Supplementary Material for: Influence of Minimal Changes in Preoperative Renal Function on Outcomes of Cardiac Surgery

Background/Aims: Cardiovascular morbidity and mortality are high in patients with chronic kidney disease. We evaluated the influence of small differences in preoperative kidney function on mortality and complications following cardiac surgery. Methods: This is an observational study that included adult patients undergoing cardiac surgery. Preoperative estimated glomerular filtration rate (eGFR) was estimated by the 4-component Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations based on preoperative creatinine levels. For analysis, patients were divided into groups according to their preoperative creatinine (0.2 mg/dl increments) and eGFR levels (15–30 ml/min/1.73 m2 decrements). Results: Data on 5,340 patients were analyzed. A significant increase in postoperative mortality was demonstrated with preoperative creatinine at high-normal versus low-normal values (OR 1.7, 95% CI: 1–2.5; p = 0.02). For preoperative creatinine >1.2 mg/dl, adjusted OR for in-hospital mortality increased stepwise with every 0.2-mg/dl increment of creatinine. In addition, a statistically significant increment of mortality was detected with every 15-ml/min/1.73 m2 decrement in preoperative eGFR. Conclusions: Minimal changes of preoperative kidney function are associated with a substantial increase in the risk of mortality and morbidity following cardiac surgery. Even within the ‘normal’ range, minimal increases in serum creatinine levels are associated with increased risk of adverse events postoperatively.

【背景与目的】慢性肾病患者的心血管发病率与死亡率均处于较高水平。本研究旨在评估术前肾功能的微小差异对心脏手术后患者死亡率及并发症的影响。【方法】本研究为观察性研究，纳入接受心脏手术的成年患者。术前估算肾小球滤过率（estimated glomerular filtration rate，eGFR）采用基于术前肌酐水平的4组分肾脏病饮食改良（Modification of Diet in Renal Disease，MDRD）公式与慢性肾脏病流行病学合作研究（Chronic Kidney Disease Epidemiology Collaboration，CKD-EPI）公式进行估算。分析时，根据术前肌酐水平（以0.2 mg/dl为增量区间）与eGFR水平（以15～30 ml/min/1.73 m²为递减区间）对患者进行分组。【结果】本研究共分析5340例患者的数据。结果显示，术前肌酐处于高正常范围相较于低正常范围的患者，术后死亡率显著升高（优势比[OR] 1.7，95%置信区间[CI]：1～2.5；p=0.02）。对于术前肌酐＞1.2 mg/dl的患者，院内死亡率的校正优势比随肌酐每升高0.2 mg/dl呈逐步升高趋势。此外，术前eGFR每降低15 ml/min/1.73 m²，患者死亡率即出现具有统计学意义的升高。【结论】术前肾功能的微小变化与心脏手术后死亡率及并发症风险的显著升高相关。即使处于‘正常’范围内，血清肌酐水平的轻微升高也与术后不良事件风险增加相关。