Clinical characteristics and risk factors for plastic bronchitis in children with severe Mycoplasma pneumoniae pneumonia: a retrospective observational study

Abstract Background: Plastic bronchitis (PB) is a rare, underdiagnosed and potentially fatal condition that should not be overlooked in children, particularly in children with severe Mycoplasma pneumoniae pneumonia (SMPP). Therefore, we explored the risk factors for PB in children with SMPP and the diagnostic value for PB. Methods: We retrospectively evaluated children with a clinical diagnosis of SMMP who were treated with bronchoscopy at Tianjin Children's Hospital from January 1, 2017, to December 31, 2021. According to the bronchoscopy and pathological examination results, the patients were divided into the PB group and the non-PB group. The clinical manifestations, laboratory data, imaging findings and treatments were analysed. Results: Data from a total of 306 children with SMMP, including 109 children in the PB group and 197 children in the non-PB group, were reviewed. Procalcitonin (PCT), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), interleukin-6 (IL-6) and bronchial lavage fluid MP-DNA copy number levels were higher (P<0.05) while platelet (PLT) levels were lower (P<0.05) in the PB group. In addition, the incidence of pleural effusion, atelectasis, wheezing symptoms and hypoxemia in the PB group was significantly higher than that in the non-PB group (P<0.05). Multivariate logistic regression analysis showed that pleural effusion (odds ratio [OR], 3.148; 95% confidence interval [CI], 1.795-5.521; P<0.001), PLT (OR, 0.584; 95% CI, 0.439-0.776; P<0.001), and LDH (OR, 5.265; 95% CI, 1.488-18.630; P=0.011) were independent predictors of PB in children with SMPP. Receiver operating characteristic (ROC) curve analysis showed that the cut-off values for PLT and LDH in the diagnosis of PB were 242*109/L [sensitivity 57.80%; specificity 69.04%; area under the curve (AUC) 0.648; P<0.001] and 542 U/L (sensitivity 58.72%; specificity 64.97%; AUC 0.646, P<0.001), respectively. Children in the PB group had longer hospital stays and corticosteroid use durations than those in the non-PB group (P<0.05). Conclusions: The PLT level (≤242*109/L), LDH level (>542 U/L) and pleural effusion were risk factors for PB in children with SMPP. This provides a basis for the early identification of PB in children with SMPP.