Construction and external validation of a predictive model for permanent stoma after sphincter-preserving surgery for rectal cancer

The postoperative conversion of a protective stoma to a permanent stoma (PS) during sphincter-preserving surgery for rectal cancer can significantly impact the patient’s quality of life. No reliable tools exist to predict the likelihood of a protective stoma becoming permanent in clinical practice. This study aimed to develop an online, dynamic nomogram for predicting PS using multicenter, large-sample data. A total of 588 patients were enrolled following screening. Predictive variables were selected using the univariate analysis. A prediction model was then created using multivariate logistic regression and presented as an online nomogram. The model’s performance was evaluated using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). External validation was performed to assess the model’s accuracy within the validation cohort. Of the 588 patients, 81 (13.7%) had a PS. 507 paitients from our and another hospital were randomly assigned to a training cohort and internal testing cohort (7:3), and 81 patients from another hospital served as the external validation cohort. Critical predictive factors in the nomogram included ASA score ≥ 3, radiotherapy, diabetes and N་stage. The area under the ROC curve (AUC) was 0.784 [95% Confidence Interval (CI) 0.708–0.860] for the training cohort, 0.785 (95% CI 0.656–0.913) for the testing cohort, and 0.737 (95% CI 0.604–0.870) for the external validation cohort. The calibration curve demonstrated a strong correlation between predicted and observed outcomes, and decision curve analysis (DCA) confirmed the nomogram’s clinical utility in predicting PS following sphincter-preserving surgery for rectal cancer. This study developed an online nomogram to identify high-risk factors for PS following rectal sphincter-preserving surgery, using multicenter data (modeling and external validation) from three hospitals in China. This tool supports clinicians in risk assessment. For high-risk patients, health education should be provided, and it may be advisable to offer the option of a colostomy.