Risk factors associated with pleural effusion in pediatric patients with severe Mycoplasma pneumonia.

Mycoplasma pneumoniae is an important cause of community-acquired pneumonia in children, and severe M pneumoniae pneumonia (SMPP) is frequently complicated by pleural effusion, yet specific risk factors for effusion in this population remain incompletely defined. In this retrospective observational study, 121 hospitalized children with SMPP admitted between January 2022 and June 2023 were enrolled and classified into a pleural effusion group (n = 32) and a non-pleural effusion group (n = 89) based on chest radiography. Demographic data, past medical history, clinical manifestations, laboratory indices, and radiologic findings were extracted from electronic records. Group comparisons were performed using independent-samples t tests and χ2 tests, and factors associated with pleural effusion were evaluated by univariate and multivariate logistic regression. Children with pleural effusion exhibited longer fever duration, higher peak temperature, faster respiratory rate, more frequent chest indrawing, and more extensive radiologic involvement than those without effusion. They also had higher white blood cell counts, neutrophil predominance, lower lymphocyte percentages, and significantly elevated C-reactive protein, procalcitonin, erythrocyte sedimentation rate, lactate dehydrogenase, and D-dimer, together with slightly lower serum albumin. Multivariate analysis identified prolonged fever duration, increased respiratory rate, and elevated C-reactive protein as independently associated with pleural effusion in children with SMPP. These readily available clinical indicators may help clinicians identify patients at higher risk of pleural effusion and facilitate closer monitoring and timely imaging evaluation.