Degree Of Acute Kidney Injury Research Articles

The incidence and significance of acute kidney injury following emergent contrast administration in patients with STEMI and stroke.

The authors have investigated the incidence of acute kidney injury (AKI) and short-term mortality following an activated STEMI and stroke alert at a tertiary referral and academic center. A single center, retrospective chart review of STEMI and stroke activation patients from January 2010 to March 2012. Data was collected and reviewed from an institutional database following IRB-approval. Inclusion criteria were STEMI patients taken for cardiac catheterization, excluding patients receiving hemodialysis due to end-stage renal disease (ESRD). Primary outcome measures were the incidence of AKI using the RIFLE criteria and short-term mortality. 745 patients were included (488 stroke, 257 STEMI). The median age was 65, and 39% were female. Overall inpatient mortality was 7.0%. 5.4% (40/745) of patients experienced some degree of AKI (8.6% of STEMI, 3.7% of stroke patients). Overall, 30% of patients with AKI died during their hospitalization. AKI was associated with a 7.1-fold (95% CI 3.4-15.1) increase in mortality in the entire cohort. Among STEMI patients, AKI was associated with a 66.6-fold (95% CI 12.9-343.4) increase in mortality. These findings follow similar trends published among critically ill patients with AKI. The risk of death with concomitant AKI in this hospital population is significant and deserves future study. Early recognition and awareness in the emergency department is paramount to the patient's survival. Future studies should focus on modalities to improve early recognition and preventative therapies.

Association Between Progression and Improvement of Acute Kidney Injury and Mortality in Critically Ill Children.

To determine whether the progression and/or improvement of acute kidney injury in critically ill children is associated with mortality. Retrospective. Multidisciplinary, tertiary care, 24-bed PICU. A TOTAL OF: 8,260 patients who were 1 month to 21 years old with no chronic kidney disease admitted between May 2003 and March 2012. We analyzed patients based on their acute kidney injury stage as per the Kidney Disease Improving Global Outcomes acute kidney injury serum creatinine staging criteria on ICU admission, peak (highest acute kidney injury stage reached), and trough (lowest acute kidney injury stage after the peak) during their ICU stay. Nonrenal organ dysfunction was measured with a modified Pediatric Logistic Organ Dysfunction score. The primary outcome was 28-day mortality. p values were based on Yates-corrected chi-square test and logistic regression. Of the 8,260 patients, 529 (6.4%) had acute kidney injury on ICU admission and 974 (11.8%) had acute kidney injury during their ICU course. The 28-day mortality was 2.7% for patients with no acute kidney injury and 25.3% for patients with acute kidney injury. Patients in whom acute kidney injury developed or had worsening acute kidney injury from admission to peak and reached acute kidney injury stage 2 or 3 had higher mortality than those who remained at an acute kidney injury stage 1 (17.3-17.8% vs 32.2-37.9%; p ≤ 0.003). Patients whose acute kidney injury resolved after the peak had lower mortality than those who retained the same degree of acute kidney injury (9-13.5% vs 37.3-44%; p ≤ 0.04). Patients with acute kidney injury that resolved still had higher mortality than those who never developed acute kidney injury (11.2% vs 2.7%; p < 0.001). Multivariate regression demonstrated that the association between mortality and acute kidney injury progression was independent of severity of illness at admission and the severity of nonrenal organ dysfunction during the first week of ICU stay (p ≤ 0.01). Progression of acute kidney injury per the Kidney Disease Improving Global Outcomes staging criteria is independently associated with increased mortality in the PICU while its improvement is associated with a stepwise decrease in mortality.

Usefulness of presepsin in the diagnosis of sepsis in patients with or without acute kidney injury.

BackgroundPresepsin is useful for differentiating sepsis from non-infection related systemic inflammatory response syndrome. However, there are no studies investigating the usefulness of presepsin in diagnosing sepsis involving patients with acute kidney injury (AKI). The purpose of this study is to determine levels of blood presepsin in patients with or without sepsis and among non-AKI patients or patients with different degrees of AKI severity.MethodsThis is a single center retrospective study. 247 patients admitted to the ICU between June 2010 and October 2012 were analyzed for their presepsin levels. We classified the patients into non-AKI and AKI according to the RIFLE (Risk, Injury, Failure, and Loss of kidney function and End-stage kidney disease or simply Loss and ESKD) criteria. We then sub-classified the patients in each group into either non-sepsis or sepsis sub-group and analyzed the accuracy of diagnosing sepsis based on their levels of presepsin.ResultsThe number of patients for each group was: non-AKI, 112; under AKI: Risk, 50; Injury, 36; Failure, 42; Loss and ESKD, 7. The levels of presepsin in sepsis groups were significantly higher than that in the non-sepsis group among the non-AKI, Risk and Injury patients (p < 0.0001, p < 0.01, p < 0.01, respectively). However, no significant difference in the level of presepsin between non-sepsis and sepsis groups among patients with Failure. In the receiver operating characteristic (ROC) analysis, the area under the curve (AUC) was 0.784 in the non-AKI group and 0.698 in the AKI comprising Risk, Injury and Failure groups. AUC value for non-AKI was not significantly different from that of AKI (p = 0.200). When 670 pg/mL was used as the cutoff value for presepsin, sensitivity and specificity were 70.3% and 81.3%, respectively. When 864 pg/mL was used as the cutoff value for presepsin, sensitivity and specificity were 71.4% and 63.8%, respectively.ConclusionsPresepsin level can be a reliable indicator of sepsis not only among non-AKI patients but also patients with less severe forms of AKI. However, it may not be a reliable indicator of sepsis in patients with a more advanced form of AKI.

Clinical Impact of Mild Acute Kidney Injury After Cardiac Surgery

Dialysis-dependent renal failure occurs infrequently after cardiac surgery but leads to substantial morbidity and mortality. In contrast, milder degrees of acute kidney injury (AKI), based on small increases in serum creatinine, occur frequently but the independent impact of mild AKI on outcome remains unclear. Between January 2010 and December 2012, 3,869 consecutive patients undergoing cardiac surgery comprised the study cohort. Acute kidney injury was defined according to the AKI Network criteria as stage I, II, or III. A nonparsimonious multivariable logistic regression model including preoperative and intraoperative variables was constructed to determine a propensity score for the development of stage I AKI followed by a greedy matching algorithm to create 1:1 propensity-matched pairs. The incidence of stage I AKI in the entire cohort was 22.4%. Stage I AKI patients were more likely to be older; to have diabetes mellitus, hypertension, preoperative renal dysfunction, and poorer left ventricle function; and to require more urgent surgery and longer cardiopulmonary bypass. After propensity matching, the 833 matched pairs were similar in terms of all of the above characteristics (all p > 0.5). Within the matched cohort, AKI patients had higher mortality (2.6% versus 1.2%, p = 0.01), higher incidence of neurologic dysfunction (15.2% versus 8.1%, p < 0.001), and longer duration of mechanical ventilation (41.7 ± 125.0 versus 19.3 ± 58.6 hours, p < 0.001). Intensive care unit stay (5.2 ± 10.7 versus 2.7 ± 3.8 days, p < 0.0001), and hospital length of stay (17.9 ± 20.1 versus 14.7 ± 18.3 days, p = 0.0007) was significantly longer for matched AKI patients. Patients with even mild degrees of AKI have increased mortality and morbidity compared with their matched counterparts. Interventions that prevent or mitigate AKI after cardiac surgery can yield substantial clinical benefit.

Impact of Mild Acute Kidney Injury Following Cardiac Surgery

Dialysis-dependent renal failure occurs infrequently following cardiac surgery but leads to substantial morbidity and mortality. In contrast, milder degrees of acute kidney injury (AKI), based on small increases in serum creatinine, occur frequently but the independent impact of mild AKI on outcome remains unclear.

Management of renal dysfunction following term perinatal hypoxia‐ischaemia

Acute kidney injury frequently develops following the term perinatal hypoxia-ischaemia. Quantifying the degree of acute kidney injury is difficult, however, as the methods currently in use are suboptimal. Acute kidney injury management is largely supportive with little evidence basis for many interventions. This review discusses management strategies and novel biomarkers that may improve diagnosis and management of renal injury following perinatal hypoxia-ischaemia. Following perinatal hypoxia-ischaemia, acute kidney injury is common. Management of neonatal acute kidney injury is largely supportive. Novel acute kidney injury biomarkers may play a role in optimizing new categorical definitions of renal injury. Studies are needed to investigate the impact of neonatal acute kidney injury on long-term outcome.

Fluid overload in infants following congenital heart surgery.

To describe postoperative fluid overload patterns and correlate degree of fluid overload with intensive care morbidity and mortality in infants undergoing congenital heart surgery. Prospective, observational study. Fluid overload (%) was calculated by two methods: 1) (Total fluid in - Total fluid out)/(Preoperative weight) × 100; and 2) (Current weight - Preoperative weight)/(Preoperative weight) × 100. Composite poor outcome included: need for renal replacement therapy, upper quartile time to extubation or intensive care length of stay (> 6.5 and 9.9 days, respectively), or death ≤ 30 days after surgery. University hospital pediatric cardiac ICU. Forty-nine infants < 6 months of age undergoing congenital heart surgery with cardiopulmonary bypass during the period of July 2009 to July 2010. None. Patients had a median age of 53 days (21 neonates) and mean weight of 4.5 ± 1.3 kg. Forty-two patients (86%) developed acute kidney injury by meeting at least Acute Kidney Injury Network and Kidney Disease Improving Global Outcomes stage 1 criteria (serum creatinine rise of 50% or ≥ 0.3mg/dL). The patients with adverse outcomes (n = 17, 35%) were younger (7 [5 - 10] vs. 98 [33 - 150] days, p = 0.001), had lower preoperative weight (3.7 ± 0.7 vs. 4.9 ± 1.4 kg, p = 0.0002), higher postoperative mean peak serum creatinine (SCr) (0.9 ± 0.3 vs. 0.6 ± 0.3mg/dL, p = 0.005), and higher mean maximum fluid overload by both method 1 (12% ± 10% vs. 6% ± 4%, p = 0.03) and method 2 (24% ± 15% vs. 14% ± 8%, p = 0.02). Predictors of a poor outcome from multivariate analyses were cardiopulmonary bypass time, use of circulatory arrest, and increased vasoactive medication requirements postoperatively. Early postoperative fluid overload is associated with suboptimal outcomes in infants following cardiac surgery. Because the majority of patients developed kidney injury without needing renal replacement therapy, fluid overload may be an important risk factor for adverse outcomes with all degrees of acute kidney injury.

Degree of Acute Kidney Injury before Dialysis Initiation and Hospital Mortality in Critically Ill Patients

In a multicenter observational cohort of patients-admitted to intensive care units (ICU), we assessed whether creatinine elevation prior to dialysis initiation in acute kidney injury (AKI-D) further discriminates risk-adjusted mortality. AKI-D was categorized into four groups (Grp) based on creatinine elevation after ICU admission but before dialysis initiation: Grp I > 0.3 mg/dL to <2-fold increase, Grp II ≥2 times but <3 times increase, Grp III ≥3-fold increase in creatinine, and Grp IV none or <0.3 mg/dl increase. Standardized mortality rates (SMR) were calculated by using a validated risk-adjusted mortality model and expressed with 95% confidence intervals (CI). 2,744 patients developed AKI-D during ICU stay; 36.7%, 20.9%, 31.2%, and 11.2% belonged to groups I, II, III, and IV, respectively. SMR showed a graded increase in Grp I, II, and III (1.40 (95% CI, 1.29–1.42), 1.84 (1.66–2.04), and 2.25 (2.07–2.45)) and was 0.98 (0.78–1.20) in Grp IV. In ICU patients with AKI-D, degree of creatinine elevation prior to dialysis initiation is independently associated with hospital mortality. It is the lowest in those experiencing minor or no elevations in creatinine and may represent reversible fluid-electrolyte disturbances.

Acute kidney injury in decompensated cirrhosis

BackgroundHepatorenal syndrome in cirrhosis with ascites is a well-defined entity with significant morbidity and mortality. It is unclear whether milder degrees of acute kidney injury (AKI), defined as a serum...

Predicting Hospital Mortality in Critically Ill Cancer Patients according to Acute Kidney Injury Severity

Background: Acute kidney injury (AKI) is a frequent complication in hospitalized patients, especially in those in intensive care units (ICU). The RIFLE classification might be a valid prognostic factor for critically ill cancer patients. The present study aims to evaluate the discriminatory capacity of RIFLE versus other general prognostic scores in predicting hospital mortality in critically ill cancer patients. Methods: This is a single-center study conducted in a cancer-specialized ICU in Brazil. All of the 288 patients hospitalized from May 2006 to June 2008 were included. RIFLE classification, APACHE II, SOFA, and SAPS II scores were calculated and the area under receiver operating characteristic (AROC) curves and logistic multiple regression were performed using hospital mortality as the outcome. Results: AKI, defined by RIFLE criteria, was observed in 156 (54.2%) patients. The distribution of patients with any degree of AKI was: risk, n = 96 (33.3%); injury, n = 30 (10.4%), and failure, n = 30 (10.4%). Mortality was 13.6% for non-AKI patients, 49% for RIFLE ‘R’ patients, 62.3% for RIFLE ‘I’ patients, and 86.8% for RIFLE ‘F’ patients (p = 0.0006). Logistic regression analysis showed that RIFLE criteria, APACHE II, SOFA, and SAPS II were independent factors for mortality in this population. The discrimination of RIFLE was good (AROC 0.801, 95% CI 0.748–0.854) but inferior compared to those of APACHE II (AROC 0.940, 95% CI 0.915–0.966), SOFA (AROC 0.910, 95% CI 0.876–0.943), and SAPS II (AROC 0.869, 95% CI 0.827–0.912). Conclusion: AKI is a frequent complication in ICU patients with cancer. RIFLE was inferior to commonly used prognostic scores for predicting mortality in this cohort of patients.

Preoperative EGFR and Rifle-Classified Postoperative AKI Predict Length of Stay Post Coronary Bypass Surgery in an Australian Setting

Introduction: Mortality rate, the preferred post CABGS outcome measure, may have decreased so much that it is no longer a useful marker of quality. Renal dysfunction is common amongst CABGS candidates [1] and studies using estimated glomerular filtration rate (eGFR), which is considered more reliable than serum creatinine, have shown that even mild degrees of preoperative renal dysfunction are associated with increased mortality and length of stay after cardiac surgery [1,2]. To classify change in renal function in the critically ill, the RIFLE criteria (acronym for degree of acute kidney injury (AKI): Risk, Injury, Failure, Loss, Endstage) have recently been validated [3].

Serum creatinine as stratified in the RIFLE score for acute kidney injury is associated with mortality and length of stay for children in the pediatric intensive care unit

To evaluate the ability of the RIFLE criteria to characterize acute kidney injury in critically ill children. Retrospective analysis of prospectively collected clinical data. Multidisciplinary, tertiary care, 20-bed pediatric intensive care unit. All 3396 admissions between July 2003 and March 2007. None. A RIFLE score was calculated for each patient based on percent change of serum creatinine from baseline (risk = serum creatinine x1.5; injury = serum creatinine x2; failure = serum creatinine x3). Primary outcome measures were mortality and intensive care unit length of stay. Logistic and linear regressions were performed to control for potential confounders and determine the association between RIFLE score and mortality and length of stay, respectively.One hundred ninety-four (5.7%) patients had some degree of acute kidney injury at the time of admission, and 339 (10%) patients had acute kidney injury develop during the pediatric intensive care unit course. Almost half of all patients with acute kidney injury had their maximum RIFLE score within 24 hrs of intensive care unit admission, and approximately 75% achieved their maximum RIFLE score by the seventh intensive care unit day. After regression analysis, any acute kidney injury on admission and any development of or worsening of acute kidney injury during the pediatric intensive care unit stay were independently associated with increased mortality, with the odds of mortality increasing with each grade increase in RIFLE score (p < .01). Patients with acute kidney injury at the time of admission had a length of stay twice that of those with normal renal function, and those who had any acute kidney injury develop during the pediatric intensive care unit course had a four-fold increase in pediatric intensive care unit length of stay. Also, other than being admitted with RIFLE risk score, an independent relationship between any acute kidney injury at the time of pediatric intensive care unit admission, any acute kidney injury present during the pediatric intensive care unit course, or any worsening RIFLE scores during the pediatric intensive care unit course and increased pediatric intensive care unit length of stay were identified after controlling for the same high-risk covariates (p < .01). RIFLE criteria serves well to describe acute kidney injury in critically ill pediatric patients.

Swarming hornet attacks: shock and acute kidney injury--a large case series from Vietnam

Social hornets attack victims in swarms in Asia, Africa and the Middle East. The venom consists of multiple proteins with myotoxin, haemotoxin, vasodilatory and anticoagulant effects. We reviewed the records of 65 patients at Cho Ray Hospital (Ho Chi Minh City, Vietnam) attacked by swarms of the lesser banded hornet, Vespa affinis. Patients were divided into four groups. Groups A and B presented within 3 days of attack and C and D after 3 days with </=50 or >50 stings, respectively. Varying degrees of acute kidney injury (AKI) were seen in 38 (58.5%) patients in all groups. Twenty nine required renal replacement therapy. AKI was likely to be myoglobin and toxin induced with a clinical course consistent with acute tubular injury. The prognosis for renal recovery is excellent in those who survive. Seven patients (one from Group A and six from Group B) developed non-anaphylactic shock which led to four deaths. The predominant finding in Groups C and D who sought delayed tertiary care is renal failure. This cases which illustrate the varied effects of hornet venom and the need to be vigilant for shock within the first 2 days and persistent AKI beyond 3 days of attack.

Acute Bilateral Renal Vein Thrombosis

Acute Bilateral Renal Vein Thrombosis

Renal insufficiency after cardiac surgery: a challenging clinical problem

Acute renal insufficiency (ARI) after cardiac surgery is a complex and frequent clinical problem. It increases short- and long-term mortality, the incidence of post-operative complications such as respiratory infections, sepsis, and gastrointestinal bleeding, and intensive care unit (ICU) and hospital lengths of stay.1,2 Identified risk factors for post-operative ARI in cardiac surgical patients include pre-operative renal insufficiency, advanced age, history of congestive heart failure, diabetes mellitus, recent exposure to nephrotoxic agents such as contrast dye, intra-aortic balloon pump, emergency operation, prolonged cardiopulmonary bypass (CPB) time, low urinary output during CPB, and need for deep hypothermic circulatory arrest ( Figure 1 ).2,3 Figure 1 Risk factors for acute renal insufficiency after cardiac surgery. Analysing the pre-operative risk factor trends in cardiac surgery during the 1990–1999 decade in the large, voluntary, nationwide STS database, Ferguson et al. 4 showed that the incidence of pre-operative renal insufficiency increased from 3.0 to 4.6%. Recently, Swaminathan et al. 5 showed that, among coronary artery bypass grafting (CABG) patients, the incidence of acute renal failure increased significantly from 1.1 to 4.1%. While the proportion of a diagnosis of acute renal failure cases requiring haemodialysis decreased from 15.8 to 8.7%, the percentage of survivors with post-operative special care requirements increased from 35.5 to 64.5%.5 Over the last few years, the prognostic importance of mildly elevated pre-operative serum creatinine levels or small increases in post-operative creatinine values became apparent, leading to a shift in our understanding of the importance of even small degrees of acute kidney injury. Antunes et al. 6 reported, among 2122 patients with pre-operative creatinine serum levels <2.0 mg/dL having CABG and an … *Corresponding author. Tel: +32 4 366 7163, Fax: +32 4 221 31 58, Email: philippe.kolh{at}chu.ulg.ac.be

Invited commentary

The grave prognosis associated with post-cardiac surgery acute kidney injury (AKI) may be due, at least in part, to the distant effects of AKI on other organ function. An AKI requiring dialysis occurs in as many as 5% of cardiac surgery patients, while an additional 8% to 15% have moderate kidney injury (eg, >1.0 mg/dL peak creatinine rise in serum creatinine). Lesser renal injuries are even more common with as many as 50% of postoperative cardiac surgery patients in some studies having a 25% or greater rise in serum creatinine. The AKI in many settings, including cardiac surgery, has been independently linked with in-hospital mortality, even after adjustment for comorbid diseases and other complications [1Chertow G.M. Levy E.M. Hammermeister K.E. Grover F. Daley J. Independent association between acute renal failure and mortality following cardiac surgery.Am J Med. 1998; 104: 343-348Abstract Full Text Full Text PDF PubMed Scopus (1023) Google Scholar]. All degrees of AKI are associated with short-term mortality and other adverse outcomes [2Stafford-Smith M. Perioperative renal dysfunction: implications and strategies for protection.in: Newman M.F. Perioperative organ protection. Lippincott Williams & Wilkins, Baltimore, MD2003: 89-124Google Scholar]. However, only a few previous studies have focused on the relationship of perioperative AKI with long-term survival. Brown and colleagues [3Brown J.R. Cochran R.P. MacKenzie T.A. et al.Long-term survival after cardiac surgery is predicted by estimated glomerular filtration rate.Ann Thorac Surg. 2008; 86: 4-12Abstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar] compare mortality rates and postoperative renal dysfunction in a population of 13,593 isolated coronary artery bypass graft procedures in terms of lowest postoperative estimated glomerular filtration rate (eGFR). What is particularly elegant in the current study relative to any of the other studies in this area is that the authors have a sufficiently large dataset to demonstrate an association with long-term survival, even when this outcome is separated from short-term in-hospital, 30-day mortality. Their finding, linking eGFR rates less than 60 mL/min with decreased long-term survival (after 30 days postoperatively) is yet further validation of the importance of postoperative renal dysfunction, including AKI. As early biomarkers start to provide better information than serum creatinine and become validated as clinical tools to diagnose AKI, the hope is that early recognition and prompt intervention similar to the strategies developed for acute myocardial infarction (AMI) may redefine the therapeutic approach to AKI and potentially, as with AMI, lead to the development of interventions that may improve outcome including long-term survival. Studies such as the one from Brown and colleagues [3Brown J.R. Cochran R.P. MacKenzie T.A. et al.Long-term survival after cardiac surgery is predicted by estimated glomerular filtration rate.Ann Thorac Surg. 2008; 86: 4-12Abstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar] that provide measurable endpoints associated with AKI may become the benchmarks against which such renoprotective interventions are compared. Long-Term Survival After Cardiac Surgery is Predicted by Estimated Glomerular Filtration RateThe Annals of Thoracic SurgeryVol. 86Issue 1PreviewEstimated glomerular filtration rate (eGFR) before coronary artery bypass graft (CABG) surgery is a key risk factor of in-hospital mortality. However, in patients with normal renal function before CABG, acute kidney injury develops after the procedure, making postoperative renal function assessment necessary for evaluation. Postoperative eGFR and its association with long-term survival have not been well studied. Full-Text PDF

Effect of off-pump coronary artery bypass graft surgery on postoperative acute kidney injury and mortality*

Risk of mortality after cardiac surgery is associated with severity of acute kidney injury. The aim of this study is to examine the effect of off-pump coronary artery bypass surgery on the risk of postoperative acute kidney injury and its association with mortality. Observational cohort study. Tertiary care center. Some 10,061 patients underwent coronary artery bypass surgery (1998-2002), of which 1,365 patients underwent off-pump surgery. Acute kidney injury was defined as either requirement of dialysis or >/=50% decline in postoperative glomerular filtration rate but not requiring dialysis. We compared on- and off-pump surgeries and used propensity score matching to examine the effect of off-pump surgery on acute kidney injury and mortality. We found that 2.6% on-pump and 1.2% off-pump patients developed acute kidney injury requiring dialysis among the 2,370 matched subjects (relative risk, 2.06; 95% confidence interval [CI], 1.36-3.36); 5.0% of on-pump patients suffered a >/=50% decline in glomerular filtration rate compared with 2.5% in off-pump group (relative risk, 2.00; 95% CI, 1.48-2.82). The mortality rate in the matched cohort was 2.3% for on-pump group vs. 0.6% in off-pump group (relative risk, 3.88; 95% CI, 2.29-9.50). Among matched patients with acute kidney injury, the risk of mortality was 13.14 (95% CI, 8.43-30.50) in patients requiring dialysis and 9.33 (95% CI, 4.83-19.00) in those with >/=50% decline in glomerular filtration rate but not requiring dialysis. Off-pump surgery is associated with a lower risk of developing acute kidney injury (regardless of its definition). The risk of mortality is incremental with worsening degrees of acute kidney injury. Lower risk of acute kidney injury may be one of the factors that offer a survival advantage after off-pump surgery.

CRITICAL CARE ISSUES FOR THE NEPHROLOGIST: The Epidemiology and Outcome of Acute Renal Failure and the Impact on Chronic Kidney Disease

AbstractAcute renal failure (ARF) is a common condition, especially among the critically ill, and confers a high mortality. Recent publications have highlighted changes in the epidemiology and improvement in mortality that was long thought to be static despite improvements in clinical care. The incidence of ARF is increasing. Efforts, such as the Acute Dialysis Quality Initiative, are being undertaken to establish a consensus definition of ARF, and to distinguish between varying degrees of acute kidney injury. Data are emerging to allow comparison of the epidemiology of ARF across institutions internationally. There is ongoing recognition of the important interaction between ARF and chronic kidney disease. Two brief case reports are offered to help frame the context and clinical impact of this disorder, followed by a review of some of the recent literature that addresses these points.

Acute Kidney Injury, Mortality, Length of Stay, and Costs in Hospitalized Patients

The marginal effects of acute kidney injury on in-hospital mortality, length of stay (LOS), and costs have not been well described. A consecutive sample of 19,982 adults who were admitted to an urban academic medical center, including 9210 who had two or more serum creatinine (SCr) determinations, was evaluated. The presence and degree of acute kidney injury were assessed using absolute and relative increases from baseline to peak SCr concentration during hospitalization. Large increases in SCr concentration were relatively rare (e.g., >or=2.0 mg/dl in 105 [1%] patients), whereas more modest increases in SCr were common (e.g., >or=0.5 mg/dl in 1237 [13%] patients). Modest changes in SCr were significantly associated with mortality, LOS, and costs, even after adjustment for age, gender, admission International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis, severity of illness (diagnosis-related group weight), and chronic kidney disease. For example, an increase in SCr >or=0.5 mg/dl was associated with a 6.5-fold (95% confidence interval 5.0 to 8.5) increase in the odds of death, a 3.5-d increase in LOS, and nearly 7500 dollars in excess hospital costs. Acute kidney injury is associated with significantly increased mortality, LOS, and costs across a broad spectrum of conditions. Moreover, outcomes are related directly to the severity of acute kidney injury, whether characterized by nominal or percentage changes in serum creatinine.