The Zhongshan score: a novel and simple anatomic classification system to predict perioperative outcomes of nephron-sparing surgery

Abstract

In the zero ischemia era of nephron-sparing surgery (NSS), a new anatomic classification system (ACS) is needed to adjust to these new surgical techniques. We devised a novel and simple ACS, and compared it with the RENAL and PADUA scores to predict the risk of NSS outcomes. We retrospectively evaluated 789 patients who underwent NSS with available imaging between January 2007 and July 2014. Demographic and clinical data were assessed. The Zhongshan (ZS) score consisted of three parameters. RENAL, PADUA, and ZS scores are divided into three groups, that is, high, moderate, and low scores. For operative time (OT), significant differences were seen between any two groups of ZS score and PADUA score (all P < 0.05). For ZS score, patients with moderate and high scores had longer warm ischemia time (WIT) and greater increase in SCr compared with low score (all P < 0.05). What is more, the differences between moderate and high scores classified by ZS score were borderline but trending toward significance in WIT (P = 0.064) and increase in SCr (P = 0.052). Interestingly, RENAL showed no significant difference between moderate and high complexity in OT, WIT, estimated blood loss, and increase in SCr. Compared with patients with a low score of ZS, those with a high or moderate score had 8.1-fold or 3.3-fold higher risk of surgical complications, respectively (all P < 0.05). As for RENAL score, patients with a high or moderate score had 5.7-fold or 1.9-fold higher risk of surgical complications, respectively (all P < 0.05). Patients with a high or moderate score of PADUA had 2.3-fold or 2.8-fold higher risk of surgical complications, respectively (all P < 0.05). In the ROC curve analysis, ZS score had the greatest AUC for surgical complications (AUC = 0.632) and the conversion to radical nephrectomy (AUC = 0.845) (all P < 0.05). In conclusion, the ability of ZS score to predict the surgical complexity and surgical complications of NSS is better than RENAL and PADUA scores. ZS score could be used to reflect the surgical complexity and predict the risk of surgical complications in patients undergoing NSS.

FIGURE 1

ZS score. Black vertical lines represent the medial lines; black and red dotted lines represent the depth of tumor invasion; green, purple, and red circles represent the lateral, medial, and central tumors, respectively. Arabic numerals represent the score points. Ri represents the maximum tumor diameter within renal parenchyma. L represents the physical location of the tumor. D represents the depth of tumor invasion.

FIGURE 2

Definition of the medial line. A, B: medial location above higher polar line; C, D: medial location between polar lines; E, F: central location touching intrarenal segmental vessels; G, H: central location touching extrarenal and intrarenal vessels.

FIGURE 3

ROC curve for the prediction of complications and the conversion to RN. AUC = area under the curve, ASA = American Society of Anesthesiologists, CI = confidence interval, PADUA = preoperative aspects and dimensions used for anatomic, RENAL = radius.exophyic/endophytic.nearness.anterior/posterior.location, ROC = receiver operating characteristic, ZS = Zhongshan.