|Year : 2018 | Volume
| Issue : 2 | Page : 310-317
|Scoring systems and outcome of chronic kidney disease patients admitted in intensive care units
Jitendra Goswami1, Manish R Balwani2, Vivek Kute3, Manoj Gumber4, Mohan Patel5, Umesh Godhani6
1 Department of Nephrology, Manipal Hospital, Jaipur, Rajasthan, India
2 Department of Nephrology, Jawaharlal Nehru Medical College, Wardha, Maharashtra, India
3 Department of Nephrology, Institute of Kidney Diseases and Research Center and Institute of Transplantation Sciences, B. J. Medical College, Ahmedabad, India
4 Department of Nephrology, Apollo Hospital, Ahmedabad, India
5 Department of Nephrology, Apollo Hospital, Nashik, India
6 Department of Nephrology, Kidney Cure Clinic, Ahmedabad, Gujarat, India
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|Date of Web Publication||10-Apr-2018|
| Abstract|| |
The outcome of chronic kidney disease (CKD) patients admitted to the Intensive Care Unit (ICU) is difficult to predict. This study assessed the outcome of CKD patients admitted to the ICU and evaluated prediction of 30-day mortality using the Acute Physiology and Chronic Health Evaluation (APACHE II), Simplified Acute Physiology Score (SAPS II), and Sequential Organ Failure Assessment (SOFA) score. One hundred consecutive CKD patients admitted to the ICU at a tertiary care hospital, Ahmedabad between 2011 and 2013 were included prospectively. Data on demographics, indication for admission, cause of CKD, use of vasoactive drugs and mechanical ventilation (MV), mode of renal replacement therapy (RRT), and 30-day mortality were recorded. The APACHE II, SAPS II, and SOFA scores were calculated based on the admission characteristics. The mean APACHE II, SAPS II, and SOFA scores were 28.22 ± 7.53, 43.04 ± 16.40, and 10.39 ± 5.20, respectively, and area under receiver operating characteristics curve in predicting 30-day mortality were 0.961, 0.994, and 0.950, respectively. The scores were significantly higher in 30-day nonsurvivors as compared to survivors (P = 0.001). During the ICU stay, MV and vasoactive drugs were required in 57% and 67% of the patients, respectively, and the requirement was significantly greater in nonsurvivors as compared to survivors (P = 0.001). About 85% of patients were on intermittent hemodialysis and 15% of patients were on continuous venovenous hemodiafiltration. Sepsis was the main reason for hospital admission, and the mean length of stay in the ICU was 7.74 ± 5.34 days. The study indicates that all three scores (APACHE II, SAPS II, and SOFA) perform equally well and have equal diagnostic utility in predicting 30-day mortality.
|How to cite this article:|
Goswami J, Balwani MR, Kute V, Gumber M, Patel M, Godhani U. Scoring systems and outcome of chronic kidney disease patients admitted in intensive care units. Saudi J Kidney Dis Transpl 2018;29:310-7
|How to cite this URL:|
Goswami J, Balwani MR, Kute V, Gumber M, Patel M, Godhani U. Scoring systems and outcome of chronic kidney disease patients admitted in intensive care units. Saudi J Kidney Dis Transpl [serial online] 2018 [cited 2020 May 28];29:310-7. Available from: http://www.sjkdt.org/text.asp?2018/29/2/310/229268
| Introduction|| |
Chronic kidney disease (CKD) is defined as a reduced glomerular filtration rate, increased urinary albumin excretion, or both, and is an increasing public health issue with an estimated prevalence of 8%–16% worldwide. There is an increase in CKD patients worldwide and consequently, end-stage renal disease (ESRD) during the last decade due to an increased prevalence of hypertension, type-2 diabetes mellitus, and an aging population. These patients are more likely to be admitted to the Intensive Care Unit (ICU) than patients with normal renal function.
It is estimated that patients with ESRD comprise 10% of the renal replacement therapy (RRT) population in the ICU. ICU provides care to these high-risk patients and demand commitment, attention, and qualified skills from clinicians. However, an excessive ICU workload may interfere with the quality of care provided. Indicators of the severity of patients’ conditions are becoming increasingly necessary to ensure quick and accurate assessments of critically ill patients.
Various scoring systems are designed as predictive modalities which are used in the ICU to predict outcome, characterize disease severity and degree of organ dysfunction, ultimately, supporting in clinical decision-making processes.
The scores that assess disease severity on admission based on the degree of derangement of routinely measured physiological variables [e.g., Acute Physiology and Chronic Health Evaluation (APACHE), Simplified Acute Physiology Score (SAPS)] and scores that assess the presence and severity of organ dysfunction [e.g., Sequential Organ Failure Assessment (SOFA)] are commonly used tools to predict outcome in ICUs. These illness severity scores have not been specifically evaluated to predict outcome in CKD patients. It is seen that the ESRD patients admitted to ICUs had considerably higher mortality and morbidity.,, However, some recent studies have contradicted this finding. Therefore, the validity of these scoring systems needs to be assessed and confirmed in ESRD patients.
This study is planned to determine the outcome of CKD patients and to evaluate the performance of scoring systems (APACHE II, SAPS II, and SOFA scores) in predicting 30- day mortality in these patients admitted to ICU.
| Materials and Methods|| |
The study was a prospective observational study, conducted in a 14 bedded ICU at the Department of Nephrology, Institute of Kidney Diseases and Research Center, B. J. Medical College and Civil Hospital, Ahmedabad from September 2011 to August 2013, in compliance with all applicable regulations and good clinical practice guidelines. The study was approved by the Institutional Ethics Committee. Written informed consents were obtained from the patients before enrollment. A total of 100 patients were enrolled in the study.
Patients of either gender with age range of 10–70 years, with confirmed diagnosis of CKD as per kidney disease improving global outcomes definition and criteria with stage-4 and stage-5 CKD and admitted to the ICU were included in the study. Patients who were shifted and transferred from different ICU, those with acute kidney injury, rapidly progressive glomerulonephritis, nephritic syndrome, nephrotic syndrome, or with no known kidney disease, were excluded from the study.
On the first day of ICU admission, baseline parameters including medical history and physical examination details including demographic data, indication for ICU admission, and cause of CKD or ESRD were recorded. The severity of illness was assessed by the APACHE II and SAPS II scoring system within 24 h of admission to the ICU. Organ dysfunction was assessed using the SOFA score. Use of vasoactive drugs, mechanical ventilation (MV), and RRT was recorded. In case of multiple admissions to ICU during single hospitalization, only the first ICU admission was considered.
The patients were managed as per standard ICU protocols with respect to use of intravenous fluids, use of antimicrobials, use of vasoactive agents (if mean arterial pressure was <55 mm Hg, despite fluid resuscitation), use of RRT (progressively increasing serum creatinine, with worsening of acidemia, with or without hyperkalemia), and MV (to protect airway or in case respiratory failure). Similarly, the patterns of weaning from vasoactive drugs and MV were according to standard ICU protocols. The decision for RRT between ischemic heart disease (IHD)/SLED and CRRT was dependent on economic affordability and patients who did not tolerate SLED. All patients were followed up for up to 30 days after discharge from the ICU or less if death occurred earlier.
Sepsis, severe sepsis, and septic shock were defined according to the American College of Chest Physicians/Society of Critical Care Medicine consensus conference. Multiple organ failure was defined as the development of two or more organ failures apart from the primary renal failure. Nonsurvivors or 30-day mortality were defined as those who died either in the ICU or within 30 days after discharge from the ICU.
APACHE II – It is the severity of disease classification system. It is scored using the values of 12 routine physiological measurements, age, and previous health status. Based on these measurements, scores are computed from 0 to 71. Higher score denotes a more severe disease and higher risk of death.
SAPS II: It is used to score the ICU patients severity. It is calculated by using 17 variables; 12 physiologic variables, age, type of admission and three disease-related variables. The scores vary from 0 to 163 points. 0–116 points for physiological variables, 0–17 points for age, and 0–30 points for the previous diagnosis. Higher scores denote more severe disease and higher risk of death.
SOFA – It is used to assess the presence and severity of organ dysfunction; it contains the data on six organ failures (respiratory, cardiovascular, renal, hepatic, central nervous, and coagulation) and scored on a scale of 0 (normal function) to 4 (most abnormal), giving a possible score of 0–24; here also, higher scores denote more severe disease.
| Statistical Analysis|| |
The data were analyzed using the Statistical Package for Social Sciences (SPSS) version 17.0 for Windows (SPSS Inc., Chicago, IL, USA). Quantitative data were presented as mean and standard deviation, and qualitative data were presented as number and percentages. Quantitative data were compared using Unpaired t-test and qualitative data were compared using Chi-square test or Fisher's exact test. Logistic regression analysis was performed to identify the association of various variables with 30-day mortality. The area under the receiver operator characteristics (AUROC) curves of APACHE II, SAPS II, and SOFA scores were compared to determine the accuracy of the three scales in predicting 30-day mortality. P ≤0.05 was considered statistically significant.
| Results|| |
The mean age of the patients was 39.04 ± 14.30 years with males contributing to 79% of the study population. Diabetic nephropathy (30%) was the leading cause of CKD followed by other causes. Sepsis was the most common reason for hospital admission (40%) followed by IHD and cerebrovascular accident (16% each). Ninety-four percent of patients were of stage-5 and 5D of CKD, and 6% were of stage- 4 CKD. Eighty-five percent of them were on intermittent hemodialysis, and 15% were on continuous venovenous hemodiafiltration. MV was needed in 57% of patients, and vasoactive drugs were needed in 67%. The mean length of stay in the ICU was 7.74 ± 5.34 days. The ICU mortality was 34%, and 30-day mortality was 39% [Table 1].
The mean APACHE II score, SAPS II score, and SOFA scores were 28.22 ± 7.53, 43.04 ± 16.40, and 10.39 ± 5.20, respectively. Comparison of these scores in 30-day survivors and nonsurvivors showed that these scores were significantly higher in nonsurvivors as compared to survivors (P = 0.001). It was seen that the mortality was significantly higher in patients receiving continuous venovenous hemodiafiltration as compared to patients receiving intermittent hemodialysis. Furthermore, the requirement of MV and vasoactive drugs were significantly greater in nonsurvivors as compared to survivors (P = 0.001) [Table 2].
|Table 2: Comparison of study parameters among 30-day survivors and nonsurvivors.|
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Logistic regression analysis was performed with 30-day mortality as the dependent variable and APACHE II, SAPS II and SOFA score as independent variables. The result showed that one unit increase in all these three scores systems significantly increases the odds of 30- day mortality. Along with these scores, RRT type, need for MV, and vasoactive drugs were also found to be significant predictors of mortality.
The sensitivity and specificity of an APACHE II score greater than or equal to 29 in predicting 30-day mortality was 92% and 100%, respectively. The sensitivity and specificity of SAPS II score ≥49.5 in predicting 30-day mortality was 95% and 100%, respectively and the sensitivity and specificity of a SOFA score ≥10.5 in predicting 30-day mortality was 85% and 100%, respectively. APACHE II and SAPS II scores performed equally well in identifying survivors from nonsurvivors.
The AUROC for APACHE II was 0.961, for SAPS II, it was 0.994, and for SOFA, it was 0.950. This shows that all three scores perform equally well and have equal diagnostic utility in predicting 30-day mortality [Figure 1].
|Figure 1: Comparison between the area under the receiver operating characteristic curves of APACHE II score, SAPS II and SOFA score in discriminating 30-day survivors from nonsurvivors.|
APACHE II: Acute Physiology and Chronic Health Evaluation, SAPS II: Simplified Acute Physiology Score, SOFA: Sequential Organ Failure Assessment.
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| Discussion|| |
This study was planned to assess the outcome of ESRD patients admitted to the ICU and to evaluate the efficacy of APACHE II, SAPS II, and SOFA scores to predict their outcome in 100 ICU-admitted CKD patients. The characteristics of the CKD patients with respect to higher mean age and higher male to female ratio were comparable to findings of Indian CKD registry and to previously published studies. In our study, diabetic nephropathy (30%) was the most common cause of ESRD. The finding is consistent with the worldwide trend of steady rise in diabetes and its contribution to ESRD. The Indian CKD registry and other Indian studies had also confirmed diabetic nephropathy as the most common cause of CKD in the Indian population.,,, Chronic glomerulonephritis (20%), presumably infection related, and CKD of undetermined etiology (15%) are other frequently reported causes of CKD. This is also in line with published literature.,,,, Sepsis (40%) and cardiovascular diseases (16%) constitute the most common reasons for admission to the ICU among ESRD patients., Repeated vascular access procedures for the purpose of dialysis, uremia-related immune deficiency, defective phagocytic function, older age, and comorbidities increase the risk of sepsis in CKD patients. In addition, these patients are at higher risk of adverse cardiac events including myocardial ischemia, pulmonary edema, cardiogenic shock, arrhythmias, and sudden cardiac death.,,,,
The reported ICU mortality (34%) in our study was higher when compared to other hospitalbased studies.,,,, This could be due to the fact that we had patients with comparatively advanced disease, reflected by mean SOFA score of 10.39 on day 1 in our study. The increased need for organ support, as evidenced by number of patients requiring invasive MV (57%) and inotropic support (67%) confirmed this finding. The 30-day mortality in our study was higher (39%) when compared to other published studies.,, This indicates a decreased physiological reserve and increase susceptibility to relapse shortly after ICU discharge. We suggest that mortality can be reduced by better post-ICU care and monitoring of these patients.
In line with other studies, we used APACHE II, SAPS II, and SOFA scores to assess the severity of illness and organ dysfunction to predict and validate the outcome of CKD patients admitted to the ICU.,, These illness-scoring systems generate the score that reflects the severity of condition resulting in ICU admission. These scores allow identification of the factors that influence outcome, which differs between patients and can be standardized to allow comparison between patients. The SOFA score is an easily applied tool with excellent prognostic abilities and can be used to draw inferences regarding patient response to therapies and interventions. In our study, the mean APACHE II and SAPS II scores were 28.22 and 43.04, respectively. When compared with 30-day survivors and nonsurvivors (30-day mortality), these scores were significantly higher in nonsurvivors when compared to survivors (P = 0.001). It is observed that ESRD patients requiring ICU care were critically unwell and had multiple co-morbidities that result in higher severity of illness score on admission. There is also the possibility of delayed referral due to a higher threshold for seeking ICU intervention with the understanding that CKD patients need to be more critically unwell before being accepted in the ICU. Thirty-day nonsurvivors required more frequent MV and vasopressors, suggesting greater severity of disease. These findings were further corroborated by the fact that most of the nonsurvivors were patients who required continuous RRT as compared to those who required IHD. Both the severity scores (APACHE II and SAPS II) in our study demonstrated good discriminatory power for predicting hospital mortality with AUC >0.95 (APACHE: 0.96 and SAPS: 0.99). The organ failure scores (SOFA) also showed good discriminatory power (0.95) for predicting hospital mortality. Various studies have shown good discriminating power for APACHE II, SAPS II, and SOFA scores for predicting hospital mortality in ESRD patients admitted in the ICU.,
In one study, the authors evaluated the APACHE II score and reported AUC of 0.87. Other authors reported AUC ranging from 0.80 to 0.90 using a smaller cohort of long-term dialysis patients., In some studies, APACHE II score overpredicted the mortality in dialysis patients.,,,, In case of SAPS II, actual hospital mortality was lower than that predicted in one of the two studies using SAPS II scores. Data on the validity of the SOFA score in patients with ESRD are conflicting. One study reported an AUC of 0.92, whereas one other study  reported that the SOFA score was less accurate with an AUC of 0.66. Our study validated the use of APACHE II, SAPS II, and SOFA as severity of illness scoring systems for ESRD patients admitted to the ICU.
All three scoring systems performed equally in predicting the mortality in our series of patients and to identify patients requiring more aggressive therapy. Thus, when used together, these scoring systems could provide more accurate indication of disease severity and prognosis, which could help in better resource allocation and performance assessment.
| Limitations|| |
This present study has some potential limitations. It was a single center study conducted on a small number of patients. This is still justifiable as many studies used small sample sizes in ICU patients with ESRD.,,,, In addition, admission bias cannot be ruled out in our study. Finally, long-term outcome and quality of life were not assessed. Therefore, prospective long-term multi-center studies with large sample sizes should be performed to validate these findings.
| Conclusion|| |
The outcome of the ESRD patients admitted to ICU is poor as seen by higher severity score. All three scoring systems showed excellent discriminating power in predicting 30-day mortality in these patients. However, large-scale studies are required to validate these findings.
Conflict of interest: None declared.
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Dr. Manish R Balwani
Department of Nephrology, Jawaharlal Nehru Medical College, Sawangi, Wardha - 442 001, Maharashtra
[Table 1], [Table 2]
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