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Objectives: Martini et al. developed a nomogram to predict significant (>25%) renal function loss after robot‐assisted partial nephrectomy and identified four risk categories. We aimed to externally validate Martini's nomogram on a large, national, multi‐institutional data set including open, laparoscopic, and robot‐assisted partial nephrectomy. Methods: Data of 2584 patients treated with partial nephrectomy for renal masses at 26 urological Italian centers (RECORD2 project) were collected. Renal function was assessed at baseline, on third postoperative day, and then at 6, 12, 24, and 48 months postoperatively. Multivariable models accounting for variables included in the Martini's nomogram were applied to each approach predicting renal function loss at all the specific timeframes. Results: Multivariable models showed high area under the curve for robot‐assisted partial nephrectomy at 6‐ and 12‐month (87.3% and 83.6%) and for laparoscopic partial nephrectomy (83.2% and 75.4%), whereas area under the curves were lower in open partial nephrectomy (78.4% and 75.2%). The predictive ability of the model decreased in all the surgical approaches at 48 months from surgery. Each Martini risk group showed an increasing percentage of patients developing a significant renal function reduction in the open, laparoscopic and robot‐assisted partial nephrectomy group, as well as an increased probability to develop a significant estimated glomerular filtration rate reduction in the considered time cutoffs, although the predictive ability of the classes was <70% at 48 months of follow‐up. Conclusions: Martini's nomogram is a valid tool for predicting the decline in renal function at 6 and 12 months after robot‐assisted partial nephrectomy and laparoscopic partial nephrectomy, whereas it showed a lower performance at longer follow‐up and in patients treated with open approach at all these time cutoffs. [ABSTRACT FROM AUTHOR]

Objectives: To compare the functional outcomes of on‐ vs off‐clamp robot‐assisted partial nephrectomy (RAPN) within a randomized controlled trial (RCT). Materials and Methods: The CLOCK study (CLamp vs Off Clamp the Kidney during robotic partial nephrectomy; NCT 02287987) is a multicentre RCT including patients with normal baseline function, two kidneys and masses with RENAL scores ≤ 10. Pre‐ and postoperative renal scintigraphy was prescribed. Renal defatting and hilum isolation were required in both study arms; in the on‐clamp arm, ischaemia was imposed until the completion of medullary renorraphy, while in the off‐clamp condition it was not allowed throughout the procedure. The primary endpoint was 6‐month absolute variation in estimated glomerular filtration rate (AV‐GFR); secondary endpoints were: 12, 18 and 24‐month AV‐GFR; 6‐month estimated glomerular filtration rate variation >25% rate (RV‐GFR >25); and absolute variation in ipsilateral split renal function (AV‐SRF). The planned sample size was 102 + 102 cases, after taking account crossover of cases to the alternate study arm; a 1:1 randomization was performed. AV‐GFR and AV‐SRF were compared using analysis of covariation, and RV‐GFR >25 was assessed using multivariable logistic regression. Intention‐to‐treat (ITT) and per‐protocol analyses (PP) were performed. Results: A total of 160 and 164 patients were randomly assigned to on‐ and off‐clamp RAPN, respectively; crossover was observed in 14% and 43% of the on‐ and off‐clamp arms, respectively. We were unable to find any statistically significant difference between on‐ vs off‐clamp with regard to the primary endpoint (ITT: 6‐month AV‐GFR −6.2 vs −5.1 mL/min, mean difference 0.2 mL/min, 95% confidence interval [CI] −3.1 to 3.4 [P = 0.8]; PP: 6‐month AV‐GFR −6.8 vs −4.2 mL/min, mean difference 1.6 mL/min, 95% CI −2.3 to 5.5 [P = 0.7]) or with regard to the secondary endpoints. The median warm ischaemia time was 14 vs 15 min in the ITT analysis and 14 vs 0 min in the PP analysis. Conclusion: In patients with regular baseline function and two kidneys, we found no evidence of differences in functional outcomes for on‐ vs off‐clamp RAPN. [ABSTRACT FROM AUTHOR]