The preoperative stratification of patients based on renal scan data is unable to predict the functional outcome after partial nephrectomy

ABSTRACT Introduction: eGFR-categories are used to predict functional outcome after partial nephrectomy (PN); no study categorized patients according to preoperative renal scan (RS) data. Aim of the study was to evaluate if stratification of patients according to RS is a reliable method to predict minor/major loss of renal function after PN. Materials and Methods: We considered patients who underwent PN and RS pre-/post-PN for T1 tumor in our Institution (2007-2017). Demographics, perioperative and specifically functional data were analysed. On the basis of the baseline Split Renal Function (SRF), patients were stratified into risk-categories: 1) baseline operated-kidney SRF range 45-55%; 2) baseline operated-kidney SRF <45%. Risk categories were analysed with postoperative functional outcome: postoperative operated-kidney SRF decrease below 90% of baseline was considered significant loss of function. Contingency tables and univariate/multivariate regression were analysed looking for independent factors of postoperative functional impairment. Results: 224 patients were analysed, 125 (55.8%) maintained >90% of their baseline function. Worse probability of maintaining ≥90 baseline renal function was found in patients with Charlson's Comorbidity Index (CCI≥3) (p=0.004) and patients with PADUA score ≥8 (p=0.023). After stratification by baseline renal function, ischemia was the only independent factor: no effect on patients with poorer baseline renal function. Patients with baseline SRF 45-55% who did not experience ischemia had the highest probability to maintain ≥90% baseline SRF (p=0.028). Ischemia >25 minutes was detrimental (p=0.017). Conclusions: Stratification of patients by SRF before PN is not a reliable predictor of renal functional outcome. Ischemia seems to scarcely influence patients with poorer renal function.

摘要
引言：估算肾小球滤过率分类（eGFR-categories）常用于预测肾部分切除术（partial nephrectomy, PN）后的功能转归，但目前尚无研究依据术前肾扫描（renal scan, RS）数据对患者进行分层。本研究的目的为评估基于肾扫描结果对患者进行分层，是否可作为预测肾部分切除术后肾功能轻/重度丢失的可靠方法。

材料与方法：纳入2007年至2017年间于本机构接受肾部分切除术，且术前、术后均行肾扫描的T1期肾肿瘤患者。对患者的人口学特征、围手术期相关指标及特异性肾功能数据进行分析。基于患侧肾脏的基线分肾功能（Split Renal Function, SRF），将患者分为两类风险分层：1）患侧肾脏基线分肾功能为45%~55%；2）患侧肾脏基线分肾功能低于45%。结合术后肾功能转归对风险分层进行分析：将患侧肾脏术后分肾功能较基线下降至基线值的90%以下定义为显著肾功能丢失。通过列联表分析、单因素及多因素回归分析，筛选术后肾功能损害的独立危险因素。

结果：共纳入224例患者，其中125例（55.8%）术后肾功能维持在基线值的90%以上。查尔森合并症指数≥3分（Charlson's Comorbidity Index, CCI≥3，p=0.004）及PADUA评分（PADUA score）≥8分（p=0.023）的患者，其肾功能维持≥90%基线值的概率更低。按基线肾功能分层后，热缺血是唯一的独立危险因素，但该因素对基线肾功能较差的患者无显著影响。基线分肾功能为45%~55%且未发生热缺血的患者，其肾功能维持≥90%基线值的概率最高（p=0.028）。热缺血时间超过25分钟会对肾功能产生不利影响（p=0.017）。

结论：术前基于分肾功能对患者进行分层并不能可靠预测肾部分切除术后的肾功能转归；热缺血对基线肾功能较差的患者影响甚微。