Multicenter Validation of Surgeon Assessment of Renal Preservation in Comparison to Measurement with 3D Image Analysis

Objective To validate the findings of a prior single-surgeon series with a multi-institutional comparison of three-dimensional imaging of volume preservation (3DVP) and surgeon assessment of volume preservation (SAVP) as predictors of renal function after partial nephrectomy (PN). Baseline renal function and preservation of functioning renal parenchyma are the strongest predictors of function after PN for presumed renal cancer. Prior studies have confirmed that measurement of volume preservation with 3DVP is accurate, but limited data exist to compare this time-consuming approach with SAVP. Materials and Methods 3DVP and SAVP were calculated for 157 patients operated on by 13 surgeons at 2 institutions having both pre- and postoperative cross-sectional imaging. Renal function was assessed by univariable and multivariable linear regression methods. Results Median ipsilateral parenchymal preservation was 87% by 3DVP (interquartile range: 76%-95%) and 85% by SAVP (interquartile range: 75%-90%). Both correlated strongly with each other (P <.0001) and no statistical differences in the correlation were observed for different individual surgeons. Each method was strongly correlated with postoperative glomerular filtration rate (P <.0001). Multivariable models using 3DVP and SAVP were statistically similar in predicting postoperative glomerular filtration rate (R² = 0.86 for both). However, SAVP was not interchangeable with 3DVP within a 5% margin of error (95% confidence interval: -0.11, 0.13) according to Bland-Altman analysis. Conclusion SAVP has been validated in a multicenter cohort of PN patients demonstrating it to provide a reliable estimate of renal functional preservation that is reproducible in contemporary practice. We propose that SAVP reporting should be performed routinely to facilitate analysis of PN outcomes and 3DVP used for research purposes.