Research on risk assessment and predictive model for gastrointestinal fistula after gastrectomy based on F-index scoring system

Gastrointestinal fistula is a serious complication after gastrectomy, leading to high morbidity and mortality. Early identification of high-risk patients is crucial for improving outcomes and reducing complications. However, a simple and effective scoring system for assessing postoperative fistula risk is still lacking. This multicenter retrospective study aimed to develop and validate a scoring system (F-index) for predicting gastrointestinal fistula risk after gastrectomy. A total of 83 patients diagnosed with postoperative gastrointestinal fistula after gastrectomy between Aug 2021 and Dec 2023 were included. Patients were divided into low-risk (0–3 points, 30 patients) and high-risk (4–7 points, 53 patients) groups. 58 patients from the Third Hospital of Jilin University were used as the training set, while 25 patients from Weifang People’s Hospital formed the validation set. Data collection included demographic information, surgical data, and postoperative outcomes. Univariate and multivariate logistic regression analyses were used to identify risk factors, and ROC curve analysis was performed to evaluate the F-index’s predictive performance. Sensitivity, subgroup analyses, and nomogram construction were also conducted to validate the model. The F-index showed good discriminatory ability for post-diagnosis risk stratification among patients with postoperative gastrointestinal fistula after gastrectomy. Multivariate analysis indicated that time to fistula recognition after surgery > 7 days (OR = 6.307, 95% CI: 1.343–29.619, p = 0.020) and fistula diameter > 1 cm (OR = 0.109, 95% CI: 0.023–0.520, p = 0.005) were independently associated with high-risk classification. ROC curve analysis demonstrated an AUC of 0.79 (95% CI: 0.528–0.972) for the training set and 0.75 (95% CI: 0.267–1.000) for the validation set. Sensitivity and subgroup analyses showed consistent performance across different age and BMI thresholds, and the calibration plot indicated good agreement between predicted and observed risks. The F-index scoring system is a simple and effective tool for post-diagnosis risk stratification in patients with postoperative gastrointestinal fistula after gastrectomy, helping identify high-risk cases and optimize postoperative management. ISRCTN47338250. Registration Date: 24/10/2024.