Global epidemiology and outcomes of acute kidney injury

Utilization of Echocardiography After Acute Kidney Injury Was Associated with Improved Outcomes in Patients in Intensive Care Unit

Background

We aimed to investigate the association between usage of transthoracic echocardiography (TTE) within 24 hours after acute kidney injury (AKI) and the prognosis of patients in intensive care unit (ICU).

Methods

The Medical Information Mart for Intensive Care III (MIMIC-III) database was used to identify AKI patients with and without TTE administration. The primary outcome was 28-day mortality. Multivariable regression was used to clarify the association between TTE and clinical outcomes and propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were utilized to validate our findings.

Results

Among 23,945 eligible AKI patients, 3361 patients who received TTE and 3361 who did not conduct TTE had similar propensity scores which were included in this study. After matching, the TTE group had a significantly lower 28-day mortality (OR 0.80, 95% CI 0.72–0.88, P<0.001). Patients in the TTE group received more fluid on day 1 and day 2 and had a more urine volume on day 1 and day 3, and the reduction in serum creatinine was greater than that in the no TTE group. The mediating effect of creatinine reduction was remarkable for the whole cohort (P=0.02 for the average causal mediation effect).

Conclusion

TTE utilization was associated with decreased risk-adjusted 28-day mortality for AKI patients in ICU and was proportionally mediated through creatinine reduction.

Ginkgolide A attenuates sepsis-associated kidney damage via upregulating microRNA-25 with NADPH oxidase 4 as the target

The aim of the present study was to explore the effects of Ginkgolide A (GA) on renal function of mice with sepsis and whether GA could attenuate sepsis-associated inflammation and apoptosis in kidney via upregulating microRNA (miR)-25 with NADPH oxidase 4 (Nox4) as the target. Experiments were carried out on lipopolysaccharide (LPS)-treated mice and kidney tubular (NRK-52E) cells. GA significantly inhibited the increases of creatinine (Cr), blood urea nitrogen (BUN) and cystatin C (CysC) in the serum of LPS-treated mice. The increases of inflammatory factors including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 in the kidneys of LPS-treated mice or NRK-52E cells were inhibited by GA administration. The changes of cleaved-caspase 3, cleaved-caspase 8, Bax, Bcl2 in mouse kidney and NRK-52E cells treated by LPS were reversed by GA administration. The sepsis-induced decrease of miR-25 was enhanced by GA treatment. The LPS-induced increases of inflammatory factors and apoptosis in mouse kidney or NRK-52E cells were attenuated after miR-25 agomiR administration. The bioinformatics analysis and luciferase reporter assays showed that Nox4 was a direct target gene of miR-25. Treatment with miR-25 inhibited Nox4 expression, while Nox4 over-expression reversed the inhibiting effects of miR-25 agomiR on LPS-induced increases of inflammatory factors and apoptosis in NRK-52E cells. These results indicated that GA could improve sepsis-induced renal damage by attenuating renal inflammation and apoptosis via upregulating miR-25 with Nox4 as the target.

Acute kidney disease in hospitalized acute kidney injury patients

Background

Acute kidney injury (AKI) and chronic kidney disease (CKD) have become worldwide public health problems, but little information is known about the epidemiology of acute kidney disease (AKD)—a state in between AKI and CKD. We aimed to explore the incidence and outcomes of hospitalized patients with AKD after AKI, and investigate the prognostic value of AKD in predicting 30-day and one-year adverse outcomes.

Methods

A total of 2,556 hospitalized AKI patients were identified from three tertiary hospitals in China in 2015 and followed up for one year.AKD and AKD stage were defined according to the consensus report of the Acute Disease Quality Initiative 16 workgroup. Multivariable regression analyses adjusted for confounding variables were used to examine the association of AKD with adverse outcomes.

Results

AKD occurred in 45.4% (1161/2556) of all AKI patients, 14.5% (141/971) of AKI stage 1 patients, 44.6% (308/691) of AKI stage 2 patients and 79.6% (712/894) of AKI stage 3 patients. AKD stage 1 conferred a greater risk of Major Adverse Kidney Events within 30 days (MAKE30) (odds ratio [OR], 2.36; 95% confidence interval 95% CI [1.66–3.36]) than AKD stage 0 but the association only maintained in AKI stage 3 when patients were stratified by AKI stage. However, compared with AKD stage 0, AKD stage 2–3 was associated with higher risks of both MAKE30 and one-year chronic dialysis and mortality independent of the effects of AKI stage with OR being 31.35 (95% CI [23.42–41.98]) and 2.68 (95% CI [2.07–3.48]) respectively. The association between AKD stage and adverse outcomes in 30 days and one year was not significantly changed in critically ill and non-critically ill AKI patients. The results indicated that AKD is common among hospitalized AKI patients. AKD stage 2–3 provides additional information in predicting 30-day and one-year adverse outcomes over AKI stage. Enhanced follow-up of renal function of these patients may be warranted.

Impact of the Natural Compound Urolithin A on Health, Disease, and Aging

Urolithin A (UA) is a natural compound produced by gut bacteria from ingested ellagitannins (ETs) and ellagic acid (EA), complex polyphenols abundant in foods such as pomegranate, berries, and nuts. UA was discovered 40 years ago, but only recently has its impact on aging and disease been explored. UA enhances cellular health by increasing mitophagy and mitochondrial function and reducing detrimental inflammation. Several preclinical studies show how UA protects against aging and age-related conditions affecting muscle, brain, joints, and other organs. In humans, benefits of UA supplementation in the muscle are supported by recent clinical trials in elderly people. Here, we review the state of the art of UA's biology and its translational potential as a nutritional intervention in humans.

Incidence and predictors of early and delayed renal function decline after aortic aneurysm repair in the Vascular Quality Initiative database

BACKGROUND

Postoperative acute kidney injury (AKI) may complicate both open and endovascular aortic aneurysm repair (EVAR) and is associated with substantial morbidity, mortality, and health care expense. We aim to evaluate the incidence of postoperative AKI and factors associated with its occurrence and the effects of postoperative AKI on long-term renal function and mortality after open and EVAR in the Society for Vascular Surgery Vascular Quality Initiative registry.

METHODS

Elective aneurysm cases were identified including thoracic endovascular aortic aneurysm repair (TEVAR) and complex endovascular aortic aneurysm repair (cEVAR), infrarenal endovascular repair (EVAR) and infrarenal open repair (OAR) from 2003 to 2019. The preoperative estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet in Renal Disease formula and stratified based on chronic kidney disease (CKD) grades. Postoperative AKI was defined per the Vascular Quality Initiative definition as a creatinine increase of 0.5 mg/dL or if postoperative dialysis was required. Patients on preprocedural hemodialysis and those with previous renal transplant were excluded. Demographics and procedural factors were evaluated for predicting in-hospital postoperative AKI (all approaches) and at 9 to 21 months of long-term follow-up (EVAR only) using logistic regression modeling.

RESULTS

We identified a total of 2813 cEVAR, 2995 TEVAR, 39,945 EVAR, and 8143 OAR patients. Of those, postoperative AKI occurred in 377 cEVAR (13.5%), 199 TEVAR (6.7%), 1099 EVAR (2.8%), and 1249 OAR (15.5%). Risk factors for postoperative AKI across all groups were worse preoperative eGFR, total number of blood transfusions, perioperative anemia, reinterventions, and postoperative respiratory complications. Additional procedure-specific risk factors of postoperative AKI were preoperative hemoglobin of less than 10 and contrast volume of 125 to 150 mL, hypertension, a low ejection fraction, and a history of percutaneous revascularization for EVAR; for both EVAR/cEVAR, renal artery coverage was a risk factor, whereas for OAR, male sex, non-White race, hypertension, suprarenal aortic cross-clamp, and increased renal ischemic time were risk factors. Among 8133 EVAR patients with long-term follow-up, a decrease in kidney function occurred in 56.7% of patients with postoperative AKI vs 19.9% without postoperative AKI (P < .001). The following risk factors were associated with a decrease in renal function at long-term follow-up: postoperative AKI, a preoperative eGFR of less than 90, and hypertension. A preoperative hemoglobin of greater than 12 was protective. Postoperative AKI was associated with significantly lower survival compared with no postoperative AKI across all procedures (log rank <0.001).

CONCLUSIONS

Postoperative AKI occurs more often in patients with worse preoperative renal function, lower preoperative hemoglobin, and in open surgeries with inter-renal or suprarenal cross-clamping. Importantly, postoperative AKI is associated with increased mortality across all types of aortic repair. Given the long-term impact of postoperative AKI on outcomes for all aortic repairs and the limitations of current insensitive functional indices, there is a need to seek more sensitive indicators of decreases in early renal structural in this population.

Particulate kidney extracellular matrix: bioactivity and proteomic analysis of a novel scaffold from porcine origin

Decellularized matrices are attractive substrates, being able to retain growth factors and proteins present in the native tissue. Several biomaterials can be produced by processing these matrices. However, new substrates capable of being injected that reverse local kidney injuries are currently scarce. Herein, we hypothesized that the decellularized particulate kidney porcine ECM (pKECM) could support renal progenitor cell cultures for posterior implantation. Briefly, kidneys are cut into pieces, decellularized by immersion on detergent solutions, lyophilized and reduced into particles. Then, ECM particles are analyzed for nuclear material remaining by DNA quantification and histological examination, molecular conformation by FITR and structural morphology by SEM. Protein extraction is also optimized for posterior identification and quantification by mass spectrometry. The results obtained confirm the collagenous structure and composition of the ECM, the effective removal of nucleic material and the preservation of ECM proteins with great similarity to human kidneys. Human renal progenitor cells (hRPCs) are seeded in different ratios with pKECM, on 3D suspensions. The conducted assays for cell viability, proliferation and distribution over 7 days of culture suggest that these matrices as biocompatible and bioactive substrates for hRPCs. Also, by analyzing CD133 expression, an optimal ratio for specific phenotypic expression is revealed, demonstrating the potential of these substrates to modulate cellular behavior. The initial hypothesis of developing and characterizing a particulate ECM biomaterial as a consistent substrate for 3D cultures is successfully validated. The findings in this manuscript suggest these particles as valuable tools for regenerative nephrology by minimizing surgeries and locally reversing small injuries which can lead to chronic renal disfunction.

Genetic and pharmacological inhibition of fatty acid-binding protein 4 alleviated inflammation and early fibrosis after toxin induced kidney injury

Considerable data have suggested that acute kidney injury (AKI) is often incompletely repaired and could lead to chronic kidney disease (CKD). As we known, toxin-induced nephropathy triggers the rapid production of proinflammatory mediators and the prolonged inflammation allows the injured kidneys to develop interstitial fibrosis. In our previous study, fatty acid-binding protein 4 (Fabp4) has been reported to be involved in the process of AKI. However, whether Fabp4 plays crucial roles in toxin-induced kidney injury remained unclear. To explore the effect and mechanism of Fabp4 on toxin induced kidney injury, folic acid (FA) and aristolochic acid (AA) animal models were used. Both FA and AA injected mice developed severe renal dysfunction and dramatically inflammatory response (IL-6, MCP1 and TNF-a), which further lead to early fibrosis confirmed by the accumulation of extracellular matrix proteins (α-Sma, Fn, Col1 and Col4). Importantly, we found that FA and AA induced-kidney injury triggered the high expression of Fabp4 mRNA/protein in tubular epithelial cells. Furthermore, pharmacological and genetic inhibition of Fabp4 significantly attenuated FA and AA induced renal dysfunction, pathological damage, and early fibrosis via the regulation of inflammation, which is mediated by suppressing p-p65/p-stat3 expression via enhancing Pparγ activity. In summary, Fabp4 in tubular epithelial cells exerted the deleterious effects during the recovery of FA and AA induced kidney injury and the inhibition of Fabp4 might be an effective therapeutic strategy against the progressive AKI.

A novel risk-predicted nomogram for sepsis associated-acute kidney injury among critically ill patients

Background

Acute kidney injury (AKI) is a prevalent and severe complication of sepsis contributing to high morbidity and mortality among critically ill patients. In this retrospective study, we develop a novel risk-predicted nomogram of sepsis associated-AKI (SA-AKI).

Methods

A total of 2,871 patients from the Medical Information Mart for Intensive Care III (MIMIC-III) critical care database were randomly assigned to primary (2,012 patients) and validation (859 patients) cohorts. A risk-predicted nomogram for SA-AKI was developed through multivariate logistic regression analysis in the primary cohort while the nomogram was evaluated in the validation cohort. Nomogram discrimination and calibration were assessed using C-index and calibration curves in the primary and external validation cohorts. The clinical utility of the final nomogram was evaluated using decision curve analysis.

Results

Risk predictors included in the prediction nomogram included length of stay in intensive care unit (LOS in ICU), baseline serum creatinine (SCr), glucose, anemia, and vasoactive drugs. Nomogram revealed moderate discrimination and calibration in estimating the risk of SA-AKI, with an unadjusted C-index of 0.752, 95 %Cl (0.730–0.774), and a bootstrap-corrected C index of 0.749. Application of the nomogram in the validation cohort provided moderate discrimination (C-index, 0.757 [95 % CI, 0.724–0.790]) and good calibration. Besides, the decision curve analysis (DCA) confirmed the clinical usefulness of the nomogram.

Conclusions

This study developed and validated an AKI risk prediction nomogram applied to critically ill patients with sepsis, which may help identify reasonable risk judgments and treatment strategies to a certain extent. Nevertheless, further verification using external data is essential to enhance its applicability in clinical practice.

The Cross-Link between Ferroptosis and Kidney Diseases

Acute and chronic kidney injuries result from structural dysfunction and metabolic disorders of the kidney in various etiologies, which significantly affect human survival and social wealth. Nephropathies are often accompanied by various forms of cell death and complex microenvironments. In recent decades, the study of kidney diseases and the traditional forms of cell death have improved. Nontraditional forms of cell death, represented by ferroptosis and necroptosis, have been discovered in the field of kidney diseases, which have reshuffled the role of traditional cell death in nephropathies. Although interactions between ferroptosis and acute kidney injury (AKI) have been continuously explored, studies on ferroptosis and chronic kidney disease (CKD) remain limited. Here, we have reviewed the therapeutic significance of ferroptosis in AKI and anticipated the curative potential of ferroptosis for CKD in the hope of providing insights into ferroptosis and CKD.

A systematic review of cost-effectiveness analyses of continuous versus intermittent renal replacement therapy in acute kidney injury

INTRODUCTION

Though cost-effectiveness analyses (CEAs) have evaluated continuous renal replacement therapy (RRTs) and intermittent RRTs in acute kidney injury (AKI) patients; it is yet to establish which RRT technique is most cost-effective. We systematically reviewed the current evidence from CEAs of CRRT versus IRRT in patients with AKI.

AREAS COVERED

PubMed, EMBASE, and Cochrane databases searched for CEAs comparing two RRTs. Overall, seven CEAs, two from Brazil and one from US, Canada, Colombia, Belgium, and Argentina were included. Five CEAs used Markov model, three reported following CHEERS, none accounted indirect costs. Time horizon varied from 1-year-lifetime. Marginal QALY gain with CRRT compared to IRRT was reported across CEAs. Older CEAs found CRRT to be costlier and not cost-effective than IRRT (ICER 2019 US$: 152,671$/QALY); latest CEAs (industry-sponsored) reported CRRT to be cost-saving versus IRRT (-117,614$/QALY). Risk of mortality, dialysis dependence, and incidence of renal recovery were the key drivers of cost-effectiveness.

EXPERT OPINION

CEAs of RRTs for AKI show conflicting findings with secular trends. Latest CEAs suggested CRRT to be cost-effective versus IRRT with dialysis dependence rate as major driver of cost-effectiveness. Future CEAs, preferably non-industry sponsored, may account for indirect costs to improve the generalizability of CEAs.

Acute kidney disease and long-term outcomes in critically ill acute kidney injury patients with sepsis: a cohort analysis

BACKGROUND

Acute kidney injury (AKI) is frequent during hospitalization and may contribute to adverse short- and long-term consequences. Acute kidney disease (AKD) reflects the continuing pathological processes and adverse events developing after AKI. We aimed to evaluate the association of AKD, long-term adverse renal function and mortality in a cohort of patients with sepsis.

METHODS

We performed a retrospective analysis of adult patients with septic AKI admitted to the Division of Intensive Medicine of the Centro Hospitalar Lisboa Norte (Lisbon, Portugal) between January 2008 and December 2014. Patients were categorized according to the development of AKI using the Kidney Disease: Improving Global Outcomes (KDIGO) classification. AKI was defined as an increase in absolute serum creatinine (SCr) ≥0.3 mg/dL or by a percentage increase in SCr ≥50% and/or by a decrease in urine output to <0.5 mL/kg/h for >6 h. AKD was defined as presenting at least KDIGO Stage 1 criteria for >7 days after an AKI initiating event. Adverse renal outcomes (need for long-term dialysis and/or a 25% decrease in estimated glomerular filtration rate after hospital discharge) and mortality after discharge were evaluated.

RESULTS

From 256 selected patients with septic AKI, 53.9% developed AKD. The 30-day mortality rate was 24.5% (n = 55). The mean long-term follow-up was 45.9 ± 43.3 months. The majority of patients experience an adverse renal outcome [n = 158 (61.7%)] and 44.1% (n = 113) of patients died during follow-up. Adverse renal outcomes, 30-day mortality and long-term mortality after hospital discharge were more frequent among AKD patients [77.5 versus 43.2% (P < 0.001), 34.1 versus 6.8% (P < 0.001) and 64.8 versus 49.1% (P = 0.025), respectively]. The 5-year cumulative probability of survival was 23.2% for AKD patients, while it was 47.5% for patients with no AKD (log-rank test, P < 0.0001). In multivariate analysis, AKD was independently associated with adverse renal outcomes {adjusted hazard ratio [HR] 2.87 [95% confidence interval (CI) 2.0-4.1]; P < 0.001} and long-term mortality [adjusted HR 1.51 (95% CI 1.0-2.2); P = 0.040].

CONCLUSIONS

AKD after septic AKI was independently associated with the risk of long-term need for dialysis and/or renal function decline and with the risk of death after hospital discharge.

Convolutional Neural Network Model for Intensive Care Unit Acute Kidney Injury Prediction

INTRODUCTION

Acute kidney injury (AKI) is common among hospitalized patients and has a significant impact on morbidity and mortality. Although early prediction of AKI has the potential to reduce adverse patient outcomes, it remains a difficult condition to predict and diagnose. The purpose of this study was to evaluate the ability of a machine learning algorithm to predict for AKI as defined by Kidney Disease: Improving Global Outcomes (KDIGO) stage 2 or 3 up to 48 hours in advance of onset using convolutional neural networks (CNNs) and patient electronic health record (EHR) data.

METHODS

A CNN prediction system was developed to use EHR data gathered during patients' stays to predict AKI up to 48 hours before onset. A total of 12,347 patient encounters were retrospectively analyzed from the Medical Information Mart for Intensive Care III (MIMIC-III) database. An XGBoost AKI prediction model and the sequential organ failure assessment (SOFA) scoring system were used as comparators. The outcome was AKI onset. The model was trained on routinely collected patient EHR data. Measurements included area under the receiver operating characteristic (AUROC) curve, positive predictive value (PPV), and a battery of additional performance metrics for advance prediction of AKI onset.

RESULTS

On a hold-out test set, the algorithm attained an AUROC of 0.86 and PPV of 0.24, relative to a cohort AKI prevalence of 7.62%, for long-horizon AKI prediction at a 48-hour window before onset.

CONCLUSION

A CNN machine learning-based AKI prediction model outperforms XGBoost and the SOFA scoring system, revealing superior performance in predicting AKI 48 hours before onset, without reliance on serum creatinine (SCr) measurements.

Hyaluronic acid coated bilirubin nanoparticles attenuate ischemia reperfusion-induced acute kidney injury

Acute kidney injury (AKI) is a common pathological process that is globally associated with a high morbidity and mortality rate. The underlying AKI mechanisms include over-produced reactive oxygen species (ROS), inflammatory cell infiltration, and high levels of inflammatory mediators. Bilirubin is an endogenous compound with antioxidant, anti-inflammatory and anti-apoptotic properties, and could, therefore, be a promising therapeutic candidate. Nanotechnology-mediated therapy has emerged as a novel drug delivery strategy for AKI treatment. In this study, we report a hyaluronic acid (HA) coated ε-polylysine-bilirubin conjugate (PLBR) nanoparticle (nHA/PLBR) that can selectively accumulate in injured kidneys and alleviate the oxidative/inflammatory-induced damage. The in vitro study revealed that nHA/PLBR has good stability, biocompatibility, and exhibited higher antioxidant as well as anti-apoptotic effects when compared to nPLBR or bilirubin. The in vivo study showed that nHA/PLBR could target and accumulate in the injured kidney, effectively relieve oxidative stress and inflammatory reactions, protect the structure and function of the mitochondria, and more importantly, inhibit the apoptosis of tubular cells in an ischemia/reperfusion-induced AKI rat model. Therefore, nHA/PLBR has the capacity to enhance specific biodistribution and delivery efficiency of bilirubin, thereby providing better treatment for AKI in the future.

Fighting the unbearable lightness of neglecting kidney health: the decade of the kidney

A brief comprehensive overview is provided of the elements constituting the burden of kidney disease [chronic kidney disease (CKD) and acute kidney injury]. This publication can be used for advocacy, emphasizing the importance and urgency of reducing this heavy and rapidly growing burden. Kidney diseases contribute to significant physical limitations, loss of quality of life, emotional and cognitive disorders, social isolation and premature death. CKD affects close to 100 million Europeans, with 300 million being at risk, and is projected to become the fifth cause of worldwide death by 2040. Kidney disease also imposes financial burdens, given the costs of accessing healthcare and inability to work. The extrapolated annual cost of all CKD is at least as high as that for cancer or diabetes. In addition, dialysis treatment of kidney diseases imposes environmental burdens by necessitating high energy and water consumption and producing plastic waste. Acute kidney injury is associated with further increases in global morbidity, mortality and economic burden. Yet investment in research for treatment of kidney disease lags behind that of other diseases. This publication is a call for European investment in research for kidney health. The innovations generated should mirror the successful European Union actions against cancer over the last 30 years. It is also a plea to nephrology professionals, patients and their families, caregivers and kidney health advocacy organizations to draw, during the Decade of the Kidney (2020–30), the attention of authorities to realize changes in understanding, research and treatment of kidney disease.

Using lipocalin as a prognostic biomarker in acute kidney injury

Introduction: Human lipocalin-2, known as neutrophil gelatinase-associated lipocalin (NGAL), is a widely studied biomarker of acute kidney injury (AKI).Areas covered: NGAL can serve as a predictor of AKI, disease progression, and mortality and can help in differentiating between AKI etiologies. We conducted a systematic review in the PubMed and Medline databases involving the clinical application of NGAL in patients with AKI.Expert opinion: In this review, we explored the usefulness of NGAL for AKI or clinical outcome prediction. The use of urine or blood NGAL levels alone or in combination with a clinical prediction model may facilitate AKI prediction, severity prediction, AKI etiological differentiation, and mortality prediction. For AKI prediction, urine and plasma NGAL levels have an area under the curve (AUC) ranging from 0.71 to 0.90 and from 0.71 to 0.89, respectively, in different populations. The diagnostic performance of NGAL alone for renal replacement therapy or successful discontinuation prediction is suboptimal (AUC range: 0.65-0.81). Sepsis limits the application of NGAL as a clinical predictor, and the prediction performance of NGAL is affected by baseline renal function, timing of sample collection, and underlying comorbidities. The lack of internationally approved reference material also limits the usefulness of NGAL.

Acute Kidney Injury in Pediatric Cardiac Intensive Care Children: Not All Admissions Are Equal: A Retrospective Study

OBJECTIVES

To describe the incidence, associated characteristics, and outcomes of the maximum severity of acute kidney injury (AKI) in a heterogeneous population of critically ill children with cardiac disease.

DESIGN

Retrospective cohort study.

SETTING

Pediatric cardiac intensive care unit (PCICU).

PARTICIPANTS

Patients admitted to the PCICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

From January 2018 to July 2020 all patients admitted to a tertiary PCICU were included. Only the first admission was considered. Neonates ≤seven days old were excluded. Of 742 patients, 53 were medical cases, 69 catheterization laboratory cases, and 620 surgical cases (with five subgroups). The median age was 2.47 years (interquartile range [IQR], 0.38-9.85 years), with a median Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery score of 2 (IQR, 1-3). Median PCICU length of stay was three days (IQR, 2-7 days), and 21 (2.8%) patients died. Any incidence of AKI occurred in 70% of patients, 26% of which were classified as mild (stage 1) and 43% as severe (stages 2 and 3). AKI was diagnosed by urine output criteria in 56%, serum creatinine in 28%, and both in 16% of patients. Severe AKI occurred in subgroups as follows: medical (38%), catheterization laboratory (45%), correction (35%), palliation (55%), transplantation (85%), mechanical assistance (70%), and redo surgery (58%). Severe AKI patients were significantly older (p = 0.004), had a higher Pediatric Index of Mortality 3 score (p = 0.0004), had a higher cumulative fluid balance (p < 0.0001), and had a longer cardiopulmonary bypass time (p < 0.0001). Early AKI (≤24 hours from admission) was the most frequent presentation, with a greater proportion of severe cases in the early group compared with the intermediate (>24 and ≤48 hours) and late (>48 hours) (p < 0.0001) groups. Presentation of late severe AKI had a higher mortality (odds ratio, 4.9; 95% confidence interval, 1.8-15; p = 0.001).

CONCLUSIONS

Severe AKI occurs in 43% of cardiac children and is diagnosed early, most often by urine output criteria. Severe AKI incidence varies significantly within subgroups of cardiac patients. Late AKI is associated with worse outcomes.

TiO2 Nano-test tubes as a solid visual platform for sensitive Pb2+ ion detection based on a fluorescence resonance energy transfer (FRET) process

A cost-effective, facile, and sensitive fluorescence sensing strategy for Pb²⁺ ion detection has been developed based on the fluorescence resonance energy transfer (FRET) between carbon quantum dots (CQDs) and Au nanoparticles (NPs). Glutathione (GSH)-synthesized CQDs acted as both the fluorescence donor and the sorbent to extract Pb²⁺ ions from the solution via Pb-GSH complexes. Pb²⁺ ions on CQDs reacted with -SH groups on AuNPs to generate sandwich-type Au-PdS-CQDs, leading to a dramatic decrease in the fluorescence of the CQDs. To expand the potential applications of this strategy, we constructed a sensing strategy using self-organized TiO₂ nanotube arrays (TiNTs). The high aspect ratio and transparency for light emitted from the CQDs enabled the TiNTs to serve as a sensitive solid visual platform for the highly selective detection of Pb²⁺ ions with a detection limit as low as 4.1 × 10^-8 mg mL^-1. More importantly, the long observation length combined with a small volume enabled a sample acquisition volume of only 2.1 × 10^-3 μL, which is smaller than the traditional fluorescence analysis in solution and on commercially available test paper, thus endowing this visual platform with the potential for use in single-cell diagnostics.

Mesenchymal stem cells and extracellular vesicles in therapy against kidney diseases

Kidney diseases pose a threat to human health due to their rising incidence and fatality rate. In preclinical and clinical studies, it has been acknowledged that mesenchymal stem cells (MSCs) are effective and safe when used to treat kidney diseases. MSCs play their role mainly by secreting trophic factors and delivering extracellular vesicles (EVs). The genetic materials and proteins contained in the MSC-derived EVs (MSC-EVs), as an important means of cellular communication, have become a research focus for targeted therapy of kidney diseases. At present, MSC-EVs have shown evident therapeutic effects on acute kidney injury (AKI), chronic kidney disease (CKD), diabetic nephropathy (DN), and atherosclerotic renovascular disease (ARVD); however, their roles in the transplanted kidney remain controversial. This review summarises the mechanisms by which MSC-EVs treat these diseases in animal models and proposes certain problems, expecting to facilitate corresponding future clinical practice.

MicroRNA-874-3p/ADAM (A Disintegrin and Metalloprotease) 19 Mediates Macrophage Activation and Renal Fibrosis After Acute Kidney Injury

[Figure: see text].

Epidemiological profile of acute kidney injury in critically ill patients admitted to intensive care units: A Prospective Brazilian Cohort

Introduction

Acute kidney injury (AKI) is a frequent syndrome affecting patients admitted to intensive care units (ICU), and it is associated with poor clinical outcomes. The aim of the present study was to understand the epidemiological profile of patients with AKI admitted to ICUs.

Methods

Prospective cohort study, carried out in three ICUs in the Federal District, Brazil. Between October/2017 and December/2018, 8,131 patients were included in the cohort. AKI was defined according to the KDIGO criteria. The main outcomes assessed were AKI development and mortality within 28 days of hospitalization.

Results

Of the 8,131 patients followed up, 1,728 developed AKI (21.3%). Of the 1,728 patients with AKI, 1,060 (61.3%) developed stage 1, while stages 2 and 3 represented 154 (8.9%) and 514 (29.7%), respectively. Of these, 459 (26.6%) underwent renal replacement therapy. The mortality was 25.7% for those with AKI, and 4.9% for those without AKI.

Discussion

Patients with AKI had higher mortality rates when compared to those without AKI. Likewise, among patients with AKI, higher disease stages were associated with higher death occurrences. AKI incidence (21.3%) and mortality (25.7%) in our study is in line with the largest meta-analysis ever conducted, in which incidence and mortality of 21.6 and 23.9% were observed, respectively. These findings confirm the importance of establishing the KDIGO guideline for the definition and management of AKI in Brazilian ICUs.

Exosomal miR-125b-5p deriving from mesenchymal stem cells promotes tubular repair by suppression of p53 in ischemic acute kidney injury

Mesenchymal stem cells-derived exosomes (MSC-exos) have attracted great interest as a cell-free therapy for acute kidney injury (AKI). However, the in vivo biodistribution of MSC-exos in ischemic AKI has not been established. The potential of MSC-exos in promoting tubular repair and the underlying mechanisms remain largely unknown. Methods: Transmission electron microscopy, nanoparticle tracking analysis, and western blotting were used to characterize the properties of human umbilical cord mesenchymal stem cells (hucMSCs) derived exosomes. The biodistribution of MSC-exos in murine ischemia/reperfusion (I/R) induced AKI was imaged by the IVIS spectrum imaging system. The therapeutic efficacy of MSC-exos was investigated in renal I/R injury. The cell cycle arrest, proliferation and apoptosis of tubular epithelial cells (TECs) were evaluated in vivo and in HK-2 cells. The exosomal miRNAs of MSC-exos were profiled by high-throughput miRNA sequencing. One of the most enriched miRNA in MSC-exos was knockdown by transfecting miRNA inhibitor to hucMSCs. Then we investigated whether this candidate miRNA was involved in MSC-exos-mediated tubular repair. Results:Ex vivo imaging showed that MSC-exos was efficiently homing to the ischemic kidney and predominantly accumulated in proximal tubules by virtue of the VLA-4 and LFA-1 on MSC-exos surface. MSC-exos alleviated murine ischemic AKI and decreased the renal tubules injury in a dose-dependent manner. Furthermore, MSC-exos significantly attenuated the cell cycle arrest and apoptosis of TECs both in vivo and in vitro. Mechanistically, miR-125b-5p, which was highly enriched in MSC-exos, repressed the protein expression of p53 in TECs, leading to not only the up-regulation of CDK1 and Cyclin B1 to rescue G2/M arrest, but also the modulation of Bcl-2 and Bax to inhibit TEC apoptosis. Finally, inhibiting miR-125b-5p could mitigate the protective effects of MSC-exos in I/R mice. Conclusion: MSC-exos exhibit preferential tropism to injured kidney and localize to proximal tubules in ischemic AKI. We demonstrate that MSC-exos ameliorate ischemic AKI and promote tubular repair by targeting the cell cycle arrest and apoptosis of TECs through miR-125b-5p/p53 pathway. This study provides a novel insight into the role of MSC-exos in renal tubule repair and highlights the potential of MSC-exos as a promising therapeutic strategy for AKI.

Serum Sodium Levels Predict Mortality in Elderly Acute Kidney Injury Patients: A Retrospective Observational Study

Purpose

We examined the relationship between different levels of serum sodium and mortality among elderly patients with acute kidney injury (AKI).

Methods

We retrospectively enrolled elderly patients from Chinese PLA General Hospital from 2007, to 2018. All-cause mortality was examined according to eight predefined sodium levels: <130.0 mmol/L, 130.0–134.9 mmol/L, 135.0–137.9 mmol/L, 138.0–141.9 mmol/L, 142.0–144.9 mmol/L, 145.0–147.9 mmol/L, 148.0–151.9 mmol/L, and ≥152.0 mmol/L. We estimated the risk of all-cause mortality using a multivariable adjusted Cox analysis, with a normal sodium level of 135.0–137.9 mmol/L as a reference.

Results

In total, 744 patients were suitable for the final evaluation. After 90 days, the mortality rates in the eight strata were 36.1, 27.8, 19.6, 24.4, 30.7, 48.6, 52.8, and 57.7%, respectively. In the multivariable adjusted analysis, patients with sodium levels <130.0 mmol/L (HR: 2.247; 95% CI: 1.117–4.521), from 142.0 to 144.9 mmol/L (HR: 1.964; 95% CI: 1.100–3.508), from 145.0 to 147.9 mmol/L (HR: 2.942; 95% CI: 1.693–5.114), from 148.0 to 151.9 mmol/L (HR: 3.455; 95% CI: 2.009–5.944), and ≥152.0 mmol/L (HR: 3.587; 95% CI: 2.151–5.983) had an increased risk of all-cause mortality. After 1 year, the mortality rates in the eight strata were 58.3, 47.8, 33.7, 38.9, 45.5, 64.3, 69.4, and 78.4%, respectively. Patients with sodium levels <130.0 mmol/L (HR: 1.944; 95% CI: 1.125–3.360), from 142.0 to 144.9 mmol/L (HR: 1.681; 95% CI: 1.062–2.660), from 145.0 to 147.9 mmol/L (HR: 2.631; 95% CI: 1.683–4.112), from 148.0 to 151.9 mmol/L (HR: 2.411; 95% CI: 1.552–3.744), and ≥152.0 mmol/L (HR: 3.037; 95% CI: 2.021–4.563) had an increased risk of all-cause mortality.

Conclusion

Sodium levels outside the interval of 130.0–141.9 mmol/L were associated with increased risks of 90-day mortality and 1-year mortality in elderly AKI patients.

Acute Kidney Injury Results in Long-Term Diastolic Dysfunction That Is Prevented by Histone Deacetylase Inhibition

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This is the first long-term (1-year) study to evaluate both the kidney and systemic sequelae of acute kidney injury in mice.

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Serial kidney function was measured via transcutaneous glomerular filtration rate.

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AKI resulted in diastolic dysfunction, followed by hypertension. Ejection fraction was preserved. One year after AKI, cardiac ATP levels were reduced compared with sham controls.

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Mice treated with the histone deacetylase inhibitor, ITF2357, maintained normal diastolic function normal blood pressure, and normal cardiac ATP after AKI.

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Metabolomics data suggest that treatment with ITF2357 preserves pathways related to energy metabolism.

Growing epidemiological data demonstrate that acute kidney injury (AKI) is associated with long-term cardiovascular morbidity and mortality. Here, the authors present a 1-year study of cardiorenal outcomes following bilateral ischemia-reperfusion injury in male mice. These data suggest that AKI causes long-term dysfunction in the cardiac metabolome, which is associated with diastolic dysfunction and hypertension. Mice treated with the histone deacetylase inhibitor, ITF2357, had preservation of cardiac function and remained normotensive throughout the study. ITF2357 did not protect against the development of kidney fibrosis after AKI.

[Acute Kidney Injury: Epidemiology, Pathophysiology, Repair Mechanisms]

Acute kidney injury (AKI) is a major complication in critically ill patients and affects up to 50% of those admitted to intensive care units. Causes of AKI include patient specific factors (susceptibility: e.g. age, pre-existing chronic kidney disease, chronic heart failure, diabetes) and patient unspecific factors (exposure: e.g. sepsis, hypovolemia, cardiac surgery, nephrotoxin application). Mortality of severe AKI is in the range of 40 - 50%.AKI is accompanied by volume overload, electrolyte disorders, acidosis, and uremia. The diagnosis of AKI is based on an increase of creatinine levels and/or a decrease in urine output within 7 days after an insult. These 2 markers are late und unspecific, especially with regard to early identification of patients at risk of AKI. New AKI markers have been investigated within the last decade including NGAL (neutrophil gelatinase-associated lipocalin), the product of IGFBP-7 (insulin like growth factor binding protein 7) and TIMP-2 (tissue inhibitor of metalloproteinase 2), KIM-1 (kidney injury molecule 1) and the cysteine-protease-inhibitor cystatin C. New markers or a panel of new markers might improve the diagnosis of patients at risk of AKI in the future.There are currently no specific therapeutics in the treatment of AKI. Therefore, the prevention of AKI is of an utmost importance. The recommended preventive measures include optimization of hemodynamics and volume status, close monitoring of creatinine levels and urine output, avoidance or discontinuation of nephrotoxic drugs, normoglycemia and the application of alternatives to radiocontrast agents if possible.As the long term prognosis of AKI highly depends on renal recovery, the 2 major goals for the future will be 1) the early identification of patients at AKI risk and 2) the support of renal recovery of AKI patients.

Multiparametric MRI assessment of renal structure and function in acute kidney injury and renal recovery

Background

Acute kidney injury (AKI) is associated with a marked increase in mortality as well as subsequent chronic kidney disease (CKD) and end-stage kidney disease. We performed multiparametric magnetic resonance imaging (MRI) with the aim of identifying potential non-invasive MRI markers of renal pathophysiology in AKI and during recovery.

Methods

Nine participants underwent inpatient MRI scans at time of AKI; seven had follow-up scans at 3 months and 1 year following AKI. Multiparametric renal MRI assessed total kidney volume (TKV), renal perfusion using arterial spin labelling, T₁ mapping and blood oxygen level-dependent (BOLD) R₂* mapping.

Results

Serum creatinine concentration had recovered to baseline levels at 1-year post-AKI in all participants. At the time of AKI, participants had increased TKV, increased cortex/medulla T₁ and reduced cortical perfusion compared with the expected ranges in healthy volunteers and people with CKD. TKV and T₁ values decreased over time after AKI and returned to expected values in most but not all patients by 1 year. Cortical perfusion improved to a lesser extent and remained below the expected range in the majority of patients by 1-year post-AKI. BOLD R₂* data showed a non-significant trend to increase over time post-AKI.

Conclusions

We observed a substantial increase in TKV and T₁ during AKI and a marked decrease in cortical perfusion. Despite biochemical recovery at 1-year post-AKI, MRI measures indicated persisting abnormalities in some patients. We propose that such patients may be more likely to have further AKI episodes or progress to CKD and further longitudinal studies are required to investigate this. .

Predicting mortality of patients with acute kidney injury in the ICU using XGBoost model

PURPOSE

The goal of this study is to construct a mortality prediction model using the XGBoot (eXtreme Gradient Boosting) decision tree model for AKI (acute kidney injury) patients in the ICU (intensive care unit), and to compare its performance with that of three other machine learning models.

METHODS

We used the eICU Collaborative Research Database (eICU-CRD) for model development and performance comparison. The prediction performance of the XGBoot model was compared with the other three machine learning models. These models included LR (logistic regression), SVM (support vector machines), and RF (random forest). In the model comparison, the AUROC (area under receiver operating curve), accuracy, precision, recall, and F1 score were used to evaluate the predictive performance of each model.

RESULTS

A total of 7548 AKI patients were analyzed in this study. The overall in-hospital mortality of AKI patients was 16.35%. The best performing algorithm in this study was XGBoost with the highest AUROC (0.796, p < 0.01), F1(0.922, p < 0.01) and accuracy (0.860). The precision (0.860) and recall (0.994) of the XGBoost model rank second among the four models.

CONCLUSION

XGBoot model had obvious advantages of performance compared to the other machine learning models. This will be helpful for risk identification and early intervention for AKI patients at risk of death.

Angiopoietin-2 outperforms other endothelial biomarkers associated with severe acute kidney injury in patients with severe sepsis and respiratory failure

BACKGROUND

Endothelial dysfunction and injury is a major pathophysiologic feature of sepsis. Sepsis is also the most frequent cause of acute kidney injury (AKI) in critically ill patients. Though most studies of AKI in sepsis have focused on tubular epithelial injury, the role of endothelial dysfunction and injury is less well studied. The goal of this study was first to investigate whether endothelial dysfunction and injury biomarkers were associated with severe AKI in sepsis patients. The second goal was to determine the best performing biomarker for severe AKI and whether this biomarker was associated with severe AKI across different etiologies of sepsis and clinical outcomes.

METHODS

We studied adults with severe sepsis and acute respiratory failure (ARF) enrolled in the prospective observational Validating Acute Lung Injury markers for Diagnosis (VALID) study. Plasma endothelial dysfunction and injury biomarkers, including angiopoietin-2, soluble vascular endothelial cadherin (sVE-cadherin), endocan and syndecan-1, were measured at study enrollment. Primary analysis focused on the association between endothelial biomarker levels with severe AKI (defined as Kidney Disease: Improving Global Outcomes [KDIGO] AKI stage 2 or 3), other organ dysfunctions (defined by Brussels organ failure scores), and comparison of pulmonary versus non-pulmonary sepsis.

RESULTS

Among 228 sepsis patients enrolled, 141 developed severe AKI. Plasma levels of angiopoietin-2, endocan, sVE-cadherin, and syndecan-1 were significantly higher in sepsis patients with severe AKI compared to those without severe AKI. Among four endothelial biomarkers, only angiopoietin-2 was independently associated with severe AKI (odds ratio 6.07 per log increase, 95% CI 2.34-15.78, p < 0.001). Plasma angiopoietin-2 levels by quartile were significantly higher in sepsis patients with hepatic, coagulation, and circulatory failure. Plasma angiopoietin-2 levels were also significantly higher in patients with non-pulmonary sepsis compared to subjects with pulmonary sepsis.

CONCLUSION

Among four biomarkers of endothelial dysfunction and injury, angiopoietin-2 had the most robust independent association with development of severe AKI in patients with severe sepsis and ARF. Plasma angiopoietin-2 levels were also associated with other organ dysfunctions, non-pulmonary sepsis, and death. These findings highlight the importance of early endothelial dysfunction and injury in the pathogenesis of sepsis-induced AKI.

EDTAKI: A Nephrology and Public Policy Committee (NPPC) Platform Call for More European Involvement in AKI

Acute Kidney Injury (AKI) is an often neglected but crucial element of clinical nephrology. The aim of the Nephrology Public Policy Committee (NPPC) of the European Renal Association - European Dialysis and Transplant Association (ERA-EDTA) is to promote several key aspects of European nephrology. One of the targets proposed by NPPC was to advance European nephrology involvement in AKI. We undertook literature analyses to define the current position of European nephrology in the field of AKI compared to other regions, and about how different European countries compare to each other. It appeared that vis-à-vis countries with a comparable socio-economic status (the US, Australia, New Zealand, Canada), the European contribution was almost 50% lower. Within Europe, Central/Eastern Europe and countries with a lower gross domestic product (GDP) showed lower scientific output. Nephrologists contributed to less than half of the output. There was no trend for a change over the last decade. It is concluded that there is room to improve the contribution of European nephrology in the field of AKI. We propose a model on how to promote clinical collaboration on AKI across Europe, the creation of a pan-European nephrology network of interested units is proposed, to improve clinical outcomes, increase nephrologist involvement and awareness outside nephrology, and stimulate research on AKI in Europe. Accordingly, we also propose a list of research priorities and stress the need for more European funding of AKI research.

Anaemia and acute kidney injury: the tip of the iceberg?

Acute kidney injury (AKI) is a common disorder that complicates the hospital course of many patients. AKI is linked with an independent risk of death, hospital length of stay and chronic kidney disease (CKD). Several preoperative predictors are found to be associated with AKI after surgery independent of its origin (cardiac versus non-cardiac). Among these, anaemia has been widely recognized and studied. Anaemia is more common within the surgical population for various reasons (iron deficiency, blood loss, anaemia of chronic disease such as inflammatory state, malignancy or CKD). Both pre- and postoperative anaemia have a deleterious impact on different clinical outcomes including AKI. In this issue, Nishimoto et al. investigated whether AKI could be a risk factor for anaemia (and not the opposite) and whether anaemia could be an independent mediator of mortality after AKI.

LINC00261 relieves the progression of sepsis-induced acute kidney injury by inhibiting NF-κB activation through targeting the miR-654-5p/SOCS3 axis

Sepsis is a life-threatening disease, which can cause the dysfunction of multiple organs, including kidney. Recently, a number of studies found that the long non-coding RNA (lncRNA) is closely associated with the development and progression of sepsis; however, the role of long intergenic non-protein coding RNA 261 (LINC00261) in sepsis-induced acute kidney injury is poorly understood. In this study, we found the expression of LINC00261 was significantly decreased in the serum of patients with sepsis than healthy controls. A similar result was also observed in the mouse model of sepsis induced by lipopolysaccharide (LPS). Further investigations revealed that overexpression of LINC00261 improved the viability, suppressed the apoptosis and reduced the generation of inflammatory cytokines in LPS-treated HK-2 cells. Mechanistically, we confirmed that LINC00261 could function as a sponge to combine with microRNA-654-5p (miR-654-5p) which inhibits nuclear factor-κB (NF-κB) activity by targeting suppressor of cytokine signaling 3 (SOCS3). In conclusion, our results demonstrate that LINC00261 may regulate the progression of sepsis-induced acute kidney injury via the miR-654-5p/SOCS3/NF-κB pathway and therefore provides a new insight into the treatment of this disease.

Interferon-regulated genetic programs and JAK/STAT pathway activate the intronic promoter of the short ACE2 isoform in renal proximal tubules

Recently, a short, interferon-inducible isoform of Angiotensin-Converting Enzyme 2 (ACE2), dACE2 was identified. ACE2 is a SARS-Cov-2 receptor and changes in its renal expression have been linked to several human nephropathies. These changes were never analyzed in context of dACE2, as its expression was not investigated in the kidney. We used Human Primary Proximal Tubule (HPPT) cells to show genome-wide gene expression patterns after cytokine stimulation, with emphasis on the ACE2/dACE2 locus. Putative regulatory elements controlling dACE2 expression were identified using ChIP-seq and RNA-seq. qRT-PCR differentiating between ACE2 and dACE2 revealed 300- and 600-fold upregulation of dACE2 by IFNα and IFNβ, respectively, while full length ACE2 expression was almost unchanged. JAK inhibitor ruxolitinib ablated STAT1 and dACE2 expression after interferon treatment. Finally, with RNA-seq, we identified a set of genes, largely immune-related, induced by cytokine treatment. These gene expression profiles provide new insights into cytokine response of proximal tubule cells.

Toll-Like Receptors in Acute Kidney Injury

Acute kidney injury (AKI) is an important health problem, affecting 13.3 million individuals/year. It is associated with increased mortality, mainly in low- and middle-income countries, where renal replacement therapy is limited. Moreover, survivors show adverse long-term outcomes, including increased risk of developing recurrent AKI bouts, cardiovascular events, and chronic kidney disease. However, there are no specific treatments to decrease the adverse consequences of AKI. Epidemiological and preclinical studies show the pathological role of inflammation in AKI, not only at the acute phase but also in the progression to chronic kidney disease. Toll-like receptors (TLRs) are key regulators of the inflammatory response and have been associated to many cellular processes activated during AKI. For that reason, a number of anti-inflammatory agents targeting TLRs have been analyzed in preclinical studies to decrease renal damage during AKI. In this review, we updated recent knowledge about the role of TLRs, mainly TLR4, in the initiation and development of AKI as well as novel compounds targeting these molecules to diminish kidney injury associated to this pathological condition.

Pragmatic Recommendations for the Prevention and Treatment of Acute Kidney Injury in Patients with COVID-19 in Low- and Middle-Income Countries

Current recommendations for the management of patients with COVID-19 and acute kidney injury (AKI) are largely based on evidence from resource-rich settings, mostly located in high-income countries. It is often unpractical to apply these recommendations to resource-restricted settings. We report on a set of pragmatic recommendations for the prevention, diagnosis, and management of patients with COVID-19 and AKI in low- and middle-income countries (LMICs). For the prevention of AKI among patients with COVID-19 in LMICs, we recommend using isotonic crystalloid solutions for expansion of intravascular volume, avoiding nephrotoxic medications, and using a conservative fluid management strategy in patients with respiratory failure. For the diagnosis of AKI, we suggest that any patient with COVID-19 presenting with an elevated serum creatinine level without available historical values be considered as having AKI. If serum creatinine testing is not available, we suggest that patients with proteinuria should be considered to have possible AKI. We suggest expansion of the use of point-of-care serum creatinine and salivary urea nitrogen testing in community health settings, as funding and availability allow. For the management of patients with AKI and COVID-19 in LMICS, we recommend judicious use of intravenous fluid resuscitation. For patients requiring dialysis who do not have acute respiratory distress syndrome (ARDS), we suggest using peritoneal dialysis (PD) as first choice, where available and feasible. For patients requiring dialysis who do have ARDS, we suggest using hemodialysis, where available and feasible, to optimize fluid removal. We suggest using locally produced PD solutions when commercially produced solutions are unavailable or unaffordable.

High-Sensitivity Cardiac Troponin, Natriuretic Peptide, and Long-Term Risk of Acute Kidney Injury: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Cardiac markers such as high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal pro-B natriuretic peptide (NTproBNP) are predictors of developing acute kidney injury (AKI) during hospitalization for surgery or revascularization. However, their associations with the long-term risk of AKI in the general population are uncharacterized.

METHODS

We conducted a prospective cohort study in 10 669 participants of the Atherosclerosis Risk in Communities Study (visit 4, 1996-1998, mean age, 63 years, 56% female, 22% black race) to examine the association of plasma concentrations of hs-cTnT and NTproBNP with the incident hospitalization with AKI. We used multivariable Cox regression analysis to estimate hazard ratios (HRs).

RESULTS

During follow-up, 1907 participants had an incident hospitalization with AKI. Participants with higher concentrations of hs-cTnT had a higher risk of hospitalization with AKI in a graded fashion (adjusted HR, 1.88 [95%CI , 1.59-2.21] for ≥14 ng/L, 1.36 [1.18-1.57] for 9-13 ng/L, and 1.16 [1.03-1.30] for 5-8 ng/L compared to <5 ng/L). The graded association was also observed for NTproBNP (HR, 2.27 [1.93-2.68] for ≥272.7 pg/mL, 1.67 [1.45-1.93] for 142.4-272.6 pg/mL, and 1.31 [1.17-1.47] for 64.0-142.3 pg/mL compared to <64.0 pg/mL). The addition of hs-cTnT and NTproBNP to a model with established predictors significantly improved 10-year risk prediction for hospitalization with AKI (Δc-statistic, 0.015 [95%CI, 0.006-0.024]).

CONCLUSIONS

In middle-aged to older black and white adults in the community, higher concentrations of hs-cTnT and NTproBNP were robustly associated with an increased risk of hospitalization with AKI. These results suggest the usefulness of hs-cTnT and NT-proBNP to identify people at risk of AKI in the general population.

11. Microvascular Complications and Foot Care: Standards of Medical Care in Diabetes-2021

The American Diabetes Association (ADA) "Standards of Medical Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, a multidisciplinary expert committee (https://doi.org/10.2337/dc21-SPPC), are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations, please refer to the Standards of Care Introduction (https://doi.org/10.2337/dc21-SINT). Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

A Review on the Application and Limitations of Administrative Health Care Data for the Study of Acute Kidney Injury Epidemiology and Outcomes in Children

Administrative health care databases contain valuable patient information generated by health care encounters. These "big data" repositories have been increasingly used in epidemiological health research internationally in recent years as they are easily accessible and cost-efficient and cover large populations for long periods. Despite these beneficial characteristics, it is also important to consider the limitations that administrative health research presents, such as issues related to data incompleteness and the limited sensitivity of the variables. These barriers potentially lead to unwanted biases and pose threats to the validity of the research being conducted. In this review, we discuss the effectiveness of health administrative data in understanding the epidemiology of and outcomes after acute kidney injury (AKI) among adults and children. In addition, we describe various validation studies of AKI diagnostic or procedural codes among adults and children. These studies reveal challenges of AKI research using administrative data and the lack of this type of research in children and other subpopulations. Additional pediatric-specific validation studies of administrative health data are needed to promote higher volume and increased validity of this type of research in pediatric AKI, to elucidate the large-scale epidemiology and patient and health systems impacts of AKI in children, and to devise and monitor programs to improve clinical outcomes and process of care.

Hypothermia related to continuous renal replacement therapy: incidence and associated factors

OBJECTIVE

To evaluate the incidence of hypothermia in patients undergoing continuous renal replacement therapy in the intensive care unit. As secondary objectives, we determined associated factors and compared the occurrence of hypothermia between two modalities of continuous renal replacement therapy.

METHODS

A prospective cohort study was conducted with adult patients who were admitted to a clinical-surgical intensive care unit and underwent continuous renal replacement therapy in a high-complexity public university hospital in southern Brazil from April 2017 to July 2018. Hypothermia was defined as a body temperature ≤ 35ºC. The patients included in the study were followed for the first 48 hours of continuous renal replacement therapy. The researchers collected data from medical records and continuous renal replacement therapy records.

RESULTS

A total of 186 patients were equally distributed between two types of continuous renal replacement therapy: hemodialysis and hemodiafiltration. The incidence of hypothermia was 52.7% and was higher in patients admitted for shock (relative risk of 2.11; 95%CI 1.21 - 3.69; p = 0.009) and in those who underwent hemodiafiltration with heating in the return line (relative risk of 1.50; 95%CI 1.13 - 1.99; p = 0.005).

CONCLUSION

Hypothermia in critically ill patients with continuous renal replacement therapy is frequent, and the intensive care team should be attentive, especially when there are associated risk factors.

In-Hospital Outcomes of Acute Kidney Injury After Pediatric Cardiac Surgery: A Meta-Analysis

Background: Cardiac surgery-associated acute kidney injury (CS-AKI) is associated with increased morbidity and mortality in both adults and children. This study aimed to investigate the in-hospital outcomes of CS-AKI in the pediatric population. Methods: PubMed/MEDLINE, Embase, Scopus, and reference lists of relevant articles were searched for studies published by August 2020. Random-effects meta-analysis was performed, comparing in-hospital outcomes between patients who developed CS-AKI and those who did not. Results: Fifty-eight publications between 2008 and 2020 consisting of 18,334 participants (AKI: 5,780; no AKI: 12,554) were included. Higher rates of in-hospital mortality (odds ratio [OR] 7.22, 95% confidence interval [CI] 5.27-9.88), need for renal replacement therapy (RRT) (OR 18.8, 95% CI 11.7-30.5), and cardiac arrhythmias (OR 2.67, 95% 1.86-4.80) were observed in patients with CS-AKI. Furthermore, patients with AKI had longer ventilation times (mean difference [MD] 1.76 days, 95% CI 1.05-2.47), pediatric intensive care unit (PICU) length of stay (MD 3.31, 95% CI 2.52-4.10), and hospital length of stay (MD 5.00, 95% CI 3.34-6.67). Conclusions: CS-AKI in the pediatric population is associated with a higher risk of mortality, cardiac arrhythmias and need for RRT, as well as greater mechanical ventilation time, PICU and hospital length of stay. These results might help improve the clinical care protocols prior to cardiac surgery to minimize the disease burden of CS-AKI in children. Furthermore, etiology-specific approaches to AKI are warranted, as outcomes are likely impacted by the underlying cause.

Postoperative acute kidney injury in adult non-cardiac surgery: joint consensus report of the Acute Disease Quality Initiative and PeriOperative Quality Initiative

Postoperative acute kidney injury (PO-AKI) is a common complication of major surgery that is strongly associated with short-term surgical complications and long-term adverse outcomes, including increased risk of chronic kidney disease, cardiovascular events and death. Risk factors for PO-AKI include older age and comorbid diseases such as chronic kidney disease and diabetes mellitus. PO-AKI is best defined as AKI occurring within 7 days of an operative intervention using the Kidney Disease Improving Global Outcomes (KDIGO) definition of AKI; however, additional prognostic information may be gained from detailed clinical assessment and other diagnostic investigations in the form of a focused kidney health assessment (KHA). Prevention of PO-AKI is largely based on identification of high baseline risk, monitoring and reduction of nephrotoxic insults, whereas treatment involves the application of a bundle of interventions to avoid secondary kidney injury and mitigate the severity of AKI. As PO-AKI is strongly associated with long-term adverse outcomes, some form of follow-up KHA is essential; however, the form and location of this will be dictated by the nature and severity of the AKI. In this Consensus Statement, we provide graded recommendations for AKI after non-cardiac surgery and highlight priorities for future research.

Clinical phenotypes of acute kidney injury are associated with unique outcomes in critically ill septic children

BACKGROUND

Assessment of acute kidney injury (AKI) in septic patients remains imprecise. In adults, the classification of septic patients by clinical AKI phenotypes (severity and timing) demonstrates unique associations with patient outcome vs. broadly defined AKI.

METHODS

In a multinational prospective observational study, AKI diagnosis in critically ill septic children was stratified by duration (transient vs. persistent) and severity (mild vs. severe by creatinine change and urine output). The outcomes of interest were mortality and intensive care unit resource complexity at 28 days.

RESULTS

Seven hundred and fifty-seven septic children were studied (male 52.7%, age 4.6 years (1.5-11.9)). Mortality (overall 12.1%) was different between severe AKI and mild AKI (18.3 vs. 4.4%, p < 0.001) as well as intensive care unit (ICU) complexity (overall 34.5%, 45 vs. 21.7%, p < 0.001). Patients with Persistent AKI had fewer ICU-free days (17 (7, 21) vs. 24 (17, 26), p < 0.001) and higher ICU complexity (52.8 vs. 22.9%, p = 0.002) than transient AKI, even after exclusion of patients with early mortality. AKI phenotypes incorporating temporal and severity data correlate with unique survival (range 4.4-21.6%) and ICU-free days (range of 15-25 days) CONCLUSIONS: The outcome of septic children with AKI changes by clinical phenotype. Our findings underscore the importance of prognostic enrichment in sepsis and AKI for the purpose of trial design and patient management.

IMPACT

Although AKI occurs commonly in patients with sepsis (S-AKI), outcomes for children with S-AKI varies based on the severity and timing of the AKI. Existing S-AKI pediatric data utilize a broad singular definition of kidney injury. Increasing the precision of AKI classification results in a new understanding of how S-AKI associates with patient outcome. A refined classification of S-AKI identifies subgroups of children, making possible a targeted and a personalized medicine approach to S-AKI study and management.

Long-term survival of children following acute peritoneal dialysis in a resource-limited setting

BACKGROUND

There is a paucity of data on long term-outcomes of children who undergo acute peritoneal dialysis (PD) in resource-limited settings. We reviewed the outcomes of children who underwent PD after 18 months of follow-up.

METHODS

We conducted a prospective cohort study in children with acute kidney injury (AKI) who underwent PD. Diagnosis of AKI was based on the 2012 Kidney Disease: Improving Global Outcomes definition. We assessed outcomes of in-hospital mortality, 18-month post-dialysis survival, factors associated with survival, and progression to chronic kidney disease (CKD).

RESULTS

Twenty-nine children with a median age of 6 (3 to 11) years underwent acute PD. In-hospital mortality was 3/29 (10.3%) and rose to 27.6% during follow-up. Seven (24.1%) children were lost to follow-up. Of the 14 remaining children, six (42.9%) experienced full recovery of renal function, while eight (57.1%) progressed to CKD. Among those who experienced full recovery, median (interquartile range) estimated glomerular filtration rate (eGFR) rose from 12.67 (7.05, 22.85) mL/min/1.73 m2 to 95.56 (64.50, 198.00) mL/min/1.73 m2, P = 0.031. No significant changes in median eGFR from baseline were observed among those who progressed to CKD (P = 0.383) or in non-survivors (P = 0.838). According to Kaplan-Meier curve analyses, 18-month survival during follow-up was 66.0% (95% CI, 45.0% to 86.5%). Age < 5 was associated with greater likelihood of survival (OR, 3.217; 95% CI, 1.240 to 8.342).

CONCLUSION

Progression of post-PD AKI to CKD occurred in more than half of survivors. Age < 5 was associated with greater likelihood of survival.

Availability, coverage, and scope of health information systems for kidney care across world countries and regions

BACKGROUND

Health information systems (HIS) are fundamental tools for the surveillance of health services, estimation of disease burden and prioritization of health resources. Several gaps in the availability of HIS for kidney disease were highlighted by the first iteration of the Global Kidney Health Atlas.

METHODS

As part of its second iteration, the International Society of Nephrology conducted a cross-sectional global survey between July and October 2018 to explore the coverage and scope of HIS for kidney disease, with a focus on kidney replacement therapy (KRT).

RESULTS

Out of a total of 182 invited countries, 154 countries responded to questions on HIS (85% response rate). KRT registries were available in almost all high-income countries, but few low-income countries, while registries for non-dialysis chronic kidney disease (CKD) or acute kidney injury (AKI) were rare. Registries in high-income countries tended to be national, in contrast to registries in low-income countries, which often operated at local or regional levels. Although cause of end-stage kidney disease, modality of KRT and source of kidney transplant donors were frequently reported, few countries collected data on patient-reported outcome measures and only half of low-income countries recorded process-based measures. Almost no countries had programs to detect AKI and practices to identify CKD-targeted individuals with diabetes, hypertension and cardiovascular disease, rather than members of high-risk ethnic groups.

CONCLUSIONS

These findings confirm significant heterogeneity in the global availability of HIS for kidney disease and highlight important gaps in their coverage and scope, especially in low-income countries and across the domains of AKI, non-dialysis CKD, patient-reported outcomes, process-based measures and quality indicators for KRT service delivery.

Rapid Multianalyte Microfluidic Homogeneous Immunoassay on Electrokinetically Driven Beads

The simplicity of homogeneous immunoassays makes them suitable for diagnostics of acute conditions. Indeed, the absence of washing steps reduces the binding reaction duration and favors a rapid and compact device, a critical asset for patients experiencing life-threatening diseases. In order to maximize analytical performance, standard systems employed in clinical laboratories rely largely on the use of high surface-to-volume ratio suspended moieties, such as microbeads, which provide at the same time a fast and efficient collection of analytes from the sample and controlled aggregation of collected material for improved readout. Here, we introduce an integrated microfluidic system that can perform analyte detection on antibody-decorated beads and their accumulation in confined regions within 15 min. We employed the system to the concomitant analysis of clinical concentrations of Neutrophil Gelatinase-Associated Lipocalin (NGAL) and Cystatin C in serum, two acute kidney injury (AKI) biomarkers. To this end, high-aspect-ratio, three-dimensional electrodes were integrated within a microfluidic channel to impart a controlled trajectory to antibody-decorated microbeads through the application of dielectrophoretic (DEP) forces. Beads were efficiently retained against the fluid flow of reagents, granting an efficient on-chip analyte-to-bead binding. Electrokinetic forces specific to the beads' size were generated in the same channel, leading differently decorated beads to different readout regions of the chip. Therefore, this microfluidic multianalyte immunoassay was demonstrated as a powerful tool for the rapid detection of acute life-threatening conditions.

Ranolazine alleviates contrast-associated acute kidney injury through modulation of calcium independent oxidative stress and apoptosis

This study investigates the role of ranolazine in contrast-associated acute kidney injury (CA-AKI) and potential mechanisms. For in vivo studies, mouse models of CA-AKI and control mice were treated with ranolazine or vehicle. Blood urea nitrogen (BUN) and serum creatinine were detected by spectrophotometry. Anti-T-cell immunoglobulin and mucin domain 1 (TIM 1) and anti-lipocalin 2 antibody (LCN2) were detected by immunofluorescence. Hemodynamic parameters were detected via invasive blood pressure measurement and renal artery color doppler ultrasound, capillary density was measured by CD31 immunofluorescence, vascular permeability assay was performed by Evans blue dye. The expressions of oxidative stress and apoptotic markers were measured and analyzed by immunofluorescence and western blotting. For in vitro studies, intracellular calcium concentration of HUVECs was measured with Fluo 3-AM under confocal microscopy. Results show that compared with control mice, serum BUN, creatinine, TIM 1 and LCN2 levels were elevated in CA-AKI mice, but this effect was alleviated by ranolazine-pretreatment. Safe doses of ranolazine (less than 64 mg/kg) had no significant effect on overall blood pressure, but substantially improved renal perfusion, reduced contrast-induced microcirculation disturbance, improved renal capillary density and attenuated renal vascular permeability in ranolazine-pretreated CA-AKI mice. Mechanistically, ranolazine markedly down-regulated oxidative stress and apoptosis markers compared to CA-AKI mice. Intracellularly, ranolazine attenuated calcium overload in HUVECs. These results indicate that ranolazine alleviates CA-AKI through modulation of calcium independent oxidative stress and apoptosis.

Randomized Controlled Trial Evidence of Cost-Effectiveness of a Multifaceted AKI Intervention Approach

Introduction

Acute kidney injury (AKI) is associated with increased health care utilization and higher costs. The Tackling AKI study was a multicenter, pragmatic, stepped-wedge cluster randomized trial that demonstrated a reduced hospital length of stay after implementation of a multifaceted AKI intervention (e-alerts, care bundle, and an education program). We tested whether this would result in cost savings.

Methods

A decision-analytic tree model from the payer perspective (National Health Service in the United Kingdom) was generated on which cost-effectiveness analyses were performed using a probabilistic sensitivity analysis, accounting only for direct medical costs. Clinical data from the Tackling AKI study were used as inputs and economic and utility data derived from relevant published literature.

Results

A total of 24,059 AKI episodes occurred during the study period, and in 18,887 admissions the patient was discharged alive. When all AKI stages were considered together, the cost per AKI admission was £5065 in the control arm and £4333 in the intervention arm, representing an incremental cost saving of £732 per admission with the intervention. Similar results were obtained when AKI stages were included as separate variables. Costs per quality-adjusted life year were £61,194 in the control group and £51,161 in the intervention group. At a willingness to pay threshold of £20,000 per quality-adjusted life year, the probability of the intervention being cost-effective compared with standard care was 90%.

Conclusion

An organizational level approach to improve standards of AKI care reduces the cost of hospital admissions and is cost effective within the National Health Service in the United Kingdom.

Renal ischemia-reperfusion leads to hypertension and changes in proximal tubule Na+ transport and renin-angiotensin-aldosterone system: Role of NADPH oxidase

Acute renal injury (AKI) is a risk factor for the development of hypertension, which involves oxidative stress, changes in Na⁺ handling, and the intrarenal renin-angiotensin-aldosterone system (RAAS) as underlying mechanisms. We investigated in rats whether renal ischemia-reperfusion (IR) leads to changes in the proximal tubule ATP-dependent Na⁺ transport and the intrarenal content of RAAS components, as well as the role of NADPH oxidase. Rats weighing 300-350 g were submitted to AKI by bilateral IR (n = 25). After IR injury, the animals were followed up for 4 weeks. One part (n = 7) received daily treatment with the NADPH oxidase inhibitor apocynin (100 mg/kg, drinking water), while another part (n = 9) received apocynin 24 h before and after IR. One group was submitted to sham surgery (n = 8). Four weeks after IR, the rats presented elevated systolic blood pressure, as well as increased lipid peroxidation, NADPH oxidase activity, (Na⁺+K⁺)ATPase activity, and upregulation of type 1 angiotensin II receptor in the renal cortex. On the other hand, there was a decrease in Na⁺-ATPase activity and downregulation of the isoforms 1 and 2 of the angiotensin-converting enzyme, type 2 angiotensin II receptor, and of the α and ε isoforms of protein kinase C. Most of these alterations was prevented by both apocynin treatment protocols. Thus, we conclude that AKI-induced by IR may induce changes in proximal tubule ATPases and RAAS components compatible with renal Na⁺ retention and hypertension. These data also indicate that the NADPH oxidase represents a key factor in the origin of these alterations.