Expression and clinical significance of miR-223 in children with severe pneumonia

Severe pneumonia poses a major life-threatening respiratory disease among children under 5 years old, and conventional laboratory markers lack sufficient specificity for its early identification and severity evaluation, highlighting an urgent need for novel sensitive and specific biomarkers. This study enrolled 107 children diagnosed with severe pneumonia and 107 age- and gender-matched healthy children from January 2024 to June 2025. Quantitative real-time PCR was applied to detect plasma miR-223 expression, and routine hematological, biochemical and coagulation indicators were simultaneously collected for all subjects. Statistical analyses including Mann-Whitney U test, multivariate logistic regression and ROC curve analysis were performed to explore the diagnostic value of miR-223. Plasma miR-223 expression was significantly elevated in children with severe pneumonia compared with healthy controls, and multivariate logistic regression identified miR-223, neutrophil percentage, albumin and fibrinogen as independent risk factors for pediatric severe pneumonia. Single miR-223 yielded an AUC of 0.90 for disease diagnosis, while the combined model of the four indicators achieved an AUC up to 0.99 with superior diagnostic accuracy and sensitivity. Age stratification analysis revealed that miR-223 upregulation existed across all age subgroups of patients, and age exerted no significant interference on its diagnostic performance. Moreover, higher miR-223 levels were correlated with severe complications, PICU admission and longer hospital stays, indicating its potential for disease stratification and short-term prognosis assessment. In summary, plasma miR-223 acts as a reliable molecular biomarker for pediatric severe pneumonia, and its combination with routine inflammatory, nutritional and coagulation markers greatly improves diagnostic efficiency, which provides a promising auxiliary tool for early diagnosis and clinical risk evaluation of children with severe pneumonia.