A Simple Preoperative Scoring System for Risk Stratification of Complicated Appendicitis in Children.

Background/Objectives: Preoperative discrimination of complicated appendicitis in children remains challenging but crucial for timely surgical decision-making and perioperative management. We aimed to develop a simple, clinically applicable scoring system for preoperative risk stratification of complicated appendicitis in children. Methods: This retrospective single-center study included children aged 5 to <16 years who underwent emergency appendectomy between 2015 and 2024. Complicated appendicitis was defined as gangrene, perforation, or intra-abdominal abscesses on intraoperative or pathological evaluation. Literature-based prespecified predictors included body temperature ≥ 38.0 °C, presence of periappendicular fluid, serum sodium level < 135 mEq/L, white blood cell (WBC) count > 12,000/μL, and C-reactive protein (CRP) level ≥ 3.0 mg/dL. A multivariable logistic regression model using Firth's penalized likelihood was developed and internally validated using bootstrap resampling. An additive scoring system was derived from the final model. Results: Among 301 patients, 102 (33.9%) had complicated appendicitis. Based on the Firth penalized multivariable model, integer point values were assigned in proportion to the regression coefficients. Serum sodium level < 135 mEq/L and CRP level ≥ 3.0 mg/dL assigned 2 points each; body temperature ≥ 38.0 °C, presence of periappendicular free fluid, and WBC count > 12,000/μL assigned 1 point each. The scoring system (range, 0-7) demonstrated good discrimination (area under the receiver operating characteristic curve, 0.880; 95% confidence interval, 0.840-0.920), minimal optimism, and good calibration. Stratification into low-, intermediate-, and high-risk categories showed an increasing prevalence of complicated appendicitis. Conclusions: This simple preoperative scoring system enables reliable and clinically interpretable risk stratification for complicated appendicitis in children aged 5 to <16 years and may support early decision-making in routine pediatric surgical practice.