Association of urinary diversion type and surgical approach with long-term renal function after radical cystectomy: a nationwide cohort study

Radical cystectomy (RC) is associated with long-term renal function deterioration. Robot-assisted RC (RARC) is increasingly used; however, its effect on renal preservation compared with open techniques remains unclear. This study aimed to investigate the long-term impact of surgical approaches (open vs. robot-assisted) on renal preservation and perioperative surgical indicators. We conducted a nationwide, population-based cohort study using the Korean National Health Insurance Service Database. Patients aged ≥ 18 years with bladder cancer who underwent RC from 2010 to 2023 were included, whereas those with pre-existing CKD, ESRD, or severe liver disease were excluded. The primary endpoint was incident CKD or ESRD after surgery. Propensity scores were calculated using logistic regression and inverse probability of treatment weighting (IPTW) was applied. The cohort included 5,777 ileal conduit (90.1% open) and 5,321 neobladder (47.5% open, 52.5% robot-assisted) patients. In the IPTW-adjusted cohort, the primary comparison showed that neobladder was associated with a lower CKD risk than conduit (SHR 0.81, 95% CI 0.75–0.88, p < 0.0001). Subsequently, in the sub-cohort analysis stratified by surgical approach, open neobladder was associated with an increased CKD risk compared to the open conduit group (HR 1.13, 95% CI 1.06–1.21, p = 0.0001). Neobladder diversion overall appears to be associated with better renal outcomes. However, this association is predominantly observed in the robotic cohort, whereas the open technique is associated with accelerated renal deterioration. These findings are hypothesis-generating and suggest that the observed renal preservation in contemporary neobladder cohorts is likely associated with robot-assisted techniques rather than solely with the diversion type.