Hydronephrosis severity as a predictor of postoperative renal function decline following laparoscopic radical nephroureterectomy.

Background: This study aimed to investigate factors, including the degree of hydronephrosis, that may be associated with decreased renal function after radical nephroureterectomy (RNU).

Methods: This study included 252 patients who underwent laparoscopic RNU with an estimated glomerular filtration rate (eGFR) ≥ 30 ml/min/1.73 m in three institutions. We assessed the association between hydronephrosis grade and perioperative renal function and performed a stepwise multivariate linear regression analysis to identify factors associated with postoperative eGFR. Patients with preoperative eGFR ≥ 50 ml/min/1.73 m were divided into a training set and an independent external validation set to develop a predictive model for postoperative renal function.

Results: The median preoperative and postoperative eGFR were 61.1 and 46.4 ml/min/1.73 m, respectively. The eGFR preservation rates were 66.9%, 66.6%, 88.1%, and 100.0% in groups without, with mild, moderate, and severe hydronephrosis, respectively, and this difference was statistically significant (p < 0.001). Multivariate analysis revealed that factors predictive of postoperative eGFR included sex, preoperative eGFR, clinical T stage (cT3-4), and the presence of moderate or severe hydronephrosis. Our predictive model, based on these factors, positively correlated with actual postoperative renal function, and the similarity in categories with or without renal function insufficiency between predicted and actual postoperative renal functions was 78% in both training and validation sets.

Conclusion: Moderate or severe hydronephrosis is associated with a modest postoperative decline in renal function, while mild hydronephrosis is not. Our predictive model may be useful in predicting postoperative renal function insufficiency and guiding decision-making for perioperative medical treatment.