ 8.23% (OR 8.83), and APTT ≤ 35.95s (OR 4.20). The combination of these predictors demonstrated strong diagnostic performance, with a sensitivity of 85.70%, specificity of 84.90%, and an area under the curve (AUC) of 0.92 for identifying PB cases. Using a scoring system based on ORs, we stratified 361 RMPP patients into risk groups: the high-risk group had 32 (60.38%) PB out of 53, the middle-risk group had 13 (22.02%) PB out of 59, and the low-risk group had 4 (1.61%) PB out of 249.

Elevated NLR, increased LDH, higher ALT, greater pulmonary lesion volume ratio, and reduced APTT were identified as independent risk factors for PB. Pulmonary lesion volume ratio combined with key laboratory markers may facilitate early risk stratification and clinical intervention for PB in pediatric RMPP.