On-clamp versus Off-clamp Partial Nephrectomy: Propensity Score Matched Comparison of Long Term Functional Outcomes

Giuseppe Simone1, Umberto Capitanio2, Alessandro Larcher2, Mariaconsiglia Ferriero1, Leonardo Misuraca1, Gabriele Tuderti1, Francesco Minisola1, Salvatore Guaglianone1, Fabio Muttin2, Alessandro Nini2, Francesco Trevisani2, Francesco Montorsi2, Roberto Bertini2, Michele Gallucci1
  • 1 Istituto Nazionale Tumori "Regina Elena", Unità di Urologia (Roma)
  • 2 Ospedale San Raffaele, Università Vita Salute, Dipartimento di Urologia (Milano)


The elective indication for off-clamp (Off-C) partial nephrectomy (PN) in patients with good baseline renal function remains controversial. The aim of this study is to compare the risks of developing a severe (stage ≥3b) chronic kidney disease (CKD) in patients with cT1-2/N0/M0 renal tumors and baseline estimated glomerular filtration rate (eGFR) >60 ml/min after either Off-C or on-clamp (On-C) PN.

Materials and Methods

A prospective “renal cancer” database of two high volume centers was queried for “cT1-2/N0/M0” tumors, "PN" and “baseline eGFR>60 mL/min”. Overall 1073 patients met the inclusion criteria (483 Off-C and 588 On-C). A 1:2 propensity score-matched (PSM) analysis was employed to minimize the selection bias of non-random treatment assignment of patients.
Kaplan–Meier method was used to compare the PSM cohorts specific risks of developing a CKD stage ≥ 3b during follow-up in the PSM cohorts, and the log-rank test was applied to assess statistical significance between groups. Univariable and multivariable Cox regression analyses were performed to identify independent predictors of developing a CKD stage ≥3b.


On-C patients were significantly younger (p=.001), less frequently smokers (.01), with a lower incidence of diabetes (.001) and hypertension (.001), lower ASA scores (<.001), higher baseline eGFR values (.003), smaller tumor sizes (<.001), and higher incidence of positive surgical margins (.021).
After applying the PSM analysis, the two cohorts of 221 On-C and 485 Off-C PN cases did not differ for all clinical and pathologic covariates (Table 1; all p ≥ .06).
The probability of developing a CKD stage ≥ 3b was significantly higher (log rank p=.006, Figure 1) in the On-C cohort (2, 5 and 8yr risk 0.9, 5.1 and 12.8% vs 0.6, 1.2 and 1.2% in the Off-C cohort, respectively). On-C technique was associated with a 5.2 fold increased risk of developing CKD stages ≥3b compared with the Off-C approach (HR 5.2 [95% CIs 1.4–18.9]; p=.012).
At multivariable regression analysis, eGFR at discharge and Off-C PN were independent predictors of outcomes. For each increasing mL/min of eGFR at the discharge the risk of developing a CKD stage ≥3b was reduced by 5% (HR 0.95 [95% CIs 0.93–0.97]), while On-C approach was associated with a 5.8 fold increased risk of developing a CKD stage ≥3b (HR 5.8 [95% CIs 1.6-20.8]).


This study highlights the beneficial role of an Off-C approach in patients with cT1-2/N0/MO renal tumors and good baseline renal function candidate to elective PN.


-Indications, techniques, outcomes, and limitations for minimally ischemic and off-clamp partial nephrectomy: a systematic review of the literature.
Simone G, Gill IS, Mottrie A, Kutikov A, Patard JJ, Alcaraz A, Rogers CG.
Eur Urol. 2015 Oct;68(4):632-40. doi: 10.1016/j.eururo.2015.04.020. Review

-To clamp or not to clamp? Long-term functional outcomes for elective off-clamp laparoscopic partial nephrectomy.
Shah PH, George AK, Moreira DM, Alom M, Okhunov Z, Salami S, Waingankar N, Schwartz MJ, Vira MA, Richstone L, Kavoussi LR.
BJU Int. 2016 Feb;117(2):293-9. doi: 10.1111/bju.13309