Risk factors for appendicitis recurrence after ERAT in patients with acute appendicitis: a multicenter cohort study with long-term follow-up.

Background: Endoscopic retrograde appendicitis therapy (ERAT) has emerged as a minimally invasive approach to treating appendicitis. Objectives: This study aimed to assess the long-term safety and efficacy of ERAT and to develop a model predicting 1‑year appendicitis recurrence in patients with acute appendicitis, to guide clinical decision-making. Design: This is a multicenter retrospective study. Consecutive patients were referred to the three participating centers. Methods: A retrospective analysis was conducted on clinical data from 435 patients with acute appendicitis who underwent ERAT at three hospitals between October 2017 and October 2024. Twenty-four clinical variables were screened, and Spearman correlation analysis revealed correlation coefficients exceeding 0.6 between some variables. To address multicollinearity, LASSO regression was employed to identify key predictive factors in the training set. A predictive model was constructed using multivariate logistic regression, and a nomogram was developed. Results: All ERAT procedures were technically successful, and a clinical success rate of 92.4% was achieved. The median follow-up period was 37 months, and the overall recurrence rate was 16.1%; most recurrences (13%) were observed in the first year. Based on LASSO regression analysis, the final predictors identified were: age >60 years (odds ratio (OR) = 2.981, 95% confidence interval (CI): 1.368-6.497, p = 0.006), recurrence appendicitis (OR = 4.048, 95% CI: 1.931-8.587, p < 0.001), Alvarado score >6 (OR = 5.649, 95% CI: 2.586-12.339, p < 0.001), fecalith (OR = 2.680, 95% CI: 1.146-6.267, p = 0.023), inexperienced operator (OR = 2.286, 95% CI: 1.141-4.580, p = 0.020), procedure time >40 min (OR = 2.472, 95% CI: 1.240-4.927, p = 0.010), appendix lumen distortion (OR = 7.634, 95% CI: 1.414-41.219, p = 0.018), and stent placement (OR = 5.970, 95% CI: 0.121-0.793, p = 0.015). Based on these eight predictive factors, a nomogram model was constructed to predict recurrence risk within 1 year after ERAT. Conclusion: ERAT is a safe and effective treatment for acute appendicitis. The risk of recurrence is highest within the first year. Eight independent risk factors for recurrence within 1 year after ERAT were identified, and a recurrence risk prediction model based on these predictive factors can assist in future clinical decision-making for ERAT.