Impact of Recurrent Acute Kidney Injury on Patient Outcomes

Dimethyl malonate preserves renal and mitochondrial functions following ischemia-reperfusion via inhibition of succinate dehydrogenase

BACKGROUND

Acute kidney injury (AKI), often experienced at the intensive care units, is associated with high morbidity/mortality where ischemia-reperfusion injury is a main causative factor. Succinate accumulation during ischemia contributes to the excessive generation of reactive oxygen species at reperfusion. Inhibition of succinate dehydrogenase has been associated with protective outcome in cardiac ischemia-reperfusion after 24h, but the effects on kidney and mitochondrial functions are less well studied.

AIM

To investigate the therapeutic potential of succinate dehydrogenase inhibition, by using dimethyl malonate (DMM), on kidney and mitochondria functions in a mouse model of AKI.

METHODS

Male C57BL/6J mice were pre-treated with DMM or placebo, i.p. 30min prior to bilateral renal ischemia (20min). After 3-days of reperfusion, glomerular filtration rate (GFR) was calculated from plasma clearance of FITC-inulin. Kidney mitochondria was isolated and mass specific and intrinsic mitochondrial function were evaluated by high resolution respirometry. Kidney sections were stained (i.e., hematoxylin-eosin and TUNEL) and analyzed for histopathological evaluation of injuries and apotosis, respectively. NADPH oxidase activity in kidney and human proximal tubular cell-line (HK2) were measured luminometrically.

RESULTS

DMM treatment improved GFR (p < 0.05) and reduced levels of blood urea nitrogen (p < 0.01) compared to untreated animals, which was associated with lower degree of ischemia-reperfusion-induced tubular injuries (P < 0.001) and apoptosis (P < 0.01). These therapeutic renal effects were linked with improved mitochondrial function, both mass-specific and intrinsic. Finally, DMM treatment prevented ischemia-reperfusion-induced NADPH oxidase activity in the kidney (p < 0.001), which was showed also in HK2 cells exposed to hypoxia and reoxygenation (P < 0.01).

CONCLUSION

Inhibition of succinate dehydrogenase with DMM, in conjunction with the ischemia-reperfusion phase, significantly improved both renal and mitochondrial functions. These findings may have clinical implications for future therapeutic strategies to prevent development of AKI and associated adverse complications, especially in high risk hospitalized patients.

Is Renal Ischemic Preconditioning an Alternative to Ameliorate the Short- and Long-Term Consequences of Acute Kidney Injury?

Acute kidney injury (AKI) is a global health problem and has recently been recognized as a risk factor for developing chronic kidney disease (CKD). Unfortunately, there are no effective treatments to reduce or prevent AKI, which results in high morbidity and mortality rates. Ischemic preconditioning (IPC) has emerged as a promising strategy to prevent, to the extent possible, renal tissue from AKI. Several studies have used this strategy, which involves short or long cycles of ischemia/reperfusion (IR) prior to a potential fatal ischemic injury. In most of these studies, IPC was effective at reducing renal damage. Since the first study that showed renoprotection due to IPC, several studies have focused on finding the best strategy to activate correctly and efficiently reparative mechanisms, generating different modalities with promising results. In addition, the studies performing remote IPC, by inducing an ischemic process in distant tissues before a renal IR, are also addressed. Here, we review in detail existing studies on IPC strategies for AKI pathophysiology and the proposed triggering mechanisms that have a positive impact on renal function and structure in animal models of AKI and in humans, as well as the prospects and challenges for its clinical application.

Incidence, predictors, clinical outcomes, and economic burden of recurrent acute kidney injury: a retrospective cohort study

OBJECTIVE

This study aimed to assess the incidence, predictors, mortality, and economic outcomes of recurrent Acute kidney injury (AKI) in Jordan.

METHODS

This was a retrospective cohort study that included adult patients who were admitted with AKI to university hospitals in the country from 2010-2019. Recurrent episodes of AKI, laboratory data, baseline medication list, and death dates were retrieved from patient's medical records. The incidence rate of recurrent AKI was estimated. Predictors of recurrent AKI and mortality during the five years post-discharge was evaluated. Total admission charges were described and evaluated in total and by service provided.

RESULTS

Among 1162 AKI patients, 57 patients (4.9%) died during the index admission (first admission during the study period), and among the survivors, 220 patients were re-hospitalized with a recurrent AKI during five years of follow-up. Patients with higher discharge serum creatinine level (SCr) at index admission had higher odds of AKI recurrence (OR = 1.001). Patients who were on respiratory, antineoplastic, or anticoagulant medications were also more susceptible to recurrence; ORs were 1.69, 2.77, and 4.16, respectively. Patients who were elderly, with recurrent AKI episodes, or with a more extended hospital stay at index admission were more likely to die during the five years post discharge. The median charge of recurrent admissions was higher than the median charge of the index admissions; 1519.17 JOD ($2142.7) versus 1362.85 JOD ($1922.2), respectively.

CONCLUSIONS

Recurrent AKI is associated with increased mortality and health expenditures. Higher discharge SCr levels at index admission, and chronic comorbidities are associated with a higher likelihood of AKI recurrence.

Effects of contralateral nephrectomy timing and ischemic conditions on kidney fibrosis after unilateral kidney ischemia-reperfusion injury

Acute kidney injury (AKI) is an important cause of chronic kidney disease (CKD), but the underlying mechanisms are unclear. Animal models are tools for studying the AKI-CKD progression. Kidney ischemia-reperfusion injury (IRI) models, especially the unilateral IRI (uIRI) model with delayed contralateral kidney resection, are commonly used to induce fibrotic progression to CKD after AKI. However, in previous studies, we found that details of the operation had a significant impact on the long-term outcomes of the kidney in this uIRI model. In this study, we investigated the effects of resection timing of the contralateral intact kidney, core body temperatures during ischemia, and time length of kidney ischemia on kidney function, histological injury and kidney fibrosis after AKI, using a mouse uIRI model with delayed contralateral nephrectomy. The results showed that all these parameters significantly affected the AKI-CKD transition. The post-AKI fibrosis worsened and the survival rate declined with a longer interval between contralateral nephrectomy and uIRI, higher ischemic body temperature, or longer ischemic duration when the other two variables were fixed. In conclusion, in the uIRI model with delayed contralateral nephrectomy, kidney fibrosis after AKI is influenced by many factors. Strictly controlling the experimental conditions is very important for the stability and consistency of the model.

Impact of Diabetes on the Recurrence and Prognosis of Acute Kidney Injury in Older Male Patients: A 10-Year Retrospective Cohort Study

INTRODUCTION

While patients with diabetes are at higher risk of developing acute kidney injury (AKI), there are few studies on the recurrence of AKI in older adult patients. This study therefore aimed to examine the impact of diabetes on AKI recurrence and long-term outcomes in older male patients.

METHODS

This retrospective cohort study included older male patients who experienced AKI during hospitalization from July 2007 to August 2011. Medical records of all patients were followed up for 10 years. Patients with AKI were classified into groups with and without diabetes. We analyzed differences in common geriatric comorbidities, AKI recurrence frequency, and severity between the two groups, identified risk factors affecting recurrence frequency, and assessed outcomes.

RESULTS

Of all 266 patients, 128 had diabetes and 138 did not. The AKI recurrence rate was significantly higher in the group with diabetes (80.5 vs. 66.7%; P = 0.011). There was a significantly higher proportion of AKI caused by infections in patients with diabetes (43.3 vs. 33.2%, P = 0.006). The proportion of patients with an AKI recurrence frequency ≥ 3 was significantly higher in the group with diabetes (44.7 vs. 29.4%, P = 0.027). Diabetes and coronary heart disease were independent risk factors for AKI recurrence (P < 0.05), diabetes control was associated with multiple AKI recurrences (P = 0.016), and no significant difference was found between the groups regarding the 10-year prognosis (P = 0.522). However, a subgroup analysis showed that patients with multiple AKI recurrences within 2 years had the worst survival outcome (P = 0.004).

CONCLUSIONS

Older male patients with diabetes are prone to AKI recurrence after initial onset of AKI. Diabetes is an independent risk factor for AKI recurrence, and active diabetes control (HbA1c < 7%) may thus reduce the recurrence of AKI and improve the very poor outcomes of patients with multiple recurrences of AKI within 2 years.

Repeated Episodes of Ischemia/Reperfusion Induce Heme-Oxygenase-1 (HO-1) and Anti-Inflammatory Responses and Protects against Chronic Kidney Disease

Preconditioning episodes of ischemia/reperfusion (IR) induce protection against acute kidney injury (AKI), however their long-term effect still unknown. We evaluated AKI to chronic kidney disease (CKD) transition, after three-mild or three-severe episodes of IR. AKI was induced by single bilateral IR (1IR), or three episodes of IR separated by 10-day intervals (3IR) of mild (20 min) or severe (45 min) ischemia. Sham-operated rats served as controls. During 9-months, the 1IR group (20 or 45 min) developed CKD evidenced by progressive proteinuria and renal fibrosis. In contrast, the long-term adverse effects of AKI were markedly ameliorated in the 3IR group. The acute response in 3IR, contrasted with the 1IR group, that was characterized by an increment in heme oxygenase-1 (HO-1) and an anti-inflammatory response mediated by a NFkB-p65 phosphorylation and IL-6 decrease, together with an increase in TGF-β, and IL-10 expression, as well as in M2-macrophages. In addition, three episodes of IR downregulated endoplasmic reticulum (ER) stress markers expression, CHOP and BiP. Thus, repeated episodes of IR with 10-day intervals induced long-term renal protection accompanied with HO-1 overexpression and M2-macrophages increase.

TLR9: A friend or a foe

The innate immune system is a primary protective line in our body. It confers its protection through different pattern recognition receptors (PRRs), especially toll like receptors (TLRs). Toll like receptor 9 (TLR9) is an intracellular TLR, expressed in different immunological and non-immunological cells. Release of cellular components, such as proteins, nucleotides, and DNA confers a beneficial inflammatory response and maintains homeostasis for removing cellular debris during normal physiological conditions. However, during pathological cellular damage and stress signals, engagement between mtDNA and TLR9 acts as an alarm for starting inflammatory and autoimmune disorders. The controversial role of TLR9 in different diseases baffled scientists if it has a protective or deleterious effect after activation during insults. Targeting the immune system, especially the TLR9 needs further investigation to provide a therapeutic strategy to control inflammation and autoimmune disorders.

Acute and chronic kidney complications in children with type 1 diabetes mellitus

Children with type 1 diabetes mellitus (T1DM) have an increased risk of developing kidney involvement. Part of the risk establishes at the beginning of T1DM. In fact, up to 65% of children during T1DM onset may experience an acute kidney injury (AKI) which predisposes to the development of a later chronic kidney disease (CKD). The other part of the risk establishes during the following course of T1DM and could be related to a poor glycemic control and the subsequent development of diabetic kidney disease. In this review, we discuss the acute and chronic effects of T1DM on the kidneys, and the implications of these events on the long-term prognosis of kidney function.

Acute Kidney Injury in Children with Acute Appendicitis

We hypothesized that—as in other common pediatric conditions—acute appendicitis (AA) could be complicated by acute kidney injury (AKI). We aimed to investigate the prevalence of, and the factors associated with AKI in a cohort of patients with AA. We retrospectively collected data of 122 children (63.9% of male gender; mean age 8.6 ± 2.9 years; range: 2.2–13.9 years) hospitalized for AA. AKI was defined according to the Kidney Disease/Improving Global Outcomes creatinine criteria. We considered a basal serum creatinine value as the value of creatinine estimated with the Hoste (age) equation, assuming that the basal estimated glomerular filtration rate (eGFR) was 120 mL/min/1.73 m². Explorative univariate logistic regression analysis was used to explore the associations with AKI. Out of 122 patients, nine (7.4%) presented with AKI. One patient had stage two AKI and the remaining had stage one AKI. The maximum AKI stage was found at admission. The patients with AKI showed a higher prevalence of fever ≥ 38.5 °C (p = 0.02), vomiting (p = 0.03), ≥5% dehydration (p = 0.03), and higher levels of both C-reactive protein (CRP) (p = 0.002) and neutrophils (p = 0.03) compared with patients without AKI. Because all patients with AKI also presented with vomiting, an Odds Ratio (OR) for the vomiting was not calculable. The exploratory univariate logistic regression analysis confirmed that fever ≥ 38.5 °C (OR = 5.0; 95% CI: 1.2/21.5; p = 0.03), ≥5% dehydration (OR = 8.4; 95% CI: 1.1/69.6; p = 0.04), CRP (OR = 1.1; 95% CI: 1.05/1.2; p = 0.01), and neutrophil levels (OR = 1.1; 95% CI: 1.01/1.3; p = 0.04) were all predictive factors of AKI. AKI can occur in 7.4% of patients with AA. Particular attention should be paid to the kidney health of patients with AA especially in the presence of vomiting, ≥5% dehydration, fever ≥ 38.5 °C, and high CRP and neutrophils levels.

Visit-to-visit variability in albuminuria predicts renal function deterioration in patients with type 2 diabetes

Aims/Introduction

We aimed to study the predictive ability of visit‐to‐visit variability in albuminuria for changes in renal function in patients with type 2 diabetes mellitus.

Materials and Methods

The cohort study was carried out in a single medical center. In the model development cohort of 1008 subjects, we developed the albuminuria variability score (AVS) to evaluate the visit‐to‐visit variability in albuminuria, which was the percentage of the number of changes in the urine albumin : creatinine ratio ≥3.39 mg/mmol among all visit‐to‐visit urine albumin : creatinine ratio differences within an individual. Multivariate logistic regression was applied to predict the influence of AVS levels on the occurrence of study end‐points. In another independent validation cohort of 310 participants, survival analysis was carried out to evaluate the ability of AVS in predicting the study end‐point.

Results

In the model development cohort, a higher AVS was associated with higher adjusted odds of having a declined or rapidly declined estimated glomerular filtration rate (eGFR) trajectory (1.84, 95% confidence interval 1.23–2.76 and 5.70, 95% confidence interval 2.28–14.25, respectively), a resultant eGFR <60 mL/min/1.73 m² (2.61, 95% confidence interval 1.63–4.16) and a >40% decline in eGFR from baseline (6.44, 95% confidence interval 2.15–19.26). In the validation cohort, a higher AVS independently predicted a 5‐year decrease of >40% in eGFR to <60 mL/min/1.73 m² (adjusted hazard ratio 3.33, 95% confidence interval 1.10–10.05). Integrated discrimination index and concordance statistics showed that AVS significantly improved the predictive ability of the models.

Conclusions

Visit‐to‐visit variability in albuminuria can independently predict long‐term renal function deterioration in patients with type 2 diabetes mellitus. Further investigations are warranted to elucidate the potential clinical applications.

Blending of Designer Synthetic Polymers to a Dual Targeted Nanoformulation for SARS-CoV-2 Associated Kidney Damage

As the COVID-19 pandemic has continued to spread, studies have shown that hospitalized COVID-19 patients are at significant risk for developing acute kidney injury (AKI), which can cause increased morbidity, the need for dialysis treatment, chronic kidney diseases, and even death. In this paper, we present a proof-of-concept study for the utilization of combination therapeutic-loaded dual-targeted biodegradable nanoparticles (NPs) to treat concurrent AKI and COVID-19 in patients by delivering the therapeutics across the gut epithelial barrier and to the kidney, in order to lower the viral load as well as reduce the symptoms of AKI. Despite recent vaccination efforts and the end of the COVID-19 pandemic in sight, problems related to the long-term effects of COVID-19 will continue to persist, including impacts on patients suffering from AKI and other chronic renal conditions. Therefore, the dual-targeted blended polymeric NP developed in this study to treat concurrent COVID-19 infection and AKI is a useful proof-of-concept nanoplatform for future treatments of these complications.

Utility of Self-Reported Heat Stress Symptoms and NGAL Biomarker to Screen for Chronic Kidney Disease of Unknown Origin (CKDu) in Sri Lanka

Objective. We examined heat stress symptoms and urine markers of chronic kidney disease (CKDu) in Sri Lanka to assess differences between endemic vs. non-endemic regions and by occupation. Sample and Methods. We assessed a total of 475 villagers. In the endemic region, 293 were agricultural workers and 67 were not working primarily in agriculture. In the non-endemic region, 76 were agricultural workers. Of the residents, 218 were assessed for neutrophil gelatinase-associated lipocalin (NGAL), an early predictor of acute kidney injury, along with urine markers of chronic kidney disease. Results. The mean (sd) age of the sample was 45.2 (12.6), with males comprising 52.7%; 7.2% reported kidney disease (n = 34), and 5.7% reported diabetes (n = 27). The heat stress index (mean (sd)) was highest among agricultural workers in the endemic region (8.05 (5.9)), intermediate in non-agricultural workers in the endemic region (4.61 (4.5)), and lowest among agricultural workers in the non-endemic region (3.85 (3.3)); p < 0.0001. Correlations were higher between NGAL and serum microalbumin in the endemic agricultural worker sample than in the other two samples (Spearman’s r = 0.34 vs. 0.15 and 0.20). Conclusions. Both heat stress symptoms and NGAL values were higher among agricultural workers in endemic CKDu regions. Correlations between NGAL and microalbumin suggested a link between acute kidney injury and chronic kidney disease in the more-exposed sample.

Developing an AKI Consensus Definition for Database Research: Findings From a Scoping Review and Expert Opinion Using a Delphi Process

RATIONALE & OBJECTIVE

The KDIGO (Kidney Disease: Improving Global Outcomes) definition of acute kidney injury (AKI) is frequently used in studies to examine the epidemiology of AKI. This definition is variably interpreted and applied to routinely collected health care data. The aim of this study was to examine this variation and to achieve consensus in how AKI should be defined for research using routinely collected health care data.

SOURCES OF EVIDENCE AND STUDY DESIGN

Scoping review via searching Medline and EMBASE for studies using health care data to examine AKI by using the KDIGO creatinine-based definition. An international panel of experts formed to participate in a modified Delphi process to attempt to generate consensus about how AKI should be defined when using routinely collected laboratory data.

CHARTING METHODS AND ANALYTICAL APPROACH

The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) extension for scoping reviews was followed. For the Delphi process, 2 rounds of questions were distributed via internet-based questionnaires to all participants with a prespecified cutoff of 75% agreement used to define consensus.

RESULTS

The scoping review found 174 studies that met the inclusion criteria. The KDIGO definition was inconsistently applied, and the methods for application were poorly described. We found 58 (33%) of papers did not provide a definition of how the baseline creatinine value was determined, and only 34 (20%) defined recovery of kidney function. Of 55 invitees to the Delphi process, 35 respondents participated in round 1, and 25 participated in round 2. Some consensus was achieved in areas related to how to define the baseline creatinine value, which patients should be excluded from analysis of routinely collected laboratory data, and how persistent chronic kidney disease or nonrecovery of AKI should be defined.

LIMITATIONS

The Delphi panel members predominantly came from the United Kingdom, the United States, and Canada, and there were low response rates for some questions in round 1.

CONCLUSIONS

The current methods for defining AKI using routinely collected data are inconsistent and poorly described in the available literature. Experts could not achieve consensus for many aspects of defining AKI and describing its sequelae. The KDIGO guidelines should be extended to include a standardized definition for how AKI should be defined when using routinely collected data.

Acute Kidney Injury and Renal Tubular Damage in Children With Type 1 Diabetes Mellitus Onset

CONTEXT

Acute kidney injury (AKI) and renal tubular damage (RTD), especially if complicated by acute tubular necrosis (ATN), could increase the risk of later chronic kidney disease. No prospective studies on AKI and RTD in children with type1diabetes mellitus (T1DM) onset are available.

OBJECTIVES

To evaluate the AKI and RTD prevalence and their rate and timing of recovery in children with T1DM onset.

DESIGN

Prospective study.

SETTINGS AND PATIENTS

185 children were followed up after 14 days from T1DM onset. The patients who did not recover from AKI/RTD were followed-up 30 and 60 days later.

MAIN OUTCOME MEASURES

AKI was defined according to the KDIGO criteria. RTD was defined by abnormal urinary beta-2-microglobulin and/or neutrophil gelatinase-associated lipocalin and/or tubular reabsorption of phosphate < 85% and/or fractional excretion of Na (FENa) > 2%. ATN was defined by RTD+AKI, prerenal (P)-AKI by AKI+FENa < 1%, and acute tubular damage (ATD) by RTD without AKI.

RESULTS

Prevalence of diabetic ketoacidosis (DKA) and AKI were 51.4% and 43.8%, respectively. Prevalence of AKI in T1DM patients with and without DKA was 65.2% and 21.1%, respectively; 33.3% reached AKI stage 2, and 66.7% of patients reached AKI stage 1. RTD was evident in 136/185 (73.5%) patients (32.4% showed ATN; 11.4%, P-AKI; 29.7%, ATD). All patients with DKA or AKI presented with RTD. The physiological and biochemical parameters of AKI and RTD were normal again in all patients. The former within 14 days and the latter within 2months.

CONCLUSIONS

Most patients with T1DM onset may develop AKI and/or RTD, especially if presenting with DKA. Over time the physiological and biochemical parameters of AKI/RTD normalize in all patients.

Effect of NAD+ boosting on kidney ischemia-reperfusion injury

Acute kidney injury (AKI) is associated with a very high mortality and an increased risk for progression to chronic kidney disease (CKD). Ischemia-reperfusion injury (IRI) is a model for AKI, which results in tubular damage, dysfunction of the mitochondria and autophagy, and in decreased cellular nicotinamide adenine dinucleotide (NAD⁺) with progressing fibrosis resulting in CKD. NAD⁺ is a co-enzyme for several proteins, including the NAD⁺ dependent sirtuins. NAD⁺ augmentation, e.g. by use of its precursor nicotinamide riboside (NR), improves mitochondrial homeostasis and organismal metabolism in many species. In the present investigation the effects of prophylactic administration of NR on IRI-induced AKI were studied in the rat. Bilateral IRI reduced kidney tissue NAD⁺, caused tubular damage, reduced α-Klotho (klotho), and altered autophagy flux. AKI initiated progression to CKD, as shown by induced profibrotic Periostin (postn) and Inhibin subunit beta-A, (activin A / Inhba), both 24 hours and 14 days after surgery. NR restored tissue NAD⁺ to that of the sham group, increased autophagy (reduced p62) and sirtuin1 (Sirt1) but did not ameliorate renal tubular damage and profibrotic genes in the 24 hours and 14 days IRI models. AKI induced NAD⁺ depletion and impaired autophagy, while augmentation of NAD⁺ by NR restored tissue NAD⁺ and increased autophagy, possibly serving as a protective response. However, prophylactic administration of NR did not ameliorate tubular damage of the IRI rats nor rescued the initiation of fibrosis in the long-term AKI to CKD model, which is a pivotal event in CKD pathogenesis.

Modulation of Endocannabinoids by Caloric Restriction Is Conserved in Mice but Is Not Required for Protection from Acute Kidney Injury

Acute kidney injury (AKI) is a frequent and critical complication in the clinical setting. In rodents, AKI can be effectively prevented through caloric restriction (CR), which has also been shown to increase lifespan in many species. In Caenorhabditis elegans (C. elegans), longevity studies revealed that a marked CR-induced reduction of endocannabinoids may be a key mechanism. Thus, we hypothesized that regulation of endocannabinoids, particularly arachidonoyl ethanolamide (AEA), might also play a role in CR-mediated protection from renal ischemia-reperfusion injury (IRI) in mammals including humans. In male C57Bl6J mice, CR significantly reduced renal IRI and led to a significant decrease of AEA. Supplementation of AEA to near-normal serum concentrations by repetitive intraperitoneal administration in CR mice, however, did not abrogate the protective effect of CR. We also analyzed serum samples taken before and after CR from patients of three different pilot trials of dietary interventions. In contrast to mice and C. elegans, we detected an increase of AEA. We conclude that endocannabinoid levels in mice are modulated by CR, but CR-mediated renal protection does not depend on this effect. Moreover, our results indicate that modulation of endocannabinoids by CR in humans may differ fundamentally from the effects in animal models.

Determinants of Outcomes of Acute Kidney Injury: Clinical Predictors and Beyond

Acute kidney injury (AKI) is a common clinical syndrome characterized by rapid impairment of kidney function. The incidence of AKI and its severe form AKI requiring dialysis (AKI-D) has been increasing over the years. AKI etiology may be multifactorial and is substantially associated with increased morbidity and mortality. The outcome of AKI-D can vary from partial or complete recovery to transitioning to chronic kidney disease, end stage kidney disease, or even death. Predicting outcomes of patients with AKI is crucial as it may allow clinicians to guide policy regarding adequate management of this problem and offer the best long-term options to their patients in advance. In this manuscript, we will review the current evidence regarding the determinants of AKI outcomes, focusing on AKI-D.

Long-term consequences of acute kidney injury: a narrative review

The incidence of acute kidney injury (AKI) has increased in the past decades. AKI complicates up to 15% of hospitalizations and can reach up to 50-60% in critically ill patients. Besides the short-term impact of AKI in patient outcomes, several studies report the association between AKI and adverse long-term outcomes, such as recurrent AKI episodes in 25-30% of cases, hospital re-admissions in up to 40% of patients, an increased risk of cardiovascular events, an increased risk of progression of chronic kidney disease (CKD) after AKI and a significantly increased long-term mortality. Despite the long-term impact of AKI, there are neither established guidelines on the follow-up care of AKI patients, nor treatment strategies to reduce the incidence of sequelae after AKI. Only a minority of patients have been referred to nephrology post-discharge care, despite the evidence of improved outcomes associated with nephrology referral by addressing cardiovascular risk and risk of progression to CKD. Indeed, AKI survivors should have specialized nephrology follow-up to assess kidney function after AKI, perform medication reconciliation, educate patients on nephrotoxic avoidance and implement strategies to prevent CKD progression. The authors provide a comprehensive review of the transition from AKI to CKD, analyse the current evidence on the long-term outcomes of AKI and describe predisposing risk factors, highlight the importance of follow-up care in these patients and describe the current therapeutic strategies which are being investigated on their impact in improving patient outcomes.

Acute kidney injury as a risk factor for mortality in oncological patients receiving check-point inhibitors

BACKGROUND

Checkpoint inhibitors (CPI) have drastically improved metastatic cancer outcomes. However, immunotherapy is associated to multiple toxicities, including acute renal injury (AKI). Data about CPI related AKI are limited. Our aim was to determine risk factors for CPI related AKI, as well as its clinical characteristics and its impact on mortality in patients undergoing immunotherapy.

METHODS

All patients under CPI at our center between March 2018 and May 2019, and with a follow up until April 2020, were included. Demographical, clinical data and laboratory results were collected. AKI was defined according to KDIGO guidelines. We performed a logistic regression model to identify independent risk factors for AKI and actuarial survival analysis to establish risk factors for mortality in this population.

RESULTS

759 patients were included, with a median age of 64 years. 59% were men and baseline median creatinine was 0.80 mg/dL. Most frequent malignance was lung cancer and 56% were receiving anti-PD1. 15.5% developed AKI during the follow-up. Age and baseline kidney function were identified as independent risk factors for AKI related ICI. At the end of follow-up, 52.3% patients had died. Type of cancer (not melanoma, lung or urogenital malignance), type of CPI (not CTLA4, PD-1, PD-L1 or their combination) and the presence of an episode of AKI were identified as risk factors for mortality.

CONCLUSIONS

15.5% of patients under immunotherapy presented AKI. A single AKI episode was identified as an independent risk factor for mortality in these patients and age and baseline renal function were risks factors for the development of AKI.

Acute kidney injury in children hospitalized for community acquired pneumonia

BACKGROUND

Acute kidney injury (AKI) enhances the risk of later chronic kidney disease. Significant prevalence of AKI is reported in adults with community acquired pneumonia (CAP). We investigated prevalence of and prognostic factors for AKI in children hospitalized for CAP.

METHODS

We retrospectively collected clinical and biochemical data of 186 children (48.4% male; mean age 2.6±2.4 years) hospitalized for X-ray-confirmed CAP. AKI was defined according to Kidney Disease/Improving Global Outcomes creatinine criteria. We considered as basal serum creatinine the value estimated with Hoste (age) equation assuming basal eGFR were median age-based eGFR normative values for children ≤ 2 years of age and eGFR= 120 mL/min/1.73m² for children > 2 years. Univariate and multivariate logistic regression models were used to explore associations with AKI.

RESULTS

AKI was found in 38/186 (20.4%) patients. No patient required hemodialysis nor reached AKI stage 3, 5 (2.7%) reached AKI stage 2, and 33 (17.7%) AKI stage 1. Mean length of stay was 6.0±1.7, 6.9±2.3, and 12.2±1.5 days, for patients without AKI, stage 1 AKI, and stage 2 AKI (p < 0.001), respectively. Duration of symptoms before hospitalization (OR 1.2; 95%CI 1.09-1.43; p = 0.001), severe pneumonia (OR 11.9; 95%CI 4.3-33.3; p < 0.001), and serum C-reactive protein levels (OR 1.1; 95%CI 1.04-1.23; p = 0.004) were independent AKI predictors.

CONCLUSIONS

About 1/5 of children hospitalized for CAP present a generally mild AKI with a longer stay for those with more severe AKI. Attention should be paid to kidney health of children with CAP especially in presence of higher duration of symptoms before hospitalization, severe pneumonia and higher serum CRP levels.

Acute kidney injury in children hospitalized for acute gastroenteritis: prevalence and risk factors

BACKGROUND

We aimed to evaluate prevalence of acute kidney injury (AKI) and its risk factors in children hospitalized for acute gastroenteritis (AGE) to identify early predictors of AKI.

METHODS

We retrospectively collected clinical and biochemical data of 114 children (57.9% male; mean age 2.9 ± 2.8 years) hospitalized for AGE. AKI was defined according to Kidney Disease/Improving Global Outcomes creatinine criteria. We considered basal serum creatinine as value of creatinine estimated with Hoste (age) equation assuming basal eGFRs were median age-based eGFR normative values for children ≤ 2 years of age, and eGFR 120 mL/min/1.73m² for children > 2 years. Univariate and multivariate logistic regression models were used to explore associations with AKI. We included in multivariate analyses only variables with significant p after Bonferroni correction.

RESULTS

AKI was found in 28/114 (24.6%) patients. No patients required hemodialysis, 2 (1.8%) reached AKI stage 3, 2 (1.8%) AKI stage 2, and 24 (21.0%) AKI stage 1. Mean length of stay was 3.6 ± 1.2, 5.0 ± 1.8, and 10.5 ± 5.8 days, for patients with no, mild, and severe AKI (p < 0.001), respectively. Duration of symptoms before hospitalization (OR = 2.5; 95% CI = 1.3-5.0; p = 0.006), dehydration > 5% (OR = 43.1; 95% CI = 5.4-344.1; p = < 0.001), and serum bicarbonate levels (OR = 1.6; 95% CI = 1.2-2.1; p = 0.001) were independent predictors of AKI.

CONCLUSIONS

About one quarter of patients hospitalized for AGE may suffer from AKI with a longer stay for patients with more severe AKI. Particular attention, however, should be paid to volemia and kidney health of patients with AGE especially in the presence of increased duration of symptoms before hospitalization, dehydration, and lower serum bicarbonate levels.

Recurrent acute kidney injury: predictors and impact in a large population-based cohort

BACKGROUND

This study examined the impact of recurrent episodes of acute kidney injury (AKI) on patient outcomes.

METHODS

The Welsh National electronic AKI reporting system was used to identify all cases of AKI in patients ≥18 years of age between April 2015 and September 2018. Patients were grouped according to the number of AKI episodes they experienced with each patient's first episode described as their index episode. We compared the demography and patient outcomes of those patients with a single AKI episode with those patients with multiple AKI episodes. Analysis included 153 776 AKI episodes in 111 528 patients.

RESULTS

Of those who experienced AKI and survived their index episode, 29.3% experienced a second episode, 9.9% a third episode and 4.0% experienced fourth or more episodes. Thirty-day mortality for those patients with multiple episodes of AKI was significantly higher than for those patients with a single episode (31.3% versus 24.9%, P < 0.001). Following a single episode, recovery to baseline renal function at 30 days was achieved in 83.6% of patients and was significantly higher than for patients who had repeated episodes (77.8%, P < 0.001). For surviving patients, non-recovery of renal function following any AKI episode was significantly associated with a higher probability of a further AKI episode (33.4% versus 41.0%, P < 0.001). Furthermore, with each episode of AKI the likelihood of a subsequent episode also increased (31.0% versus 43.2% versus 51.2% versus 51.7% following a first, second, third and fourth episode, P < 0.001 for all comparisons).

CONCLUSIONS

The results of this study provide an important contribution to the debate regarding the need for risk stratification for recurrent AKI. The data suggest that such a tool would be useful given the poor patient and renal outcomes associated with recurrent AKI episodes as highlighted by this study.

Acute Kidney Injury in Children Based on Electronic Alerts

OBJECTIVE

To define the incidence and outcome of acute kidney injury (AKI) in pediatrics using data collected from a national electronic alert system.

STUDY DESIGN

A prospective national cohort study was undertaken to collect data on all cases of pediatric AKI, excluding neonates, identified by an e-alert, from April 2015 to March 2019.

RESULTS

There were 2472 alerts in a total of 1719 patients, giving an incidence of 77.3 per 100 000 person-years. Of the patients, 84.2% of all AKI were stage 1 and 58.3% occurred with a triggering creatinine within the reference range. The incidence of AKI was associated with measures of social deprivation. Thirty-day mortality was 1.7% but was significantly higher in hospital-acquired AKI (2.1%), compared with community-acquired AKI (0.8%, P < .001) and was associated with the severity of AKI at presentation. A significant proportion of patients had no repeat measure of creatinine (39.8%). This was higher in community-acquired AKI (69.7%) compared with hospital-acquired AKI (43.0%, P < .001), and higher in patients alerting with patients triggering with a creatinine within the reference range (48.4% vs 24.5%, P < .001). The majority of patients (84.7%) experienced only 1 AKI episode. Repeated episodes of AKI were associated with increased 30-mortaltiy (11.6% vs 4.6%, P < .001) and higher residual renal impairment (13.3% vs 5.4%, P < .001).

CONCLUSIONS

The results suggest that the significance of the alert is missed in many cases reflecting that a large proportion of cases represent modest elevations in serum creatinine (SCr), triggered by a SCr level that may be interpreted as being normal despite a significant increase from the baseline for the patient.

Effect of multiple episodes of acute kidney injury on mortality: an observational study

Background

Patients who survive an episode of acute kidney injury (AKI) are more likely to have further episodes of AKI. AKI is associated with increased mortality, with a further increase with recurrent episodes. It is not clear whether this is due to AKI or as a result of other patient characteristics. The aim of this study was to establish whether recurrence of AKI is an independent risk factor for mortality or if excess mortality is explained by other factors.

Methods

This observational cohort study included adult people from the Tayside region of Scotland, with an episode of AKI between 1 January 2009 and 31 December 2009. AKI was defined using the creatinine-based Kidney Disease: Improving Global Outcomes definition. Associations between recurrent AKI and mortality were examined using a Cox proportional hazards model.

Results

Survival was worse in the group identified to have recurrent AKI compared with those with a single episode of AKI [hazard ratio = 1.49, 95% confidence interval (CI) 1.37-1.63; P < 0.001]. After adjustment for comorbidities, stage of reference AKI, sex, age, medicines that predispose to renal impairment or, in the 3 months prior to the reference AKI, deprivation and baseline estimated glomerular filtration rate (eGFR), recurrent AKI was independently associated with an increase in mortality (hazard ratio = 1.25, 95% CI 1.14-1.37; P < 0.001). Increasing stage of reference AKI, age, deprivation, baseline eGFR, male sex, previous myocardial infarction, cerebrovascular disease and diuretic use were all associated with an increased risk of mortality in patients with recurrent AKI.

Conclusions

Recurrent AKI is associated with increased mortality. After adjusting for patient characteristics, the increase in mortality is independently associated with recurrent AKI and is not solely explained by other risk factors.

Phenotypes and Baseline Risk Factors of Acute Kidney Injury in Children After Allogeneic Hematopoietic Stem Cell Transplantation

Background: Acute kidney injury (AKI) is a frequent and widely recognized complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Despite relatively high prevalence, AKI after allo-HSCT and its risk factors in children remain obscure. The aim of this study was to describe the prevalence and course of AKI during the first 100 days after allo-HSCT in children and to investigate its associations with baseline characteristics. Methods: Retrospective single-center chart review of all patients under 18 who underwent allo-HSCT during 2011-2017 was performed. AKI was defined using the pediatric RIFLE criteria and only the patients with pRIFLE stage I (eGFR decrease by 50% or more) or higher were considered for the analysis. Recurrent AKI and acute kidney disease (AKD) were defined according to the Acute Disease Quality Initiative consensus. Demographic, clinical, and procedure-related characteristics were recorded at the day of HSCT. Results: Fifty-one patients (68.6% boys) with a median age of 9 years (range: 0.25-17) were included. During a median follow-up of 82 (IQR, 60-98) days, 27 (52.9%) patients experienced a total of 39 AKI episodes, translating into one AKI episode per 100 patient days. Multiple AKIs occurred in 11 (21.6%) patients and 18 (35.3%) progressed to AKD. Four patients died, all with ongoing or previous AKI. Patients with AKD were, on average, older (10 vs. 6 years; p = 0.03) and had higher baseline body mass index (BMI) [standard deviation score (SDS) 0.83 vs. 0.04, p = 0.05], whereas patients with recurrent AKI had higher baseline estimated glomerular filtration rate (eGFR) (244.1 vs. 193.9 ml/min/1.73 m², p = 0.02). In the adjusted Cox models (HR; 95% CI), older age (1.10; 1.01-1.20) was associated with higher risk of overall AKI and higher eGFR (1.02; 1.01-1.04) was associated with higher risk of recurrent AKI, while older age (1.17; 1.04-1.31), higher eGFR (HR 1.01; 1.0-1.02), and higher BMI SDS (1.66; 1.01-2.72) were associated with higher risk of AKD. Conclusions: AKI is a frequent early complication of allo-HSCT in children, and approximately one fifth experience AKI recurrence and one third develop AKD. Older age, higher BMI, and higher eGFR at the day of transplant may have an effect on the risk of AKI development and its course.

Role of ADAM17 in kidney disease

It is known that the renin-angiotensin system plays a major role in the pathophysiology of cardiovascular disease and renal injury. Within the renin-angiotensin system, angiotensin-converting enzyme 2 (ACE2) cleaves ANG II to generate ANG(1–7) peptide, which counteracts the adverse effects of ANG II accumulation. ACE2 can undergo cleavage or shedding to release the catalytically active ectodomain into the circulation by a disintegrin and metalloprotease (ADAM)17, also known as TNF-α-converting enzyme. ADAM17 is involved in many pathological processes such as cancer, inflammatory diseases, neurological diseases, cardiovascular diseases, atherosclerosis, diabetes, and hypertension. Clinical and experimental studies have shown that ADAM17 is involved in chronic kidney disease (CKD) with a proinflammatory and profibrotic role, suggesting that it could be an important mediator of CKD progression. ADAM17 inhibition attenuates fibrosis and inflammation, suggesting that its inhibition may be a possible new valuable therapeutic tool in fibrotic kidney disease treatment. In addition, in renal disease, some experimental studies have demonstrated that ADAM17 is differently expressed in the kidney. Thus, ADAM17 is highly expressed in distal renal tubules and increased in the whole kidney in diabetic models. In this article, we will review the role of ADAM17 under physiological and pathological conditions. We will mainly focus on the importance of ADAM17 in the context of CKD.

The influence of multiple episodes of acute kidney injury on survival and progression to end stage kidney disease in patients with chronic kidney disease

Background

Acute kidney injury (AKI) and chronic kidney disease (CKD) are common syndromes associated with significant morbidity, mortality and cost. The extent to which repeated AKI episodes may cumulatively affect the rate of progression of all-cause CKD has not previously been investigated. In this study, we explored the hypothesis that repeated episodes of AKI increase the rate of renal functional deterioration loss in patients recruited to a large, all-cause CKD cohort.

Methods

Patients from the Salford Kidney Study (SKS) were considered. Application of KDIGO criteria to all available laboratory measurements of renal function identified episodes of AKI. A competing risks model was specified for four survival events: Stage 1 AKI; stage 2 or 3 AKI; dialysis initiation or transplant before AKI event; death before AKI event. The model was adjusted for patient age, gender, smoking status, alcohol intake, diabetic status, cardiovascular co-morbidities, and primary renal disease. Analyses were performed for patients’ first, second, and third or more AKI episodes.

Results

A total of 48,338 creatinine measurements were available for 2287 patients (median 13 measures per patient [IQR 6–26]). There was a median age of 66.8years, median eGFR of 28.4 and 31.6% had type 1 or 2 diabetes. Six hundred and forty three (28.1%) patients suffered one or more AKI events; 1000 AKI events (58% AKI 1) in total were observed over a median follow-up of 2.6 years [IQR 1.1–3.2]. In patients who suffered an AKI, a second AKI was more likely to be a stage 2 or 3 AKI than stage 1 [HR 2.04, p 0.01]. AKI events were associated with progression to RRT, with multiple episodes of AKI progressively increasing likelihood of progression to RRT [HR 14.4 after 1 episode of AKI, HR 28.4 after 2 episodes of AKI]. However, suffering one or more AKI events was not associated with an increased risk of mortality.

Conclusions

AKI events are associated with more rapid CKD deterioration as hypothesised, and also with a greater severity of subsequent AKI. However, our study did not find an association of AKI with increased mortality risk in this CKD cohort.

Association between the recurrence period of acute kidney injury and mortality: a single-centre retrospective observational study in Japan

OBJECTIVES

Recurrent acute kidney injury (AKI) is a recognised risk factor for mortality. However, it is unclear whether the period until AKI recurrence may have a major factor on patient outcome or not. To explore this issue, we (1) framed the hypothesis that early recurrence increases the risk of mortality and (2) evaluated the prognosis of recurrent AKI cases by setting 21 days as the cut-off period.

METHODS

All studied cases were admitted and followed up at the Kanazawa University Hospital (Kanazawa, Japan) between 1 November 2006 and 31 October 2007. In total, 21 939 patients were retrospectively evaluated in their recurrences of AKI for 2 years and followed up until 31 October 2016. Risks for death were evaluated by the recurrences of AKI (Analysis 1). Patients who developed AKI recurrence before 21 days were defined as the early-recurrence group and the remaining cases as the late-recurrence group. Risks for death were evaluated by the two groups (Analysis 2).

RESULTS

510 patients (2.3%) developed the first AKI. Of these, 151 developed recurrent AKI within 2 years. The number of early-recurrence cases was 44 and that of non-recurrence or late-recurrence was 357. A total of 196 cases (38.4%) died, and higher risk for death was observed in the recurrent AKI group (Analysis 1; p=0.015, log-rank test). We found that the rate of all-cause mortality was higher in the early-recurrence group involving 33.8 deaths per 100 person-years, whereas the non-recurrence or late-recurrence group included only 6.2 deaths per 100 person-years (Analysis 2; p<0.001, log-rank test).

CONCLUSIONS

Patients experiencing recurrent AKI before 21 days from the first AKI clearly showed a relatively poor prognosis. Evidently, careful follow-up for at least 21 days after AKI would be highly useful to detect a recurrence event, possibly leading to a better prognosis after AKI.

Exaggerated Interventricular Dependence among Trauma and Burn Patients: A Relationship with Kidney Function—An Exploratory Study

Acute kidney injury (AKI) is a serious condition that affects critically ill patients admitted to the ICU. In this study, we report the association between right ventricle shape and AKI in a cohort of burn and trauma patients. This study is a retrospective review of trauma and burn patients who were admitted to our ICU between 2013 and 2016 who underwent hemodynamic transesophageal echocardiography. Left ventricular eccentricity index (LVEI) measurements were performed on still images obtained from transgastric short-axis view clips at end diastole. LVEI was used as a surrogate of right ventricular volume loading. There were 132 patients, the mean age was 50.8 years, and they were predominantly white and males. Using logistic regression and adjusting for age, race, gender, injury mechanism, and injury severity, higher LVEI was independently significantly associated with lower incidence of AKI (odds ratio 0.03, confidence interval 0.00–0.69). Higher LVEI is associated with a lower incidence of AKI in critically injured trauma and burn patients.

The impact of the NHS electronic-alert system on the recognition and management of acute kidney injury in acute medicine

To address inconsistencies in the recognition and management of acute kidney injury (AKI), an electronic-alert (e-alert) system was implemented by NHS England in 2015. This study aimed to describe its impact within acute medicine in the West Midlands. All admissions to included acute medical units were screened for AKI in two phases, before and after the e-alert was introduced. Data describing recognition and management of patients with AKI were collected. In the 10 units that participated in both phases, recognition of AKI by clinicians significantly improved from 67.9% in 2015 to 76.1% in 2016 (p=0.04). Further analysis of the data found that the presence of an e-alert had a limited effect on recognition and management, suggesting it was not the primary cause of the improvements. Multiple avenues of research have been recommended to clarify the impact of the e-alert system and to improve deficiencies in management that were identified in the data.

Late onset neonatal acute kidney injury: results from the AWAKEN Study

BACKGROUND

Most studies of neonatal acute kidney injury (AKI) have focused on the first week following birth. Here, we determined the outcomes and risk factors for late AKI (>7d).

METHODS

The international AWAKEN study examined AKI in neonates admitted to an intensive care unit. Late AKI was defined as occurring >7 days after birth according to the KDIGO criteria. Models were constructed to assess the association between late AKI and death or length of stay. Unadjusted and adjusted odds for late AKI were calculated for each perinatal factor.

RESULTS

Late AKI occurred in 202/2152 (9%) of enrolled neonates. After adjustment, infants with late AKI had higher odds of death (aOR:2.1, p = 0.02) and longer length of stay (parameter estimate: 21.9, p < 0.001). Risk factors included intubation, oligo- and polyhydramnios, mild-moderate renal anomalies, admission diagnoses of congenital heart disease, necrotizing enterocolitis, surgical need, exposure to diuretics, vasopressors, and NSAIDs, discharge diagnoses of patent ductus arteriosus, necrotizing enterocolitis, sepsis, and urinary tract infection.

CONCLUSIONS

Late AKI is common, independently associated with poor short-term outcomes and associated with unique risk factors. These should guide the development of protocols to screen for AKI and research to improve prevention strategies to mitigate the consequences of late AKI.