Survivors of acute renal failure who do not recover renal function

Factors associated with post-hospitalization dialysis dependence in ECMO patients who required continuous renal replacement therapy

OBJECTIVE

This single center retrospective study aimed to describe the variables associated with outpatient dialysis dependence in extracorporeal membrane oxygenation (ECMO) patients who needed continuous renal replacement therapy (CRRT) for acute kidney injury (AKI) during their hospitalization.

METHODS

Retrospective study of patients who required ECMO-CRRT.

RESULTS

Between the years of 2016 and 2022, 202 patients required ECMO-CRRT. One hundred and six patients (52.5%) survived their hospitalization and were followed up for a median of 391 [133, 1005] days. Eighty-one patients (76.5%) recovered kidney function and were dialysis-free before hospital discharge. Twenty-five patients (23.5%) were hemodialysis-dependent after hospitalization. On multivariate regression analysis, hyperlipidemia (odds ratio, OR 6.08 [1.67-22]) and CRRT duration (OR 1.09 [1.03-1.15]) were associated with the need for dialysis post-hospitalization. In this group, 16 patients eventually became dialysis-free, after a median of 49 [34.7, 78.5] days. These patients had a higher median baseline glomerular filtration rate (GFR) compared to those who never recovered renal function (93 mL/min/1.73 m2 [82.4, 104.3] vs. 63.8 mL/min/1.73 m2 [37.9, 83], p = .009). Their follow-up GFR was lower compared to those who recovered renal function before hospital discharge; (87 mL/min/1.73 m2 [68.2, 98.9] vs. 99 mL/min/1.73 m2 [79, 118], p = .07).

CONCLUSIONS

AKI requiring CRRT was associated with high mortality in patients receiving ECMO. Nonetheless, most ECMO survivors became dialysis-free before hospital discharge. Variables associated with the need for outpatient dialysis included hyperlipidemia and prolonged need for CRRT during hospitalization.

Long-term renal outcomes of patients with COVID-19: a meta-analysis of observational studies

BACKGROUND

Kidney involvement is common in hospitalized coronavirus disease 2019 (COVID-19) patients during the acute phase, little is known about the long-term impact of COVID-19 on the kidney.

METHODS

This is a systematic review and meta-analysis on long-term renal outcomes among COVID-19 patients. We carried out a systematic literature search in PUBMED, EMBASE, SCOPUS, and Cochrane COVID-19 study register and performed the random-effects meta-analysis of rates. The search was last updated on November 23, 2022.

RESULTS

The study included 12 moderate to high-quality cohort studies involving 6976 patients with COVID-19-associated acute kidney injury and 5223 COVID-19 patients without acute kidney injury. The summarized long-term renal non-recovery rate, dialysis-dependent rate, and complete recovery rate among patients with COVID-19-associated AKI was 22% (12-33%), 6% (2-12%), and 63% (44-81%) during a follow-up of 90-326.5 days. Heterogeneity could be explained by differences in the prevalence of chronic kidney disease and proportion of acute kidney injury requiring renal replacement therapy using meta-regression; patients with more comorbidities or higher renal replacement therapy rate had higher non-recovery rates. The summarized long-term kidney function decrease rate among patients without acute kidney injury was 22% (3-51%) in 90-199 days, with heterogeneity partially explained by severity of infection.

CONCLUSION

Patients with more comorbidities tend to have a higher renal non recovery rate after COVID-19-associated acute kidney injury; for COVID-19 patients without acute kidney injury, decrease in kidney function may occur during long-term follow-up. Regular evaluation of kidney function during the post-COVID-19 follow-up among high-risk patients may be necessary.

Transitions of dialysis status and outcomes after the unplanned first dialysis: a nationwide population-based cohort study

In Taiwan, most first-time dialysis was started without the creation of an arteriovenous shunt. Here, we aimed to elucidate the transitions of dialysis status in the unplanned first dialysis patients and determine factors associated with their outcomes. A total of 50,315 unplanned first dialysis patients aged more than 18 years were identified from the National Health Insurance Dataset in Taiwan between 2001 and 2012. All patients were followed for 5 years for the transitions in dialysis status, including robust (dialysis-free), sporadic dialysis, continued dialysis, and death. Furthermore, factors associated with the development of continued dialysis and death were examined by the Cox proportional hazard models. After 5 years after the first dialysis occurrence, there were 5.39% with robust status, 1.67% with sporadic dialysis, 8.45% with continued dialysis, and 84.48% with death. Notably, we have identified common risk factors for developing maintenance dialysis and deaths, including male gender, older age, diabetes, coronary heart disease, stroke, heart failure, sepsis, and surgery. There was an extremely high mortality rate among the first unplanned dialysis patients in Taiwan. Less than 10% of these patients underwent continued dialysis during the 5-year follow-up period. This study highlighted the urgent need for interventions to improve patient outcomes.

The incidence, mortality and renal outcomes of acute kidney injury in patients with suspected infection at the emergency department

Background

Acute kidney injury (AKI) is a major health problem associated with considerable mortality and morbidity. Studies on clinical outcomes and mortality of AKI in the emergency department are scarce. The aim of this study is to assess incidence, mortality and renal outcomes after AKI in patients with suspected infection at the emergency department.

Methods

We used data from the SPACE-cohort (SePsis in the ACutely ill patients in the Emergency department), which included consecutive patients that presented to the emergency department of the internal medicine with suspected infection. Hazard ratios (HR) were assessed using Cox regression to investigate the association between AKI, 30-days mortality and renal function decline up to 1 year after AKI. Survival in patients with and without AKI was assessed using Kaplan-Meier analyses.

Results

Of the 3105 patients in the SPACE-cohort, we included 1716 patients who fulfilled the inclusion criteria. Of these patients, 10.8% had an AKI episode. Mortality was 12.4% for the AKI group and 4.2% for the non-AKI patients. The adjusted HR for all-cause mortality at 30-days in AKI patients was 2.8 (95% CI 1.7–4.8). Moreover, the cumulative incidence of renal function decline was 69.8% for AKI patients and 39.3% for non-AKI patients. Patients with an episode of AKI had higher risk of developing renal function decline (adjusted HR 3.3, 95% CI 2.4–4.5) at one year after initial AKI-episode at the emergency department.

Conclusion

Acute kidney injury is common in patients with suspected infection in the emergency department and is significantly associated with 30-days mortality and renal function decline one year after AKI.

Recovery after Critical Illness and Acute Kidney Injury

AKI is a common complication in hospitalized and critically ill patients. Its incidence has steadily increased over the past decade. Whether transient or prolonged, AKI is an independent risk factor associated with poor short- and long-term outcomes, even if patients do not require KRT. Most patients with early AKI improve with conservative management; however, some will require dialysis for a few days, a few weeks, or even months. Approximately 10%-30% of AKI survivors may still need dialysis after hospital discharge. These patients have a higher associated risk of death, rehospitalization, recurrent AKI, and CKD, and a lower quality of life. Survivors of critical illness may also suffer from cognitive dysfunction, muscle weakness, prolonged ventilator dependence, malnutrition, infections, chronic pain, and poor wound healing. Collaboration and communication among nephrologists, primary care physicians, rehabilitation providers, physical therapists, nutritionists, nurses, pharmacists, and other members of the health care team are essential to create a holistic and patient-centric care plan for overall recovery. Integration of the patient and family members in health care decisions, and ongoing education throughout the process, are vital to improve patient well-being. From the nephrologist standpoint, assessing and promoting recovery of kidney function, and providing appropriate short- and long-term follow-up, are crucial to prevent rehospitalizations and to reduce complications. Return to baseline functional status is the ultimate goal for most patients, and dialysis independence is an important part of that goal. In this review, we seek to highlight the varying aspects and stages of recovery from AKI complicating critical illness, and propose viable strategies to promote recovery of kidney function and dialysis independence. We also emphasize the need for ongoing research and multidisciplinary collaboration to improve outcomes in this vulnerable population.

Risk factors and prognosis assessment for acute kidney injury: The 2020 consensus of the Taiwan AKI Task Force

Risk and prognostic factors for acute kidney injury (AKI) have been published in various studies across various populations. We aimed to explore recent advancements in and provide updated recommendations on AKI risk stratification and information about local AKI risk factors. The Taiwan Acute Kidney Injury Task Force reviewed relevant recently published literature and reached a consensus after group meetings. Systemic review and group discussion were performed. We conducted a meta-analysis according to the PRISMA statement for evaluating the diagnostic performance of the furosemide stress test. Several risk and susceptibility factors were identified through literature review. Contrast-associated AKI prediction models after coronary angiography were one of the most discussed prediction models we found. The basic approach and evaluation of patients with AKI was also discussed. Our meta-analysis found that the furosemide stress test can be used as a prognostic tool for AKI progression and to identify patients with AKI who are at low risk of renal replacement therapy. Factors associated with de novo chronic kidney injury or renal non-recovery after AKI were identified and summarized. Our review provided practical information about early identification of patients at high risk of AKI or disease progression for Taiwan local clinics.

Mortality and Recovery Associated with Kidney Failure due to Acute Kidney Injury

BACKGROUND AND OBJECTIVES

AKI requiring dialysis is a contributor to the growing burden of kidney failure, yet little is known about the frequency and patterns of recovery of AKI and its effect on outcomes in patients on incident dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using the US Renal Data System, we evaluated a cohort of 1,045,540 patients on incident dialysis from January 1, 2005 to December 31, 2014, retrospectively. We examined the association of kidney failure due to AKI with the outcome of all-cause mortality and the associations of sex and race with kidney recovery.

RESULTS

Mean age was 63±15 years, and 32,598 (3%) patients on incident dialysis had kidney failure due to AKI. Compared with kidney failure due to diabetes mellitus, kidney failure attributed to AKI was associated with a higher mortality in the first 0-3 months following dialysis initiation (adjusted hazard ratio, 1.28; 95% confidence interval, 1.24 to 1.32) and 3-6 months (adjusted hazard ratio, 1.16; 95% confidence interval, 1.11 to 1.20). Of the patients with kidney failure due to AKI, 11,498 (35%) eventually recovered their kidney function, 95% of those within 12 months. Women had a lower likelihood of kidney recovery than men (adjusted hazard ratio, 0.86; 95% confidence interval, 0.83 to 0.90). Compared with whites, blacks (adjusted hazard ratio, 0.68; 95% confidence interval, 0.64 to 0.72), Asians (adjusted hazard ratio, 0.82; 95% confidence interval, 0.69 to 0.96), Hispanics (adjusted hazard ratio, 0.82; 95% confidence interval, 0.76 to 0.89), and Native Americans (adjusted hazard ratio, 0.72; 95% confidence interval, 0.54 to 0.95) had lower likelihoods of kidney recovery.

CONCLUSIONS

Kidney failure due to AKI confers a higher risk of mortality in the first 6 months compared with kidney failure due to diabetes or other causes. Recovery within 12 months is common, although less so among women than men and among black, Asian, Hispanic, and Native American patients than white patients.

The future for diagnostic tests of acute kidney injury in critical care: evidence synthesis, care pathway analysis and research prioritisation

BACKGROUND

Acute kidney injury (AKI) is highly prevalent in hospital inpatient populations, leading to significant mortality and morbidity, reduced quality of life and high short- and long-term health-care costs for the NHS. New diagnostic tests may offer an earlier diagnosis or improved care, but evidence of benefit to patients and of value to the NHS is required before national adoption.

OBJECTIVES

To evaluate the potential for AKI in vitro diagnostic tests to enhance the NHS care of patients admitted to the intensive care unit (ICU) and identify an efficient supporting research strategy.

DATA SOURCES

We searched ClinicalTrials.gov, The Cochrane Library databases, Embase, Health Management Information Consortium, International Clinical Trials Registry Platform, MEDLINE, metaRegister of Current Controlled Trials, PubMed and Web of Science databases from their inception dates until September 2014 (review 1), November 2015 (review 2) and July 2015 (economic model). Details of databases used for each review and coverage dates are listed in the main report.

REVIEW METHODS

The AKI-Diagnostics project included horizon scanning, systematic reviewing, meta-analysis of sensitivity and specificity, appraisal of analytical validity, care pathway analysis, model-based lifetime economic evaluation from a UK NHS perspective and value of information (VOI) analysis.

RESULTS

The horizon-scanning search identified 152 potential tests and biomarkers. Three tests, Nephrocheck^® (Astute Medical, Inc., San Diego, CA, USA), NGAL and cystatin C, were subjected to detailed review. The meta-analysis was limited by variable reporting standards, study quality and heterogeneity, but sensitivity was between 0.54 and 0.92 and specificity was between 0.49 and 0.95 depending on the test. A bespoke critical appraisal framework demonstrated that analytical validity was also poorly reported in many instances. In the economic model the incremental cost-effectiveness ratios ranged from £11,476 to £19,324 per quality-adjusted life-year (QALY), with a probability of cost-effectiveness between 48% and 54% when tests were compared with current standard care.

LIMITATIONS

The major limitation in the evidence on tests was the heterogeneity between studies in the definitions of AKI and the timing of testing.

CONCLUSIONS

Diagnostic tests for AKI in the ICU offer the potential to improve patient care and add value to the NHS, but cost-effectiveness remains highly uncertain. Further research should focus on the mechanisms by which a new test might change current care processes in the ICU and the subsequent cost and QALY implications. The VOI analysis suggested that further observational research to better define the prevalence of AKI developing in the ICU would be worthwhile. A formal randomised controlled trial of biomarker use linked to a standardised AKI care pathway is necessary to provide definitive evidence on whether or not adoption of tests by the NHS would be of value.

STUDY REGISTRATION

The systematic review within this study is registered as PROSPERO CRD42014013919.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Outcomes of acute kidney injury in a nephrology ward

Acute kidney injury (AKI) is a global problem which predicts immediate and long-term adverse outcomes. We evaluated the AKI progression to end-stage renal disease, as well as the mortality associated with AKI and the in-hospital readmission rate because of a cardiovascular event in AKI patients admitted in a nephrology ward. A 5-year retrospective study was set in a nephrology department, with a follow-up period of up to 8 years. In a total of 191 patients, mean age was 73.83 ± 12.49 years, and 137 (71.7%) patients had history of chronic kidney disease. One hundred and twenty-four (65%) patients needed RRT and two (1%) needed surgery. Upon discharge, 107 (56%) patients had recovered the renal function, 41 (21.6%) patients had partial recovery, 25 (13%) patients were RRT dependent, 16 (8.4%) died, and two (1%) patients had outcomes unknown to us, because they were transferred to other hospitals. The median survival time free of RRT was 74 months. The median survival time of the followed patients was 34 months (95% CI 23.3-44.7). The mortality rate in the follow-up period in this sample was 18 deaths/100 patients-years, and the incidence of a composite cardiovascular endpoint of heart failure, acute coronary syndrome, and stroke was 6 events/100 patients-years. The mortality rate in the follow-up period was higher than usually described for patients outside intensive care unit, probably because our patients were old and had many comorbidities.

Long-term outcome of severe acute kidney injury survivors followed by nephrologists in a developing country

AIM

This study aimed to evaluate the long-term outcome of patients after a severe episode of acute kidney injury (AKI) on survival and progression to chronic kidney disease (CKD) and to identify risk factors associated with these outcomes.

METHODS

We performed a prospective study that evaluated the long-term outcome of 509 AKI stage 3 patients who were followed by nephrologists in a Brazilian University Hospital from 2004 to 2013.

RESULTS

Age was 60.2 years (47.5-71) and the follow-up time was 25 months (12-44). The late mortality was 38.1% and age (HR 2.89, 95% CI=1.88 to 4.46, P < 0.0001), diabetes (HR 1.46, 95% CI=1 0.02 to 2.16, P < 0.047), liver disease (HR 2.95, 95% CI=1.19 to 7.3, P = 0.02) and creatinine (Cr) at the time of hospital discharge (HR 1.21, 95% CI=1.04 to 1.41, P = 0.01) were associated with poor long-term survival. At the moment of hospital discharge, 52.1% of patients had complete recovery of renal function, 39.7% had partial recovery and 8.3% had not recovered renal function. After 36 months, 43.5% of patients progressed to CKD, and 5.3% needed for chronic dialysis. Factors associated with progression to CKD were age (HR 1.02, 95% CI=1.008 to 1.035, P = 0.009), CKD (HR 1.05 95% CI=1.007 to 1.09, P = 0.04), diabetes (HR 1.12, CI 1.008-1.035, P = 0.009) and number of AKI episodes (HR 1.65, 95% CI=1.19 to 2.2, P = 0.0023).

CONCLUSION

This study showed that AKI patients have high mortality after hospital discharge and age, diabetes, liver disease, and Cr value at the time of discharge were factors associated with long-term mortality. The risk factors for this progression to CKD were age, the presence of diabetes and the number of AKI episodes.

DNA repair in ischemic acute kidney injury

Ischemia-reperfusion injury (IRI) is a common cause of acute kidney injury leading to an induction of oxidative stress, cellular dysfunction, and loss of renal function. DNA damage, including oxidative base modifications and physical DNA strand breaks, is a consequence of renal IRI. Like many other organs in the body, a redundant and highly conserved set of endogenous repair pathways have evolved to selectively recognize the various types of cellular DNA damage and combat its negative effects on cell viability. Severe damage to the DNA, however, can trigger cell death and elimination of the injured tubular epithelial cells. In this minireview, we summarize the state of the current field of DNA damage and repair in the kidney and provide some expected and, in some cases, unexpected effects of IRI on DNA damage and repair in the kidney. These findings may be applicable to other forms of acute kidney injury and could provide new opportunities for renal research.

Health status, renal function, and quality of life after multiorgan failure and acute kidney injury requiring renal replacement therapy

Background

Critically ill patients with acute kidney injury (AKI) in need of renal replacement therapy (RRT) may have a protracted and often incomplete rehabilitation. Their long-term outcome has rarely been investigated.

Study design

Survivors of the HANnover Dialysis OUTcome (HANDOUT) study were evaluated after 5 years for survival, health status, renal function, and quality of life (QoL). The HANDOUT study had examinded mortality and renal recovery of patients with AKI receiving either standard extendend or intensified dialysis after multi organ failure.

Results

One hundred fifty-six former HANDOUT participants were analyzed. In-hospital mortality was 56.4%. Five-year survival after AKI/RRT was 40.1% (86.5% if discharged from hospital). Main causes of death were cardiovascular complications and sepsis. A total of 19 survivors presented to the outpatient department of our clinic and had good renal recovery (mean estimated glomerular filtration rate 72.5±30 mL/min/1.73 m²; mean proteinuria 89±84 mg/d). One person required maintenance dialysis. Seventy-nine percent of the patients had a pathological kidney sonomorphology. The Charlson comorbidity score was 2.2±1.4 and adjusted for age 3.3±2.1 years. Numbers of comorbid conditions averaged 2.38±1.72 per patient (heart failure [52%] > chronic kidney disease/myocardial infarction [each 29%]). Median 36-item short form health survey (SF-36™) index was 0.657 (0.69 physical health/0.66 mental health). Quality-adjusted life-years after 5 years were 3.365.

Conclusion

Mortality after severe AKI is higher than short-term prospective studies show, and morbidity is significant. Kidney recovery as well as general health remains incomplete. Reduction of QoL is minor, and social rehabilitation is very good. Affectivity is heterogeneous, but most patients experience emotional well-being. In summary, AKI in critically ill patients leads to incomplete rehabilitation but acceptable QoL after 5 years.

Promoting Kidney Function Recovery in Patients with AKI Requiring RRT

AKI requiring RRT is associated with high mortality, morbidity, and long-term consequences, including CKD and ESRD. Many patients never recover kidney function; in others, kidney function improves over a period of many weeks or months. Methodologic constraints of the available literature limit our understanding of the recovery process and hamper adequate intervention. Current management strategies have focused on acute care and short-term mortality, but new data indicate that long-term consequences of AKI requiring RRT are substantial. Promotion of kidney function recovery is a neglected focus of research and intervention. This lack of emphasis on recovery is illustrated by the relative paucity of research in this area and by the lack of demonstrated effective management strategies. In this article the epidemiologic implications of kidney recovery after AKI requiring RRT are discussed, the available literature and its methodologic constraints are reviewed, and strategies to improve the understanding of factors that affect kidney function recovery are proposed. Measures to promote kidney function recovery are a serious unmet need, with a great potential to improve short- and long-term patient outcomes.

Long-term outcomes of survivors of ICU acute kidney injury requiring renal replacement therapy: a 10-year prospective cohort study

BACKGROUND

Acute kidney injury (AKI) requiring renal replacement therapy (RRT) is associated with high in-hospital morbidity and mortality in critically ill patients. Long-term outcomes have received little attention.

METHODS

The aim of this study was to characterize AKI-chronic kidney disease (CKD) nexus in critically ill patients with AKI (RIFLE class F). We performed a single-centre prospective observational study of 425 consecutive critically ill patients with AKI requiring RRT. None of these patients had pre-existing kidney disease. Primary outcomes were vital status and renal function at hospital discharge and at 5 and 10 years of follow-up.

RESULTS

The overall in-hospital mortality of the study cohort was 47%, the mortality rates at 1, 5 and 10 years were 65, 75 and 80%, respectively. At hospital discharge, recovery of renal function was complete in 56% of survivors. None of these patients developed CKD during follow-up. Ninety percent of the 100 survivors with partial recovery of renal function had ongoing CKD during long-term follow-up. CKD progressed to end-stage renal disease (ESRD) in 12 patients (3% of the cohort or 5% of survivors). The patients with post-AKICKD had a higher prevalence of hypertension, a higher rate of fatal cardiac diseases and a higher all-cause death rate.

CONCLUSION

Long-term survival of critically ill patients with AKI requiring RRT is poor and determined by the development of de novo CKD. There is a need for close follow-up of patients surviving AKI to prevent progressive CKD and to reduce associated lethal cardiac events.

Bicarbonate- versus lactate-buffered solutions for acute continuous haemodiafiltration or haemofiltration

BACKGROUND

Acute kidney injury (AKI) is a severe loss of kidney function that results in patients' inability to appropriately excrete nitrogenous wastes and creatinine. Continuous haemodiafiltration (HDF) or haemofiltration (HF) are commonly used renal replacement therapies for people with AKI. Buffered dialysates and solutions used in HDF or HF have varying effects on acid-base physiology and several electrolytes. The benefits and harms of bicarbonate- versus lactate-buffered HDF or HF solutions for treating patients with AKI remain unclear.

OBJECTIVES

To assess the benefits and harms of bicarbonate- versus lactate-buffered solutions for HDF or HF for treating people with AKI.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 6 January 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review. We also searched the Chinese Biomedical Literature Database.

SELECTION CRITERIA

All randomised controlled trials (RCT) and quasi-RCTs that reported comparisons of bicarbonate-buffered solutions with lactate-buffered solutions for AKI were selected for inclusion irrespective of publication status or language.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed titles and abstracts, and where necessary the full text of studies, to determine which satisfied our inclusion criteria. Data were extracted by two authors who independently assessed studies for eligibility and quality using a standardised data extraction form. Methodological quality was assessed using the Cochrane risk of bias tool. Results were expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

We identified four studies (171 patients) that met our inclusion criteria. Overall, study quality was suboptimal. There were significant reporting omissions related to methodological issues and potential harms. Outcome measures were not defined or reported adequately. The studies were small and lacked follow-up phases.Serum lactate levels were significantly lower in patients treated with bicarbonate-buffered solutions (4 studies, 171 participants: MD -1.09 mmol/L, 95% CI -1.30 to -0.87; I(2) = 0%). There were no differences in mortality (3 studies, 163 participants: RR 0.76, 95% CI 0.50 to 1.15; I(2) = 0%); serum bicarbonate levels (3 studies, 163 participants: MD 0.27 mmol/L, 95% CI -1.45 to 1.99; I(2) = 78%), serum creatinine (2 studies, 137 participants: MD -22.81 µmol/L, 95% CI -129.61 to 83.99; I(2) = 73%), serum base excess (3 studies, 145 participants: MD 0.80, 95% CI -0.91 to 2.50; I(2) = 38%), serum pH (4 studies, 171 participants: MD 0.01, 95% CI -0.02 to 0.03; I(2) = 70%) or carbon dioxide partial pressure (3 studies, 151 participants: MD -1.04, 95% CI -3.84 to 1.76; I(2) = 83%). A single study reported fewer cardiovascular events (RR 0.39, 95% CI 0.20 to 0.79), higher mean arterial pressure (10.25 mm Hg, 95% CI 6.68 to 13.82) and less hypotensive events (RR 0.44, 95% CI 0.26 to 0.75) in patients receiving bicarbonate-buffered solutions. One study reported no significant difference in central venous pressure (MD 2.00 cm H2O, 95% CI -0.7 to, 4.77). Total length of hospital and ICU stay and relapse were not reported by any of the included studies.

AUTHORS' CONCLUSIONS

There were no significant different between bicarbonate- and lactate-buffered solutions for mortality, serum bicarbonate levels, serum creatinine, serum base excess, serum pH, carbon dioxide partial pressure, central venous pressure and serum electrolytes. Patients treated with bicarbonate-buffered solutions may experience fewer cardiovascular events, lower serum lactate levels, higher mean arterial pressure and less hypotensive events. With the exception of mortality, we were not able to assess the main primary outcomes of this review - length of time in ICU, total length of hospital stay and relapse.

End-stage renal disease attributed to acute tubular necrosis in the United States, 2001-2010

BACKGROUND/AIMS

Though end-stage renal disease (ESRD) is increasingly attributed to acute tubular necrosis (ATN), contemporary trends in the rates of incidence and recovery of renal function are poorly defined. Hence, we set out to describe the clinical epidemiology of ESRD due to ATN between 2001 and 2010.

METHODS

We examined United States Renal Data System data (n = 1,070,490) for 2001 through 2010 to calculate the incidence rates and rates of renal recovery and death for patients with ESRD due to ATN treated with renal replacement therapy (RRT, n = 27,603).

RESULTS

Standardized incidence ratios increased between 2001-2002 and 2009-2010 in the overall population (ratio 2.14), having risen in all demographic subgroups examined. Recovery of renal function was more likely in patients with ATN than in matched controls (cumulative incidence 23% vs. 2% at 12 weeks, 34% vs. 4% at 1 year), as was death (cumulative incidence 38% vs. 27% at 1 year). Hazards ratios for renal recovery increased stepwise with year of RRT inception to 1.34 (95% confidence interval 1.24-1.45) for 2009-2010 (vs. 2001-2002). In contrast, hazards ratios for death declined stepwise to 0.83 (0.79-0.87) in 2009-2010.

CONCLUSION

While the incidence of ESRD attributed to ATN has increased, prospects of renal recovery and survival have also increased. Despite substantial mortality risk on RRT, renal recovery is not a rare occurrence.

Clinical determinants of renal recovery

Acute kidney injury (AKI) is associated with increased mortality, prolonged hospitalization, and renal replacement therapy. Until recently, it was believed that the vast majority of patients recover from AKI without subsequent consequences. It is now recognized that patients with AKI may have very different renal outcomes, including complete recovery, incipient and progressive chronic kidney disease, and end-stage renal disease. Factors that influence these different outcomes have not been thoroughly evaluated and so are not currently understood. The patient's baseline demographic characteristics, subsequent clinical evolution, and factors associated with the treatment of these patients may all influence global and renal outcomes. Recovery from AKI is a potentially modifiable event and should be targeted for therapy. Useful tools are needed to monitor renal recovery and identify the patients at high risk for adverse outcomes.

Repair or progression after AKI: a role for biomarkers?

Recent progress in biomarkers represents a paradigm shift in acute kidney injury (AKI) research. Most studies have evaluated the use of these biomarkers for early diagnosis of AKI. However, the role of novel biomarkers in predicting renal recovery, though less understood, holds great clinical promise. Accurate prediction would help physicians distinguish patients with poor renal prognosis in whom further therapy is unlikely to be useful from those who are likely to have good renal prognosis. Unfortunately, current general clinical severity scores (APACHE, SOFA, etc.) and AKI-specific severity scores are not good predictors of renal recovery. The biology of renal recovery requires the repopulation by surviving renal tubular epithelial cells with the assistance of certain renal epithelial cell and specific growth factors such as neutrophil gelatinase-associated lipocalin (NGAL), hepatocyte growth factor (HGF), epidermal growth factor, and insulin-like growth factor-1 (IGF-1), etc. These markers play a major role in the recovery process. This review will describe the mechanisms of the renal recovery, epidemiology, the role of conventional clinical predictors and finally the role of novel biomarkers (NGAL, HGF, IL-8, IL-18, TNFR-1, IGF-binding protein-7 and tissue inhibitor of metalloproteinase-2) in predicting renal recovery.

Syndrome of rapid onset end stage renal disease in incident Mayo Clinic chronic hemodialysis patient

Despite decades of research, a full understanding of chronic kidney disease (CKD)-end stage renal disease (ESRD) progression remains elusive. The common consensus is a predictable, linear, progressive and time-dependent decline of CKD to ESRD. Acute kidney injury (AKI) on CKD is usually assumed to be transient, with recovery as the expected outcome. AKI-ESRD association in current nephrology literature is blamed on the so-called "residual confounding." We had previously described a relationship between AKI events and rapid onset yet irreversible ESRD happening in a continuum in a high-risk CKD cohort. However, the contribution of the syndrome of rapid onset-ESRD (SORO-ESRD) to incident United States ESRD population remained conjectural. In this retrospective analysis, we analyzed serum creatinine trajectories of the last 100 consecutive ESRD patients in 4 Mayo Clinic chronic hemodialysis units to determine the incidence of SORO-ESRD. Excluding 9 patients, 31 (34%) patients, including two renal transplant recipients, had SORO-ESRD: 18 males and 13 females age 72 (range 50-92) years. Precipitating AKI followed pneumonia (8), acutely decompensated heart failure (7), pyelonephritis (4), post-operative (5), sepsis (3), contrast-induced nephropathy (2), and others (2). Time to dialysis was shortest following surgical procedures. Concurrent renin angiotensin aldosterone system blockade was higher with SORO-ESRD - 23% versus 5%, P = 0.0113. In conclusion, SORO-ESRD is not uncommon among the incident general US ESRD population. The implications for ESRD care planning, AV-fistula-first programs, general CKD care and any associations with renal ageing/senescence warrant further study.

[Perioperative acute kidney injury and failure]

Perioperative period is very likely to lead to acute renal failure because of anesthesia (general or perimedullary) and/or surgery which can cause acute kidney injury. Characterization of acute renal failure is based on serum creatinine level which is imprecise during and following surgery. Studies are based on various definitions of acute renal failure with different thresholds which skewed their comparisons. The RIFLE classification (risk, injury, failure, loss, end stage kidney disease) allows clinicians to distinguish in a similar manner between different stages of acute kidney injury rather than using a unique definition of acute renal failure. Acute renal failure during the perioperative period can mainly be explained by iatrogenic, hemodynamic or surgical causes and can result in an increased morbi-mortality. Prevention of this complication requires hemodynamic optimization (venous return, cardiac output, vascular resistance), discontinuation of nephrotoxic drugs but also knowledge of the different steps of the surgery to avoid further degradation of renal perfusion. Diuretics do not prevent acute renal failure and may even push it forward especially during the perioperative period when venous retourn is already reduced. Edema or weight gain following surgery are not correlated with the vascular compartment volume, much less with renal perfusion. Treatment of perioperative acute renal failure is similar to other acute renal failure. Renal replacement therapy must be mastered to prevent any additional risk of hemodynamic instability or hydro-electrolytic imbalance.

CDK4/6 inhibition induces epithelial cell cycle arrest and ameliorates acute kidney injury

Acute kidney injury (AKI) is common and urgently requires new preventative therapies. Expression of a cyclin-dependent kinase (CDK) inhibitor transgene protects against AKI, suggesting that manipulating the tubular epithelial cell cycle may be a viable therapeutic strategy. Broad spectrum small molecule CDK inhibitors are protective in some kidney injury models, but these have toxicities and epithelial proliferation is eventually required for renal repair. Here, we tested a well-tolerated, novel and specific small molecule inhibitor of CDK4 and CDK6, PD 0332991, to investigate the effects of transient cell cycle inhibition on epithelial survival in vitro and kidney injury in vivo. We report that CDK4/6 inhibition induced G0/G1 cycle arrest in cultured human renal proximal tubule cells (hRPTC) at baseline and after injury. Induction of transient G0/G1 cycle arrest through CDK4/6 inhibition protected hRPTC from DNA damage and caspase 3/7 activation following exposure to the nephrotoxins cisplatin, etoposide, and antimycin A. In vivo, mice treated with PD 0332991 before ischemia-reperfusion injury (IRI) exhibited dramatically reduced epithelial progression through S phase 24 h after IRI. Despite reduced epithelial proliferation, PD 0332991 ameliorated kidney injury as reflected by improved serum creatinine and blood urea nitrogen levels 24 h after injury. Inflammatory markers and macrophage infiltration were significantly decreased in injured kidneys 3 days following IRI. These results indicate that induction of proximal tubule cell cycle arrest with specific CDK4/6 inhibitors, or "pharmacological quiescence," represents a novel strategy to prevent AKI.

Evidence of the syndrome of rapid onset end-stage renal disease (SORO-ESRD) in the acute kidney injury (AKI) literature--preventable causes of AKI and SORO-ESRD--a call for re-engineering of nephrology practice paradigms

INTRODUCTION

We described the previously unrecognized syndrome of rapid-onset end-stage renal disease (SORO-ESRD) in 2010, in the journal Renal Failure, as distinct from the classic CKD-ESRD progression of a methodical, linear, time-dependent and predictable progression from CKD through CKD stages I-V, ending in ESRD requiring renal replacement therapy (RRT). It remains unclear to what extent this syndrome may have been identified in the past without acknowledging its uniqueness.

METHODS

We reviewed AKI reports and ascertained cases of SORO-ESRD as defined by patients with a priori stable kidney function who subsequently exhibited unanticipated and irreversible ESRD requiring RRT following new AKI episodes.

RESULTS

Fifteen AKI reports demonstrating SORO-ESRD were analyzed. The reports span most regions of the world. The 15 studies with 20 to 1095 AKI patients each, mean age 39-65 years, published between 1975 and 2010, demonstrated SORO-ESRD rates from 1% to 85% of the AKI series. AKI was caused by hypovolemia/hypotension, infections/sepsis and exposure to nephrotoxics especially radiocontrast, NSAIDs, aminoglycosides and RAAS blocking agents, ACEIs and ARBs.

DISCUSSION

Irreversible ESRD following AKI, consistent with our recent description of a new and unrecognized syndrome has been sporadically reported in the AKI literature, without a clear mandate as a syndrome, potentially distinct from the classic ESRD. The contribution of SORO-ESRD to the global ESRD pandemic, the impact of SORO-ESRD on AV-Fistula planning, any differential behavior of SORO-ESRD versus classic ESRD in terms of mortality outcomes and any predisposing factors to SORO-ESRD as advanced age and nephrotoxic exposure all call for serious research study.

Cardiac surgery-associated acute kidney injury

Cardiac surgery-associated acute kidney injury (AKI) is a major health problem that is extremely common and has a significant effect on cardiac surgical outcomes. AKI occurs in nearly 30 % of patients undergoing cardiac surgery, with about 1-2 % of these ultimately requiring dialysis. The development of AKI predicts a significant increase in morbidity and mortality independent of other risk factors. The pathogenetic mechanisms associated with cardiac surgery-associated AKI include several biochemical pathways, of which the most important are hemodynamic, inflammatory and nephrotoxic factors. Risk factors for AKI have been identified in several models, and these facilitate physicians to prognosticate and develop a strategy for tackling patients predisposed to developing renal dysfunction. Effective therapy of the condition is still suboptimal, and hence the accent has always been on risk factor modification. Thus, strategies for reducing preoperative anemia, perioperative blood transfusions and surgical re-explorations may be effective in attenuating the incidence and severity of this complication.

Renoprevention: A new concept for reengineering nephrology care--an economic impact and patient outcome analysis of two hypothetical patient management paradigms in the CCU

BACKGROUND

The impact of acute kidney injury (AKI) on chronic kidney disease (CKD) progression remains uncertain; the common belief is that AKI in CKD is short-lived with subsequent full recovery. However 25.2% of end-stage renal disease (ESRD) Medicare patients all experienced antecedent AKI. We recently described a new syndrome of ESRD following AKI, the syndrome of rapid-onset end-stage renal disease (SORO-ESRD). Renoprevention, which we described in 2009, is the application of preventative measures to reduce AKI incidence.

METHODS

This is a descriptive study based on real clinical experience. Two hypothetical 69-year-old Caucasian male patients, A and B, with symptomatic coronary artery disease (CAD) presented for elective cardiac catheterization and subsequent coronary artery bypass graft procedures; renoprevention was applied in patient A but not in B.

RESULTS

Aggressive fluid repletion, withholding Lisinopril 40 mg once daily (QD) 1 week before hospitalization (hydralazine substituted) in A-earlier discharge after 6 days, transient minimal change in serum creatinine. Patient B continued on Lisinopril 40 mg QD, experienced prolonged hypotension needing pressors-severe oliguric AKI, volume overload, daily RRT for 6 days, recovered kidney function, was discharged after 20 days. Hospital charges were $68,580 (A) versus $154,650 (B). If patient B had developed ESRD (SORO-ESRD), the savings would be humongous.

CONCLUSION

A more forceful and pragmatic application of renoprevention strategies in the coronary care unit (CCU)-preemptive withholding of nephrotoxics including renin angiotensin aldosterone system (RAAS) blockers, aggressive prevention of perioperative hypotension, avoiding nephrotoxic exposure as contrast, and antibiotics-leads to less AKI, potentially less SORO-ESRD, better patient outcomes, and massive dollar savings. Such paradigm shifts would constitute major rethinking in current nephrology practice, a form of nephrology practice reengineering.

The impact of an "acute dialysis start" on the mortality attributed to the use of central venous catheters: a retrospective cohort study

Background

Central venous catheters (CVCs) are associated with early mortality in dialysis patients. However, some patients progress to end stage renal disease after an acute illness, prior to reaching an estimated glomerular filtration rate (eGFR) at which one would expect to establish alternative access (fistula/peritoneal dialysis catheter). The purpose of this study was to determine if exclusion of this “acute start” patient group alters the association between CVCs and mortality.

Methods

We conducted a retrospective cohort study of 406 incident dialysis patients from 1 Jan 2006 to 31 Dec 2009. Patients were classified as acute starts if 1) the eGFR was >25 ml/min/1.73 m², ≤3 months prior to dialysis initiation and declined after an acute event (n = 45), or 2) in those without prior eGFR measurements, there was no supporting evidence of chronic kidney disease on history or imaging (n = 12). Remaining patients were classified as chronic start (n = 349).

Results

98 % and 52 % of acute and chronic starts initiated dialysis with a CVC. There were 148 deaths. The adjusted mortality hazard ratio (HR) for acute vs. chronic start patients was 1.84, (95 % CI [1.19-2.85]). The adjusted mortality HR for patients dialyzing with a CVC compared to alternative access was 1.19 (95 % CI [0.80-1.77]). After excluding acute start patients, the adjusted HR fell to 1.03 (95 % CI [0.67-1.57]).

Conclusions

A significant proportion of early dialysis mortality occurs after an acute start. Exclusion of this population attenuates the mortality risk associated with CVCs.

Adverse effects of α-ketoglutarate/malate in a rat model of acute kidney injury

Acute kidney injury (AKI) is the most common kidney disease in hospitalized patients with high mortality. Ischemia and reperfusion (I/R) is one of the major causes of AKI. The combination of α-ketoglutarate+malate (αKG/MAL) showed the ability to reduce hypoxia-induced damage to isolated proximal tubules. The present study utilizes a rat model of I/R-induced AKI accompanied by intensive biomonitoring to examine whether αKG/MAL provides protection in vivo. AKI was induced in male Sprague-Dawley rats by bilateral renal clamping (40 min) followed by reperfusion (240 min). αKG/MAL was infused continuously for 60 min before and 45 min after ischemia. Normoxic and I/R control groups received 0.9% NaCl solution. The effect of αKG/MAL was evaluated by biomonitoring, blood and plasma parameters, histopathology, and immunohistochemical staining for kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL), as well as by determination of tissue ATP and nonesterified fatty acid concentrations. Intravenous infusion of αKG/MAL at a cumulative dose of 1 mmol/kg each (146 mg/kg αKG and 134 mg/kg MAL) did not prevent I/R-induced increases in plasma creatinine, histopathological alterations, or cortical ATP depletion. On the contrary, the most notable adverse affect in animals receiving αKG/MAL was the decrease in mean arterial blood pressure, which was also accompanied by a reduction in heart rate. Supplementation with αKG/MAL, which is very protective against hypoxia-induced injury in isolated proximal tubules, does not protect against I/R-induced renal injury in vivo, possibly due to cardiovascular depressive effects.

Long-term follow-up of patients after acute kidney injury: patterns of renal functional recovery

BACKGROUND AND OBJECTIVES

Patients who survive acute kidney injury (AKI), especially those with partial renal recovery, present a higher long-term mortality risk. However, there is no consensus on the best time to assess renal function after an episode of acute kidney injury or agreement on the definition of renal recovery. In addition, only limited data regarding predictors of recovery are available.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

From 1984 to 2009, 84 adult survivors of acute kidney injury were followed by the same nephrologist (RCRMA) for a median time of 4.1 years. Patients were seen at least once each year after discharge until end stage renal disease (ESRD) or death. In each consultation serum creatinine was measured and glomerular filtration rate estimated. Renal recovery was defined as a glomerular filtration rate value ≥60 mL/min/1.73 m2. A multiple logistic regression was performed to evaluate factors independently associated with renal recovery.

RESULTS

The median length of follow-up was 50 months (30-90 months). All patients had stabilized their glomerular filtration rates by 18 months and 83% of them stabilized earlier: up to 12 months. Renal recovery occurred in 16 patients (19%) at discharge and in 54 (64%) by 18 months. Six patients died and four patients progressed to ESRD during the follow up period. Age (OR 1.09, p<0.0001) and serum creatinine at hospital discharge (OR 2.48, p = 0.007) were independent factors associated with non renal recovery. The acute kidney injury severity, evaluated by peak serum creatinine and need for dialysis, was not associated with non renal recovery.

CONCLUSIONS

Renal recovery must be evaluated no earlier than one year after an acute kidney injury episode. Nephrology referral should be considered mainly for older patients and those with elevated serum creatinine at hospital discharge.

[Acute kidney injury]

Acute kidney injury plays a pivotal role in intensive care medicine and exerts crucial adverse effects on the course of the disease and overall prognosis of the critically ill patient. Intensive renal support, including initiation of earlier dialysis or maximal uremic toxin removal by higher dosage and frequency of renal replacement therapy, and individualized selection of modality were not able to decrease excessive mortality in this population. Systemic acute inflammation, mediated, at least in part, by cytokines, and not secondary uremic side effects, seems to have a major impact on nonrenal organ damage. Assessment of short-term outcome in critically ill patients who develop acute kidney injury may underestimate the true burden of disease. The overall survival at 5 years in patients discharged alive after severe acute kidney injury necessitating renal replacement therapy is only 20-30%, comparable to cancer patients. In addition, acute renal damage was identified as an independent risk factor for progression of chronic renal insufficiency. Current research focuses on strategies for the prevention of acute kidney injury and on the establishment of effective biomarkers for the early recognition and accurate diagnosis of subclinical renal damage.

Long-term outcome after acute renal replacement therapy: a narrative review

BACKGROUND

Acute kidney injury (AKI) necessitating renal replacement therapy (RRT) is associated with high short-term mortality, relatively little however is known of the long-term outcome in these patients. This narrative review describes renal recovery, long-term mortality, and quality of life in RRT patients with acute kidney injury.

METHODS

A literature search using the PubMed search engine from the year 2000 to present with the MeSH terms 1) acute kidney injury, renal replacement therapy, prognosis, and 2) acute kidney injury, quality of life, prognosis, was performed, including studies addressing long-term outcome (over 60 days) in adults with AKI on RRT.

RESULTS

According to inclusion criteria, twenty two studies were eligible. Outcome varied depending on AKI aetiology, setting, co-morbidity and pre-morbid renal function. Five-year-survival was between 15% and 35%, with dialysis dependence in less than 10% of survivors. Renal recovery, even if incomplete occurred during the first year. Quality of life assessment amongst survivors indicated moderate physical impairment and reduced mental health scores. A majority of patients returned to employment and self-sustainability and reported acceptable to good quality of life. Over 90% of patients indicated that they would undergo the same treatment again.

DISCUSSION AND CONCLUSIONS

Early initiation of treatment and fine-tuning of the RRT technique may improve outcome. Consensus regarding AKI definitions, renal function measurement and standardised follow-up regimens are required. Further long-term studies are needed.

Short and long-term outcome of patients with severe acute kidney injury requiring renal replacement therapy

BACKGROUND

Severe acute kidney injury (AKI) occurs in 2-7% of all hospital admissions and is an independent poor prognostic marker. Nevertheless, information on the long-term outcome of AKI and the factors influencing this is limited.

AIM

To describe the short- and long-term outcome of patients requiring renal replacement therapy (RRT) for severe AKI and to examine factors affecting patient survival and renal recovery.

DESIGN AND METHODS

Single centre retrospective analysis of 481 consecutive patients over a period of 39 months.

FOLLOW-UP

12 months.

PRIMARY AND SECONDARY OUTCOMES

overall mortality and RRT dependency at 30 days, 90 days and 1 year.

RESULTS

Survival at 30 days, 90 days and 1 year was 54.4, 47.2 and 37.6%, respectively. RRT independency at 30 days, 90 days and 1 year was 35.2, 27.2 and 25.8%, respectively. Of those RRT independent at 90 days, 55% had ongoing chronic kidney disease. There were two distinct groups of patients: Group A (haemofiltration in ITU) and Group B (intermittent haemodialysis in the renal unit). Patient survival was worse in Group A while RRT independence was higher. Independent predictors of survival included renal cause of AKI and lower CI score in Group A and renal or post-renal cause of AKI, younger age and the absence of malignancy in Group B. Independent predictors of renal recovery included the presence of sepsis in Group A and pre- or post-renal cause of AKI in Group B.

CONCLUSIONS

The short- and long-term survival outcome of severe AKI requiring RRT remains poor. Among those who survive, a significant number either continue to require RRT or have residual renal impairment necessitating ongoing follow-up.

Urinary biomarkers and renal recovery in critically ill patients with renal support

BACKGROUND AND OBJECTIVES

Despite significant advances in the epidemiology of acute kidney injury (AKI), prognostication remains a major clinical challenge. Unfortunately, no reliable method to predict renal recovery exists. The discovery of biomarkers to aid in clinical risk prediction for recovery after AKI would represent a significant advance over current practice.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted the Biological Markers of Recovery for the Kidney study as an ancillary to the Acute Renal Failure Trial Network study. Urine samples were collected on days 1, 7, and 14 from 76 patients who developed AKI and received renal replacement therapy (RRT) in the intensive care unit. We explored whether levels of urinary neutrophil gelatinase-associated lipocalin (uNGAL), urinary hepatocyte growth factor (uHGF), urinary cystatin C (uCystatin C), IL-18, neutrophil gelatinase-associated lipocalin/matrix metalloproteinase-9, and urine creatinine could predict subsequent renal recovery.

RESULTS

We defined renal recovery as alive and free of dialysis at 60 days from the start of RRT. Patients who recovered had higher uCystatin C on day 1 (7.27 versus 6.60 ng/mg·creatinine) and lower uHGF on days 7 and 14 (2.97 versus 3.48 ng/mg·creatinine; 2.24 versus 3.40 ng/mg·creatinine). For predicting recovery, decreasing uNGAL and uHGF in the first 14 days was associated with greater odds of renal recovery. The most predictive model combined relative changes in biomarkers with clinical variables and resulted in an area under the receiver-operator characteristic curve of 0.94.

CONCLUSIONS

We showed that a panel of urine biomarkers can augment clinical risk prediction for recovery after AKI.

The changing pattern of referral in acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is not only managed by nephrologists, but also by several other subspecialists. The referral rate to nephrologists and the factors influencing it are unknown.

AIMS

To determine the referral rate, factors affecting referral and outcomes across the spectrum of AKI in a population based study.

METHODS

We identified all patients with serum creatinine concentrations ≥150 µmol/l (male) or ≥130 µmol/l (female) over a 6-month period. AKI was defined according to the RIFLE classification (risk, injury, failure, loss, end stage renal disease [ESRD]). Clinical information and outcomes were obtained from each patient's case records.

RESULTS

A total of 562 patients were identified as having AKI (incidence 2147 per million population/year [pmp/y]). One hundred and sixty-four patients (29%) were referred to nephrologists-referral rate 627 pmp/y. Forty-nine percent of patients whose serum creatinine rose to >300 µmol/l were referred compared with 22% in our previous study of 1997. Forty-eight patients required renal replacement therapy-incidence 184 pmp/y in comparison to 50 pmp/y in our previous study of 1997. Patients had higher odds of referral if they were male, of younger age and were in the F category of the RIFLE classification. Patients had lower odds of referral if they had multiple co-morbid conditions or if they were managed in a hospital without a nephrology service.

CONCLUSION

There has been a significant rise in the referral rate of patients with AKI to nephrologists but even during our period of study only one-third of such patients were being referred. With rising incidence and increased awareness, the referral rate will certainly rise putting a significant burden on the nephrology services.

Clinical cause of presumed acute tubular necrosis requiring renal replacement therapy and outcome of critically ill patients: post hoc analysis of a prospective 7-year cohort study

BACKGROUND

Acute kidney injury (AKI) secondary to acute tubular necrosis (ATN) is common in critically ill patients, and causes significant morbidity and mortality. The underlying etiology of ATN can be divided into pure ischemic, pure nephrotoxic, and mixed causes. This post-hoc analysis of a prospective cohort study aimed to investigate whether the cause (pure vs. mixed) of ATN affects the short- and long-term outcome of critically-ill patients.

METHODS

A total of 425 critically-ill patients with AKI secondary to clinically diagnosed ATN were divided into three groups according to the cause of ATN. Of these patients, 215 had mixed ATN, 203 had pure ischemic ATN, and seven had pure nephrotoxic ATN. All patients had one episode of AKI only. No patient had pre-existing chronic kidney disease. Patients were followed throughout their hospital stay (mortality rate, recovery of renal function at discharge) and up to 7 years thereafter.

RESULTS

The three patient groups differed in their demographic and clinical characteristics. The in-hospital mortality rates were 55% in the presumably mixed-cause ATN group, 39% in the pure ischemic group, and 29% in the pure nephrotoxic group. Complete renal recovery at discharge was documented in five out of five surviving patients with nephrotoxic ATN (100%) and in 92 out of 124 surviving patients with pure ischemic ATN (74%), but only in 29 out of 97 patients with mixed ATN (30%). None of the surviving patients was lost during the 7-year follow-up. At the end of the observation period, 60% of the survivors of pure ATN, compared with 22% of the survivors of mixed ATN, were alive. After 7 years, 6% of the living patients with pure ATN had mild-to-moderate chronic kidney disease, whereas 38% of the mixed group patients had advanced CKD or end-stage renal disease.

CONCLUSIONS

The cause of presumed ATN has a profound impact on short- as well as long-term outcomes of critically-ill patients with AKI requiring renal replacement therapy. The challenge for intensivists is to avoid further injury to the kidneys of these patients.

End-stage renal disease preceded by rapid declines in kidney function: a case series

Background

Few studies have defined alternate pathways by which chronic kidney disease (CKD) patients transition into end-stage renal disease (ESRD).

Methods

We studied all consecutive patients initiated on maintenance hemodialysis or peritoneal dialysis over several years at two dialysis units in Northern California. Rapid decline in kidney function was considered to have occurred if a patient was documented to have estimated GFR > 30 ml/min/1.73 m² within three months prior to the initiation of chronic dialysis.

Results

We found that 8 out of 105 incident chronic dialysis patients one dialysis unit (7.6%; 95% confidence interval 3.4-14.5%) and 9 out of 71 incident patients at another (12.7%, 95% CI 6.0%-22.7%) suffered rapid decline in kidney function that was the immediate precipitant for the need for permanent renal replacement therapy. All these patients started hemodialysis and all relied on catheters for vascular access. Documentation submitted to United States Renal Data System did not fully reflect the health status of these patients during their "pre-ESRD" period.

Conclusions

A sizeable minority of ESRD cases are preceded by rapid declines in kidney function. The importance of these periods of rapid decline may have been under-appreciated in prior studies of the natural history of CKD and ESRD.

Renal function recovery in chronic dialysis patients

Renal function recovery (RFR) from acute kidney injury requiring dialysis occurs at a high frequency. RFR from chronic dialysis, on the other hand, is an uncommon but well-recognized phenomenon, occurring at a rate of 1.0-2.4% according to data from large observational studies. The underlying etiology of renal failure is the single most important predicting factor of RFR in chronic dialysis patients. The disease types with the highest RFR rates are atheroembolic renal disease, systemic autoimmune disease, renovascular diseases, and scleroderma. The disease types with the lowest RFR rates are diabetic nephropathy and cystic kidney disease. Initial dialysis modality does not appear to influence RFR. Careful observation and history taking are needed to recognize the often nonspecific clinical and laboratory signs of RFR. When RFR is suspected in a chronic dialysis patient, a 24-hour urine urea and creatinine clearance should be measured. Based on the renal clearance, along with other clinical factors, the dialysis prescription may be gradually reduced until a complete discontinuation of dialysis. After RFR from maintenance dialysis, patients require close follow-up in an office setting for chronic kidney disease management.

Novel aspects of pharmacological therapies for acute renal failure

Acute renal failure (ARF) comprises several syndromes that are associated with a sudden decrease in renal function. ARF is common among critically ill patients, is typically multifactorial and is of great prognostic significance. Indeed, even moderate changes in renal function significantly add to the morbidity and worsen mortality associated with ARF. Recent definitions, namely the renal Risk, Injury, Failure, Loss of renal function and End-stage kidney disease (RIFLE) classification or Acute Kidney Injury Network (AKIN) criteria, which incorporate the levels of oliguria in addition to fractional serum creatinine elevation, are important because the magnitude of kidney injury according to those definitions correlates very well with both short- and long-term patient survival. However, preventive strategies are most effective when started before oliguria or elevated serum creatinine is detectable, as those criteria already reflect established renal tubular cell injury. New biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), liver-type fatty acid binding protein (L-FABP) or kidney injury molecule-1 (KIM-1) that increase prior to the serum creatinine elevation are promising and have been proven to be useful in this regard in a few clinical trials. In addition, genetic profiling may define patients at risk earlier and help to individualize preventive strategies. Well established strategies include limiting dehydration and hypotension by the use of intravenous isotonic fluids at an optimal and individualized rate, as well as avoiding exposure to nephrotoxins, which include aminoglycosides, amphotericin or non-ionic contrast. Generally accepted and evidence-based pharmacological preventive or therapeutic options have not yet been established, although many drugs (e.g. renal vasodilators, diuretics and HMG-CoA reductase inhibitors [statins]) have been tested. New promising agents interfere with the apoptotic signalling that can occur in the setting of toxin exposure or ischaemia-reperfusion injury, limit inflammatory responses or modulate endothelial cell activation. In the future, these new approaches will enable us to extend our therapeutic repertoire.

Outcome of acute kidney injury with different treatment options: long-term follow-up

BACKGROUND AND OBJECTIVES

The multicenter Stuivenberg Hospital Acute Renal Failure 4 study investigated outcome in patients with acute kidney injury (AKI) stratified according to disease severity by the Stuivenberg Hospital Acute Renal Failure score. Patients in need of renal replacement therapy (RRT) received intermittent RRT or continuous RRT. This study investigated long-term mortality, renal function, comorbidity, and quality of life.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

All AKI hospital survivors were included. Mortality at 1 and 2 years of follow-up was traced for all patients. Between 1 and 2 years after hospital discharge, survivors were visited at home to determine morbidity (renal function), comorbidity (Charlson comorbidity index [CCI]), and quality of life (Medical Outcome Survey SF-36).

RESULTS

The baseline population consisted of 595 AKI patients. Mortality rates were 23.0 and 7.6%, respectively, during the first and second year after discharge. Total mortality increased from 50.7% at discharge to 65.7% 2 years after AKI and was not related to disease severity or treatment modality offered during hospitalization. Two hundred four survivors could be visited at home. Mean serum creatinine did not differ between discharge and follow-up. CCI was only related with age. SF-36 scores were negatively correlated with CCI, age, and body mass index, but not with disease severity, renal function, or dialysis modality.

CONCLUSIONS

Long-term outcome of AKI consists of a high additional mortality unrelated to treatment modality offered during hospitalization, varying evolution of renal recovery, and many comorbidities, but a mental health at the same level as the general population.

Acute renal failure in the State of Qatar: presentation and outcome

Despite major improvements in health care, acute renal failure is still one of the main prognostic factors in terms of patient mortality and long-term morbidity. This cohort prospective study to evaluate the patterns and outcomes of renal failure in Qatar was performed between January and June 2005. Of the 213 patients followed prospectively from referral to the end of their hospitalization, 66.7% were males and 33.3% females. Their overall mean age was 60 years; the majority were referred from critical care units. Comorbidity was present in 87% of all patients. Volume depletion, hypotension, and sepsis were the main predisposing factors for renal failure. Eighty three patients (39%) needed renal replacement treatment and 130 (61%) were treated conservatively. The majority of critical care patients needed dialysis. Overall mortality was 23.9%, 7% needed chronic dialysis, and 69.1% were discharged with normal or mild renal impairment. This study showed that acute renal failure was a major factor affecting patient mortality in Qatar. Early treatment of predisposing factors may improve overall patient outcomes.

Nonrecovery of kidney function and death after acute on chronic renal failure

BACKGROUND AND OBJECTIVES

Relatively little is known about clinical outcomes, especially long-term outcomes, among patients who have chronic kidney disease (CKD) and experience superimposed acute renal failure (ARF; acute on chronic renal failure).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We tracked 39,805 members of an integrated health care delivery system in northern California who were hospitalized during 1996 through 2003 and had prehospitalization estimated GFR (eGFR) <45 ml/min per 1.73 m(2). Superimposed ARF was defined as having both a peak inpatient serum creatinine greater than the last outpatient serum creatinine by > or =50% and receipt of acute dialysis.

RESULTS

Overall, 26% of CKD patients who suffered superimposed ARF died during the index hospitalization. There was a high risk for developing ESRD within 30 d of hospital discharge that varied with preadmission renal function, being 42% among hospital survivors with baseline eGFR 30-44 ml/min per 1.73 m(2) and 63% among hospital survivors with baseline eGFR 15-29 ml/min per 1.73 m(2). Compared with patients who had CKD and did not experience superimposed ARF, those who did had a 30% higher long-term risk for death or ESRD.

CONCLUSIONS

In a large, community-based cohort of patients with CKD, an episode of superimposed dialysis-requiring ARF was associated with very high risk for nonrecovery of renal function. Dialysis-requiring ARF also seemed to be an independent risk factor for long-term risk for death or ESRD.

Long-term risk of mortality and other adverse outcomes after acute kidney injury: a systematic review and meta-analysis

BACKGROUND

Acute kidney injury (AKI) is common in hospitalized patients. The impact of AKI on long-term outcomes is controversial.

STUDY DESIGN

Systematic review and meta-analysis.

SETTING & PARTICIPANTS

Persons with AKI.

SELECTION CRITERIA FOR STUDIES

MEDLINE and EMBASE databases were searched from 1985 through October 2007. Original studies describing outcomes of AKI for patients who survived hospital discharge were included. Studies were excluded from review when participants were followed up for less than 6 months.

PREDICTOR

AKI, defined as acute changes in serum creatinine level or acute need for renal replacement therapy.

OUTCOMES

Chronic kidney disease (CKD), cardiovascular disease, and mortality.

RESULTS

48 studies that contained a total of 47,017 participants were reviewed; 15 studies reported long-term data for patients without AKI. The incidence rate of mortality was 8.9 deaths/100 person-years in survivors of AKI and 4.3 deaths/100 patient-years in survivors without AKI (rate ratio [RR], 2.59; 95% confidence interval, 1.97 to 3.42). AKI was associated independently with mortality risk in 6 of 6 studies that performed multivariate adjustment (adjusted RR, 1.6 to 3.9) and with myocardial infarction in 2 of 2 studies (RR, 2.05; 95% confidence interval, 1.61 to 2.61). The incidence rate of CKD after an episode of AKI was 7.8 events/100 patient-years, and the rate of end-stage renal disease was 4.9 events/100 patient-years.

LIMITATIONS

The relative risk for CKD and end-stage renal disease after AKI was unattainable because of lack of follow-up of appropriate controls without AKI.

CONCLUSIONS

The development of AKI, defined as acute changes in serum creatinine level, characterizes hospitalized patients at increased risk of long-term adverse outcomes.

Renal recovery following acute kidney injury

PURPOSE OF REVIEW

Renal recovery after acute kidney injury (AKI) is an important outcome, most commonly defined as dialysis independence at hospital discharge. This review focuses on the epidemiology of renal recovery after AKI and provides a framework for determining the relationship of a lack of renal recovery and subsequent outcomes including the development of chronic kidney disease.

RECENT FINDINGS

The majority of studies addressing renal recovery includes only critically ill patients requiring dialysis and considers renal recovery as dialysis independency at hospital discharge. However, a significant proportion of AKI patients are not in the ICU, are not dialyzed, and may require alternate definitions for assessing renal recovery. There is emerging evidence that an AKI episode can lead to chronic kidney disease and can accelerate the progression to end stage renal disease. Patients that survive after AKI present a higher long-term mortality risk, especially those with partial renal recovery.

SUMMARY

Patients with incomplete renal recovery after AKI are underrepresented in most epidemiologic studies and the precise effect on the incidence and prevalence of end stage renal disease population has yet to be determined. A standardized definition for renal recovery is needed and the influence of an AKI episode on long-term outcomes needs to be better evaluated.

Long-term prognosis after acute kidney injury requiring renal replacement therapy

BACKGROUND

Data on the long-term survival and renal function of patients with acute kidney injury (AKI) treated with continuous renal replacement therapy are scarce.

METHODS

We investigated the 3-year survival and need for chronic dialysis in critically ill patients, who had survived an episode of AKI requiring continuous renal replacement therapy.

RESULTS

A total of 206 ICU patients with AKI were randomized in a trial comparing haemofiltration versus haemodiafiltration. Of these, 95 (46%) survived at 90 days. Post-discharge information relating to 3-year survival and renal function was successfully obtained in 89 (94%) of the patients. Of the 89 patients studied, chronic kidney disease (CKD) was present in 32 subjects from the onset, and CKD developed de novo in 25 patients following AKI. End-stage renal disease (ESRD) developed in 9 patients (of whom 8 had pre-existing CKD) and 29 patients died. Three-year survival was 67% overall; the mortality at 3 years was 50% for those with pre-existing kidney disease, and 71 and 82% for those with de novo and without CKD, respectively.

CONCLUSION

After an episode of AKI necessitating a continuous renal replacement therapy, rapid progression to ESKD is commonly observed in patients with pre-existing chronic renal impairment. Medical care with an emphasis on nephroprotection is necessary in these patients.

Acute kidney injury increases risk of ESRD among elderly

Risk for ESRD among elderly patients with acute kidney injury (AKI) has not been studied in a large, representative sample. This study aimed to determine incidence rates and hazard ratios for developing ESRD in elderly individuals, with and without chronic kidney disease (CKD), who had AKI. In the 2000 5% random sample of Medicare beneficiaries, clinical conditions were identified using Medicare claims; ESRD treatment information was obtained from ESRD registration during 2 yr of follow-up. Our cohort of 233,803 patients were hospitalized in 2000, were aged > or = 67 yr on discharge, did not have previous ESRD or AKI, and were Medicare-entitled for > or = 2 yr before discharge. In this cohort, 3.1% survived to discharge with a diagnosis of AKI, and 5.3 per 1000 developed ESRD. Among patients who received treatment for ESRD, 25.2% had a previous history of AKI. After adjustment for age, gender, race, diabetes, and hypertension, the hazard ratio for developing ESRD was 41.2 (95% confidence interval [CI] 34.6 to 49.1) for patients with AKI and CKD relative to those without kidney disease, 13.0 (95% CI 10.6 to 16.0) for patients with AKI and without previous CKD, and 8.4 (95% CI 7.4 to 9.6) for patients with CKD and without AKI. In summary, elderly individuals with AKI, particularly those with previously diagnosed CKD, are at significantly increased risk for ESRD, suggesting that episodes of AKI may accelerate progression of renal disease.

Management of acute renal failure in the elderly patient: a clinician's guide

Numerous anatomical and functional changes occurring in the aging kidney lead to reduced glomerular filtration rate, lower renal blood flow and impaired renal autoregulation. The elderly are especially vulnerable to the development of renal dysfunction and in this population acute renal failure (ARF) is a common problem. ARF is often iatrogenic and multifactorial; common iatrogenic combinations include pre-existing renal dysfunction and exposure to nephrotoxins such as radiocontrast agents or aminoglycosides, use of NSAIDs in patients with congestive cardiac failure and use of ACE inhibitors and diuretics in patients with underlying atherosclerotic renal artery stenosis. The aetiology of ARF is classically grouped into three categories: prerenal, intrinsic and postrenal. Prerenal ARF is the second most common cause of ARF in the elderly, accounting for nearly one-third of all hospitalized cases. Common causes can be grouped into true volume depletion (e.g. decreased fluid intake), decreased effective blood volume (e.g. systemic vasodilation) and haemodynamic (e.g. renal artery stenosis, NSAID use). Acute tubular necrosis (ATN) is the most common cause of intrinsic ARF and is responsible for over 50% of ARF in hospitalized patients, and up to 76% of cases in patients in intensive care units. ATN usually occurs after an acute ischaemic or toxic event. The pathogenesis of ATN involves an interplay of processes that include endothelial injury, microvascular flow disruption, tubular hypoxia, dysfunction and apoptosis, tubular obstruction and trans-tubular back-leak. Vasculitis causing ARF should not be missed as this condition is potentially life threatening. The likelihood of a postrenal cause for ARF increases with age. Benign prostatic hypertrophy, prostatic carcinoma and pelvic malignancies are all important causes. Early identification of ARF secondary to obstruction with renal imaging is essential, and complete or partial renal recovery usually ensues following relief of the obstruction.A comprehensive medical and drug history and physical examination are all invaluable. Particular attention should be paid to the fluid status of the patient (skin turgor, jugular venous pressure, lying and standing blood pressure, urine output). Urinalysis should be performed to detect evidence of proteinuria and haematuria, which will aid diagnosis. Fractional excretion of sodium and urine osmolality may be measured but the widespread use of diuretics in the elderly gives rise to unreliable results. Renal imaging, usually ultrasound scanning, is routinely performed for assessment of renal size and to exclude urinary obstruction. In some cases, renal biopsy is necessary to provide specific diagnostic information. The general principles of managing ARF include treatment of life-threatening features such as shock, respiratory failure, hyperkalaemia, pulmonary oedema, metabolic acidosis and sepsis; stopping and avoiding administration of nephrotoxins; optimization of haemodynamic and fluid status; adjustment of drug dosage appropriate to glomerular filtration rate; early nutritional support; and early referral to nephrologists for diagnosis of ARF cause, timely initiation of dialysis and initiation of specific treatment. The treatment of prerenal and ATN ARF is largely supportive with little evidence of benefit from current pharmacological therapies. Despite advances in critical care medicine and renal replacement therapy, the mortality of ARF has not changed significantly over the last 40 years, with current mortality rates being up to 75%.

Acute kidney injury and chronic kidney disease after cardiac surgery

Kidney dysfunction is common after cardiac surgery and predicts mortality risk and poorer long-term outcome, particularly when acute injury superimposes upon chronic kidney disease. Numerous insults contribute to perioperative renal impairment including major surgical trespass, procedure-specific interventions (eg, deep hypothermic circulatory arrest), and postoperative complications. Regardless of cause, evidence supports a role for renal impairment and accumulation of "uremic toxins" as direct contributors to adverse outcome. No one has yet characterized a loss of renal function small enough to be insignificant. Despite considerable research focus, progress in development of interventions aimed at perioperative renoprotection has been disappointing. However, practice modifications can influence the likelihood of acute kidney injury, and several recent advances provide hope for the future. We review pathophysiologic understanding of this disorder; evaluate the confusing relationship (causal v epiphenomena) among acute kidney injury, chronic kidney disease, and adverse outcome after cardiac surgery; and provide an evidence-based assessment of the conduct of cardiac surgery and renoprotection strategies.

Renal replacement therapy in acute kidney injury: intermittent versus continuous? How much is enough?

Approximately 4% of all critically ill patients will require renal replacement therapy (RRT). Despite its potential reversibility, acute kidney injury has a significant impact on morbidity and mortality. Numerous studies have addressed the questions of modality choice and dose of RRT in the intensive care unit setting. There is no clear evidence that one renal replacement modality is superior to another. Two multicenter trials focusing on dialysis dose will probably be published in the next year, either confirming or invalidating the benefit of higher effluent rates. Another key aspect in the treatment of acute kidney injury is the consequence of RRT on long-term renal function. Although cohort studies have shown that continuous RRT shortens dialysis-dependence compared with intermittent hemodialysis, randomized trials and meta-analyses do not support these findings. Several unanswered questions, such as the timing of initiation and cessation of RRT, the modification of dialysis parameters over the course of acute kidney injury and the influence of fluid status need to be addressed in future trials in order to improve outcomes related to this condition.