Validation of 3D volumetric-based renal function prediction calculator for nephron sparing surgery.
OBJECTIVE
To evaluate a recently published volume-based renal function prediction calculator intended to be used in small renal mass surgical counseling.


METHODS
Retrospective data collection included three-dimensional calculation of renal mass and parenchyma of patients who have undergone extirpative therapy. The predicted glomerular filtration rate (GFR) was calculated using the online calculator. The predicted GFR was compared with the actual 6-month GFR. The Pearson correlation coefficient, paired t test and root-mean-square error (RMSE) are utilized for statistical analysis.


RESULTS
After institutional review board approval, three institutions provided data for analysis. After patients with renal mass size >300 cc, renal size >400 cc or preoperative CKD ≥stage 3 had been excluded, we retrospectively analyzed data from 136 patients. The median mass volume was 22.2 cc (IQR 7-49). In multiple linear regression analysis, the most significant variables predicting postoperative GFR were partial versus radical nephrectomy and preoperative GFR with an overall R2of .68 (F = 26.13, P < .001). The predicted GFR was 75.4 mL/min/1.73 m2compared to an actual GFR of 70.7 mL/min/1.73 m2(P < .001, paired t test). The predicted GFR was highly correlated with the actual postoperative GFR at 6 months (Pearson correlation, r = .65, P < .001). RMSE of the validation cohort was 16.87.


CONCLUSIONS
The predictive tool to determine renal function benefit of nephron sparing surgery compared to radical nephrectomy online calculator effectively predicts GFR and could potentially be used to help urologists and patients discuss renal function prior to extirpative renal surgery.
Department of Urology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Renato
R
Corradi
Department of Urology, University of Texas Health Science Center San Antonio, 7703, Floyd Curl Drive, San Antonio, TX, USA.
Aashish
A
Kabra
Department of Urology, University of California-Irvine, Irvine, CA, USA.
Melissa
M
Suarez
Department of Urology, University of Texas Health Science Center San Antonio, 7703, Floyd Curl Drive, San Antonio, TX, USA.
Jacob
J
Oppenheimer
Department of Urology, University of California-Irvine, Irvine, CA, USA.
Zhamshid
Z
Okhunov
Department of Radiology, University of Texas Health Science Center San Antonio, San Antonio, TX, USA.
Hugh
H
White
Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.|INSERM, U1194, Institut de Recherche en Cancérologie de Montpellier (IRCM), Montpellier, France.|Service de Radiologie, Institut Régional du Cancer de Montpellier, Montpellier, France.
Stephanie
S
Nougaret
Department of Urology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Hebert A
HA
Vargas
Department of Urology, University of California-Irvine, Irvine, CA, USA.
Jaime
J
Landman
Department of Urology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Jonathan
J
Coleman
Department of Urology, University of Texas Health Science Center San Antonio, 7703, Floyd Curl Drive, San Antonio, TX, USA. liss@uthscsa.edu.
Michael A
MA
Liss
D000368:Aged; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D000066491:Clinical Decision-Making; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D021621:Imaging, Three-Dimensional; D020407:Internet; D007668:Kidney / Q000503:physiopathology*; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D009392:Nephrectomy / Q000379:methods; D009399:Nephrons / Q000601:surgery; D059351:Organ Sparing Treatments; D011184:Postoperative Period; D011237:Predictive Value of Tests; D057234:Preoperative Period; D012189:Retrospective Studies; D012984:Software; D047368:Tumor Burden
Calculator; Chronic kidney disease; Partial nephrectomy; Renal cancer; Renal mass