Development of a prediction model for urinary tract infection risk after open reimplantation in children with primary unilateral vesicoureteral reflux: A multicentre study

Objectives To develop a predictive model for symptomatic postoperative febrile urinary tract infections (UTIs) in children undergoing open reimplantation for vesicoureteral reflux (VUR) and evaluate the association with VUR recurrence. Patients and methods This multicentre retrospective study included children with unilateral VUR (grades III–V) who underwent open Cohen or Lich‐Gregoir reimplantation (2010–2022), had recurrent febrile UTIs, and ≥1 year follow‐up. Analyses used 10‐pooled multiple imputation, with complete case for sensitivity. Full and Least Absolute Shrinkage and Selection Operator (LASSO) Weibull regression models with centre clustering, bootstrapping, and 10‐fold cross‐validation identified predictors. Prediction used demographic, clinical, procedural and antibiotic factors. The non‐scaled LASSO model informed the nomogram, evaluated using C‐indices, calibration and decision curve analysis (DCA). UTI and VUR recurrence were analysed via cumulative incidence. Results A total of 404 children (median age 8 (6–9) years; follow‐up 2.3 (2.0–3.3) years, 233 complete‐case) were analysed. Median preoperative febrile UTIs were four, 74.5% had antibiotic resistance and median postoperative prophylaxis was two days. The 3‐year cumulative incidence of postoperative UTI was 27.2% (95% CI: 22.9–31.6). LASSO‐significant predictors included operative time (HR 1.10, 95% CI 1.03–1.16); in sensitivity analyses, prior injection (HR 2.08, 95% CI 1.88–2.30) and postoperative antibiotic duration (HR 0.81, 95% CI 0.69–0.97) were also significant. The nomogram included preoperative fever, antibiogram resistance, renal defect, VUR phase, prior injection, surgical indication, catheterization, hospitalization and stenting. The model performed well (C‐indices = 0.743; calibration slope = 1), with DCA supporting clinical utility for 10–40% predicted risk. Recurrent VUR grade ≥II after 12 months (3.3%–12.7% at 1–3 years, n = 273) did not increase UTI risk. Conclusions Children with unilateral dilating VUR remained at risk of postoperative febrile UTIs. The nomogram can assist in identifying high‐risk children for targeted interventions, but requires external validation and refinement.