Comparative Diagnostic Performance of Six Clinical Scoring Systems for Identifying Complicated Appendicitis in School-Aged Children: A Multicenter Prospective Study.

BACKGROUND: Complicated appendicitis (CA) in children is associated with increased morbidity and prolonged hospitalization. Early identification of patients at higher risk may facilitate timely surgical management and optimize resource utilization. AIM: to compare the diagnostic performance of six clinical scoring systems for identifying CA in school-aged children. PATIENTS AND METHODS: A multicenter prospective observational study was conducted among children aged 10-15 years with histopathologically confirmed acute appendicitis between January 2024 and December 2025. The Appendicitis Inflammatory Response (AIR), Modified Alvarado Scoring System (MASS), Paediatric Appendicitis Score (PAS), Modified PAS (MPAS), Lintula, and Tzanakis scores were calculated prospectively before surgery. Complicated appendicitis was defined according to the World Society of Emergency Surgery criteria. Diagnostic performance was assessed using receiver operating characteristic (ROC) analysis, comparison of areas under the curve (AUCs), calibration analysis, and decision curve analysis. RESULTS: Among 360 children included, 132 (36.7%) had complicated appendicitis and 228 (63.3%) had uncomplicated disease. The AIR score demonstrated the highest discriminatory performance, with an AUC of 0.78 (95% confidence interval [CI]: 0.74-0.82), sensitivity of 76.8%, and specificity of 73.8% at a cut-off value of ≥9. MASS showed moderate discrimination (AUC 0.72, 95% CI: 0.67-0.77), followed by Lintula (AUC 0.71), PAS (AUC 0.69), Tzanakis (AUC 0.68), and MPAS (AUC 0.65). DeLong comparison demonstrated significantly higher discrimination of AIR compared with other scoring systems. The AIR score showed the best calibration and highest net clinical benefit on decision curve analysis. CONCLUSION: The AIR score demonstrated superior diagnostic performance among six evaluated scoring systems for identifying complicated appendicitis in school-aged children. Its use may improve early risk stratification and clinical decision-making, particularly in settings where advanced imaging resources are limited. External validation in broader paediatric populations is recommended.