Potentially Modifiable Predictors for Renal Replacement Therapy in Patients with Cardiac Surgery Associated-Acute Kidney Injury: a Propensity Score-Matched Case-Control Study

Abstract Objective: To discover potentially modifiable perioperative predictors for renal replacement therapy (RRT) in patients with cardiac surgery-associated acute kidney injury (CSA-AKI). Methods: A cohort of 1773 consecutive cardiac surgery patients with postoperative acute kidney injury (AKI) from January 2013 to December 2015 were included retrospectively. AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. The primary outcome was CSA-AKI requiring renal replacement therapy (AKI-RRT). The initiation of RRT was based on clinical judgment regarding severe volume overload, metabolic abnormality (e.g., acidosis, hyperkalemia), and oliguria. Patients with AKI-RRT were matched 1:1 with patients without AKI-RRT by a propensity score, to exclude the influence of patients' demographics, comorbidities, and baseline renal function. Multivariable regression was performed to identify the predictors in the matched sample. Results: AKI-RRT occurred in 4.4% of the entire cohort (n=78/1773), with 28.2% of in-hospital mortality (n=22/78). With the propensity score, 78 pairs of patients were matched 1:1 and the variables found to be predictors of AKI-RRT included the contrast exposure within 3 days before surgery (odds ratio [OR]=2.932), central venous pressure (CVP) >10 mmHg on intensive care unit (ICU) admission (OR=1.646 per mmHg increase), and erythrocyte transfusions on the 1st day of surgery (OR=1.742 per unit increase). Conclusion: AKI-RRT is associated with high mortality. The potentially modifiable predictors found in this study require concern and interventions to prevent CSA-AKI patients from worsening prognosis.摘要 研究目的：探寻心脏手术相关急性肾损伤（cardiac surgery-associated acute kidney injury, CSA-AKI）患者中，可干预的围手术期肾脏替代治疗（renal replacement therapy, RRT）预测因素。 研究方法：本研究回顾性纳入2013年1月至2015年12月期间的1773例连续术后急性肾损伤（acute kidney injury, AKI）心脏手术患者。AKI的诊断依据改善全球肾脏病预后组织（Kidney Disease: Improving Global Outcomes, KDIGO）制定的标准。本研究的主要结局为需接受肾脏替代治疗的心脏手术相关急性肾损伤（AKI-RRT）。肾脏替代治疗的启动依据临床判断，指征包括严重容量负荷过重、代谢异常（如酸中毒、高钾血症）以及少尿。采用倾向得分匹配法以1:1的比例将AKI-RRT患者与非AKI-RRT患者进行匹配，以排除患者人口学特征、合并症及基线肾功能的影响。随后在匹配后的队列中开展多变量回归分析，以筛选AKI-RRT的预测因素。 研究结果：全队列中4.4%的患者发生AKI-RRT（78/1773），该亚组患者的院内死亡率为28.2%（22/78）。经倾向得分匹配后，共得到78对匹配患者。最终筛选出的AKI-RRT预测因素包括：术前3天内接受造影剂暴露（比值比[OR]=2.932）、入住重症监护病房（intensive care unit, ICU）时中心静脉压（central venous pressure, CVP）>10 mmHg（每升高1 mmHg，OR=1.646）以及手术当日输注红细胞（每输注1单位，OR=1.742）。 研究结论：AKI-RRT与较高的院内死亡率相关。本研究发现的可干预预测因素值得临床关注，需采取相应干预措施以避免心脏手术相关急性肾损伤患者预后恶化。