Combined Metabolic–Inflammatory Biomarkers for Predicting Complicated Acute Appendicitis: A Comparative Analysis

INTRODUCTION: Early identification of complicated acute appendicitis remains clinically important for guiding timely surgical management. Composite indices integrating metabolic and inflammatory parameters have recently been proposed as potential predictors of disease severity. This study aimed to compare the diagnostic performance of metabolic-inflammatory composite indices with conventional hematological markers in predicting complicated acute appendicitis. METHODS: This retrospective cohort study included adult patients who underwent appendectomy between January 2022 and January 2025. Complicated appendicitis was defined by intraoperative findings of perforation, gangrene, periappendiceal abscess, or generalized peritonitis. Various inflammatory and metabolic indices were calculated from routine laboratory parameters. Diagnostic performance was evaluated using ROC analysis and logistic regression models. RESULTS: A total of 1,871 patients were included, of whom 210 (11.2%) had complicated appendicitis. The C-reactive protein-to-albumin ratio (CAR) showed the highest diagnostic performance (AUC = 0.734). In multivariable analysis, both CAR and the inflammatory metabolic index (IMI) remained independent predictors. The final model incorporating age, sex, CAR, and IMI demonstrated the best discriminative performance (AUC = 0.795). CONCLUSION: Metabolic-inflammatory composite biomarkers, particularly CAR, may provide valuable adjunctive information for early prediction of complicated acute appendicitis.