|Year : 2015 | Volume
| Issue : 4 | Page : 725-732
|Clinical outcomes of acute kidney injury patients treated in a single-center, sub-urban satellite hospital
Fariz Safhan Mohd Nor1, Che Rosle Draman2, Mohd Ramli Seman1, Norasmiza Abd Manaf1, Azril Shahreez Abd Ghani1, Khairul Anuar Hassan1
1 Department of Nephrology, Hospital Tengku Ampuan Afzan, Kuantan, Pahang Darul Makmur, Malaysia
2 Department of Internal Medicine, Kulliyyah of Medicine, International Islamic University Malaysia, Pahang, Malaysia
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|Date of Web Publication||8-Jul-2015|
| Abstract|| |
Acute kidney injury (AKI) is a common diagnosis among critically ill patients. Although the etiology of AKI will determine the appropriate initial management, the definitive management of established AKI is still debatable. This is a retrospective, observational, single-center analysis of a cohort of patients referred to the nephrology unit for AKI from 1st August 2010 to 31st January 2011. Those patients with indications for dialysis were treated with continuous renal replacement therapy, intermittent hemodialysis or stiff-catheter peritoneal dialysis as determined by their hemodynamic status and the technical availability of the method. The 30-day mortality rate, renal outcomes and independent prognostic factors were analyzed statistically. Seventy-five patients were reviewed. The mean age was 52.9 ± 14.5 years. Two-thirds were males and 75% were Malays. 53.3% were referred from intensive wards. Pre-renal AKI and intra-renal AKI were diagnosed in 21.3% and 73.3% patients, respectively. Sepsis was the most common cause (n = 59). The pathogens were successfully cultured in 42.3% of the cases. The median urea and creatinine were 30.4 [interquartile range (IQR) 20.3] mmol/L and 474 (IQR 398.0) μmol/L, respectively. Seventy-six percent had metabolic acidosis. Oliguria was only noted in 38.7% of the patients. Sixty percent (n = 45) of the referrals were treated with conventional, intermittent hemodialysis and 22.7% (n = 17) with continuous veno-venous hemofiltration. The 30-day mortality rate was 28%, and was higher in intensive wards (37.5% versus 17.1%). Thirty-one percent (n = 20) had complete recovery, 17 (26.6%) had partial recovery without dialysis and seven (10.9%) became dialysis dependent. The 30-day mortality rate was 28%. Referral from intensive wards was the only significant poor prognostic factor in our patients and not the dialysis modalities.
|How to cite this article:|
Mohd Nor FS, Draman CR, Seman M, Abd Manaf N, Abd Ghani AS, Hassan KA. Clinical outcomes of acute kidney injury patients treated in a single-center, sub-urban satellite hospital. Saudi J Kidney Dis Transpl 2015;26:725-32
|How to cite this URL:|
Mohd Nor FS, Draman CR, Seman M, Abd Manaf N, Abd Ghani AS, Hassan KA. Clinical outcomes of acute kidney injury patients treated in a single-center, sub-urban satellite hospital. Saudi J Kidney Dis Transpl [serial online] 2015 [cited 2022 Jan 26];26:725-32. Available from: https://www.sjkdt.org/text.asp?2015/26/4/725/160273
| Introduction|| |
Acute kidney injury (AKI) is commonly diagnosed in daily clinical practice. The incidence and outcome however vary between centers due to the differences in case definition and the populations studied. ,, The Acute Kidney Injury Network (AKIN) and the Acute Dialysis Quality Initiative (ADQI) groups had recently published the diagnostic criteria for AKI and, since then, the disease burden and clinical outcomes were clearly defined. , Although only 5-10% of hospital admissions were due to AKI, the AKI-related mortality is significantly high at 60-70%. , The rate remains high despite better understanding of the disease mechanism and improved dialysis technology. Delay in the diagnosis and ineffective treatment of the established cases were the reasons for the poor clinical outcomes. ,,, Although continuous renal replacement therapy (CRRT) is best tolerated by the AKI patients, this mode of treatment was however limited, especially in the developing countries. Furthermore, CRRT did not necessarily improve the overall outcomes of AKI patients compared with conventional hemodialysis.
| Objectives|| |
The aim of this study is to determine the mortality and renal function recovery rate of AKI patients treated with different modalities over a period of 30 days and to identify the clinical prognostic factors for AKI recovery in our patients.
| Patients and Methods|| |
This is a retrospective, observational, single-center analysis of a cohort of patients with AKI referred to the nephrology unit from 1 st August 2010 to 31 st January 2011. These patients were diagnosed with AKI and consecutively referred to the nephrology unit from both general medical and surgical wards and intensive wards, which included the high-dependency ward and the coronary care and intensive care units. Patients aged 18-80 years old were eligible for the review and AKI was defined according to the serum creatinine component of the AKIN diagnostic criteria. The indications for dialysis were clinically determined, which included fluid overload, metabolic acidosis and/or hyperkalemia resistant to optimal medical treatments, encephalopathy, pericarditis or worsening uremia. Depending on their hemodynamic status, these patients were either treated with CRRT, intermittent hemodialysis or peritoneal dialysis. CRRT was started on hemodynamically unstable patients. Hemodynamically stable patients were treated with intermittent hemodialysis or stiff-catheter peritoneal dialysis depending on the availability of a well-functioning vascular access and the hemodialysis facilities. Other aspects of clinical management, including hydration and choice of antibiotic, were determined by the primary physician.
Continuous veno-venous hemofiltration (CVVH) with 20 mL/kg/h of bicarbonate-based replacement volume was prescribed. The patients underwent the procedure for at least 24 h through a temporary catheter frequently placed in the femoral veins and depending on their coagulation profile; the treatments were either prescribed with or without heparin. Ultrafiltration volume was clinically estimated. Hematological and bio-chemical parameters of each patient on dialysis were regularly monitored, which included full blood count, urea, creatinine, potassium, arterial blood gases, coagulation profile and other electrolytes. Conventional, three-times a week, hemodialysis treatments were delivered through a femoral catheter with a blood pump speed of at least 180-300 mL/min as tolerated by the patients. The bicarbonate-based dialysate solution was used at 500 mL/min and the dialysis was continued for four hours per session. A standard, low-volume peritoneal dialysis through a stiff abdominal catheter was prescribed whenever clinically, hemodynamically and anatomically appropriate. Forty to sixty liters of pre-prepared lactate-based dialysis solution were continuously delivered for at least 72 h, with an hour dwell in-between the cycles. Different concentrations were utilized to achieve the expected ultrafiltration volume throughout the treatment period. The demographic, clinical and biochemical parameters of each patient were then recorded and analyzed. The 30-day mortality rate was estimated and renal recovery was identified. Complete renal recovery was defined as normalization of serum creatinine to the baseline and partial recovery as at least 50% improvement with or without dialysis dependency. The length of hospital stay from the day of referral and discharge from the hospital were determined and analyzed in relation to the dialysis modalities in all the survivals. Finally, the significant prognostic factors, other than dialysis modality, were also analyzed.
| Statistical analysis|| |
All the data were recorded and analyzed using SPSS version 17.0. The parametric and non-parametric data were presented as mean ± standard deviation and median (inter-quartile range), respectively. Student t test and Mann Whitney U test were applied for continuous variables accordingly and chi square test was applied for categorical variables. Bi-variate analysis was then applied to determine the significant prognostic factors for patient and renal recovery followed by Kaplan-Meir analysis to determine the survival rate of our patients. The significant findings were defined as P-value <0.05.
| Results|| |
The records of a total of 75 AKI patients were reviewed. The mean age was 52.9 ± 14.5 years (range, 16-79 years). Two-thirds were males and 75% were Malays followed by 16% Chinese and 9% Indians. Co-morbid illnesses such as diabetes, hypertension and coronary heart disease were commonly diagnosed. More than half of them were hypertensive and 48% were diabetic. However, coronary heart disease was only confirmed in 12%. Almost equal numbers of patients were referred from general and intensive wards (46.7% versus 53.3%). 73.3% were due to intra-renal AKI and 21.3% were due to pre-renal AKI. Postrenal AKI were only noted in 5.3% of them. Specifically, sepsis was the most common diagnosis associated with AKI (n = 59, 78.7%) and, in 42.3% of the patients, the pathogens were successfully cultured and identified, which included Leptospira sp (12 cases), Acinetobacter sp (two cases), methicillin-resistant Staphylococcus aureus (one case) and other organisms (18 cases).
During the referral, the urea and creatinine were 30.4 [interquartile range (IQR) 20.3] mmol/L and 474 (IQR 398.0) mmol/L, respectively. The hemoglobin was 10.3 (IQR 3.5) g/dL, while the white-cell and platelet count were 14,000 (IQR 10700) and 208,000 (IQR 148,000) per mL, respectively. The serum albumin was 26 (IQR 7.9) g/L and 76% of them had metabolic acidosis. Majority of our patients had non-oliguric AKI during the referral, and oliguria was only noted in 38.7% of them. Throughout the study, 21 mortalities were recorded with a 30-day mortality rate of 28% and the median ward stay was 11.5 (IQR 7) days [Table 1]. [Figure 1] shows the AKI patients during the referral. Most of the referrals were AKI-3 (n = 65, 86.7%) patients. Two (2.7%) were AKI-2 and eight (10.7%) were AKI-1 patients.
|Figure 1: Stage of AKI during the referral according to the Acute Kidney Injury Network classification.|
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Of all the referrals, 85.3% (n = 64) were started on dialysis whereas 14.7% (n = 11) were not. Conventional, intermittent hemo-dialysis was the most common modality prescribed (n = 45, 60%) and CVVH was prescribed to 17 patients (22.7%). Only two patients (2.7%) were started on stiff-catheter peritoneal dialysis [Figure 2]. Most of the CVVH treatments were prescribed through a temporary catheter and 20 mL/kg/h of Hemosol solution® was frequently utilized for at least 24 h. A standard volume peritoneal dialysis, through a stiffperitoneal catheter, was prescribed to a very selective patient. The treatment was continued for 72 h with 40-60 L of dialysate volume.
|Figure 2: Various forms of renal replacement therapy applied to the reviewed patients. Some had their medical management optimized without any dialysis support.|
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Those treated with dialysis, 68.8% (n = 44), had survived, with 31.3% (n = 20) of them having complete renal recovery. Seventeen (26.6%) patients had partial, dialysis-independent recovery and only seven (10.9%) patients continued with dialysis beyond the first 30 days. Although CRRT were associated with shorter hospital stay (10 versus 30 days, P = 0.04), it did not significantly improve the renal recovery or mortality rate as compared with conventional hemodialysis (χ2 = 1.1, P >0.05) treatments.
At least 53.3% were referred from intensive wards, while 46.7% were referred from the general wards [Table 2]. Eighty-five percent (n = 34) of the referrals from the intensive wards and 60% (n = 21) of the referrals from the general wards were due to the intra-renal AKI and all four post-renal AKI patients were from the general wards. Sepsis was diagnosed in 87.5% (n = 35) of the referrals from the intensive wards and 68% (n = 24) of the general wards. Severe AKI or AKI-3 were mostly referred from the intensive wards than the general wards (39 versus 26 cases, P = 0.003) and they frequently required dialysis supports, (39 versus 25 cases, P = 0.001). The AKI patients from intensive wards also had a higher mortality rate as compared with the general wards (37.5% versus 17.1%).
|Table 2: The clinical parameter and outcomes of the studied patients in both general and intensive wards.|
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As for all the mortalities, 15 were from the intensive wards and six from the general wards, with mortality rates of 37.5% and 17.1%, respectively. Other than referral from intensive wards, factors such as age, gender, comorbidities, etiology, laboratory parameters such as urea and creatinine and the dialysis modality were not found to be factors adversally affecting recovery in our AKI patients.
| Discussion|| |
In our daily practice, the AKIN diagnostic criteria were usually applied. It was generally accepted that the incidence rate for AKI episodes was comparable either by the AKIN or by the RIFLE diagnostic criteria. According to the data from Australian and New Zealand intensive care unit (ICU) admissions, the difference in the incidence rate of AKI episodes between the two criteria was <1%. In contrast to AKI-1, AKI-2 was less frequently diagnosed through the AKIN diagnostic criteria. Other than similar incidence rate, the diagnostic criteria also revealed a comparable mortality rate. 
Not only was markedly raised serum creatinine significant, a slightly raised serum creatinine above the baseline was also a predictor for poor clinical outcome. Uchino et al in their recent publication also reported that even an AKI episode <24 h had significant impacts on the mortality rate. 
The AKIN diagnostic criteria defined AKI-3 as any patients requiring dialysis treatment. Although non-renal indications for dialysis were well described, its clinical application is still limited. Ravindra suggested that AKI patients had different dialysis requirements from stable end-stage renal failure patients; hence, their dialysis approach should be also different. The author also suggested that rather than treatment of a single organ failure, dialysis in AKI should be considered as a supportive treatment modality for other organs during the period. Thus, the indications for dialysis not only determined by the status of kidney failure but also other organs function. 
During the study, 21 cases of mortality were recorded and the 30-day mortality rate was estimated at 28%. Thus, the mortality rate was comparable to that reported in general ICU settings worldwide. The mortality rate is also correlated well with the severity of AKI and, according to Hoste et al, the mortality rate for RIFLE class R, I and F was 8.8%, 11.4% and 26.3%, respectively.  Because our cohorts were mostly AKI-3 or RIFLE F, a higher mortality rate was expected. Among the developing countries, Rashid Nassem et al reported the lowest mortality rate of 13% in their cohort from Pakistan. The study however involved only a non-diabetic and non-hypertensive kidney disease population and their patients were also younger, with a mean age of 43 years; most of them were treated conservatively.  However, Kohli et al from India reported a mortality rate of 61% in which elderly patients had a significantly higher mortality risk compared with the younger patients, i.e. 60.9% versus 59.6%. The authors also concluded that the possibility of substandard management of elderly AKI in limited-resource settings was a possibility in their practice.  Although co-morbid illnesses were commonly diagnosed in our patients, they were however relatively young. Their mean age was 52 years as compared with 62 years in the Kohli et al study. They were also less critically ill, with mild hypoalbuminemia.
Apart from that, early dialysis might contribute to a better survival rate. The urea was 30.4 mcmol/L at the time of the dialysis and Liu et al in their sub-group analysis of PICARD study population had showed that early dialysis improved clinical outcome. The relative risk of death was 1.85 when the dialysis was started at a urea level higher than 27 mcmol/L. 
Sepsis was the most common diagnosis in our cohorts, and, although the outcome was expected to be worst, appropriate antibiotic selections against the identified pathogens otherwise improved the outcome. In 43% of them, the pathogens were successfully identified and antibiotics were then appropriately selected. Data from animal studies have demonstrated that appropriately selected antibacterials had significantly improved the AKI-related mortality despite worsening inflammation following the antibiotic administrations. 
Our cohorts were also mostly non-oliguric patients in whom the prognosis was expected to be better than oliguric patients. According to Ethiene Mecado et al, oliguria was not only an important diagnostic marker but also a wellrecognized predictor for higher mortality rate in AKI patients. Oliguria lasted more than 12 h or more than three episodes were associated with higher mortality rate in their patients.  In fact, oliguria was the only independent poor prognosis factor in the multi-variate analysis of a study from Pakistan above other factors such as increasing age, higher level of FeNa, urea, creatinine and potassium, association with medical illness and acidosis. 
As a standard practice, CRRT was only prescribed to our patients primarily managed or transferred to the intensive wards. Ronco and Bellamo had emphasized that there were clear physiological benefits of CRRT compared with conventional intermittent hemodialysis, especially in a hemodynamically unstable patient. However, few trials had failed to demonstrate the benefit of CRRT over IHD due to the poor technical application and, frequently, these trials had inappropriate randomization and treatment cross-over was commonly observed. 
As part of the treatment protocol, CRRT was started at 20 mL/kg/h. Although trials published before 2008 demonstrated a clear benefit of higher CRRT dose, subsequent multicenter clinical trials were unable to reproduce the earlier results.  Theoretically, high-volume hemofiltration (HVHF) with 40-45 mL/kg/h was appropriate in septic patients; however, it was rarely prescribed in our hospital due to the limited resources and complexity of the treatment procedure.
In our patients, the only significant prognostic factor for higher mortality was referral from the intensive wards. The age, gender, co-morbidities, causes of AKI, biochemical or the clinical parameter during the dialysis and dialysis modality were not found to be factors adversely affecting recovery in our AKI patients. The Collaborative group for treatment of acute renal failure in ICU had also agreed that dialysis modality was not a determinant factor for survival in AKI patients. In their report, the mortality was comparable between the treatment groups, although recruitment bias in favor of the intermittent dialysis group was noted. This trial also did not adequately control the treatment variables and confounders, which could determine the final outcomes such as nutritional, hemodynamic supports and dialysis dose.  Hence, it was likely that overall severity and the disease burden were the most important prognostic factors and, as expected, multi-organ failure and septic shock were commonly encountered in the intensive wards.
The study had few limitations, which include its retrospective nature in which recruitment bias and unidentified confounders are commonly encountered. Clinical causes of AKI were also not specifically identified and most of the cases had multiple insults. As patients were referred from general wards and intensive care settings, their severity was not objectively scored and some investigations commonly monitored in the ICU were not routinely monitored in the general wards, such as serum lactate and arterial blood gases. The mortality rate for patients treated with peritoneal dialysis and conservative measures could not be analyzed as the numbers were too small.
In conclusion, our review revealed that the 30day mortality rate was comparable to the earlier publications. The dialysis modality, especially CRRT, had not significantly improved the overall clinical outcome. The only significant prognostic factor for poor clinical outcome was referrals from intensive wards. The age, gender, co-morbidities, causes of AKI, biochemical or clinical parameter during the dialysis and the dialysis modality were not prognostic markers.
Conflict of interest: None declared.
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Che Rosle Draman
Department of Internal Medicine, Kulliyyah of Medicine, International Islamic University Malaysia, Pahang
[Figure 1], [Figure 2]
[Table 1], [Table 2]
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