Robotic Versus Open Partial Nephrectomy: From the "Shadows" of Randomized Controlled Trials to the "Reality" of Value-based Care for Patients with Localized Renal Masses

Abstract Purpose To evaluate the relationship between warm ischemia time (WIT) duration and renal function after robot-assisted partial nephrectomy (RAPN). Methods The CLOCK trial is a phase 3 randomized controlled trial comparing on- vs of-clamp RAPN. All patients underwent pre- and postoperative renal scintigraphy. Six-month absolute variation of eGFR (AV-GFR), rate of relative variation in eGFR over 25% (RV-GFR>25), absolute variation of split renal function (SRF) at scintigraphy (AV-SRF). The relationships WIT/outcomes were assessed by correlation graphs and then modeled by uni- and multivariable regression. Results 324 patients were included (206 on-clamp, 118 of-clamp RAPN). Correlation graphs showed a threshold on WIT equal to 10 min. The diferences in outcome measures between cases with WIT25 9.3% vs 17.8% (p=0.008). Multivariable models found that AV-GFR was related to WIT≥10 min (regression coefcient [RC] − 0.52, p=0.019), age (RC − 0.35, p=0.001) and baseline eGFR (RC − 0.30, p<0.001); RV-GFR>25 to WIT≥10 min (odds ratio [OR] 1.11, p=0.007) and acute kidney injury defned as>50% increase in serum creatinine (OR 19.7, p=0.009); AV-SRF to WIT≥10 min (RC − 0.30, p=0.018), baseline SRF (RC − 0.76, p<0.001) and RENAL score (RC − 0.60. p=0.028). The main limitation was that the CLOCK trial was designed on a diferent endpoint and therefore the present analysis could be underpowered. Conclusions Up to 10 min WIT had no consequences on functional outcomes. Above the 10-min threshold, a statistically signifcant, but clinically negligible impact was found.