AbstractBackgroundThis study aimed to investigate the efficacy of the Pediatric Appendicitis Score (PAS) and other indicators to enable the prediction of complicated appendicitis (CA) in children.MethodsThis retrospective cohort study evaluated children (n = 161) aged ≤16 years with acute appendicitis between 2008 and 2020. Demographic data, symptoms, physical findings, laboratory data, and PASs were collected. Multivariate analysis was performed to identify predictors for CA. Receiver operating characteristic (ROC) curves were constructed. The diagnostic performance of each predictor was evaluated.ResultsMultivariate analysis identified three predictors for CA: duration of symptoms >1 day, C‐reactive protein (CRP) level > 4 mg/dL, and PAS ≥ 8. The ROC curve of the combined three predictors showed an area under the curve of 0.91. The multivariate ROC curve revealed that the presence of a PAS contributed to a significant improvement in the diagnosis of CA compared to the absence of PAS. When combined, the three predictors had a high specificity of 99% and positive predictive value of 98%.ConclusionsA symptom duration >1 day, CRP > 4 mg/dL, and PAS ≥ 8 were predictors for CA. The PAS can be useful for prediction of CA when combined with the duration of symptoms, CRP, or both.