Clinical prediction model for gangrenous appendicitis: A retrospective single-center study

Background and aims: Gangrenous appendicitis, a type of complicated appendicitis, is an indication of emergency surgery due to a high risk of perforation. However, it can be challenging to diagnose preoperatively. This study aimed to validate the predictive factors of patients with gangrenous appendicitis and develop a novel scoring model based on objective parameters. Methods: This retrospective single-center study included 171 of 302 consecutive patients undergoing appendectomy between April 2014 and December 2023. Patients with perforation, chronic appendicitis, and appendicitis presenting with an abscess were excluded from the analysis. In other words, the study targeted Grades 1 and 2 on the American Association for the Surgery of Trauma (AAST) severity assessment scale. Computed tomography (CT) scan value was defined as the average value of fluid in the appendix lumen on plain CT scan. Univariate and multivariate analyses were performed to identify the independent objective predictors of gangrenous appendicitis. A new scoring model was developed based on the logistic regression coefficients of the independent predictors. The scores were then classified into three categories, and the probability of gangrenous appendicitis for each category was evaluated. Results: Overall, 46 (27%) and 125 (73%) patients presented with gangrenous appendicitis (=AAST Grade 2) and non-gangrenous (uncomplicated) appendicitis (=AAST Grade 1), respectively. The independent predictive factors of gangrenous appendicitis included a CT value of ≥24 HU, an appendiceal diameter of ≥12 mm, the presence of cecal mucosal edema, and a C-reactive protein level of ≥5.4 mg/dL. The scoring model, based on these four independent predictors, ranged from 0 to 4. The probability values of gangrenous appendicitis were 0%, 15%, and 97% in the low (0)-, moderate (1, 2)-, and high (3, 4)-risk categories, respectively. Conclusion: Our scoring model may assist in decision-making concerning emergency surgery and appendicitis management.