Abstract
OBJECTIVE: Preoperative risk assessment of complicated appendicitis in children holds substantial clinical importance. This study aimed to evaluate the association between the neutrophil percentage-to-albumin ratio (NPAR) and the occurrence of complicated appendicitis in pediatric patients. METHODS: A total of 814 pediatric patients who underwent laparoscopic appendectomy in a single-centre retrospective cohort design were enrolled in this study. The primary outcome was defined as the occurrence of complicated appendicitis. Multivariate logistic regression analysis was performed to assess the association between NPAR and complicated appendicitis, complemented by stratified and threshold effect analyses. The regression model was adjusted for potential confounders including age, gender, body mass index (BMI), duration of symptoms, vomiting, C-reactive protein (CRP), and appendiceal fecalith. The discriminative performance of NPAR and other inflammatory markers for complicated appendicitis was evaluated using receiver operating characteristic (ROC) curve analysis. The ROC analyses were conducted as univariable analyses for each biomarker. RESULTS: After adjusting for potential confounders, NPAR demonstrated a non-linear association with the risk of complicated appendicitis, with an identified threshold value of 19.53. For NPAR values below this threshold, each unit increase was significantly associated with an elevated risk of complicated appendicitis (OR = 1.46, 95%CI: 1.27-1.68, P < 0.001), whereas above the threshold, no significant association was observed (P > 0.05). The ROC curve analysis revealed that NPAR exhibited good univariable discrimination in identifying complicated appendicitis (AUC = 0.811, 95%CI: 0.777-0.844). CONCLUSION: NPAR shows promise as a readily accessible biomarker derived from routine blood tests for risk stratification of complicated appendicitis in pediatric patients. The identified non-linear association pattern provides valuable insights for clinical risk assessment. Internal validation confirmed the stability of our model, and these findings warrant further validation in prospective multicenter studies before broad clinical implementation.