Renal Functional and perioperative outcomes of off-clamp versus clamped robot-assisted partial nephrectomy: Matched cohort study

Objective: To evaluate the potential benefit of performing off-clamp robot-assisted partial nephrectomy as it relates to renal functional outcomes, while assessing the safety profile of this unconventional surgical approach. Methods: Twenty-nine patients who underwent off-clamp robot-assisted partial nephrectomy for suspected renal cell carcinoma at Washington University between March 2008 and September 2011 (group 1) were matched to 29 patients with identical nephrometry scores and comparable baseline renal function who underwent robot-assisted partial nephrectomy with hilar clamping during the same period (group 2). The matched cohorts' perioperative and renal functional outcomes were compared at a mean 9-month follow-up. Results: Mean estimated blood loss was 146.4 mL in group 1, versus 103.9 mL in group 2 (P =.039). Mean hilar clamp time was 0 minutes in group 1 and 14.7 minutes in group 2. No perioperative complications were encountered in group 1; 1 Clavien-2 complication (3.4%) occurred in group 2 (P = 1.000). At 9-month follow-up, mean estimated glomerular filtration rate in group 1 was 79.9 versus 84.8 mL/min/1.73 m² preoperatively (P =.013); mean estimated glomerular filtration rate in group 2 was 74.1 versus 85.8 mL/min/1.73 m² preoperatively (P <.001). Hence, estimated glomerular filtration rate declined by a mean of 4.9 mL/min/1.73 m² in group 1 versus 11.7 mL/min/1.73 m² in group 2 (P =.033). Conclusion: Off-clamp robot-assisted partial nephrectomy is associated with a favorable morbidity profile and relatively greater renal functional preservation compared to clamped robot-assisted partial nephrectomy. Nevertheless, the benefit is small in renal functional terms and may have very limited clinical relevance.