| Abstract|| |
The incidence of acute renal failure (ARF) is increasing and will nearly double over the next decades as the population ages. As a result of ARF, patients will have longer hospital stays and may require dialysis as outpatients. The aim of this cohort study was to examine the renal recovery after the hospital discharge of surviving critically ill patients who developed ARF that required dialysis. During the 3-year study, there were 2574 patients admitted to the intensive care unit; 308 (12%) patients developed ARF and needed dialysis, 86 (28%) patients survived to hospital discharge and 40 (47%) patients continued to require dialysis after discharge. There were no differences of age or gender in the dialysis group from the non-dialysis group. In addition, there were no differences between the groups in terms of the severity of illness, use of mechanical ventilation, history of hypertension, creatinine levels, urine output or use of inotropes. It was not uncommon for surviving patients with ARF that required dialysis to be dialysis dependent upon hospital discharge, which represents an important cause of chronic kidney disease.
|How to cite this article:|
Alsultan MA. The renal recovery of critically ill patients with acute renal failure requiring dialysis
. Saudi J Kidney Dis Transpl 2013;24:1175-9
|How to cite this URL:|
Alsultan MA. The renal recovery of critically ill patients with acute renal failure requiring dialysis
. Saudi J Kidney Dis Transpl [serial online] 2013 [cited 2019 Aug 20];24:1175-9. Available from: http://www.sjkdt.org/text.asp?2013/24/6/1175/121275
| Introduction|| |
The incidence of acute renal failure (ARF) is increasing and will nearly double over the next decades as the population ages. As a result, ARF patients will have longer hospital stays and may require dialysis as outpatients.  The incidence of ARF during hospitalization ranges from 3% to 25%, depending on the criteria used.  A failure to recover from renal failure can have a negative impact on the performance of an individual. 
Many countries are affected by the rising incidence of end-stage renal failure (ESRD), but the contribution of ARF to this issue has not been adequately studied.  Amdur and his colleagues found that ARF was associated with a significant decline in renal function over time after hospital discharge, and these findings support the fact that survivors of ARF are likely to progress to ESRD.  ARF requires continuous surveillance and rigorous avoidance of potentially nephrotoxic drugs and contrast agents, which may lead to progression to ESRD.  Critically ill ARF patients have particularly poor prognosis.  Hospital mortality ranges from 45 to 79% for patients with ARF requiring hemodialysis and, of the survivors, up to 15% require dialysis at the time of discharge.  Many studies have demonstrated that patients who survive ARF are at risk of developing chronic renal failure. ,, The prognosis of surviving critically ill patients who developed ARF that required dialysis is poor. It is estimated that the 5-year mortality is up to 50% in ARF patients, who will often not survive long enough to develop ESRD.  A meta-analysis found that younger survivors with ARF recover renal function, in contrast to the elderly. 
Many studies found a greater prevalence of ARF in men than in women, which could be explained by the role of sex hormones in the pathogenesis of ARF. ,,
Prior studies were conducted in North America, Europe and Australia,  but little is known about the prognosis in our region. Prognostic implications include resource allocation and long-term dialysis planning.
The aim of this study was to assess renal recovery after the hospital discharge of surviving critically ill patients who developed ARF that required dialysis.
| Materials and Methods|| |
The study was conducted in a 21-bed medical and surgical intensive care unit (ICU) in an 800-bed tertiary care teaching hospital in Riyadh, Saudi Arabia. This ICU is a closed unit run by in-house, full-time, board-certified intensivists. This ICU has more than 1000 admissions per year.
All surviving patients with ARF treated with renal replacement therapy (RRT) in the ICU were eligible for inclusion in the study. Patients with pre-existing chronic renal failure treated with RRT and re-admission were excluded.
Data from surviving patients with ARF on RRT admitted to the ICU were included in the analysis from a prospectively collected ICU database. We collected the following data: Age, gender, body mass index (BMI), Glasgow coma score (GCS), lactate levels, type of admission and admission diagnoses. Acute Physiology and Chronic Health Evaluation II (APACHE II) scores,  vasopressor use and placement of mechanical ventilation (MV) were recorded. Patients were followed-up until discharge from the hospital.
The endpoint of our study was the need for dialysis at discharge among the surviving critically ill patients with ARF.
| Statistical Analysis|| |
Continuous data were expressed as means ± standard deviations (SDs) and compared using Student's t-test. Categorical data were expressed as percentages 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 an alfa less than 0.05. Statistical analysis was performed using Minitab for Windows (release 13.1).
| Results|| |
During the 3-year study period, there were 2574 patients admitted to the ICU. In this study, 308 (12%) patients developed ARF and needed RRT and only 86 (28%) patients survived to hospital discharge. Overall, 46 (53%) patients were off dialysis when they were discharged home. The mean age of the patients who were off dialysis when discharged home was 51 ± 21 years, and it was not significantly different from that of the patients who were on dialysis when discharged home (57 ± 12 years). In addition, there was no significant difference in gender in both groups (P = 0.145) [Table 1].
|Table 1: Demographics of the critically ill patients with ARF requiring RRT.|
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The most common indication for ICU admission was sepsis in both groups. The common indications for admission to the ICU are summarized in [Table 2].
|Table 2. Univariate analysis of factors associated with required hemodialysis upon hospital discharge.|
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There were 40 (47%) patients who were discharged home while dependent on dialysis. There were no significant differences between the groups regarding severity of illness, use of mechanical ventilation, history of hypertension, creatinine levels, urine output or use of inotropes. The univariate analysis showed that history of diabetes was a predictor of dialysis dependence in the patients surviving to hospital discharge [Table 3].
The multivariate analysis failed to indicate any of these variables as an independent risk factor for dialysis dependence upon the hospital discharge of critically ill patients who developed ARF.
| Discussion|| |
This study showed that only 28% of the critically ill patients who developed ARF that required dialysis survived to discharge, and 53% of the surviving critically ill patients who developed ARF that required dialysis were off dialysis upon hospital discharge. Age, gender, creatinine levels, albumin levels, history of diabetes, use of inotropes and APACHE scores were not independent risk factors for recovery of renal function. Many studies have addressed the long-term effect of ARF on renal function and included patients with abnormal renal function, similar to this study. ,, In accordance with the findings of this study, several studies found that approximately 65% of the critically ill patients who developed ARF that required dialysis were off dialysis upon hospital discharge. , In contrast, Schiffl et al  found that 53% of the critically ill patients who developed ARF that necessitated dialysis survived to hospital discharge and that none of the discharged patients were dependent on dialysis. This discrepancy can be explained by the difference in the underlying causes of ARF, which are mostly cardiac, following either cardiovascular surgery or cardiogenic shock, and the exclusion of critically ill patients with renal impairment. An Australian epidemiologic, prospective study found that only 15% of the surviving patients became dialysis dependent upon hospital discharge and that 80% of these patients had pre-morbid chronic renal impairment. The critical care physicians and nurses managed severe ARF with limited consultative nephrologist input.  Our finding, like the other data, supports the observation that critically ill patients with acute on chronic renal failure often fail to regain adequate renal function. The prevalence of renal impairment in critically ill patients has been estimated to be up to 35% based on the ICU populations.  The increased incidence and poor outcome of ARF is most likely because admitted critically ill patients are older and sicker. Illness severity scores may provide an inaccurate assessment of the predicted mortality in the specific population, but are useful for general comparisons and have been widely used.  Septic shock was the most common contributing factor in the critically ill patients requiring RRT, which is comparable to the finding of a multinational, multicenter study.  A population-based cohort study of patients admitted to Ontario hospitals over a 10-year period found that survivors of hospitalization for complicated ARF requiring dialysis were three-times more likely to require chronic dialysis compared with patients without ARF. 
The findings of this study are consistent with the results of many other studies that showed that age, gender, ventilation, clinical severity of ARF and use of vasopressors were not risk factors for irreversible renal failure. , Uehlinger et al  revealed that pre-existing chronic renal failure was the only independent predictor of renal recovery.
The long-term fate of patients surviving ATN that requires RRT is largely unknown.  The survivors of ARF who require dialysis are more likely to progress to ESRD. , Critically ill patients who developed ARF and survived to hospital discharge could benefit from a close follow-up with nephrologists to address the prognosis and complications of CKD.  Over one-third of the ARF patients who are dialysis dependent see nephrologists within 30 days of discharge. 
Indeed, for many patients, measurements of kidney function during post-discharge follow-up could not be obtained. From the available data, it was not possible to identify the clinical parameters independently associated with the risk of developing ESRD.
The current study has several limitations. First, this is an observational study, conducted at a single center and the database did not include post-discharge, long-term follow-up data or an assessment of potentially significant variables, such as the timing of the beginning of RRT, the number of organs failing and exposure to nephrotoxic drugs. However, there are several strengths in this study. A full-time, dedicated data collector gathered and entered the data prospectively and the ICU is a closed unit operated by board-certified critical care specialists, making the management homogenous.
In conclusion, this study suggests that the mortality of patients who developed ARF that required dialysis is high. It is not uncommon for surviving patients with ARF that required dialysis to become dialysis dependent upon hospital discharge, which represents an important cause of chronic kidney disease.
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Mohammed A Alsultan
Emergency Medicine Department and Critical Care Medicine, King Abdulaziz Medical City, Associate Professor, College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Riyadh
[Table 1], [Table 2], [Table 3]