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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2010  |  Volume : 21  |  Issue : 6  |  Page : 1106-1110
Outcome and prognostic factors of critically ill patients with acute renal failure requiring continuous renal replacement therapy


Critical Care Department, King Saud Bin Abdulaziz University for Medical Sciences, Riyadh, Saudi Arabia

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Date of Web Publication4-Nov-2010
 

   Abstract 

Continuous renal replacement therapy (CRRT) has proved to be beneficial for the treatment of critically ill patients with acute renal failure (ARF). The aim of this study is to determine the outcome and identify the predictors of mortality of critically ill patients treated with CRRT for ARF in the intensive care unit (ICU). This prospective cohort study of critically ill patients with ARF requiring CRRT admitted to the ICU was carried out at a tertiary care hospital in Saudi Arabia from 2002 to 2008. A total of 644 of 7173 patients with ARF required CRRT were studied. About 9% of the ARF patients required CRRT and comprised mainly those with medical causes, carrying a mortality of 64%. Multivariate analysis found high serum creatinine as an independent factor for better outcome and requirement of mechanical ventilation (MV) as an independent factor for worse outcome. In our cohort study, ARF requiring CRRT in the ICU was associated with a high mortality.

How to cite this article:
Aldawood A. Outcome and prognostic factors of critically ill patients with acute renal failure requiring continuous renal replacement therapy. Saudi J Kidney Dis Transpl 2010;21:1106-10

How to cite this URL:
Aldawood A. Outcome and prognostic factors of critically ill patients with acute renal failure requiring continuous renal replacement therapy. Saudi J Kidney Dis Transpl [serial online] 2010 [cited 2019 Jul 17];21:1106-10. Available from: http://www.sjkdt.org/text.asp?2010/21/6/1106/72299

   Introduction Top


Acute renal failure (ARF) requiring renal re­placement therapy (RRT) occurs in 5-6% of the critically ill patients and is associated with high mortality and significant health care resource utilization. [1] The introduction and development of continuous renal replacement therapy (CRRT) represents one of the most significant changes in the management of critically ill patients in the intensive care unit (ICU). Despite improve­ments in the management of critically ill pa­tients and advances made in renal replacement techniques, the mortality of ARF in the ICU continues to be high. [2] Depending on the etio­logy of ARF as well as the associated comor­bid conditions, the in-hospital mortality rate is about 30%, and may go up to 90% when ARF is accompanied by other organ failures, [3] and when ARF frequently occurs as a part of multiple organ failure. [4] The ICU is one of the most expensive places in the hospital setting. [5] Therefore, management of ARF in the ICU represents a challenge to healthcare providers. [6] The first choice for patients with ARF who need RRT is CRRT, because the majority of critically ill patients are hemodynamically un­stable. [7] CRRT has proven to be beneficial in the treatment of critically ill patients with ARF; the advantages of CRRT include more precise fluid control and decreased hemody­namic instability. [8] The aim of this study was to determine the outcome and identify the pre­dictors of mortality of critically ill patients treated with CRRT for ARF in the ICU.


   Materials and Methods Top


The study was approved by the Institutional Review Board (IRB) and was conducted in a 21-bed medical and surgical ICU in an 800­bed tertiary care teaching hospital in Riyadh, Saudi Arabia. This ICU is a closed unit, run by in-house, full-time, board-certified intensivists, and has more than 1100 admissions per year.

Study population

All patients diagnosed as having ARF and treated with CRRT in the ICU were eligible for inclusion in the study. Patients with pre­existing chronic renal failure treated with renal replacement therapy were excluded.

Data collection

Data on patients with ARF on CRRT admit­ted to the ICU were included in the analysis from a prospectively collected ICU database. The following data were collected: baseline demographics, including gender, age, body mass index, Glasgow Coma Score (GCS), lac­tate level and the type of admission with pre­specified admission diagnoses. Acute Physiology and Chronic Health Evaluation II (APACHE II) scores [9] and length of stay (LOS) in the ICU, calculated as number of calendar days, as well as the hospital LOS were recorded. The use of vasopressors and requirement of mechanical ventilation (MV) were recorded. The patients were followed-up until discharge from the hos­pital or death, whichever occurred first.

End points

The ICU mortality was the primary outcome. The secondary outcomes were hospital morta­lity and requirement of MV during the ICU stay.


   Statistical Analysis Top


Continuous data are expressed as mean ± standard deviation (SD) and compared using the Student's t-test. Categorical data are ex­pressed as a percentage and compared using the chi-square test. Univariate analysis was performed to examine the association with ICU mortality. Variables with significant asso­ciation were tested by multivariate analysis. Statistical significance was defined as alpha less than 0.05. Statistical analysis was per­formed using Minitab for Windows (release 13.1).


   Results Top


During the seven-year study period, there were 7173 patients admitted to the ICU. Of them, 644 patients (9%) developed ARF and required CRRT. Among survivors, 58%were males with mean age of 60 years, while among non-survivors 52% were male with mean age of 59.8 years. The main characteristics of patients with ARF requiring CRRT are summarized in [Table 1].
Table 1 :Baseline characteristics of patients with acute renal failure requiring CRRT admitted to the ICU.

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The main indication for admission to the hospital was medical, with sepsis being the most common indication for admission to the ICU. The common diagnoses at admission to the ICU are mentioned in [Table 2].
Table 2 :Indications for admission to the ICU in the study patients.

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Predictive outcomes

The ICU and hospital mortality rates were 64% and 80%, respectively. A total of 592 pa­tients (91.9%) required MV during their stay in the ICU. Based on the APACHE II scores, the predictive mortality score was 73 ± 21.7 for the non-survivor group. [Table 3] shows the comparison between the survivor and the non­survivor groups. Univariate analysis showed that worse outcomes were seen in patients with low GCS, high lactic acid and requirement of MV. On the other hand, high serum creatinine and high platelet count were associated with better outcome. Multivariate analysis showed that requirement of MV during stay in the ICU was an independent risk factor for mortality and that high serum creatinine was an inde­pendent risk factor for better outcome.
Table 3 :Univariate analysis of factors associated with outcome in the ICU.

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   Discussion Top


Our study showed that the incidence of ARF treated with CRRT was 9%; the incidence has ranged from 1.1% to 25% according to the pa­tient population studied and the definition of ARF. [4] Only few studies [4],[10],[11],[12] have focused on

ARF requiring RRT. The mortality rate of pa­tients with ARF treated with CRRT in our study was 64%. Thus, it is evident that the out­come of patients with ARF requiring CRRT is poor. Our results are in agreement with mor­tality rates reported earlier, [11],[12],[13] which could partly be explained by an increased severity of illness at admission to the ICU. The predicted mortality based on the APACHE II scores is 73 ± 21.7, but was not associated with death after adjusting for the confounding variables.

The Severities-of-Illness scoring systems have become clinically and scientifically applicable in a variety of settings. However, most of the studies have shown that these scoring systems underestimate the mortality and are not useful predictors of outcome in patients with ARF requiring CRRT. [4],[7],[14] We found that require­ment of MV during stay in the ICU is an independent risk factor for mortality and that high serum creatinine is an independent risk factor for better outcome.

Many studies [4],[10],[13] have evaluated the prog­nostic factors predicting outcome of patients with ARF requiring CRRT. In a study from France, Soubrier et al. [4] found that patients who required MV, inotropic support and had ische­mic acute tubular necrosis carried a poor prog­nosis, while those with high serum creatinine and high urine output were associated with good prognosis. In a selected group of patients, Charbonney et al. [15] showed that no significant independent predictor was found in patients with ARF requiring RRT after solid organ trans­plantation. Saski and colleagues [7] found that elevated serum bilirubin and lactate levels in addition to the presence of hepatic failure are associated with worse outcome in patients with ARF treated with CRRT.

Debates exist regarding the impact of high serum creatinine level on favorable outcome. The possible explanation is that decreased crea­tinine production by liver disease, reduced muscle mass and ageing are associated with lower serum creatinine levels, and that a higher serum creatinine may reflect the absence of these co-morbid conditions. These findings were noted in a study from France, [4] where the authors found that high serum creatinine predicted a favorable outcome. Several studies [11],[13],[16],[17],[18] have shown that the need of MV predicted a worse outcome. Our results support this. The need of MV may reflect increased severity of illness. The need for ino­tropes, advanced age and urine volume were not identified as predictors of worse outcome in previous studies. [4],[14],[17],[19],[20] It is clear from the available studies that there are no absolute pre­dictors of ICU outcome of critically ill patients with ARF requiring CRRT. However, our study has some limitations; it is a retrospective study performed in patients recruited from a single center and we did not include some po­tentially important variables, such as mode of CRRT, timing of the beginning of treatment, number of organ failure, incidence of hypoten­sion and nephrotoxicity due to drugs. Our study has several strengths. A full-time dedicated data collector gathered and entered our data pros­pectively. Our ICU is a closed unit and is operated mainly by critical care board-certified intensivists, which makes the management rather homogenous.

In conclusion, the prevalence of patients with ARF requiring CRRT is high. These patients were associated with a high ICU mortality (64%). One of the predicting factors of better outcome is high serum creatinine and, for worse outcome, is the requirement of MV during the ICU stay.

 
   References Top

1.Vesconi S, Cruz DN, Fumagalli R, et al. Delivered dose of renal replacement therapy and mortality in critically ill patients with acute kidney injury. Crit Care 2009;13(2):R57.  Back to cited text no. 1
    
2.Mehta RL, McDonald B, Gabbai FB, et al. A randomized clinical trial of continuous versus intermittent dialysis for acute renal failure. Kidney Int 2001;60(3):1154-63.  Back to cited text no. 2
    
3.Liano F, Junco E, Pascual J, Madero R, Verde E. The spectrum of acute renal failure in the intensive care unit compared with that seen in other settings: The Madrid Acute Renal Failure Study Group. Kidney Int Suppl 1998;66:S16-24.  Back to cited text no. 3
    
4.Soubrier S, Leroy O, Devos P, et al. Epide­miology and prognostic factors of critically ill patients treated with hemodiafiltration. J Crit Care 2006;21(1):66-72.  Back to cited text no. 4
    
5.Secco LM, Castilho V. Expenditure survey on continued veno-venous hemodialysis proce­dure in the intensive care unit. Rev Lat Am Enfermagem 2007;15(6):1138-43.  Back to cited text no. 5
    
6.John S, Eckardt KU. Renal replacement strategies in the ICU. Chest 2007;132(4):1379-88.  Back to cited text no. 6
    
7.Sasaki S, Gando S, Kobayashi S, et al. Pre­dictors of mortality in patients treated with continuous hemodiafiltration for acute renal failure in an intensive care setting. ASAIO J 2001;47(1):86-91.  Back to cited text no. 7
    
8.Pannu N, Gibney RN. Renal replacement therapy in the intensive care unit. Ther Clin Risk Manag 2005;1(2):141-50.  Back to cited text no. 8
    
9.Knaus WA, Draper EA, Wagner DP, Zimmer­man JE. APACHE II: A severity of disease classification system. Crit Care Med 1985;13 (10):818-29.  Back to cited text no. 9
    
10.Chertow GM, Christiansen CL, Cleary PD, Munro C, Lazarus JM. Prognostic stratification in critically ill patients with acute renal failure requiring dialysis. Arch Intern Med 1995;155 (14):1505-11.  Back to cited text no. 10
    
11.Schaefer JH, Jochimsen F, Keller F, Wegs­cheider K, Distler A. Outcome prediction of acute renal failure in medical intensive care. Intensive Care Med 1991;17(1):19-24.  Back to cited text no. 11
    
12.Cole L, Bellomo R, Silvester W, Reeves JH. A prospective, multicenter study of the epide­miology, management, and outcome of severe acute renal failure in a "closed" ICU system. Am J Respir Crit Care Med 2000;162(1):191-6.  Back to cited text no. 12
    
13.Schwilk B, Wiedeck H, Stein B, Reinelt H, Treiber H, Bothner U. Epidemiology of acute renal failure and outcome of haemodiafiltration in intensive care. Intensive Care Med 1997; 23(12):1204-11.  Back to cited text no. 13
    
14.Metnitz PG, Krenn CG, Steltzer H, et al. Effect of acute renal failure requiring renal replace­ment therapy on outcome in critically ill pa­tients. Crit Care Med 2002;30(9):2051-8.  Back to cited text no. 14
    
15.Charbonney E, Saudan P, Triverio PA, Quinn K, Mentha G, Martin PY. Prognosis of acute kidney injury requiring renal replacement therapy in solid organ transplanted patients. Transpl Int 2009;22(11):1058-63.  Back to cited text no. 15
    
16.de Mendonca A, Vincent JL, Suter PM, et al. Acute renal failure in the ICU: Risk factors and outcome evaluated by the SOFA score. Intensive Care Med 2000;26(7):915-21.  Back to cited text no. 16
    
17.Brivet FG, Kleinknecht DJ, Loirat P, Landais PJ. Acute renal failure in intensive care units-­causes, outcome, and prognostic factors of hospital mortality: A prospective, multicenter study: French Study Group on Acute Renal Failure. Crit Care Med 1996;24(2):192-8.  Back to cited text no. 17
    
18.Liano F, Pascual J. Epidemiology of acute renal failure: A prospective, multicenter, com­munity-based study: Madrid Acute Renal Failure Study Group. Kidney Int 1996;50(3): 811-8.  Back to cited text no. 18
    
19.Barton IK, Hilton PJ, Taub NA, et al. Acute renal failure treated by haemofiltration: Factors affecting outcome. Q J Med 1993;86(2):81-90.  Back to cited text no. 19
    
20.Liano F, Gallego A, Pascual J, et al. Prognosis of acute tubular necrosis: An extended pros­pectively contrasted study. Nephron 1993;63 (1):21-31.  Back to cited text no. 20
    

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Correspondence Address:
Abdulaziz Aldawood
Associate Professor of Medicine, King Saud Bin Abdulaziz University for Medical Sciences, Deputy Chairman of Critical Care Department, P.O. Box 1149, Riyadh, 11322
Saudi Arabia
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    Tables

  [Table 1], [Table 2], [Table 3]

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