Impact of ischaemia duration and clamping strategy in patients with solitary kidney undergoing partial nephrectomy

Objectives: To explore the effects of ischaemia time (IT) in a multicentre cohort of patients with solitary kidney (SK), treated with partial nephrectomy (PN) for a renal mass, on short- and long-term kidney function, haemorrhagic risk and pathological outcomes. Methods: This is an observational study of 426 patients with SK treated with on- and off-clamp PN for a single cT1–3 N0M0 renal mass from 2000 to 2023 at 19 global institutions. The primary outcomes were postoperative and 1-year renal function. The secondary outcomes of the study were haemorrhagic risk, defined as estimated blood loss (EBL) and peri-operative transfusions, and presence of positive surgical margins. The effect of IT and arterial clamping strategy was estimated using linear and logistic regressions for continuous and categorical outcomes, respectively. Results: On-clamp PN was performed in 56% of patients (n = 237). The median (interquartile range [IQR]) age, body mass index, preoperative estimated glomerular filtration rate (eGFR), clinical size and PADUA score were 65 (58–71) years, 27 (24–29) kg/m2, 58 (45–46) mL/min, 3 (2–4.2) cm and 8 (7–10), respectively. The median (IQR) duration of IT was 19 (13–25) min. In multivariable linear and logistic regression analyses (MVA), IT was not associated with decreased postoperative eGFR (estimate −0.08 mL/min; P = 0.3) or 1-year eGFR (estimate −0.1 mL/min; P = 0.2). No association between on-clamp strategy and eGFR decline was recorded either postoperatively (estimate −3.11 mL/min; P = 0.1) or at 1 year (estimate −3.12 mL/min; P = 0.1). The median (IQR) EBL was lower in the on-clamp group at 200 (100–400) mL vs 300 (145–500) mL in the off-clamp group. In MVA predicting haemorrhagic risk, arterial clamping was associated with lower risk of transfusions (odds ratio 0.45; P = 0.01). Conclusions: In patients with SK, on-clamp PN did not affect long-term renal function and was associated with a modestly lower need for peri-operative transfusion. The routine use of the off-clamp technique is therefore not supported by these findings, although its selective application may remain appropriate in cases with a high risk of renal function decline.