Interobserver variability of R.E.N.A.L., PADUA, and centrality index nephrometry score systems
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To assess interobserver variability of R.E.N.A.L., preoperative aspects and dimensions used for an anatomical classification system (PADUA), and centrality index (C-Index) systems among observers with varying degrees of clinical experience and each system’s subscale correlation with surgical outcome metrics.
Computed tomography images of 90 patients who underwent open, laparoscopic, or robot-assisted laparoscopic partial nephrectomy were scored by one radiology fellow, two urology fellows, one radiology resident, and one 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 estimated glomerular filtration rate (eGFR) were evaluated using Spearman’s correlation.
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, and 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.
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.
KeywordsKidney neoplasms Nephrometry Observer variability Partial nephrectomy Outcome assessment
American Society of Anesthesiologists
Chronic Kidney Disease Epidemiology Collaboration
Estimated glomerular filtration rate
Intraclass correlation coefficient
Memorial Sloan Kettering Cancer Center
Non-medical secondary school student
Preoperative aspects and dimensions used for an anatomical classification system
Physicians (urology fellows + radiology resident)
Radius, exophytic/endophytic, nearness, anterior/posterior, location
Supported in part by NIH/NCI Cancer Center Support Grant to MSKCC (award number P30 CA008748) and The Thompson Family Foundation. The manuscript does not contain clinical studies or patient data.
Conflict of interest
The authors declare that they have no conflict of interest.
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