# Initial presentation, etiology and risk factors for adverse outcomes in infection-associated plastic bronchitis in children: a retrospective study

## TL;DR

This study examines infection-associated plastic bronchitis in children, focusing on Mycoplasma pneumoniae as the main cause and identifying biomarkers like LDH and D-dimer that predict poor outcomes.

## Contribution

The study identifies Mycoplasma pneumoniae as the primary pathogen and highlights LDH and D-dimer as potential early biomarkers for adverse outcomes in children with infection-associated plastic bronchitis.

## Key findings

- Mycoplasma pneumoniae was the main cause in 94.2% of infection-associated plastic bronchitis cases.
- Elevated LDH and D-dimer levels were significantly associated with poor prognosis in affected children.
- Adverse outcomes included persistent atelectasis, bronchiectasis, and the need for surgical intervention.

## Abstract

To summarize the pathogen distribution, imaging features, radiologic outcomes, and risk factors for poor prognosis in children with infection-associated plastic bronchitis (PB).

This retrospective study included 86 hospitalized children diagnosed with infection-associated PB at Henan Children's Hospital from January 2021 to December 2023. Patients were grouped based on radiologic findings and outcomes into favorable prognosis, poor prognosis, and indeterminate outcome groups. Clinical data and laboratory results were compared between the favorable and poor prognosis groups to identify potential risk factors for adverse outcomes.

Among 86 children with infection-associated PB, 81 (94.2%) were caused by Mycoplasma pneumoniae (MP), including 29 (35.8%) co-infections. Of the MP-associated cases, 65 (80.2%) showed a good outcome, and 10 (12.3%) had unclear outcomes, while 6 (7.4%) developed adverse outcomes. These included 1 case requiring surgery, 3 with persistent atelectasis, 1 with both atelectasis and bronchiectasis, and 1 with persistent bronchiectasis. Patients with adverse outcomes exhibited significantly higher levels of LDH (788.5 U/L vs. 408 U/L, p = 0.01) and D-dimer (2.20 μg/mL vs. 0.81 μg/mL, p = 0.01) compared to the good-outcome group. The adverse-outcome group also required more bronchoscopic interventions (median 3.5 vs. 2, p < 0.01), higher glucocorticoid doses (methylprednisolone 20 mg/kg/day vs. 5 mg/kg/day, p = 0.01), and more frequent use of low molecular weight heparin (100% vs. 21.5%, p < 0.01) and intravenous immunoglobulin (50% vs. 9.2%, p = 0.02).

Mycoplasma pneumoniae is the predominant pathogen in infection-associated PB. All patients with poor outcomes were infected with M. pneumoniae. Although most children responded well to treatment, a subset developed long-term complications such as bronchiectasis and atelectasis, even requiring lobectomy. Elevated LDH and D-dimer levels may serve as early biomarkers for predicting unfavorable outcomes.