On-clamp versus off-clamp partial nephrectomy: Propensity score-matched comparison of long-term functional outcomes

Objectives: To compare long-term functional outcomes of off-clamp or on-clamp partial nephrectomy patients of two high-volume centers with cT1-2/N0 M0 renal tumors and baseline estimated glomerular filtration rate >60 mL/min.

Methods: A 3:1 propensity score-matched analysis was used to select two homogeneous cohorts to compare off-clamp versus on-clamp partial nephrectomy. Joinpoint regression analysis was used to compare the 2-8-year probabilities of estimated glomerular filtration rate modifications in both selected cohorts. The Kaplan-Meier method assessed the risk of developing a stage ≥3b chronic kidney disease during follow up. Multivariable analyses aimed to identify predictors of renal function deterioration. Perioperative complications and oncological outcomes were compared.

Results: Overall, 1073 patients were included (588 on-clamp and 485 off-clamp). After applying the propensity score-matched analysis, the two cohorts of 157 on-clamp and 472 off-clamp patients did not differ for all covariates, except for warm ischemia time and last estimated glomerular filtration rate. At joinpoint analysis, the off-clamp group showed higher probabilities of maintaining an unmodified estimated glomerular filtration rate (P = 0.02). The probability of developing a stage ≥3b chronic kidney disease was significantly higher (P < 0.001) in the on-clamp cohort. At multivariable analysis, estimated glomerular filtration rate at discharge and off-clamp approach were independent predictors of improved functional outcomes. Perioperative complications were comparable among the two cohorts (P = 0.67). There were not any statistically significant differences in terms of cancer-specific survival (P = 0.26) and overall survival (P = 0.18).

Conclusions: Off-clamp partial nephrectomy seems to offer a higher probability of maintaining 100% estimated glomerular filtration rate after surgery. In our cohort, patients undergoing on-clamp partial nephrectomy presented a 7.3-fold increased risk of developing a severe chronic kidney disease during follow up.