Predictors of postoperative renal function recovery in patients with ureteral stones: asymptomatic Vs symptomatic ureteral stones

Purpose This study aimed to comprehensively compare the clinical, radiological, and functional characteristics of asymptomatic and symptomatic ureteral stones, and identify independent predictors of postoperative renal function recovery in patients with ureteral stones. Methods A two-center retrospective cohort study was conducted at tertiary hospitals from March 2018 to March 2023. Consecutive patients who underwent ureteroscopic lithotripsy (URSL) for ureteral stones were included, while those with incomplete follow-up data or other exclusion criteria were excluded. Patients were divided into asymptomatic and symptomatic groups. Baseline characteristics, stone parameters, surgical data, and postoperative renal function were collected. Renal function recovery was defined as postoperative glomerular filtration rate(GFR) of the affected kidney exceeding 90% of the contralateral normal kidney’s GFR at 1 year. Statistical analyses included t-tests, chi-square tests, Cox regression, and nomogram development with internal validation. Results A total of 635 patients with ureteral stones who underwent ureteroscopic lithotripsy (URSL) were enrolled in this study, and divided into two groups based on the presence of stone-related symptoms: the asymptomatic group (n = 38, 5.98%) and the symptomatic group (n = 597, 94.02%). Regarding baseline characteristics, the asymptomatic group showed significantly higher rates of diabetes mellitus (DM, 40.8% vs. 8.0%), larger stone size (17 ± 4 mm vs. 13 ± 4 mm), higher proportion of upper ureteral stones (63.8% vs. 17.0%), and higher incidence of Grade IV hydronephrosis (52.0% vs. 21.3%) compared with the symptomatic group (all p < 0.001). Preoperatively, the glomerular filtration rate (GFR) of the asymptomatic group (21 ± 13 mL/min/1.73m²) was significantly lower than that of the symptomatic group (36 ± 8 mL/min/1.73m²) (p < 0.001). Postoperatively, the symptomatic group exhibited a significant increase in GFR, while the asymptomatic group showed no significant change in GFR and maintained a persistently lower level. Multivariate Cox regression analysis identified six independent predictors of postoperative renal function recovery (all p < 0.05): older age, DM, Grade IV hydronephrosis, and complete intraoperative obstruction were negative predictors, while a higher preoperative GFR ratio (ipsilateral/contralateral normal kidney) and symptomatic status were positive predictors. A nomogram constructed based on these predictors showed good discriminative ability (area under the receiver operating characteristic curve, AUC = 0.841) and calibration performance (mean absolute error, MAE = 0.02). Conclusion Asymptomatic ureteral stones exhibit distinct features (larger size, upper ureteral location, severe hydronephrosis) and poorer postoperative renal function recovery than symptomatic stones, mainly due to chronic obstruction-induced irreversible injury. Age, DM, Grade IV hydronephrosis, complete obstruction, and low preoperative split renal function are key predictors of poor recovery. The validated nomogram facilitates accurate recovery risk prediction, supporting personalized treatment and monitoring to preserve renal function.