Purpose: To compare renal functional outcomes in patients with a small renal mass undergoing robot-assisted partial nephrectomy using warm ischemia (wRAPN) or open partial nephrectomy using cold ischemia (cOPN).
Methods: This study included 185 patients who underwent partial nephrectomy and were assessed by preoperative and postoperative diethylene triamine penta-acetic acid renal scintigraphy. Variables associated with postoperative operated-side glomerular filtration rate decrement (ΔGFR) were assessed using multivariate analysis. Exact 1:1 propensity score matching was performed using variables related to ΔGFR. Furthermore, 30 patients who underwent wRAPN were matched with 30 patients who underwent cOPN, and their differences in ΔGFR were calculated.
Results: Patients who underwent cOPN were older (p = 0.025) and had shorter ischemia time (p < 0.001) than patients who underwent wRAPN. Multivariate analysis showed that surgical method, preoperative operated-side GFR and RENAL nephrometry score were significantly associated with operated-side ΔGFR. After propensity score matching, postoperative 3-month (14.8 vs. 7.3 mL/min/1.73 m(2), p = 0.057) and 1-year operated-side ΔGFR (11.4 vs. 2.8 mL/min/1.73 m(2), p = 0.031) was higher after wRAPN than after cOPN in patients with ischemia time ≥25 min, but did not differ in patients with ischemia time <25 min. Within the matched pairs, cOPN resulted in lower operated-side ΔGFR than wRAPN in patients with ischemia time ≥25 min (-6.9 mL/min/1.73 m(2), p = 0.047). Moreover, total GFR decrement was slightly lower with cOPN than with wRAPN (-7.2 mL/min/1.73 m(2), p = 0.086).
Conclusions: cOPN was superior to wRAPN in patients with a small renal mass and ischemia time ≥25 min. However, wRAPN yielded renal functional outcomes comparable to those of cOPN when ischemia time was <25 min.
Keywords: Cold ischemia; Glomerular filtration rate; Nephrectomy; Warm ischemia.