Interobserver variability of R.E.N.A.L., PADUA, and centrality index nephrometry score systems

Abstract

Purpose To assess interobserver variability of R.E.N.A.L., PADUA, and C-Index systems among observers with varying degrees of clinical experience and each system's subscale correlation with surgical outcome metrics. Methods Computed tomography images of 90 patients who underwent open, laparoscopic, or robot-assisted laparoscopic partial nephrectomy were scored by 1 radiology fellow, 2 urology fellows, 1 radiology resident, and 1 secondary school student. Agreement among readers was determined calculating intraclass correlation coefficients. Associations between radiology fellow scores (reference standard as reader with greatest clinical experience), ischemia time, and percent change in postoperative eGFR were evaluated using Spearman correlation. Results Agreement using C-Index method (ICC = 0.773) was higher than with PADUA (ICC = 0.677) or R.E.N.A.L (ICC = 0.660). Agreement between reference and secondary school student was lower than with other physicians, although the differences were not statistically significant. The reference's scores were significantly (p <0.05) associated with ischemia time on all three scoring systems and with percent change in eGFR at 6 weeks using C-index (p = 0.016). Tumor size, nearness to sinus, location relative to polar lines (R.E.N.A.L.) and tumor size, renal sinus involvement and collecting system involvement (PADUA) correlated with ischemia time (all p ≤0.001). No R.E.N.A.L. or PADUA subscales significantly correlated with percent change in postoperative eGFR. Conclusions Clinical experience reduces interobserver variability of existing nephrometry systems though not significantly and less so when using directly measureable anatomic variables. Consistently, only measures of tumor size and distance to intrarenal structures were useful in predicting clinically relevant outcomes.

An Arterial Based Complexity (ABC) Scoring System to Assess the Morbidity Profile of Partial Nephrectomy

“…The RENAL and PADUA scoring systems were built on the morphologic attributes of renal tumors primarily to facilitate communication of tumor anatomy [1,2]. However, cutoff values for some of these systems’ components, for example, maximal tumor size or nearness to the renal sinus structures were chosen based on simplicity rather than proven clinical relevance in predicting surgical outcomes [1,13]. In a recent critical evaluation of the RENAL and PADUA scoring systems and centrality index, only four predictors of complexity (radius, nearness to the collecting system, location relative to the lateral rim, and centrality) were found to be clinically significant variables on multivariable analysis [21].…”

“…In a recent study, we found that increasing radiological and clinical experience reduced the interobserver variability of these systems and that only subscales measuring tumor size and distance to intrarenal structures had clinical significance [13]. Other contemporary studies confirmed that reproducibility of nephrometry scores is affected by the level of the reader’s training and experience [14,15].…”

“…Furthermore, each system’s ability to predict clinical outcomes of PN has been inconsistent between studies [4,12,16–20]. Finally, morphologic descriptors such as the exophytic rate and anterior/posterior descriptor in the RENAL nephrometry scoring system and the anterior or posterior face, longitudinal, and rim tumor location, and exophytic rate in the preoperative aspects and dimensions used for an anatomical (PADUA) scoring system, appear clinically irrelevant for predicting clinical outcomes of PN [5,13]…”

External validation of the Arterial Based Complexity (ABC) scoring system in renal tumors treated by minimally invasive partial nephrectomy

“…However, they were not devoid of limitations. A recent study indicated that the inter‐observer variability of these systems can be reduced by enhanced radiological and clinical experience . Other studies verified that the level of the observer's training and experience has an influence on reproducibility of nephrometry scores .…”

“…Moreover, each nephrometry score's ability to predict clinically relevant outcomes of PN ranges from study to study . Lastly, nephrometry score constituents such as descriptor of posterior or anterior and location relative to polar lines used for RENAL nephrometry score; posterior or anterior face, polar location, and margin location of the tumor, and exophytic rate in the PADUA scoring system, seem to perform poor in predicting clinically relevant outcomes of PN …”