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

Giuseppe Simone1, Umberto Capitanio2, Alessandro Larcher2, Gabriele Tuderti1, Mariaconsiglia Ferriero1, Leonardo Misuraca1, Manuela Costantini1, Francesco Minisola1, Salvatore Guaglianone1, Fabio Muttin2, Alessandro Nini2, Francesco Trevisani2, Francesco Montorsi2, Roberto Bertini2, Michele Gallucci1
  • 1 Istituto Nazionale Tumori "Regina Elena" (Roma)
  • 2 Ospedale San Raffaele Università Vita-Salute, Dipartimento di Urologia (Milano)


To compare renal functional outcomes after either off-clamp (Off-C) or on-clamp (On-C) PN in patients with cT1- 2/N0 M0 renal tumors and baseline estimated eGFR >60 ml/min.

Materials and Methods

A prospective 'renal cancer" database of two high volume centers was queried for cT1-2/N0/M0 tumors and baseline eGFR>60 mL/min. Overall 1073 patients met the inclusion criteria, 588 On-C PN and 485 Off-C PN. A 1:3 propensity score-matched (PSM) analysis was employed to minimize the potential selection bias.
Joinpoint regression analysis was used to plot the 2 to 8 yrs probabilities of experiencing eGFR decreases of 0%,< 25% and between 25 and 50% in both PSM cohorts and, therefore,to compare the trends for each of these 3 subgroups.
Kaplan-Meier method was used to compare the risk of developing a CKD stage>=3b during follow-up in the PSM cohorts. Univariable and multivariable analyses were performed to identify independent predictors of developing a CKD stage>=3b.


In the whole cohort On-C patients were significantly younger (p=0.001), less frequently smokers (p=0.01), with a lower incidence of diabetes (p=0.001) and hypertension (p=0.001), lower ASA scores (p<0.001), higher baseline eGFR values (p=0.003), smaller tumor sizes (p<0.001), longer warm ischemia time (17 minutes vs 0, p<0.001) and higher incidence of positive surgical margins (p=0.021). After applying the PSM analysis, the two cohorts of 157 On-C and 471 Off-C PN cases did not differ for all clinical and pathologic covariates (all p>0.08), except for mean warm ischemia time (p<0.001).
At Joinpoint regression analysis Off-C group displayed significantly higher probabilities of maintaining unmodified eGFR after surgery (p=0.02), and significantly lower probabilities of experiencing eGFR decrease >25% in the first 8-yr follow-up (p=0.02).
The probability of developing a CKD stage>=3b was significantly higher (log rank p=0.006) in the On-C cohort (2, 5 and 8yr risk 0.9%, 5.1% and 12.8% versus 0.6%, 1.2% and 1.2% in the Off-C cohort, respectively.
At multivariable Cox regression analysis, eGFR at discharge (HR 0.94; 95% CIs 0.91-0.98, p=0.002) and Off-clamp approach (HR 7.33; 95% CIs 1.8-29.4, p=0.005) were independent predictors of improved renal functional outcomes.


Off-C PN is associated with a significantly higher probability of maintaining 100% eGFR after surgery compared with On-C PN in patients with cT1-2/N0/MO renal tumors and good baseline renal function candidate to elective PN. Patients treated with On-C PN had a 7.3 fold increased risk of developing a severe CKD during follow-up.


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