Longitudinal changes in renal function and renal parenchymal width in patients with malignant ureteral obstruction...

Malignant ureteral obstruction (MUO) often requires urinary drainage, but longitudinal changes in renal function and renal parenchymal width (PW) among patients managed with ureteral stents remain poorly characterized.

We retrospectively analyzed 99 patients with MUO who underwent ureteral stenting between 2015 and 2025. Longitudinal changes in estimated glomerular filtration rate and PW were evaluated using linear mixed-effects models. The primary exploratory imaging endpoint was defined as a ≥20% relative decline in PW from baseline to a fixed 24 month assessment among patients with evaluable paired baseline and 24 month measurements. Factors associated with this endpoint were explored using logistic regression.A three-component exploratory PDRS and a baseline-PW-excluded sensitivity PDRS were evaluated for descriptive risk stratification. Clinical stent failure was analyzed separately using a competing-risk framework with death treated as a competing event.

During longitudinal follow-up, eGFR and PW showed different trajectories, with relatively stable eGFR during early and intermediate follow-up and a progressive decrease in PW. Among 61 patients with evaluable paired baseline and 24 month PW measurements, 32 (52.5%) had a ≥20% PW decline. Median absolute PW reduction at 24 months was 3.65 mm. In exploratory multivariable analysis, greater baseline affected-side PW remained associated with ≥20% PW decline (adjusted OR, 26.80,95% CI 3.58-200.57, P=0.001), whereas bladder invasion and PLaCT score were not statistically significant after adjustment. The main exploratory PDRS showed moderate discrimination (apparent AUC, 0.786,bootstrap 95% CI 0.677-0.877,mean bootstrap optimism, 0.0224,bootstrap optimism-corrected AUC, 0.763), whereas the baseline-PW-excluded sensitivity PDRS showed lower discrimination (apparent AUC, 0.658,bootstrap 95% CI 0.538-0.772). Clinical stent failure occurred in 35 patients (35.4%),the cumulative incidence was 30.8% at 24 months and 49.7% at 60 months.

In patients with MUO managed with ureteral stents, renal function and renal parenchymal width showed distinct longitudinal patterns. PW decreased over time despite relatively stable eGFR during early and intermediate follow-up, suggesting that structural imaging measures may provide information complementary to serum-based renal function assessment. The ≥20% PW-decline endpoint and PDRS should be interpreted as exploratory, and the findings do not establish that ureteral stenting preserved renal function or caused, prevented, or attenuated parenchymal change.