Influence of acute kidney injury on short- and long-term outcomes in patients undergoing cardiac surgery: risk factors and prognostic value of a modified RIFLE classification

Abstract

IntroductionThe development of acute kidney injury (AKI) is associated with poor outcome. The modified RIFLE (risk, injury, failure, loss of kidney function, and end-stage renal failure) classification for AKI, which classifies patients with renal replacement therapy needs according to RIFLE failure class, improves the predictive value of AKI in patients undergoing cardiac surgery. Our aim was to assess risk factors for post-operative AKI and the impact of renal function on short- and long-term survival among all AKI subgroups using the modified RIFLE classification.MethodsWe prospectively studied 2,940 consecutive cardiosurgical patients between January 2004 and July 2009. AKI was defined according to the modified RIFLE system. Pre-operative, operative and post-operative variables usually measured on and during admission, which included main outcomes, were recorded together with cardiac surgery scores and ICU scores. These data were evaluated for association with AKI and staging in the different RIFLE groups by means of multivariable analyses. Survival was analyzed via Kaplan-Meier and a risk-adjusted Cox proportional hazards regression model. A complete follow-up (mean 6.9 ± 4.3 years) was performed in 2,840 patients up to April 2013.ResultsOf those patients studied, 14% (n = 409) were diagnosed with AKI. We identified one intra-operative (higher cardiopulmonary bypass time) and two post-operative (a longer need for vasoactive drugs and higher arterial lactate 24 hours after admission) predictors of AKI. The worst outcomes, including in-hospital mortality, were associated with the worst RIFLE class. Kaplan-Meier analysis showed survival of 74.9% in the RIFLE risk group, 42.9% in the RIFLE injury group and 22.3% in the RIFLE failure group (P <0.001). Classification at RIFLE injury (Hazard ratio (HR) = 2.347, 95% confidence interval (CI) 1.122 to 4.907, P = 0.023) and RIFLE failure (HR = 3.093, 95% CI 1.460 to 6.550, P = 0.003) were independent predictors for long-term patient mortality.ConclusionsAKI development after cardiac surgery is associated mainly with post-operative variables, which ultimately could lead to a worst RIFLE class. Staging at the RIFLE injury and RIFLE failure class is associated with higher short- and long-term mortality in our population.

Serum creatinine role in predicting outcome after cardiac surgery beyond acute kidney injury

“…Moreover, higher degrees of preoperative kidney insufficiency are accompanied by a proportionally higher risk of CSA-AKI and need for RRT [20] . Pathophysiological studies indicate that cardiac patients with AKI are more likely to have progressive renal changes beyond the acute episode even after reduction of serum creatinine to normal levels [19,21,22] . AKI has been divided into pre-renal, renal and post-renal with regards to etiology.…”

“…Modified RIFLE stages anyone who needs RRT in category F (failure) regardless of the level of serum creatinine. A recent study performed with this method reported an incidence of 14% for AKI and showed that CSA-AKI aggravated short and long term outcomes in cardiac patients [19] . Nevertheless, a large survey of 1881 patients by Bastin et al [61] indicated that the incidence of AKI with both AKIN and RIFLE criteria was mostly equal (25.9% and 24.9%, respectively), but hospital mortality was predicted more precisely by AKIN.…”

“…The risk of AKI increases in valvular and combined surgery compared to myocardial revascularization two to four times, respectively [11,14,15] . It has been indicated repeatedly in different studies that serum creatinine rise after cardiac surgery is followed by long-term chronic kidney disease (CKD) and mortality [16][17][18][19] . Moreover, higher degrees of preoperative kidney insufficiency are accompanied by a proportionally higher risk of CSA-AKI and need for RRT [20] .…”

Risk factors of acute kidney injury requiring renal replacement therapy based on regional registry data

“…Both the use of catecholamines and intra-aortic counterpulsation balloons are considered risk factors for AKI [13]. Moreover, according to the guidelines mentioned above [12] and in other studies [14], an extensive surgical procedure is an AKI-inducing factor. This finding is consistent with our data as surgery performed during the ICU stay doubled the risk of AKI (OR = 2.05).…”

Outcomes of abdominal surgery in patients with liver cirrhosis

“…LC may cause renal dysfunction and HRS; which occurs in conjunction with microcirculatory dysfunction in other organs, including the heart and the peripheral vascular bed [53] . Assessment of preoperative renal function is of paramount importance due to the high influence of AKI on postoperative survival in LC patients [54,55] . Thus, the identification of high creatinine levels as an independent predictor of complications and mortality in LC patients undergoing surgery was not surprising [56] .…”