End-stage Kidney Disease Criteria Research Articles

The meaning of the blood urea nitrogen/creatinine ratio in acute kidney injury.

Background.A blood urea nitrogen (BUN)/creatinine ratio (BCR) >20 (0.081 in international unit) is used to distinguish pre-renal azotemia (PRA) and acute tubular necrosis (ATN). However, there is little evidence that BCR can distinguish between these two conditions and/or is clinically useful.Methods.We conducted a retrospective study using a large hospital database. Patients were divided into three groups: ‘low BCR’ (if BCR when acute kidney injury (AKI) developed was ≤20), ‘high BCR’ (if BCR when AKI developed was >20) and ‘no AKI’ if patients did not satisfy any of the Risk, Injury, Failure, Loss and End-stage kidney disease criteria for AKI during hospitalization.Results.Among 20 126 study patients, 3641 (18.1%) had AKI. Among these patients, 1704 (46.8%) had a BCR <20 at AKI diagnosis (‘low BCR’) and 1937 (53.2%) had a BCR >20 (‘high BCR’). The average BCR for the two groups was 15.8 versus 26.1 (P < 0.001). Hospital mortality was significantly less in the ‘low-BCR’ group (18.4 versus 29.9%, P < 0.001). Multivariable logistic regression analysis for hospital mortality (‘no AKI’ as a reference) showed that the odds ratio of ‘high BCR’ (5.73) was higher than that of ‘low BCR’ (3.32).Conclusions.Approximately half of the patients with AKI have a BCR >20, the traditional threshold of diagnosing PRA. Unlike PRA patients who have a lower mortality than ATN patients, high BCR patients had higher hospital mortality compared with low BCR patients, which was confirmed with multivariable analysis. These findings do not support BCR as a marker of PRA.

Acute kidney injury classification: AKIN and RIFLE criteria in critical patients

Acute kidney injury (AKI) is a common and serious complication in critically ill patients. The mortality rate remains high despite improved renal replacement techniques. A possible cause of the high mortality rate is that intensive care unit patients tend to be older and more debilitated than before. Pathophysiological factors associated with AKI are also implicated in the failure of other organs, indicating that AKI is often part of a multiple organ failure syndrome. Until recently, there was a lack of consensus as to the best definition, characterization, and evaluation of acute renal failure. This lack of a standard definition has been a major impediment to progress in clinical and basic research. The introduction of the risk, injury, failure, loss, and end-stage kidney disease criteria and the modified version proposed by the Acute Kidney Injury Network have increased the conceptual understanding of AKI syndrome, and these criteria have been successfully tested in clinical studies. This article reviews current findings concerning the application of these criteria for assessing epidemiology and predicting outcome in specific homogeneous critically ill patient groups.

Acute kidney injury as defined by the RIFLE criteria is a risk factor for kidney transplant graft failure

Acute kidney injury (AKI) is not recognized as a major complication at the maintenance phase after kidney transplantation (KTx). Moreover, it is not clear whether the onset of AKI leads to graft failure. We examined the incidence of AKI that developed three months or later after KTx at our institute. We examined whether the incidence of AKI defined by the Risk of renal dysfunction, Injury to the kidney, Failure of kidney function, Loss of kidney function and End-stage kidney disease criteria associates with graft failure by matched-pair Cox regression analysis. A total of 289 patients were available for the final analysis. The overall incidence of AKI was 20.4%, and the common etiology of AKI was bacterial infectious diseases. The group that developed AKI had significantly lower graft survival than non-AKI group independently of acute rejection. AKI Risk represented a high risk for graft failure and AKI Injury/Failure represented a higher risk for graft failure. The analysis by the AKIN classification yielded the similar results. These results indicate that AKI is a relatively common complication of KTx and represents the major risk for graft failure. We should make every effort in the prevention and early detection to avoid the occurrence of AKI and the subsequent graft failure after KTx.

Greater increase in urinary hepcidin predicts protection from acute kidney injury after cardiopulmonary bypass

Acute kidney injury (AKI) is a common and serious complication of cardiopulmonary bypass (CPB) surgery. Hepcidin, a peptide hormone that regulates iron homeostasis, is a potential biomarker of AKI following CPB. We investigated the association between post-operative changes in serum and urinary hepcidin and AKI in 93 patients undergoing CPB. Twenty-five patients developed AKI based on the Risk, Injury, Failure, Loss, End-stage kidney disease (RIFLE) criteria in the first 5 days. Serum hepcidin, urine hepcidin concentration, the urinary hepcidin:creatinine ratio and fractional excretion of hepcidin in urine rose significantly after surgery. However, urine hepcidin concentration and urinary hepcidin:creatinine ratio were significantly lower at 24 h in patients with RIFLE-Risk, Injury or Failure compared to those without AKI (P = 0.0009 and P < 0.0001, respectively). Receiver operator characteristic analysis showed that lower 24-h urine hepcidin concentration and urinary hepcidin:creatinine ratio were sensitive and specific predictors of AKI. The urinary hepcidin:creatinine ratio had an area under the curve for the diagnosis of RIFLE ≥ risk at 24 h of 0.77 and of 0.84 for RIFLE ≥ injury. Urinary hepcidin had similar predictive accuracy. Such predictive ability remained when patients with early creatinine increases were excluded. Urinary hepcidin and hepcidin:creatinine ratio are biomarkers of AKI after CPB, with an inverse association between its increase at 24 h and risk of AKI in the first five post-operative days. Measuring hepcidin in the urine on the first day following surgery may deliver earlier diagnosis and interventions.

Implications of acute kidney injury after heart transplantation: what a surgeon should know

Data regarding risks and consequences of acute kidney injury (AKI) after cardiac transplantation are dismissingly few and unclear. This study defined the incidence, risk factors and prognostic implication of AKI in a single-center cohort operated on between January 1999 and December 2008. Data from 307 consecutive recipients (mean age: 47.42 ± 13.58, 20.5% female, 18.9% diabetics, 19.5% with previous cardiac operations, 26.4% hospitalized, 78.4 ± 33.7 ml min(-1) preoperative glomerular filtration rate (eGFR)) were analyzed using multivariable logistic regression modeling. AKI was defined according to RIFLE (Risk, Injury, and Failure; and Loss, and End-stage kidney disease) criteria. RIFLE scores of I or F were detected in 14%, and continuous venovenous hemofiltration was needed in 6.1%. Risk factors for AKI were: previous cardiac operation (odds ratio (OR) 2.35; 95% confidence interval (CI), 1.11-4.9), blood transfusion (OR 1.08; 95% CI, 1.011-1.16), troponin I release >10 (OR 1.031; 95% CI, 1.001-1.064), length of ischemic time (OR 1.008; 95% CI, 1.011-1.16). Overall hospital mortality averaged 7.8% and overall 1-year mortality was 10.4%; both mortality rates increased with each RIFLE stratification (Normal 3.4%, RIFLE R = 7.1%; RIFLE I = 25.7%; and RIFLE F = 37.5% and Normal 5.6%, RIFLE R = 11.8%, RIFLE I = 25.7%, and RIFLE F = 37.5%, respectively). AKI proved independent predictors of both early and 1-year mortality. The burden of AKI significantly affected 1-year kidney function (Δ preoperative GFR-1-year GFR in AKI vs no AKI = -25.872 ± 22.54 vs -7.968 ± 34.18, p = 0.015). AKI is a highly prevalent and prognostically important complication. Some of the risk factors for AKI identified may be modifiable.

Post-operative acute kidney injury in patients with renal cell carcinoma is a potent risk factor for new-onset chronic kidney disease after radical nephrectomy

Radical nephrectomy is a significant risk factor for chronic kidney disease (CKD). There are few reports on the renal outcome of acute kidney injury (AKI) after radical nephrectomy. The aim of this study was to determine the incidence of AKI and whether post-operative AKI is associated with new-onset CKD after radical nephrectomy for renal cell cancer (RCC). We conducted a retrospective study of 519 adult patients (>40 years old) with normal renal function who underwent unilateral radical nephrectomy for a solitary renal cortical tumour and were pathologically diagnosed with RCC between January 2000 and February 2007. Post-operative AKI was classed using risk, injury, failure, loss and end-stage kidney disease (RIFLE) criteria. CKD was defined as a decrease in estimated glomerular filtration rate (GFR) to <60 mL/min/1.73 m(2). According to the RIFLE criteria, 165 of 175 patients fell into the AKI risk category, 8 patients fell into the AKI injury category and 2 patients fell into the AKI failure category. Multivariate analysis revealed that older age [odds ratio (OR) 1.02, 95% confidence interval (CI) 1.00-1.05], male gender (OR 3.13, 95% CI 1.91-5.12), higher body mass index (OR 1.08, 95% CI 1.01-1.15), smaller RCC size (OR 0.87, 95% CI 0.81-0.93) and higher preoperative GFR (OR 1.04, 95% CI 1.03-1.06) were independent risk factors for post-operative AKI. CKD was more prevalent in the AKI risk group than in patients without AKI 1 year after surgery (54.7% versus 43.9%, respectively; P = 0.006) and 3 years after surgery (50% versus 32%, respectively; P = 0.003). Patients who experienced post-operative AKI had a 4.24-fold higher risk of new-onset CKD after multiple adjustments were made to the data (95% CI 2.28-7.89, P < 0.001). AKI after radical nephrectomy in patients with RCC is a potent risk factor for new-onset CKD. Prevention of post-operative AKI is essential for reducing the incidence of CKD after nephrectomy.

Risk Factors of Acute Kidney Injury According to RIFLE Criteria After Lung Cancer Surgery

Perioperative acute kidney injury (AKI) is associated with increased mortality and morbidity. Our aim was to evaluate the incidence and determinants of AKI using the risk, injury, failure, loss of function, and end-stage kidney disease (RIFLE) criteria in thoracic surgical patients. We retrospectively analyzed a cohort of patients undergoing lung cancer surgery from 1996 to 2009. Patient management was protocol-driven, and postoperative complications were prospectively collected. The primary outcome was AKI within 3 days after surgery. A variety of patient comorbidities and operative characteristics were evaluated as potential predictors of AKI using a multiple logistic regression model. Complete data were obtained from 1,345 patients, and the incidence of AKI was 6.8%. Four independent risk factors for AKI were identified: American Society of Anesthesiologists classes 3 and 4 (odds ratio [OR] 2.60, 95% confidence interval [CI]: 1.03 to 6.55), forced expiratory volume in 1 second (OR 0.55, 95% CI: 0.32 to 0.96), the use of vasopressors (OR 1.015, 95% CI: 0.998 to 1.035), and the duration of anesthesia (OR 1.044, 95% CI: 1.001 to 1.008). Patients who experienced AKI were more frequently admitted to the intensive care unit (24.2% versus 3.5% for patients without AKI, p < 0.05); they had increased mortality (19.8% versus 1.1%, p < 0.05) and a threefold to fourfold higher incidence of cardiopulmonary complications. The RIFLE classification is a valuable tool to assess AKI after lung cancer surgery. The severity of perioperative renal impairment is associated with increased mortality and morbidity.

Invited Commentary

Invited Commentary

Cardiac Surgery-Associated Acute Kidney Injury: A Comparison of Two Consensus Criteria

Cardiac surgery-related acute kidney injury has short- and long-term impact on patients' risk for further morbidity and mortality. Consensus statements have yielded criteria--such as the risk, injury, failure, loss, and end-stage kidney disease (RIFLE) criteria, and the Acute Kidney Injury Network (AKIN) criteria--to define the type and consequence of acute kidney injury. We sought to estimate the ability of both the RIFLE and and AKIN criteria to predict the risk of in-hospital mortality in the setting of cardiac surgery. Data were collected on 25,086 patients undergoing cardiac surgery in Northern New England from January 2001 to December 2007, excluding 339 patients on preoperative dialysis. The AKIN and RIFLE criteria were used to classify patients postoperatively, using the last preoperative and the highest postoperative serum creatinine. We compared the diagnostic properties of both criteria, and calculated the areas under the receiver operating characteristic curve. Acute kidney injury occurred in 30% of patients using the AKIN criteria and in 31% of patients using the RIFLE criteria. The areas under the receiver operating characteristic curve for in-hospital mortality estimated by AKIN and RIFLE criteria were 0.79 (95% confidence interval: 0.77 to 0.80) and 0.78 (95% confidence interval: 0.76 to 0.80), respectively (p = 0.369). The AKIN and RIFLE criteria are accurate early predictors of mortality. The high incidence of cardiac surgery postoperative acute kidney injury should prompt the use of either AKIN or RIFLE criteria to identify patients at risk and to stimulate institutional measures that target acute kidney injury as a quality improvement initiative.

Invited Commentary

Invited Commentary

Pre-Transplant Predictors and Post-Transplant Sequels of Acute Kidney Injury After Allogeneic Stem Cell Transplantation.

AbstractAbstract 4515 Introduction:Acute kidney injury (AKI) is one of the most common complications after allogeneic stem cell transplantation (SCT). Although various post-transplant risk factors for AKI have been reported, there have been few studies which comprehensively assessed pre-transplant comorbidities and investigated their impact on the occurrence of AKI. Methods:We performed a retrospective analysis of 207 consecutive adult patients undergoing myeloablative or non-myeloablative SCT between 2001 and 2009. Cumulative incidence of AKI during the first 100 days was analyzed. AKI was defined and classified according to Risk, Injury, Failure, Loss, and End-stage kidney disease (RIFLE) criteria. Renal dysfunction considered to be associated with multiple organ dysfunction syndromes before death was excluded. The time to the development of severe AKI (defined as RIFLE class I or class F) was calculated and the multivariate analysis of pre- and post-transplant variables was performed by a Cox proportional hazards model. Post-transplant factors were assessed as time-dependent variables. As a representative of pre-transplant comorbidities, we used the hematopoietic cell transplantation-specific comorbidity index (HCT-CI). To analyze the outcomes of patients who developed AKI, the multivariate analysis of OS and NRM was carried out by a landmark approach, in which the follow-up was started at the onset of AKI class R or severe AKI in patients who developed AKI class R or severe AKI, and at the median time of the incidence of AKI in patients who did not develop AKI. Results:Among 207 patients, myeloablative SCT was performed in 149 patients and non-myeloablative SCT in 58 patients. Overall, 158 patients (76.3%) developed AKI, and 92 patients (44.4%) developed severe AKI. The median interval to the occurrence of severe AKI was 30 days after SCT. The cumulative incidence of severe AKI within 100 days in patients with a HCT-CI score 0, 1–2, and ≥3 was 21.3 %, 48.8%, and 73.9%, respectively. In a multivariate analysis, the HCT-CI was independently and most strongly associated with severe AKI (HCT-CI 1–2: adjusted hazard ratio [HR] 2.42, P<0.01; HCT-CI ≥3: adjusted HR 4.69, P<0.01), although no patients had renal dysfunction defined by the HCT-CI scoring system (pre-transplant creatinine > 2.0 mg/dl) before SCT in our cohort. Among post-transplant factors, sepsis (HR 2.66, P<0.01) and use of vancomycin (HR 1.79, P=0.04) were significantly associated with the development of severe AKI. In total, 101 of 207 patients (48.8%) died, of which 52 patients (51.5%) died of non-relapse causes. In a landmark analysis, the 3-year OS was 61.4% in patients without AKI, 53.9% in patients with AKI class R, and 39.3% in patients with severe AKI (P<0.01). The 3-year NRM was 5.6% in patients without AKI, 16.6% in patients with AKI class R, and 40.8% in patients with severe AKI (P<0.01). Multivariate analysis showed that severe AKI was a significant risk factor for worse OS (HR: 2.10, P=0.01) and NRM (HR: 6.15, P<0.01), while the occurrence of AKI class R did not have a strong impact on OS (HR: 1.14, P=0.69) or NRM (HR: 2.31, P=0.20). According to the cause of death, 24 patients died of severe AKI within 100 days after SCT, consisting of 2 on-disease patients (8.3% of the 24 patients who relapsed within 100 days after SCT) and 22 patients in remission (12.0% of the 183 patients who did not relapse within 100 days after SCT). There was no significant difference in the proportions of severe AKI as a mortality cause between patients with or without relapse (P=1.0). Conclusions:We found that high HCT-CI scores, particularly ≥3, were the most important pre-transplant predictor of severe AKI. The development of severe AKI within the first 100 days after SCT was independently associated with worse prognosis, irrespective of the status of the primary disease. Therefore, the strategy to prevent the occurrence of life-threatening severe AKI in patients with a high HCT-CI score would be imperative to improve their survival after allogeneic SCT. Disclosures:No relevant conflicts of interest to declare.

Statins and the “Healthy User Bias” in Cardiac Surgery

Statins and the “Healthy User Bias” in Cardiac Surgery

Pretransplant Predictors and Posttransplant Sequels of Acute Kidney Injury after Allogeneic Stem Cell Transplantation

Acute kidney injury (AKI) is a common complication after allogeneic stem cell transplantation (SCT). Although various risk factors for AKI have been reported, the influence of pretransplant comorbidity on the incidence of AKI has not been well investigated. We performed a retrospective analysis of 207 consecutive patients undergoing myeloablative or nonmyeloablative SCT between 2001 and 2009, using the hematopoietic cell transplantation-specific comorbidity index (HCT-CI) as a representative of pretransplant comorbidities. According to Risk, Injury, Failure, Loss, and End-stage kidney disease (RIFLE) criteria, 158 patients (76.3%) developed AKI, and 92 patients (44.4%) developed severe AKI (RIFLE class I or class F) within 100 days after SCT. The cumulative incidence of severe AKI within 100 days in patients with an HCT-CI score 0, 1-2, and ≥3 was 21.3%, 48.8%, and 73.9%, respectively. In multivariate analysis, the HCT-CI was independently associated with severe AKI (HCT-CI 1-2: adjusted hazard ratio [HR] 2.42, P < .01; HCT-CI ≥3: adjusted HR 4.69, P < .01). In a landmark analysis, patients with severe AKI had a lower 3-year overall survival (OS) (39.3% versus 61.4%, P < .01), and a higher 3-year nonrelapse mortality (NRM) (40.8% versus 5.6%, P < .01) than those without AKI. Multivariate analysis showed that severe AKI was a significant risk factor for worse OS (HR: 2.10, P = .01) and NRM (HR: 6.15, P < .01). Thus, it is important to assess the HCT-CI to predict the incidence of AKI, which is a strong indicator of worse prognosis after SCT.

RIFLE Criteria for Cardiac Surgery–Associated Acute Kidney Injury: Risk Factors and Outcomes

The aims of this study were to identify risk factors and evaluate the association with clinical outcomes of postoperative cardiac surgery-associated acute kidney injury (CSA-AKI). Data from 2488 consecutive adult patients were analyzed. Patients were classified as having CSA-AKI based on the risk, injury, failure, loss of kidney function, and end-stage kidney disease (RIFLE) criteria using peak postoperative creatinine in the postoperative intensive care unit (ICU). Multiple stepwise logistic regression analysis was used to identify independent risk factors for CSA-AKI. CSA-AKI occurred in 584 patients (23.5%). CSA-AKI patients had significantly longer aortic cross-clamp and cardiopulmonary bypass times. Furthermore, CSA-AKI patients had higher hospital mortality (5.5% vs 1.5%, P<.001) and significantly longer ICU and hospital stays. Independent risk factors for CSA-AKI were age, peripheral vascular disease, hypertension, left ventricular ejection fraction, cardiopulmonary bypass time, and surgery on the thoracic aorta. In conclusion, patients who develop CSA-AKI have a higher preoperative risk profile, more complex surgery, and worse clinical outcomes.

Scoring short-term mortality after liver transplantation

Liver transplantation can prolong survival and improve the quality of life of patients with end-stage liver disease. This study retrospectively reviewed the medical records of 149 patients who had received liver transplants in a tertiary care university hospital from January 2000 to December 2007. Demographic, clinical, and laboratory variables were recorded. Each patient was assessed by 4 scoring systems before transplantation and on postoperative days 1, 3, 7, and 14. The overall 1-year survival rate was 77.9%. The Sequential Organ Failure Assessment (SOFA) score had better discriminatory power than the Child-Pugh points, Model for End-Stage Liver Disease score, and RIFLE (risk of renal dysfunction, injury to the kidney, failure of the kidney, loss of kidney function, and end-stage kidney disease) criteria. Moreover, the SOFA score on day 7 post-liver transplant had the best Youden index and highest overall correctness of prediction for 3-month (0.86, 93%) and 1-year mortality (0.62, 81%). Cumulative survival rates at the 1-year follow-up after liver transplantation differed significantly (P < 0.001) between patients who had SOFA scores < or = 7 on post-liver transplant day 7 and those who had SOFA scores > 7 on post-liver transplant day 7. In conclusion, of the 4 evaluated scoring systems, only the SOFA scores calculated before liver transplantation were statistically significant predictors of 3-month and 1-year posttransplant mortality. SOFA on post-liver transplant day 7 had the best discriminative power for predicting 3-month and 1-year mortality after liver transplantation.

Predictors of acute kidney injury associated with intravenous colistin treatment

Colistimethate sodium (CMS) was recently re-introduced into clinical practice as a last resort for the treatment of nosocomial infections caused by multiresistant bacteria. This retrospective cohort study was designed to identify predictors of acute kidney injury (AKI) associated with intravenous (i.v.) CMS treatment. From March 2007 to July 2008, 71 adult patients receiving CMS for ≥72 h were enrolled. AKI was defined using Risk, Injury, Failure, Loss and End-stage kidney disease (RIFLE) criteria according to serum creatinine. The median total dose of CMS was 54.3 mg/kg (range 27.5–94.5 mg/kg). AKI developed in 38 patients (53.5%). Cox regression analysis based of cumulative CMS dose (mg/kg) identified four independent predictors of AKI: male sex [hazard ratio (HR) = 3.55, 95% confidence interval (CI), 1.47–8.55]; concomitant use of a calcineurin inhibitor (HR = 6.74, 95% CI 2.49–18.24); hypoalbuminaemia (serum albumin level <2.0 g/dL) (HR = 6.29, 95% CI 2.04–19.39); and hyperbilirubinaemia (total bilirubin level >5 mg/dL) (HR = 3.53, 95% CI 1.17–10.71). In conclusion, AKI was a common complication of i.v. CMS treatment. Male sex, concomitant use of calcineurin inhibitors, hypoalbuminaemia and hyperbilirubinaemia were independent predictors of AKI. The effect of AKI on patient outcomes was not determined.

Predictors of Acute Renal Dysfunction After Ventricular Assist Device Placement

Background Acute renal dysfunction (ARD) is a frequent complication after ventricular assist device (VAD) implantation. The purpose was to identify predictors associated with ARD after VAD implantation. Methods and Results ARD was defined using the risk of renal dysfunction, injury to the kidney, failure of kidney function, loss of kidney function, end-stage kidney disease (RIFLE) criteria. Patients who developed ARD during VAD support (ARD, n = 24) were compared with patients who did not (NoARD, n = 29). Patients with ARD before implant were excluded. Patient characteristics pre-VAD implant, incidence of complications during support and survival were analyzed. Baseline characteristics were similar. The ARD group had longer cardiopulmonary bypass (CPB) time, greater need for reoperation and higher risk of bleeding (>1 L) intraoperatively ( P < .05). The ARD group had a higher incidence of infections (17% vs. 50%, OR 5, 95%CI 1.3-17), liver injury (58% vs. 17%, OR 7, 95%CI 2-24), ventricular arrhythmias (42% vs. 14%, OR 4, 95%CI 1.1-16), and right ventricular failure (73% vs. 30%, OR 7, 95%CI 2-24). Need for dialysis was associated with higher pre-VAD creatinine and worse outcomes. Survival was significantly lower in the ARD group (HR 8.5, 95%CI 2-29). Conclusions Acute renal dysfunction is a common and serious complication post-VAD implantation and is associated with reduced survival. Longer CPB time, higher intraoperative blood loss, and reoperation are associated factors with the development of this disease.

Acute kidney injury in intensive care unit patients: a comparison between the RIFLE and the Acute Kidney Injury Network classifications

IntroductionWhether discernible advantages in terms of sensitivity and specificity exist with Acute Kidney Injury Network (AKIN) criteria versus Risk, Injury, Failure, Loss of Kidney Function, End-stage Kidney Disease (RIFLE) criteria is currently unknown. We evaluated the incidence of acute kidney injury and compared the ability of the maximum RIFLE and of the maximum AKIN within intensive care unit hospitalization in predicting inhospital mortality of critically ill patients.MethodsPatients admitted to the Department of Intensive Medicine of our hospital between January 2003 and December 2006 were retrospectively evaluated. Chronic kidney disease patients undergoing dialysis or renal transplant patients were excluded from the analysis.ResultsIn total, 662 patients (mean age, 58.6 ± 19.2 years; 392 males) were evaluated. AKIN criteria allowed the identification of more patients as having acute kidney injury (50.4% versus 43.8%, P = 0.018) and classified more patients with Stage 1 (risk in RIFLE) (21.1% versus 14.7%, P = 0.003), but no differences were observed for Stage 2 (injury in RIFLE) (10.1% versus 11%, P = 0.655) and for Stage 3 (failure in RIFLE) (19.2% versus 18.1%, P = 0.672). Mortality was significantly higher for acute kidney injury defined by any of the RIFLE criteria (41.3% versus 11%, P < 0.0001; odds ratio = 2.78, 95% confidence interval = 1.74 to 4.45, P < 0.0001) or of the AKIN criteria (39.8% versus 8.5%, P < 0.0001; odds ratio = 3.59, 95% confidence interval = 2.14 to 6.01, P < 0.0001). The area under the receiver operator characteristic curve for inhospital mortality was 0.733 for RIFLE criteria (P < 0.0001) and was 0.750 for AKIN criteria (P < 0.0001). There were no statistical differences in mortality by the acute kidney injury definition/classification criteria (P = 0.72).ConclusionsAlthough AKIN criteria could improve the sensitivity of the acute kidney injury diagnosis, it does not seem to improve on the ability of the RIFLE criteria in predicting inhospital mortality of critically ill patients.

Urinary interleukin-18 is an acute kidney injury biomarker in critically ill children

Urinary interleukin-18 (uIL-18) is an earlier acute kidney injury (AKI) biomarker than serum creatinine (SCr) in specific populations. In the present study, the relationship between uIL-18 and AKI was determined in a heterogeneous group of critically ill children. We studied critically ill children to determine whether uIL-18 was an early predictor of AKI. SCr was determined daily for up to 14 days from mechanical ventilation initiation and up to four serial urine specimens were collected for the uIL-18 measurement. AKI was graded by paediatric modified risk, injury, failure, loss, end-stage kidney disease (pRIFLE) criteria. Day 0 was defined as the day of attaining pRIFLE AKI. One hundred thirty-seven children aged 6.5 +/- 6.4 years (53% male) were studied. The peak levels of IL-18 correlated with the severity of AKI by pRIFLE classification (P < 0.05). In non-septic AKI patients, uIL-18 rose to a level higher than control levels 2 days prior to a significant rise in SCr. Urinary IL-18 concentration from the first urine specimen was associated with AKI development within 48 h (odds ratio = 3.5, P < 0.05) independent of the paediatric risk of mortality (PRISM II) score. Urinary IL-18 concentration > or = 100 pg/ml had a specificity and negative predictive value of 81 and 83% to predict AKI development within 24 h. Urinary IL-18 > or = 200 pg/ml collected within 24 h of Day 0 had a specificity and positive predictive value of 93 and 88% respectively to predict the AKI duration > or = 48 h. Urinary IL-18 was associated with mortality (odds ratio = 1.29, P < 0.05), independent of the PRISM II score. Urinary IL-18 rises prior to SCr in non-septic critically ill children, predicts severity of AKI and is an independent predictor of mortality.

Epidemiology of acute kidney injury after cardiac surgery: an update

This aim of this review is to highlight recent studies that have furthered our understanding of the epidemiology, risk factors, and prognosis of acute kidney injury (AKI) following cardiac surgery. AKI is an important postoperative complication of cardiac surgery and is an independent risk factor for perioperative mortality. A consensus definition of AKI, the risk, injury, failure, loss, end-stage kidney disease (RIFLE) criteria, has recently been evaluated in the cardiac surgery population. AKI is an independent risk factor for postoperative death and is associated with increased postoperative complications and overall resource utilization. Despite the high early mortality rate, patients with postoperative AKI who survive to hospital discharge have a reasonable long-term prognosis. The identification of risk factors for AKI has allowed the development of preoperative risk stratification strategies. Future studies are necessary to determine if preoperative risk stratification leads to improved outcomes by...