Assessment of volume preservation performed before or after partial nephrectomy accurately predicts postoperative renal function: Results from a prospective multicenter study

•Partial nephrectomy (PN) better preserves renal function than radical nephrectomy.•Renal function after PN is closely linked to parenchymal volume preservation (VP).•Surgeon assessment of VP, like 3D calculation of VP, correlates with function.•Preoperative assessment of VP provides similar predictive ability prior to PN.•Estimation of postoperative glomerular filtration rate can impact patient-decision making and counseling. Partial nephrectomy (PN) is standard for small renal masses, improving renal function by preserving renal parenchyma compared with radical nephrectomy. Recent work demonstrated that postoperative surgeon assessment of volume preservation (SAVP) and 3D imaging measurements agree and correlate with postoperative function. We hypothesize preoperative assessment of volume preservation (PAVP) with PN based on preoperative imaging will reliably indicate postoperative renal function. Data were collected from 336 patients undergoing PN for suspected renal cancer by 40 surgeons at 12 centers in Europe and the United States within the Surface-Intermediate-Base International Consortium. Surgeons recorded PAVP and SAVP for individual patients; pre- and postoperative glomerular filtration rate (GFR) was estimated by Chronic Kidney Disease Epidemiology Collaboration equations. Correlations between PAVP, SAVP, and postoperative GFR were assessed with linear regression models. Bland–Altman analysis was used to assess agreement between PAVP and SAVP with a significant cutoff of 5%. Median PAVP was 90% (interquartile range [IQR] 85%–100%) and SAVP was 90% (IQR: 80%–94%). PAVP and SAVP were moderately correlated (R2 = 0.67, P < 0.0001) and deemed “interchangeable” by Bland–Altman analysis at a 5% acceptable rate of difference (95% CI: −5.4, −3.1). Median postoperative GFR was 77.3 (IQR: 56.2, 92.0). Both PAVP (R2 = 0.82, P < 0.0001) and SAVP (R2 = 0.83, P < 0.0001) were correlated with postoperative GFR. Multivariable models utilizing volume-adjusted GFR based on PAVP or SAVP significantly and similarly predicted postoperative GFR (R2 = 0.72 for each). Renal function is closely linked to the amount of parenchymal volume preservation, whether estimated prior to surgery (PAVP) or afterward (SAVP). PAVP provides reasonably accurate information for decision-making in patients considering PN.