Comparison of kidney disease: improving global outcomes and acute kidney injury network criteria for assessing patients in intensive care units

Urine output is an early and strong predictor of acute kidney injury and associated mortality: a systematic literature review of 50 clinical studies

BACKGROUND

Although the present diagnosis of acute kidney injury (AKI) involves measurement of acute increases in serum creatinine (SC) and reduced urine output (UO), measurement of UO is underutilized for diagnosis of AKI in clinical practice. The purpose of this investigation was to conduct a systematic literature review of published studies that evaluate both UO and SC in the detection of AKI to better understand incidence, healthcare resource use, and mortality in relation to these diagnostic measures and how these outcomes may vary by population subtype.

METHODS

The systematic literature review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Data were extracted from comparative studies focused on the diagnostic accuracy of UO and SC, relevant clinical outcomes, and resource usage. Quality and validity were assessed using the National Institute for Health and Care Excellence (NICE) single technology appraisal quality checklist for randomized controlled trials and the Newcastle-Ottawa Quality Assessment Scale for observational studies.

RESULTS

A total of 1729 publications were screened, with 50 studies eligible for inclusion. A majority of studies (76%) used the Kidney Disease: Improving Global Outcomes (KDIGO) criteria to classify AKI and focused on the comparison of UO alone versus SC alone, while few studies analyzed a diagnosis of AKI based on the presence of both UO and SC, or the presence of at least one of UO or SC indicators. Of the included studies, 33% analyzed patients treated for cardiovascular diseases and 30% analyzed patients treated in a general intensive care unit. The use of UO criteria was more often associated with increased incidence of AKI (36%), than was the application of SC criteria (21%), which was consistent across the subgroup analyses performed. Furthermore, the use of UO criteria was associated with an earlier diagnosis of AKI (2.4-46.0 h). Both diagnostic modalities accurately predicted risk of AKI-related mortality.

CONCLUSIONS

Evidence suggests that the inclusion of UO criteria provides substantial diagnostic and prognostic value to the detection of AKI.

Post-treatment With Irisin Attenuates Acute Kidney Injury in Sepsis Mice Through Anti-Ferroptosis via the SIRT1/Nrf2 Pathway

Kidney is one of the most vulnerable organs in sepsis, resulting in sepsis-associated acute kidney injury (SA-AKI), which brings about not only morbidity but also mortality of sepsis. Ferroptosis is a new kind of death type of cells elicited by iron-dependent lipid peroxidation, which participates in pathogenesis of sepsis. The aim of this study was to verify the occurrence of ferroptosis in the SA-AKI pathogenesis and demonstrate that post-treatment with irisin could restrain ferroptosis and alleviate SA-AKI via activating the SIRT1/Nrf2 signaling pathway. We established a SA-AKI model by cecal ligation and puncture (CLP) operation and an in vitro model in LPS-induced HK2 cells, respectively. Our result exhibited that irisin inhibited the level of ferroptosis and ameliorated kidney injury in CLP mice, as evidenced by reducing the ROS production, iron content, and MDA level and increasing the GSH level, as well as the alteration of ferroptosis-related protein (GPX4 and ACSL4) expressions in renal, which was consistent with the ferroptosis inhibitor ferrostatin-1 (Fer-1). Additionally, we consistently observed that irisin inhibited ROS accumulation, iron production, and ameliorated mitochondrial dysfunction in LPS-stimulated HK-2 cells. Furthermore, our result also revealed that irisin could activate SIRT1/Nrf2 signaling pathways both in vivo and vitro. However, the beneficial effects of irisin were weakened by EX527 (an inhibitor of SIRT1) in vivo and by SIRT1 siRNA in vitro. In conclusion, irisin could protect against SA-AKI through ferroptotic resistance via activating the SIRT1/Nrf2 signaling pathway.

Urinary Metabolome Analyses of Patients with Acute Kidney Injury Using Capillary Electrophoresis-Mass Spectrometry

Acute kidney injury (AKI) is defined as a rapid decline in kidney function. The associated syndromes may lead to increased morbidity and mortality, but its early detection remains difficult. Using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS), we analyzed the urinary metabolomic profile of patients admitted to the intensive care unit (ICU) after invasive surgery. Urine samples were collected at six time points: before surgery, at ICU admission and 6, 12, 24 and 48 h after. First, urine samples from 61 initial patients (non-AKI: 23, mild AKI: 24, severe AKI: 14) were measured, followed by the measurement of urine samples from 60 additional patients (non-AKI: 40, mild AKI: 20). Glycine and ethanolamine were decreased in patients with AKI compared with non-AKI patients at 6-24 h in the two groups. The linear statistical model constructed at each time point by machine learning achieved the best performance at 24 h (median AUC, area under the curve: 89%, cross-validated) for the 1st group. When cross-validated between the two groups, the AUC showed the best value of 70% at 12 h. These results identified metabolites and time points that show patterns specific to subjects who develop AKI, paving the way for the development of better biomarkers.

Protection of procyanidin B2 on mitochondrial dynamics in sepsis associated acute kidney injury via promoting Nrf2 nuclear translocation

In septic acute kidney injury (SAKI), the positive feedback between damaged mitochondria and accumulation of reactive oxygen species results in cell and tissue damage through multiple mechanisms. Removing the damaged mitochondria or neutralizing the reactive oxygen species has been considered beneficial to alleviating cell damage. The antioxidant Procyanidin B2 has been reported to inhibits reactive oxygen species and thereby reduces cell injury. However, it is unclear whether this effect is associated with clearance of damaged mitochondria. Here, we evaluated the efficacy of procyanidin B2 on SAKI, and focused on its effects on mitochondrial dynamics and removing damaged mitochondria via mitophagy. The results showed that the renal function, renal tubular cell vacuolization and oxidative stress were decreased in SAKI mice treated with procyanidin B2, moreover, skewed mitochondrial fusion/fission, mitochondrial mediated apoptosis and impaired mitophagy were improved in SAKI mice treated with procyanidin B2. In mechanism, the improvement of procyanidin B2 on mitochondrial dynamics were associated with increased nuclear translocation of the transcription factor, Nrf2. In summary, our findings highlighted that the protective efficacy of procyanidin B2 in reducing cellular damage in SAKI, and mechanisms improving mitochondrial dynamics and quality control at least in part by promoting Nrf2 translocation into the nucleus.

A systematic review and meta-analysis of acute kidney injury in the intensive care units of developed and developing countries

Objectives

Although the majority of the global population lives in developing countries, most of the epidemiological data related to intensive care unit (ICU) acute kidney injury (AKI) comes from developed countries. This systematic review aims to ascertain the methodology of studies on ICU AKI patients in developing and developed countries, to determine whether epidemiological comparisons between these two settings are possible, and to present a summary estimate of AKI incidence.

Methods

A systematic review of published studies reporting AKI in intensive care units (2005–2015) identified in PubMed, LILACS, and IBECs databases was conducted. We compared developed and developing countries by evaluating study methodology, AKI reference serum creatinine definitions, population characteristics, AKI incidence and mortality. AKI incidence was calculated with a random-effects model.

Results

Ninety-two studies were included, one of which reported data from both country categories: 60 from developed countries (1,057,332 patients) and 33 from developing countries (34,539 patients). In 78% of the studies, AKI was defined by the RIFLE, AKIN or KDIGO criteria. Oliguria had 11 different definitions and reference creatinine 23 different values. For the meta-analysis, 38 studies from developed and 18 from developing countries were selected, with similar AKI incidence: 39.3% and 35.1%, respectively. The need for dialysis, length of ICU stay and mortality were higher in developing countries.

Conclusion

Although patient characteristics and AKI incidence were similar in developed and developing countries, main outcomes were worse in developing country studies. There are significant caveats when comparing AKI epidemiology in developed and developing countries, including lack of standardization of reference serum creatinine, oliguria and the timeframe for AKI assessment. Larger, prospective, multicenter studies from developing countries are urgently needed to capture AKI data from the overall population without ICU access.

Disturbance of mitochondrial dynamics and mitophagy in sepsis-induced acute kidney injury

AIMS

The renal tubule cells require a large number of mitochondria to supply ATP due to their high-energy demand during reabsorption and secretion against chemical gradients and result in mitochondria susceptible to disorder and injury during stress conditions. Injured mitochondria are eventually degraded by mitophagy, and disturbances in mitophagy are associated with the pathogenesis of acute kidney injury (AKI) such as diabetic nephropathy and glomerulosclerosis. However, whether a disturbance in mitophagy has occurred and the role it plays in (SAKI) is still unclear. Therefore, the aim of this study was to investigate the key features of mitophagy and mitochondrial dynamics in sepsis-induced acute kidney injury (SAKI).

MAIN METHODS

In this study, a murine septic AKI model induced by cecal ligation and puncture (CLP) was built; mitophagy and mitochondrial dynamics were measured in mice kidney in different time point.

KEY FINDINGS

The results showed that mitochondrial dynamics were characterized by fission/fusion aberrant, however more inclined to fission, and mitochondrial associated apoptosis was elevated over-time during SAKI. Furthermore, mitophagy was impaired in the later phase of SAKI, although elevated in early stage of SAKI. The results indicate that the underlying mechanisms of impaired mitophagy may associate with the cleavage of Parkin via caspases activated by NLRP3, at least partly.

SIGNIFICANCE

It is conceivable that this selective autophagic process and quality control machinery was impaired, leading to the accumulation of damaged mitochondria, oxidative stress, and cell death. Therefore, a targeted approach, by enhancing mitophagy during SAKI, may be a promising therapeutic strategy.

The Japanese clinical practice guideline for acute kidney injury 2016

Acute kidney injury (AKI) is a syndrome which has a broad range of etiologic factors depending on different clinical settings. Because AKI has significant impacts on prognosis in any clinical settings, early detection and intervention is necessary to improve the outcomes of AKI patients. This clinical guideline for AKI was developed by a multidisciplinary approach with nephrology, intensive care medicine, blood purification, and pediatrics. Of note, clinical practice for AKI management which was widely performed in Japan was also evaluated with comprehensive literature search.

The Japanese Clinical Practice Guideline for acute kidney injury 2016

Acute kidney injury (AKI) is a syndrome which has a broad range of etiologic factors depending on different clinical settings. Because AKI has significant impacts on prognosis in any clinical settings, early detection and intervention are necessary to improve the outcomes of AKI patients. This clinical guideline for AKI was developed by a multidisciplinary approach with nephrology, intensive care medicine, blood purification, and pediatrics. Of note, clinical practice for AKI management which was widely performed in Japan was also evaluated with comprehensive literature search.

Diagnosis, management, and prognosis of patients with acute kidney injury in Japanese intensive care units: The JAKID study

PURPOSE

To determine the proportion of diagnosis and outcomes of critically ill patients with acute kidney injury (AKI), and its association with mortality using the complete Kidney Disease Improving Global Outcomes (KDIGO) classification and Sepsis-3 definition.

METHODS

We conducted a multicenter prospective cohort study of 13 intensive care units (ICU) in Japan. Patients admitted to the ICUs during six months in 2016 were consecutively enrolled.

RESULTS

Among 2292 patients, AKI was diagnosed in 1024 (44.7%) patients, using the KDIGO classification. Sepsis was diagnosed in 424 patients (18.5%), of whom 281 patients (66.3%) had AKI. Septic shock was diagnosed in 166 patients (7.2%), of whom 125 patients (75.3%) had AKI. Of 1024 patients with AKI, renal replacement therapy was applied to 171 patients (16.7% of AKI) during the ICU stay. The adjusted odds ratio (aOR) of AKI to hospital mortality was 1.66 (95% confidence intervals 1.26-2.18), while that among sepsis was 0.87 (95% confidence intervals 0.55-1.37).

CONCLUSIONS

AKI accounted for >40% of ICU patients with the KDIGO classification and was associated with increased risk of hospital mortality. Septic AKI was diagnosed in three-fourths of patients with sepsis, while the impact of AKI on hospital mortality among sepsis was not observed.

Cost and determinants of acute kidney injury after elective primary total joint arthroplasty

Background

Acute kidney injury (AKI) is a serious complication after major surgery, which may lead to increased morbidity and mortality. The aim of this study was to identify cost and determinants of AKI after total joint arthroplasty.

Methods

A retrospective case-controlled study was conducted with 1719 primary elective total hip or knee replacements performed from January 2004 through September 2015 at an urban teaching hospital. Patients who developed AKI were matched in a 1:3 ratio with those in a control group who did not develop AKI based on age, sex, race, operated joint, and comorbidities including hypertension and diabetes. Increased postoperative serum creatinine was considered indicative of AKI.

Results

Fifty-four patients (3.1%) had AKI that was significantly associated with increased length of hospital stay (8.07 days) compared with that of the control group (4.50 days, P < .0001) and incurred significantly higher hospital charges ($224,533) than those of the control group ($142,753, P < .0001). We identified high body mass index, undergoing bilateral surgery in one session, high estimated blood loss, and longer duration of surgery as significant risk factors for AKI in univariate analysis. Elevated preoperative creatinine, large postoperative drop in hemoglobin, and high American Society of Anesthesiologists physical status scores were significant independent predictors of AKI in multivariate analysis.

Conclusions

Health-care providers and patients should work together to manage risk factors and to lower the risk of morbidity and mortality, longer in-hospital stay, and high associated costs of AKI.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2016 (J-SSCG 2016)

BACKGROUND AND PURPOSE

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2016 (J-SSCG 2016), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in February 2017 and published in the Journal of JSICM, [2017; Volume 24 (supplement 2)] 10.3918/jsicm.24S0001 and Journal of Japanese Association for Acute Medicine [2017; Volume 28, (supplement 1)] http://onlinelibrary.wiley.com/doi/10.1002/jja2.2017.28.issue-S1/issuetoc.This abridged English edition of the J-SSCG 2016 was produced with permission from the Japanese Association of Acute Medicine and the Japanese Society for Intensive Care Medicine.

METHODS

Members of the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine were selected and organized into 19 committee members and 52 working group members. The guidelines were prepared in accordance with the Medical Information Network Distribution Service (Minds) creation procedures. The Academic Guidelines Promotion Team was organized to oversee and provide academic support to the respective activities allocated to each Guideline Creation Team. To improve quality assurance and workflow transparency, a mutual peer review system was established, and discussions within each team were open to the public. Public comments were collected once after the initial formulation of a clinical question (CQ) and twice during the review of the final draft. Recommendations were determined to have been adopted after obtaining support from a two-thirds (> 66.6%) majority vote of each of the 19 committee members.

RESULTS

A total of 87 CQs were selected among 19 clinical areas, including pediatric topics and several other important areas not covered in the first edition of the Japanese guidelines (J-SSCG 2012). The approval rate obtained through committee voting, in addition to ratings of the strengths of the recommendation, and its supporting evidence were also added to each recommendation statement. We conducted meta-analyses for 29 CQs. Thirty-seven CQs contained recommendations in the form of an expert consensus due to insufficient evidence. No recommendations were provided for five CQs.

CONCLUSIONS

Based on the evidence gathered, we were able to formulate Japanese-specific clinical practice guidelines that are tailored to the Japanese context in a highly transparent manner. These guidelines can easily be used not only by specialists, but also by non-specialists, general clinicians, nurses, pharmacists, clinical engineers, and other healthcare professionals.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2016 (J-SSCG 2016)

Background and Purpose

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2016 (J-SSCG 2016), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in February 2017 in Japanese. An English-language version of these guidelines was created based on the contents of the original Japanese-language version.

Methods

Members of the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine were selected and organized into 19 committee members and 52 working group members. The guidelines were prepared in accordance with the Medical Information Network Distribution Service (Minds) creation procedures. The Academic Guidelines Promotion Team was organized to oversee and provide academic support to the respective activities allocated to each Guideline Creation Team. To improve quality assurance and workflow transparency, a mutual peer review system was established, and discussions within each team were open to the public. Public comments were collected once after the initial formulation of a clinical question (CQ), and twice during the review of the final draft. Recommendations were determined to have been adopted after obtaining support from a two-thirds (>66.6%) majority vote of each of the 19 committee members.

Results

A total of 87 CQs were selected among 19 clinical areas, including pediatric topics and several other important areas not covered in the first edition of the Japanese guidelines (J-SSCG 2012). The approval rate obtained through committee voting, in addition to ratings of the strengths of the recommendation and its supporting evidence were also added to each recommendation statement. We conducted meta-analyses for 29 CQs. Thirty seven CQs contained recommendations in the form of an expert consensus due to insufficient evidence. No recommendations were provided for 5 CQs.

Conclusions

Based on the evidence gathered, we were able to formulate Japanese-specific clinical practice guidelines that are tailored to the Japanese context in a highly transparent manner. These guidelines can easily be used not only by specialists, but also by non-specialists, general clinicians, nurses, pharmacists, clinical engineers, and other healthcare professionals.

Comparison of RIFLE, AKIN, and KDIGO classifications for assessing prognosis of patients on extracorporeal membrane oxygenation

BACKGROUND/PURPOSE

Acute kidney injury (AKI) developing during extracorporeal membrane oxygenation (ECMO) is associated with very poor outcome. The Kidney Disease: Improving Global Outcomes (KDIGO) group published a new AKI definition in 2012. This study analyzed the outcomes of patients treated with ECMO and identified the relationship between the prognosis and the KDIGO classification.

METHODS

This study examined total 312 patients initially, and finally reviewed the medical records of 167 patients on ECMO support at a tertiary care university hospital between March 2002 and November 2011. Demographic, clinical, and laboratory variables were retrospectively collected as survival predicators.

RESULTS

The overall mortality rate was 55.7%. In the analysis of the areas under the receiver operating characteristic curves, the KDIGO classification showed relatively higher discriminatory power (0.840 ± 0.032) than the Risk of renal failure, Injury to the kidney, Failure of kidney function, Loss of kidney function, and End-stage renal failure (RIFLE) (0.826 ± 0.033) and Acute Kidney Injury Network (AKIN) (0.836 ± 0.032) criteria in predicting in-hospital mortality. Furthermore, multiple logistic regression analysis showed that KDIGO, hemoglobin, and Glasgow Coma Scale score on the first day of patients on ECMO were independent predictors for in-hospital mortality. Finally, cumulative survival rates at 6-month follow-up after hospital discharge differed significantly for KDIGO stage 3 versus KDIGO stage 0, 1, and 2 (p < 0.001); and KDIGO stage 2 versus KDIGO stage 0 (p < 0.05).

CONCLUSION

For those patients with ECMO support, the KDIGO classification proved to be a more reproducible evaluation tool with excellent prognostic abilities than RIFLE or AKIN classification.

Incidence, timing and outcome of AKI in critically ill patients varies with the definition used and the addition of urine output criteria

Background

Acute kidney injury (AKI) is a serious complication of critical illness with both attributed morbidity and mortality at short-term and long-term. The incidence of AKI reported in critically ill patients varies substantially with the population evaluated and the definitions used. We aimed to assess which of the AKI definitions (RIFLE, AKIN or KDIGO) with or without urine output criteria recognizes AKI most frequently and quickest. Additionally, we conducted a review on the comparison of incidence proportions of varying AKI definitions in populations of critically ill patients.

Methods

We included all patients with index admissions to our intensive care unit (ICU) from January 1^st, 2014 until June 11^th, 2014 to determine the incidence and onset of AKI by RIFLE, AKIN and KDIGO during the first 7 days of ICU admission. We conducted a sensitive search using PubMed evaluating the comparison of RIFLE, AKIN and KDIGO in critically ill patients

Results

AKI incidence proportions were 15, 21 and 20% respectively using serum creatinine criteria of RIFLE, AKIN and KDIGO. Adding urine output criteria increased AKI incidence proportions to 35, 38 and 38% using RIFLE, AKIN and KDIGO definitions. Urine output criteria detected AKI in patients without AKI at ICU admission in a median of 13 h (IQR 7–22 h; using RIFLE definition) after admission compared to a median of 24 h using serum creatinine criteria (IQR24-48 h). In the literature a large heterogeneity exists in patients included, AKI definition used, reference or baseline serum creatinine used, and whether urine output in the staging of AKI is used.

Conclusion

AKIN and KDIGO criteria detect more patients with AKI compared to RIFLE criteria. Addition of urine output criteria detect patients with AKI 11 h earlier than serum creatinine criteria and may double AKI incidences in critically ill patients. This could explain the large heterogeneity observed in literature.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0487-8) contains supplementary material, which is available to authorized users.

Incidence and Outcomes of Acute Kidney Injury Requiring Renal Replacement Therapy: A Retrospective Cohort Study

BACKGROUND

Incidence of acute kidney injury (AKI), requiring dialysis, is on the rise globally and is associated with high mortality and morbidity.

AIM

This study is aimed at examining the incidence of AKI requiring renal replacement therapy (RRT) in the Tayside region of Scotland and the impact of RRT for AKI on morbidity, mortality and length of hospital stay.

METHODS

One hundred seventy eight patients (>18 years of age) who received acute RRT between January 1, 2012 and December 31, 2012 were retrospectively selected for inclusion in the longitudinal cohort study. Incidence rate was calculated. Length of hospital stay, likely cause of AKI, renal recovery and mortality data were collected for a follow-up period of 1 year or until death. Chi-square test was used to compare the morbidity and mortality data between subgroups. RRT-free survival and time-until-event (death or RRT) analysis was performed using Kaplan-Meier plots. Cox-regression was used to examine the relationship between age, sex, diabetes and chronic kidney disease (CKD) on survival.

RESULTS

Incidence of AKI requiring RRT was 430 per million population per year. Median length of hospital stay was 21 days. In-patient mortality was 36%, mortality at 90 days was 44% and at 1 year 54%. Median time from start of RRT until death or chronic RRT was 90 days (95% CI 14-166). One-year cumulative RRT-free survival was 26% in the ward, 36% in high dependency units and 48% in intensive care unit subgroups. Diabetes, gender and CKD at baseline did not affect RRT-free survival in the cohort being studied. A quarter of the cohort regained full renal function and 15% of survivors were on a chronic dialysis programme at 1 year.

CONCLUSIONS

This study gives a comprehensive summary of renal outcomes and mortality after a single episode of AKI requiring RRT. The findings of the study confirm that dialysis-dependent AKI is associated with increased length of hospital stay, high mortality and loss of renal function long term, emphasizing the importance of recognition, classification and prevention of AKI.

Acute Kidney Injury in Asia

BACKGROUND

Acute kidney injury (AKI) is a common disorder and is associated with a high morbidity and mortality worldwide. The diversity of the climate and of the socioeconomic and developmental status in Asia has a great influence on the etiology and presentation of AKI in different regions. In view of the International Society of Nephrology's 0by25 initiative, more and more attention has been paid to AKI in Asian countries.

SUMMARY

In this review, we summarize the recent achievements with regard to the prevalence and clinical patterns of AKI in Asian countries. Epidemiological studies have revealed the huge medical and economic burden of AKI in Eastern Asian countries, whereas the true epidemiological picture of AKI in the tropical areas is still not well understood. In high-income Asian regions, the presentation of AKI resembles that in other developed countries in Europe and North America. In low-income regions and tropical areas, infections, environmental toxins, and obstetric complications remain the major culprits in most cases of AKI. Preventive opportunities are missed because of failure to recognize the risk factors and early signs of AKI. Patients often present late for treatment or are recognized late by physicians, which leads to more severe kidney injury, multiorgan involvement, and increased mortality. There is significant undertreatment of AKI in many regions, and medical resources for renal replacement therapy are not universally available.

KEY MESSAGES

More efforts should be made to increase public awareness, establish preventive approaches in communities, educate health-care practitioner entities to achieve better recognition, and form specialist renal teams to improve the treatment of AKI. The choice of renal replacement therapy should fit patients' needs, and peritoneal dialysis can be practiced more frequently in the treatment of AKI patients.

FACTS FROM EAST AND WEST

(1) More than 90% of the patients recruited in AKI studies using KDIGO-equivalent criteria originate from North America, Europe, or Oceania, although these regions represent less than a fifth of the global population. However, the pooled incidence of AKI in hospitalized patients reaches 20% globally with moderate variance between regions. (2) The lower incidence rates observed in Asian countries (except Japan) may be due to a poorer recognition rate, for instance because of less systematically performed serum creatinine tests. (3) AKI patients in South and Southeastern Asia are younger than in East Asia and Western countries and present with fewer comorbidities. (4) Asian countries (and to a certain extent Latin America) face specific challenges that lead to AKI: nephrotoxicity of traditional herbal and less strictly regulated nonprescription medicines, environmental toxins (snake, bee, and wasp venoms), and tropical infectious diseases (malaria and leptospirosis). A higher incidence and less efficient management of natural disasters (particularly earthquakes) are also causes of AKI that Western countries are less likely to encounter. (5) The incidence of obstetric AKI decreased globally together with an improvement in socioeconomic levels particularly in China and India in the last decades. However, antenatal care and abortion management must be improved to reduce AKI in women, particularly in rural areas. (6) Earlier nephrology referral and better access to peritoneal dialysis should improve the outcome of AKI patients.

A comparison of RIFLE, AKIN, KDIGO, and Cys-C criteria for the definition of acute kidney injury in critically ill patients

PURPOSE

AKI is a major clinical problem and predictor of prognosis in critically ill patients. The aim of our study was to determine whether the new Cys-C criteria for identification and prognosis of AKI were superior to the RIFLE, AKIN, and KDIGO criteria.

METHODS

In the retrospective and multicenter study, the incidence of AKI was identified by the four criteria. Receiver operating characteristic (ROC) curve was applied to compare the predictive ability for 28-day mortality, and logistic regression analysis was used for the calculation of odds ratios and 95 % confidence intervals.

RESULTS

In the 1036 patients enrolled, the incidences of AKI were 26.4, 34.1, 37.8, and 36.1 %, respectively, under the four criteria. Patients with AKI had higher mortality and longer length of stay than those without in all definitions. Concordance in AKI diagnosis between Cys-C and KDIGO criteria was 95.9 %, higher than AKIN and RIFLE criteria (p < 0.0001). The area under ROC curves was 0.7023 for Cys-C criteria, which was a significantly greater discrimination (p < 0.05).

CONCLUSION

KDIGO criteria identified significantly more AKI and AKI patients had significantly higher 28-day mortality than patients without AKI. The Cys-C criteria were more predictive for short-term outcomes than other three criteria among critically ill patients.

The Frequency and Outcome of Acute Kidney Injury in a Tertiary Hospital: Which Factors Affect Mortality?

Acute kidney injury (AKI) is a major cause of mortality and morbidity in hospitalized patients. Incidence and mortality rates vary from country to country, and according to different in-hospital monitoring units and definitions of AKI. The aim of this study was to determine factors affecting frequency of AKI and mortality in our hospital. We retrospectively evaluated data for 1550 patients diagnosed with AKI and 788 patients meeting the Kidney Disease: Improving Global Outcomes (KDIGO) guideline AKI criteria out of a total of 174 852 patients hospitalized in our institution between January 1, 2007 and December 31, 2012. Staging was performed based on KDIGO Clinical Practice for Acute Kidney Injury and RIFLE (Risk, Injury, Failure, Loss of kidney function and End-stage renal failure). Demographic and biochemical data were recorded and correlations with mortality were assessed. The frequency of AKI in our hospital was 0.9%, with an in-hospital mortality rate of 34.6%. At multivariate analysis, diastolic blood pressure (OR 0.89, 95% CI 0.87-0.92; P < 0.001), monitoring in the intensive care unit (OR 0.18, 95% CI 0.09-0.38; P < 0.001), urine output (OR 4.00, 95% CI 2.03-7.89; P < 0.001), duration of oliguria (OR 1.51, 95% CI 1.34-1.69; P < 0.001), length of hospitalization (OR 0.83, 95% CI 0.79-0.88; P < 0.001), dialysis requirement (OR 2.30, 95% CI 1.12-4.71; P < 0.05), APACHE II score (OR 1.16, 95% CI 1.09-1.24; P < 0.001), and albumin level (OR 0.32, 95% CI 0.21-0.50; P < 0.001) were identified as independent determinants affecting mortality. Frequency of AKI and associated mortality rates in our regional reference hospital were compatible with those in the literature. This study shows that KDIGO criteria are more sensitive in determining AKI. Mortality was not correlated with staging based on RIFLE or KDIGO. Nonetheless, our identification of urine output as one of the independent determinants of mortality suggests that this parameter should be used in assessing the correlation between staging and mortality.