Clinical and Laboratory Prediction of Histopathologically Complicated Acute Appendicitis and Associated Surgical Outcomes: A Retrospective Cohort Study

Background/Objectives: Preoperative recognition of complicated acute appendicitis remains difficult, although severity influences treatment and perioperative planning. This study examined clinical and laboratory correlates of histopathologically complicated appendicitis and associated short-term outcomes and developed a preoperative prediction model.

Methods

This single-center retrospective cohort included 500 adults undergoing appendectomy for suspected acute appendicitis (2021–2025). The primary outcome was gangrenous or perforated appendicitis on histopathology. Fifty preoperative candidate predictors were analyzed using least absolute shrinkage and selection operator (LASSO) logistic regression with nested cross-validation, calibration and predictor-selection reproducibility assessment, comparison with the Appendicitis Inflammatory Response (AIR) and Alvarado scores, and same-center temporal evaluation (2025 cohort).