Comparison of retroperitoneal and transperitoneal robotic partial nephrectomy for Pentafecta perioperative and renal functional outcomes

Background: We compared quality outcomes between transperitoneal (TRPN) and retroperitoneal robotic partial nephrectomy (RRPN). Methods: Two-center retrospective analysis of TRPN and RRPN from 10/2009 to 10/2015. Perioperative/renal function outcomes were analyzed. Primary endpoint was Pentafecta, a composite measure of quality [negative margin, no 30-day complication, ischemia time ≤25 min, return of glomerular filtration rate (eGFR) to >90% from baseline at last follow-up, and no chronic kidney disease upstaging]. Multivariable analysis (MVA) for factors associated with lack of optimal outcome was performed. Results: 404 patients (TRPN 263, RRPN 141) were analyzed. Comparing TRPN vs. RRPN, mean tumor size (3.1 vs. 2.9 cm, p = 0.122) and RENAL score (7.4 vs. 7.2, p = 0.503) were similar. Most TRPN were anterior (65.0%) and most RRPN posterior (65.3%, p < 0.001). Operative time (p = 0.001) was less for RRPN. No significant differences between TRPN vs. RRPN were noted for ischemia time (23.1 vs. 22.8 min, p = 0.313), blood loss (p = 0.772), positive margins (p = 0.590), complications (p = 0.537), length of stay (p = 0.296), ΔeGFR (p = 0.246), eGFR recovery to >90% (55.9 vs. 57.4%, p = 0.833), and lack of CKD upstaging (84.0 vs. 87.2%, p = 0.464). Pentafecta rates were not significantly different (TRPN 33.9 vs. RRPN 43.3%, p = 0.526). MVA revealed increasing RENAL score (OR 1.5, p < 0.001) and decreasing baseline eGFR (OR 2.4, p = 0.017) as predictive for lack of Pentafecta. Conclusions: TRPN and RRPN have similar quality outcomes, though RRPN may offer modest benefit for operative time and have utility in posterior tumors. Association of increasing RENAL score and decreased baseline eGFR with lack of Pentafecta suggests dominant role of non-modifiable factors.