Predicting GFR after radical nephrectomy: the importance of split renal function

• DOI: 10.1007/s00345-021-03918-9
• Publication Date: 2022-01-12T17:02:52Z
• Authors: Nityam Rathi; Diego A. Palacios; Emily Abramczyk; Hajime Tanaka; Yunlin Ye; Jianbo Li; Yosuke Yasuda; Robert Abouassaly; Mohamed Eltemamy; Alvin Wee; Christopher Weight; Steven C. Campbell
• Keywords: 03 medical and health sciences; 0302 clinical medicine; Humans; Kidney; Carcinoma, Renal Cell; Nephrectomy; Kidney Neoplasms; Glomerular Filtration Rate; Retrospective Studies; 3. Good health

To evaluate a conceptually simple model to predict new-baseline-glomerular-filtration-rate (NBGFR) after radical nephrectomy (RN) based on split-renal-function (SRF) and renal-functional-compensation (RFC), and to compare its predictive accuracy against a validated non-SRF-based model. RN should only be considered when the tumor has increased oncologic potential and/or when there is concern about perioperative morbidity with PN due to increased tumor complexity. In these circumstances, accurate prediction of NBGFR after RN can be important, with a threshold NBGFR > 45 ml/min/1.73m2 correlating with improved overall survival.236 RCC patients who underwent RN (2010-2012) with preoperative imaging (CT/MRI) and relevant functional data were included. NBGFR was defined as GFR 3-12 months post-RN. SRF was determined using semi-automated software that provides differential parenchymal-volume-analysis (PVA) from preoperative imaging. Our SRF-based model was: Predicted NBGFR = 1.24 (× Global GFRPre-RN) (× SRFContralateral), with 1.24 representing the mean RFC estimate from independent analyses. A non-SRF-based model was also assessed: Predicted NBGFR = 17 + preoperative GFR (× 0.65)-age (× 0.25) + 3 (if tumor > 7 cm)-2 (if diabetes). Alignment between predicted/observed NBGFR was assessed by comparing correlation coefficients and area-under-the-curve (AUC) analyses.The correlation-coefficients (r) were 0.87/0.72 for SRF-based/non-SRF-based models, respectively (p = 0.005). For prediction of NBGFR > 45 ml/min/1.73m2, the SRF-based/non-SRF-based models provided AUC of 0.94/0.87, respectively (p = 0.044).Previous non-SRF-based models to predict NBGFR post-RN are complex and omit two important parameters: SRF and RFC. Our proposed model prioritizes these parameters and provides a conceptually simple, accurate, and clinically implementable approach to predict NBGFR post-RN. SRF can be easily obtained using PVA software that is affordable, readily available (FUJIFILM-Medical-Systems), and more accurate than nuclear-renal-scans. The SRF-based model demonstrates greater predictive-accuracy than a non-SRF-based model, including the clinically-important predictive-threshold of NBGFR > 45 ml/min/1.73m2.