A nomogram estimates postoperative urinary tract infection risk after upper urinary tract stone surgery with double-J stents
摘要
Postoperative urinary tract infection (UTI) is common after upper urinary tract stone surgery in patients with indwelling double-J stents, but dedicated risk-stratification tools for this peri-stent period remain limited. We aimed to develop and related-center validate a nomogram for individualized UTI risk estimation, while distinguishing earlier postoperative risk prediction from near-removal risk updating. In this retrospective two-center cohort study conducted from January 2023 to July 2025, 756 eligible patients were analyzed. Patients from the Affiliated Hospital of Zunyi Medical University (Hospital A) were randomly divided into training (n = 382) and internal validation (n = 164) cohorts, while patients from the Second Affiliated Hospital of Zunyi Medical University (Hospital B) formed a related-center validation cohort (n = 210). LASSO and multivariable logistic regression were used to construct the model. A pre-removal model included antecedent predictors available before the stent-removal encounter, whereas an updated at-removal model additionally incorporated urine nitrite positivity measured at stent removal. Postoperative UTI occurred in 17.5% of the training cohort and 18.6% of the related-center validation cohort. The pre-removal model included postoperative residual fragments (> 4 mm), longer DJ stent dwell time, prior UTI, moderate-to-severe hydronephrosis, and daily fluid intake > 3000 mL/day as a protective factor. The updated at-removal model additionally incorporated urine nitrite positivity at stent removal. The updated at-removal nomogram showed good discrimination, with AUCs of 0.873 in the training cohort, 0.835 in the internal validation cohort, and 0.932 in the related-center validation cohort. The pre-removal model also maintained good discrimination, with AUCs of 0.852, 0.807, and 0.926, respectively. This nomogram may serve as a potentially useful decision-support tool for structured postoperative surveillance in DJ-stented patients after upper urinary tract stone surgery. Because the study was retrospective and validation was performed within a related institutional network, broader prospective validation across more heterogeneous healthcare settings is required before routine clinical implementation.