Biomarkers for prediction of renal replacement therapy in acute kidney injury: a systematic review and meta-analysis

Current role of biomarkers in the initiation and weaning of kidney replacement therapy in acute kidney injury

The occurrence of acute kidney injury (AKI) in critically ill patients is often associated with increased morbidity and mortality rates. Despite extensive research, a consensus is yet to be arrived, especially regarding the optimal timing and indications for initiation of kidney replacement therapy (KRT) for critically ill patients. There is no clear guidance available on the timing of weaning from KRT. More recently, various biomarkers have produced promising prognostic prediction in such patients, regarding the need for KRT and its termination. Most of these biomarkers are indicative of kidney damage and stress, rather than recovery. However, large-scale validation studies are required to guide the cutoff values of these biomarkers among different patient cohorts so as to identify the optimum timing for KRT. This article reviews the kidney biomarkers in detail and summarizes the individual roles of biomarkers in the decision-making process for initiation and termination of the KRT among critically ill AKI patients and the supportive literature.

The efficacy of novel biomarkers for the early detection and management of acute kidney injury: A systematic review

Acute kidney injury (AKI) is a frequent clinical complication lacking early diagnostic tests and effective treatments. Novel biomarkers have shown promise for enabling earlier detection, risk stratification, and guiding management of AKI. We conducted a systematic review to synthesize evidence on the efficacy of novel biomarkers for AKI detection and management. Database searches yielded 17 relevant studies which were critically appraised. Key themes were biomarker efficacy in predicting AKI risk and severity before functional changes; potential to improve clinical management through earlier diagnosis, prognostic enrichment, and guiding interventions; emerging roles as therapeutic targets and prognostic tools; and ongoing challenges requiring further validation. Overall, novel biomarkers like neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and cell cycle arrest markers ([TIMP-2] •[IGFBP7]) demonstrate capability for very early AKI prediction and accurate risk stratification. Their incorporation has potential to facilitate timely targeted interventions and personalized management. However, factors influencing biomarker performance, optimal cutoffs, cost-effectiveness, and impact on patient outcomes require robust validation across diverse settings before widespread implementation. Addressing these limitations through ongoing research can help translate novel biomarkers into improved detection, prognosis, and management of AKI in clinical practice.

Acute Kidney Injury Prognosis Prediction Using Machine Learning Methods: A Systematic Review

Rationale & Objective

Accurate estimation of in-hospital outcomes for patients with acute kidney injury (AKI) is crucial for aiding physicians in making optimal clinical decisions. We aimed to review prediction models constructed by machine learning methods for predicting AKI prognosis using administrative databases.

Study Design

A systematic review following PRISMA guidelines.

Setting & Study Populations

Adult patients diagnosed with AKI who are admitted to either hospitals or intensive care units.

Search Strategy & Sources

We searched PubMed, Embase, Web of Science, Scopus, and Cumulative Index to Nursing and Allied Health for studies published between January 1, 2014 and February 29, 2024. Eligible studies employed machine learning models to predict in-hospital outcomes of AKI based on administrative databases.

Data Extraction

Extracted data included prediction outcomes and population, prediction models with performance, feature selection methods, and predictive features.

Analytical Approach

The included studies were qualitatively synthesized with assessments of quality and bias. We calculated the pooled model discrimination of different AKI prognoses using random-effects models.

Results

Of 3,029 studies, 27 studies were eligible for qualitative review. In-hospital outcomes for patients with AKI included acute kidney disease, chronic kidney disease, renal function recovery or kidney failure, and mortality. Compared with models predicting the mortality of patients with AKI during hospitalization, the prediction performance of models on kidney function recovery was less accurate. Meta-analysis showed that machine learning methods outperformed traditional approaches in mortality prediction (area under the receiver operating characteristic curve, 0.831; 95% CI, 0.799-0.859 vs 0.772; 95% CI, 0.744-0.797). The overlapping predictive features for in-hospital mortality identified from ≥6 studies were age, serum creatinine level, serum urea nitrogen level, anion gap, and white blood cell count. Similarly, age, serum creatinine level, AKI stage, estimated glomerular filtration rate, and comorbid conditions were the common predictive features for kidney function recovery.

Limitations

Many studies developed prediction models within specific hospital settings without broad validation, restricting their generalizability and clinical application.

Conclusions

Machine learning models outperformed traditional approaches in predicting mortality for patients with AKI, although they are less accurate in predicting kidney function recovery. Overall, these models demonstrate significant potential to help physicians improve clinical decision making and patient outcomes.

Registration

CRD42024535965.

Prediction of Acute Kidney Injury Development in Critically Ill Septic Patients Based on NGAL Determination

Acute kidney injury (AKI) is a consequence of several diseases that can severely damage kidney function. It is a frequent complication of hospitalization and very common in critically ill patients because of other serious illnesses, such as septic conditions. New diagnostic options, including renal biomarkers, may help in early diagnosis. Our study included 46 patients, 31 with AKI and 15 without AKI on admission. Blood samples were collected on the first, fourth, and seventh days of treatment, and in addition to basic biochemical parameters, neutrophil gelatinase-associated lipocalin (NGAL) levels in serum were also examined. Data from the first and seventh day were used for statistical analysis. On the first follow-up day, NGAL values were categorized according to an optimal cut-off value of 290 µg/l. We demonstrated that if NGAL levels were higher, the risk of renal injury increased approximately 16 times. Other results showed that NGAL levels were moderately correlated with serum creatinine (r = 0.613, p < 0.0001), procalcitonin (PCT) (r = 0.627, p < 0.0001), and AKI stage (r = 0.589, p < 0.0001). There was also a significant positive correlation with SOFA (Sequential Organ Failure Assessment) score (r = 0.395, p = 0.007). Early diagnosis and treatment are crucial in managing AKI and preventing further kidney damage. NGAL levels can increase within a few hours after injury, making it a useful tool for early AKI detection and diagnosis. Key words: Acute kidney injury, Biomarker, NGAL, Sepsis.

Acute kidney injury subphenotyping and personalized medicine

PURPOSE OF REVIEW

This review discusses novel concepts of acute kidney injury (AKI), including subphenotyping, which may facilitate the development of target treatment strategies for specific subgroups of patients to achieve precision medicine.

RECENT FINDINGS

AKI is a multifaceted syndrome with a major impact on morbidity and mortality. As efforts to identify treatment strategies have largely failed, it is becoming increasingly apparent that there are different subphenotypes that require different treatment strategies. Various ways of subphenotyping AKI have been investigated, including the use of novel renal biomarkers, machine learning and artificial intelligence, some of which have already been implemented in the clinical setting. Thus, novel renal biomarkers have been recommended for inclusion in new definition criteria for AKI and for the use of biomarker bundled strategies for the prevention of AKI. Computational models have been explored and require future research.

SUMMARY

Subphenotyping of AKI may provide a new understanding of this syndrome and guide targeted treatment strategies in order to improve patient outcomes.

Exploring therapeutic mechanisms of Chuan Huang Fang-II in the treatment of acute kidney injury on chronic kidney disease patients from the perspective of lipidomics

OBJECTIVE

This study aims to assess the clinical efficacy and safety of CHF-II in combination with RG for treating AKI on CKD (A on C), and to explore potential therapeutic mechanisms through lipidomics analysis.

METHODS

98 patients were enrolled and randomly assigned to the RG or RG + CHF groups. Both groups received RG therapy, with RG + CHF group additionally receiving CHF-II treatment over a duration of two weeks. Evaluation endpoints included changes in renal function, blood lipid profiles, urinary AKI biomarkers, and TCM symptoms before and after treatment. Serum samples were collected for lipid metabolite analysis.

RESULTS

The total clinical effective rate in RG + CHF group was 73.5%, and that of RG group was 40.8%. TCM syndrome scores in RG + CHF group showed a more pronounced decrease (p < 0.05). Scr, BUN, and UA levels decreased while eGFR levels increased in both groups (p < 0.05), with a greater magnitude of change observed in the RG + CHF group. Urinary AKI biomarkers decreased more in RG + CHF group (p < 0.05). No serious adverse events occurred during the trial. 58 different lipid metabolites and 48 lipid biomarkers were identified. According to the KEGG database, the possible metabolic pathways involved triglyceride metabolic pathway and fat digestion and absorption metabolic pathways.

CONCLUSION

CHF-II effectively alleviated kidney injury and improved TCM syndrome scores in patients with A on C. Lipid differential metabolites could serve as diagnostic indicators for AKI in patients with CKD. The possible metabolic pathways might be implicated in therapeutic action of CHF-II in the prevention and treatment of patients with A on C.

Kidney replacement therapy in COVID-19-Related acute kidney injury: The impact of timing on mortality

The objective of this study was to determine the impact of the timing of KRT, dichotomized by a temporal criterion or by creatinine level, in patients with COVID-19-related AKI. This was a retrospective study involving 512 adult patients admitted to the ICU. All participants had laboratory-confirmed COVID-19 and a confirmed diagnosis of AKI. The potential predictors were the determination of the timing of KRT based on a temporal criterion (days since hospital admission) and that based on a serum creatinine cutoff criterion. Covariates included age, sex, and the SOFA score, as well as the need for mechanical ventilation and vasopressors. The main outcome measure was in-hospital mortality. We evaluated 512 patients, of whom 69.1% were men. The median age was 64 years. Of the 512 patients, 76.6% required dialysis after admission. The overall in-hospital mortality rate was 72.5%. When the timing of KRT was determined by the temporal criterion, the risk of in-hospital mortality was significantly higher for later KRT than for earlier KRT-84% higher in the univariate analysis (OR = 1.84, 95%, [CI]: 1.10-3.09) and 140% higher after adjustment for age, sex, and SOFA score (OR = 2.40, 95% CI: 1.36-4.24). When it was determined by the creatinine cutoff criterion, there was no such difference between high and low creatinine at KRT initiation. In patients with COVID-19-related AKI, earlier KRT might be associated with lower in-hospital mortality.

Biomarkers in acute kidney injury

Acute kidney injury (AKI) is a multifactorial syndrome with a high risk of short- and long-term complications as well as increased health care costs. The traditional biomarkers of AKI, serum creatinine and urine output, have important limitations. The discovery of new functional and damage/stress biomarkers has enabled a more precise delineation of the aetiology, pathophysiology, site, mechanisms, and severity of injury. This has allowed earlier diagnosis, better prognostication, and the identification of AKI sub-phenotypes. In this review, we summarize the roles and challenges of these new biomarkers in clinical practice and research.

Dimensions of muddy brown granular casts in patients with acute tubular injury

BACKGROUND

The presence of "muddy" brown granular casts (MBGC) in the urine sediment is pathognomonic for acute tubular injury (ATI). Although MBGC have been noted for years, there are no reports regarding their length nor width. The objective of this study was to measure MBGC using images obtained by light microscopy and investigate associations with clinically relevant parameters.

METHODS

Patients with diagnosis of ATI as evidenced by visualization of abundant MBGC (>30% low power fields) were sampled. Bright-field images were measured using ImageJ. Twenty-five patients were included: 44% women; median age 64 yrs; 52% white, 36% black. Mean MBGC width (n = 350) was 34.4 ± 13.1 µm (range: 9 to 110 µm).

RESULTS

Mean MBGC length was 98.7 ± 42.7 µm (range: 33 to 317 µm). Based on a previous report of cortical tubular diameters, MBGC width corresponded well with the median reported range. MBGC width was positively correlated with patient height (ρ=0.41, p=0.04), and length was positively correlated with fractional excretion of sodium (ρ=0.57. p=0.02) and urine chloride concentration (ρ=0.90, p=0.001). Mean MBGC length was negatively correlated with age (ρ=-0.47, p=0.02) and urine phosphate concentration (ρ=-0.72, p=0.03). There were no differences between cases that required renal replacement therapy (RRT, n =10) and those that did not require RRT (n=15).

CONCLUSION

This is the first study reporting dimensions of MBGC from cases with ATI. Clinical implications of these observations require further study.

When to start renal replacement therapy in acute kidney injury: What are we waiting for?

Acute kidney injury remains a serious condition with a high mortality risk. In the absence of any new drugs, renal replacement therapy (RRT) is the most important treatment option. Randomized controlled trials have concluded that in critically ill patients without an emergency indication for RRT, a watchful waiting strategy is safe; however, further delays in RRT did not seem to confer any benefit, rather was associated with potential harm. During this process, balancing the risks of complications due to an unnecessary intervention with the risk of not correcting a potentially life-threatening complication remains a challenge. Dynamic renal function assessment, especially dynamic assessment of renal demand-capacity matching, combined with renal biomarkers such as neutrophil gelatinase-associated lipocalin and furosemide stress test, is helpful to identify which patients and when the patients may benefit from RRT.

Plasma proenkephalin and neutrophil gelatinase-associated lipocalin predict mortality in ICU patients with acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is a common complication in patients admitted to intensive care unit (ICU) and mortality rates for this condition are high. To reduce the high incidence of short-term mortality, reliable prognostic indicators are required to facilitate early diagnosis and treatment of AKI. We assessed the ability of plasma proenkephalin (p‑PENK) and plasma neutrophil gelatinase-associated lipocalin (p‑NGAL) to predict 28-day mortality in AKI patients in intensive care.

METHODS

This prospective study, carried out between January 2019 and December 2019, comprised 150 patients (100 male) diagnosed with AKI after excluding 20 patients discharged within 24 h and those with missing hospitalization data. Blood samples were collected to determine admission p-PENK and p-NGAL levels. The study outcome was 28‑day mortality.

RESULTS

The mean patient age was 68 years (female, 33%). The average P‑PENK and p‑NGAL levels were 0.24 ng/µL and 223.70 ng/mL, respectively. P‑PENK levels >0.36 ng/µL and p‑NGAL levels >230.30 ng/mL were used as critical values to reliably indicate 28‑day mortality for patients with AKI (adjusted hazard ratios 0.785 [95% confidence interval 0.706-0.865, P<0.001] and 0.700 [95% confidence interval 0.611-0.789, P<0.001], respectively). This association was significant for mortality in patients in intensive care with AKI. Baseline p-PENK (0.36 ng/µL) and p-NGAL (230.30 ng/mL) levels and their respective cut-off values showed clinical value in predicting 28-day mortality.

CONCLUSION

Serum PENK and NGAL levels, when used in conjunction, improved the accuracy of predicting 28-day mortality in patients with AKI while retaining sensitivity and specificity.

Adverse renal effects associated with cardiopulmonary bypass

Cardiac surgery on cardiopulmonary bypass (CPB) is associated with postoperative renal dysfunction, one of the most common complications of this surgical cohort. Acute kidney injury (AKI) is associated with increased short-term morbidity and mortality and has been the focus of much research. There is increasing recognition of the role of AKI as the key pathophysiological state leading to the disease entities acute and chronic kidney disease (AKD and CKD). In this narrative review, we will consider the epidemiology of renal dysfunction after cardiac surgery on CPB and the clinical manifestations across the spectrum of disease. We will discuss the transition between different states of injury and dysfunction, and, importantly, the relevance to clinicians. The specific facets of kidney injury on extracorporeal circulation will be described and the current evidence evaluated for the use of perfusion-based techniques to reduce the incidence and mitigate the complications of renal dysfunction after cardiac surgery.

Elevated strong ion gap: A predictor of the initiation of continuous renal replacement therapy in acute kidney injury

BACKGROUND

There is no optimal timing for continuous renal replacement therapy (CRRT) in acute kidney injury (AKI). AKI is a reason for the increased unmeasured anions, which refers to the increased organic acids in the blood, and they can be detected by calculating strong ion gap (SIG). SIG level at the moment of the AKI diagnosis may be a predictor for the initiation of CRRT.

METHODS

Patients who were diagnosed with AKI in the first week of the intensive care unit (ICU) period were included in this prospective observational study. At the moment of the AKI diagnosis, blood gas samples were recorded, and SIG was calculated.

RESULTS

The median level of SIG at the moment of the AKI diagnosis of CRRT (+) patients was significantly higher than CRRT (-) patients (7.4 and 3.2 mmol L-1, respectively). In the multivariate Cox regression analysis, the likelihood of the initiation of CRRT was increased 1.16-fold (1.01-1.33) and 4.0-fold (1.9-8.7) by only 1 mmol L-1 increases in SIG and SIG ≥6 mmol L-1 at the moment of AKI diagnosis, respectively (p = 0.035 and p < 0.001).

CONCLUSIONS

Increased SIG at the moment of the AKI diagnosis in patients with AKI may be a predictive marker to initiate CRRT.

Increasing community prevalence of extended-spectrum beta-lactamase-producing Escherichia coli in urine is associated with increasing district-level antibiotic consumption

This study aimed to analyze ESBL-producing Escherichia coli prevalence in urine samples collected between 2011-2019 in Curitiba, a large city in Brazil, and relating it to antibiotic consumption and sanitary conditions. This is a longitudinal study correlating prevalence of ESBL-producing E. coli isolates from urine samples with district-level antibiotic consumption and sociodemographic data during 2011-2019. E. coli isolates were tested for antibiotic susceptibility and ESBL by an automated method. Statistical analysis applied linear regressions, pooled ordinary least squares, and fixed effects models for districts or years. The Chow and Hausman tests indicated that the fixed effects model for individual districts fitted best. Chi-square test was used for qualitative variables (statistical significance was set when P < 0.05). Among the 886 535 urine sample cultures, 9.9% of isolates were ESBL-producing E. coli. Their prevalence increased from 4.7% in 2012 to 19.3% in 2019 (P < 0.0001; R2 = 0.922). This progressive increase correlated with age (P = 0.007; R2 = 0.8725) and male gender (P < 0.001) and increased antibiotic consumption (P = 0.0386; R2 = 0.47). The fixed effects model showed that district influences ESBL prevalence and that antibiotic consumption explains 20%-30% of this variation, with an increase of one defined daily dose accounting for an increase of 0.02084 percentage points of ESBL. The increasing prevalence of ESBL-producing E. coli can, to a considerable extent, be explained by increasing antibiotic consumption.

The role of urinary Dickkopf-3 in the prediction of acute kidney injury: a systematic review meta-analysis

BACKGROUND

To systematically evaluate the diagnostic efficacy of urinary Dickkopf-Related Protein 3 (DKK-3) in acute kidney injury and to explore the clinical application value of urinary DKK-3.

METHOD

English databases (PubMed, Embase, Cochrane, and WOS) and Chinese databases (VIP, WanFang data, and China National Knowledge Internet) were screened for relevant papers published before March 12, 2023. After literature screening and data extraction, quality assessment was performed according to the QUADAS-2 scoring system. Then, the combined diagnostic and predictive parameters were calculated using a bivariate mixed effect meta-analysis model. Deek's funnel plot asymmetry test assessed publication bias, and Fagan's nomogram plot was used to verify its clinical utility.

RESULT

A total of 5 studies involving 2787 patients were included in this meta-analysis, of which 4 focused on contrast-induced acute kidney injury (CI-AKI) and 1 focused on AKI associated with cardiac surgery. The analysis showed that urine Dickkopf-3 has high diagnostic accuracy for AKI, with a sensitivity of 0.55 (95% CI [0.41, 0.68]), specificity of 0.80 (95% CI [0.70, 0.87]), positive likelihood ratio (PLR) of 2.7 [1.8, 4.1], negative likelihood ratio (NLR) of 0.56 [0.42, 0.75], diagnostic odds ratio (DOR) of 5 [3, 9], and AUC of 0.74 [0.70-0.77]. We did not perform subgroup analyses for predictive value due to the small number of included studies.

CONCLUSION

Urinary DKK3 may have limited predictive ability for acute kidney injury, especially for AKI associated with cardiac surgery. Therefore, urinary DKK3 may serve as a potential predictor for AKI. However, clinical studies with larger samples are still needed for validation.

Biomarkers for prediction of acute kidney injury in pediatric patients: a systematic review and meta-analysis of diagnostic test accuracy studies

BACKGROUND

Severity of acute kidney injury (AKI) confers higher odds of mortality. Timely recognition and early initiation of preventive measures may help mitigate the injury further. Novel biomarkers may aid in the early detection of AKI. The utility of these biomarkers across various clinical settings in children has not been evaluated systematically.

OBJECTIVE

To synthesize the currently available evidence on different novel biomarkers for the early diagnosis of AKI in pediatric patients.

DATA SOURCES

We searched four electronic databases (PubMed, Web of Science, Embase, and Cochrane Library) for studies published between 2004 and May 2022.

STUDY ELIGIBILITY CRITERIA

Cohort and cross-sectional studies evaluating the diagnostic performance of biomarkers in predicting AKI in children were included.

PARTICIPANTS AND INTERVENTIONS

Participants in the study included children (aged less than 18 years) at risk of AKI.

STUDY APPRAISAL AND SYNTHESIS METHODS

We used the QUADAS-2 tool for the quality assessment of the included studies. The area under the receiver operating characteristics (AUROC) was meta-analyzed using the random-effect inverse-variance method. Pooled sensitivity and specificity were generated using the hierarchical summary receiver operating characteristic (HSROC) model.

RESULTS

We included 92 studies evaluating 13,097 participants. Urinary NGAL and serum cystatin C were the two most studied biomarkers, with summary AUROC of 0.82 (0.77-0.86) and 0.80 (0.76-0.85), respectively. Among others, urine TIMP-2*IGFBP7, L-FABP, and IL-18 showed fair to good predicting ability for AKI. We observed good diagnostic performance for predicting severe AKI by urine L-FABP, NGAL, and serum cystatin C.

LIMITATIONS

Limitations were significant heterogeneity and lack of well-defined cutoff value for various biomarkers.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Urine NGAL, L-FABP, TIMP-2*IGFBP7, and cystatin C showed satisfactory diagnostic accuracy in the early prediction of AKI. To further improve the performance of biomarkers, they need to be integrated with other risk stratification models.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42021222698). A higher resolution version of the Graphical abstract is available as "Supplementary information".

Extracorporeal blood purification therapies for sepsis-associated acute kidney injury in critically ill patients: expert opinion from the SIAARTI-SIN joint commission

Sepsis-Associated Acute Kidney Injury is a life-threatening condition leading to high morbidity and mortality in critically ill patients admitted to the intensive care unit. Over the past decades, several extracorporeal blood purification therapies have been developed for both sepsis and sepsis-associated acute kidney injury management. Despite the widespread use of extracorporeal blood purification therapies in clinical practice, it is still unclear when to start this kind of treatment and how to define its efficacy. Indeed, several questions on sepsis-associated acute kidney injury and extracorporeal blood purification therapy still remain unresolved, including the indications and timing of renal replacement therapy in patients with septic vs. non-septic acute kidney injury, the optimal dialysis dose for renal replacement therapy modalities in sepsis-associated acute kidney injury patients, and the rationale for using extracorporeal blood purification therapies in septic patients without acute kidney injury. Moreover, the development of novel extracorporeal blood purification therapies, including those based on the use of adsorption devices, raised the attention of the scientific community both on the clearance of specific mediators released by microorganisms and by injured cells and potentially involved in the pathogenic mechanisms of organ dysfunction including sepsis-associated acute kidney injury, and on antibiotic removal. Based on these considerations, the joint commission of the Italian Society of Anesthesiology and Critical Care (SIAARTI) and the Italian Society of Nephrology (SIN) herein addressed some of these issues, proposed some recommendations for clinical practice and developed a common framework for future clinical research in this field.

C/EBPβ-TFAM-Mediated NLRP3 Inflammasome Activation Contributes to Arsenic-Induced Rat Kidney Injury

Compelling evidence has demonstrated that arsenic (As) exposure is associated with kidney injuries. Given that inflammatory responses and immune imbalances are the root causes of several kidney diseases, this study investigated the potential mechanisms underlying NLRP3 inflammasome activation in As-induced kidney injury. A rat model of sub-chronic As exposure was established via oral administration of NaAsO2. The results revealed that urinary β-2-microglobulin (β2-MG), N-acetyl-β-D-glucosidase (NAG) and albumin (ALB) were increased in the As-exposed group, reflecting kidney impairment. Moreover, significant glomerular vacuole-like changes, tubular dilatation and inflammatory cell infiltration were observed. Meanwhile, the expression levels of neutrophil gelatinase-associated lipocalin (NGAL), IL-1β and IL-18 were enhanced in the kidney tissues of As-treated rats. Further, increased expression of NLRP3, ASC and caspase-1, which are NLRP3 inflammasome-associated proteins, were observed in the kidney tissues of rats in the As-treated groups. The expression levels of the NLRP3 upstream regulators C/EBPβ and TFAM were also elevated. These findings suggest that sub-chronic As exposure triggers inflammatory responses in rat kidney tissue and impairs kidney function. The underlying mechanisms may be related to the C/EBPβ-TFAM pathway and activation of the NLRP3 inflammasome pathway.

Predicting the Development of Renal Replacement Therapy Indications by Combining the Furosemide Stress Test and Chemokine (C-C Motif) Ligand 14 in a Cohort of Postsurgical Patients

OBJECTIVES

Optimal timing of renal replacement therapy (RRT) initiation in severe acute kidney injury (AKI) remains controversial. Initiation of treatment early in the course of AKI may lead to some patients undergoing unnecessary RRT, whereas delayed treatment is associated with increased mortality. This study aims to investigate whether the combination of the furosemide stress test (FST) and AKI-associated biomarkers can predict the development of indications for RRT.

DESIGN

Single-center, prospective, observational study.

SETTING

University Hospital of Muenster, Germany.

PATIENTS

Critically ill, postoperative patients with moderate AKI (Kidney Disease: Improving Global Outcomes stage 2) and risk factors for further progression (vasopressors and/or mechanical ventilation) receiving an FST.

INTERVENTIONS

Sample collection and measurement of different biomarkers (chemokine [C-C motif] ligand 14 [CCL14], neutrophil gelatinase-associated lipocalin, dipeptidyl peptidase 3).

MEASUREMENT AND MAIN RESULTS

The primary endpoint was the development of greater than or equal to one predefined RRT indications (hyperkalemia [≥ 6 mmol/L], diuretic-resistant hypervolemia, high urea serum levels [≥ 150 mg/dL], severe metabolic acidosis [pH ≤ 7.15], oliguria [urinary output < 200 mL/12 hr], or anuria). Two hundred eight patients were available for the primary analysis with 108 having a negative FST (urine output < 200 mL in 2 hr following FST). Ninety-eight patients (47%) met the primary endpoint, 82% in the FST negative cohort. At the time of inclusion, the combination of a negative FST test and high urinary CCL14 levels had a significantly higher predictive value for the primary endpoint with an area under the receiver operating characteristic curve (AUC) of 0.87 (95% CI, 0.82-0.92) compared with FST or CCL14 alone (AUC, 0.79; 95% CI, 0.74-0.85 and AUC, 0.83; 95% CI, 0.77-0.89; p < 0.001, respectively). Other biomarkers showed lower AUCs.

CONCLUSIONS

The combination of the FST with the renal biomarker CCL14 predicts the development of indications for RRT.

Renal scintigraphy to predict persistent renal failure after acute kidney injury: an observational study

INTRODUCTION

Renal scintigraphy (RS) is occasionally performed to assess the risk of persistent renal failure (PRF) in patients with acute kidney disease (AKD). However, its diagnostic performance has never been assessed.

METHODS

We identified all patients with AKD for whom RS was performed in our institution between 2010 and 2017. PRF was defined as persistently low (< 33% of baseline) estimated glomerular filtration rates (eGFR), 1 year after RS. Nuclear medicine specialists reviewed RS data and rated, for each patient, the likelihood of PRF ("PRF score"). We evaluated the performance to predict PRF (area under the ROC curve (AUC)) of RS-derived parameters such as renal accumulation index, accumulation slope, and new parameters derived from serial kidney activity counts. We tested the ability of those parameters to improve a clinical model including hypertension, diabetes, AKI severity and baseline eGFR. Finally, we conducted sensitivity analyses using alternate PRF definitions.

RESULTS

Among 97 patients included, 57 (59%) fulfilled the criteria for PRF. The PRF score was able to predict PRF with an AUC of 0.63. Similarly, the accumulation index and accumulation slope respective AUCs were 0.64 and 0.63. None of these parameters were able to improve the performance of the clinical model. Among new parameters, the 3rd/2nd minute activity ratio and 3rd/2nd minute activity slope had fair diagnostic performance (AUC 0.72 and 0.74, respectively) and improved the performance of the clinical model. Results were confirmed in sensitivity analyses.

CONCLUSION

Conventional renal scintigraphy can identify patients at high risk of PRF with a high specificity but a low sensitivity. New parameters, with comparable diagnostic abilities can be obtained within three minutes of injection.

suPAR links a dysregulated immune response to tissue inflammation and sepsis-induced acute kidney injury

Acute kidney injury (AKI) secondary to sepsis results in poor outcomes and conventional kidney function indicators lack diagnostic value. Soluble urokinase plasminogen activator receptor (suPAR) is an innate immune-derived molecule implicated in inflammatory organ damage. We characterized the diagnostic ability of longitudinal serum suPAR levels to discriminate severity and course of sepsis-induced AKI (SI-AKI) in 200 critically ill patients meeting Sepsis-3 criteria. The pathophysiologic relevance of varying suPAR levels in SI-AKI was explored in a polymicrobial sepsis model in WT, (s)uPAR-knockout, and transgenic suPAR-overexpressing mice. At all time points studied, suPAR provided a robust classification of SI-AKI disease severity, with improved prediction of renal replacement therapy (RRT) and mortality compared with established kidney biomarkers. Patients with suPAR levels of greater than 12.7 ng/mL were at highest risk for RRT or death, with an adjusted odds ratio of 7.48 (95% CI, 3.00-18.63). suPAR deficiency protected mice against SI-AKI. suPAR-overexpressing mice exhibited greater kidney damage and poorer survival through inflamed kidneys, accompanied by local upregulation of potent chemoattractants and pronounced kidney T cell infiltration. Hence, suPAR allows for an innate immune-derived and kidney function-independent staging of SI-AKI and offers improved longitudinal risk stratification. suPAR promotes T cell-based kidney inflammation, while suPAR deficiency improves SI-AKI.

Diagnosis, pathophysiology and preventive strategies for cardiac surgery-associated acute kidney injury: a narrative review

Acute kidney injury (AKI) is a common and serious complication of cardiac surgery and is associated with increased mortality and morbidity, accompanied by a substantial economic burden. The pathogenesis of cardiac surgery-associated acute kidney injury (CSA-AKI) is multifactorial and complex, with a variety of pathophysiological theories. In addition to the existing diagnostic criteria, the exploration and validation of biomarkers is the focus of research in the field of CSA-AKI diagnosis. Prevention remains the key to the management of CSA-AKI, and common strategies include maintenance of renal perfusion, individualized blood pressure targets, balanced fluid management, goal-directed oxygen delivery, and avoidance of nephrotoxins. This article reviews the pathogenesis, definition and diagnosis, and pharmacological and nonpharmacological prevention strategies of AKI in cardiac surgical patients.

Indications for and Timing of Initiation of KRT

KRT is considered for patients with severe AKI and associated complications. The exact indications for initiating KRT have been debated for decades. There is a general consensus that KRT should be considered in patients with AKI and medically refractory complications ("urgent indications"). "Relative indications" are more common but defined with less precision. In this review, we summarize the latest evidence from recent landmark clinical trials, discuss strategies to anticipate the need for KRT in individual patients, and propose an algorithm for decision making. We emphasize that the decision to consider KRT should be made in conjunction with other forms of organ support therapies and important nonkidney factors, including the patient's preferences and overall goals of care. We also suggest future research to differentiate patients who benefit from timely initiation of KRT from those with imminent recovery of kidney function. Until then, efforts are needed to optimize the initiation and delivery of KRT in routine clinical practice, to minimize nonessential variation, and to ensure that patients with persistent AKI or progressive organ failure affected by AKI receive KRT in a timely manner.

Perioperative Management of the Patient at High-Risk for Cardiac Surgery-Associated Acute Kidney Injury

Acute kidney injury (AKI) is one of the most common major complications of cardiac surgery, and is associated with increased morbidity and mortality. Cardiac surgery-associated AKI has a complex, multifactorial etiology, including numerous factors such as primary cardiac dysfunction, hemodynamic derangements of cardiac surgery and cardiopulmonary bypass, and the possibility of a large volume of blood transfusion. There are no truly effective pharmacologic therapies for the management of AKI, and, therefore, anesthesiologists, intensivists, and cardiac surgeons must remain vigilant and attempt to minimize the risk of developing renal dysfunction. This narrative review describes the current state of the scientific literature concerning the specific aspects of cardiac surgery-associated AKI, and presents it in a chronological fashion to aid the perioperative clinician in their approach to this high-risk patient group. The evidence was considered for risk prediction models, preoperative optimization, and the intraoperative and postoperative management of cardiac surgery patients to improve renal outcomes.

Cystatin C and derived measures of renal function as risk factors for mortality and acute kidney injury in sepsis - A post-hoc analysis of the FINNAKI cohort

PURPOSE

To assess the association between cystatin C-derived estimates of kidney function and mortality and acute kidney injury (AKI) in sepsis.

MATERIALS AND METHODS

Post-hoc analysis of sepsis patients in the FINNAKI-cohort (n = 802). Primary outcome was 90-day mortality. We measured plasma cystatin C and creatinine at intensive care unit (ICU) admission and estimated glomerular filtration rates (eGFR_cys, eGFR_crea) and shrunken pore syndrome (SPS; defined as eGFR_cys/eGFR_crea ratio < 0.7). Associations were assessed using Cox- or logistic regression.

RESULTS

Increased cystatin C and decreased eGFR_cys were associated with mortality in unadjusted analyses and in analyses adjusted for illness severity and creatinine. Hazard ratios (HRs) in unadjusted analyses were 3.30 (95% CI; 2.12-5.13, p < 0.001) and 3.26 (95% CI; 2.12-5.02, p < 0.001) respectively. SPS was associated with mortality in an unadjusted- (HR 1.78, 95% CI; 1.33-2.37, p < 0.001) and in an adjusted analysis (HR 1.54, 95% CI; 1.07-2.22, p = 0.021). All cystatin C-derived measures were associated with mortality also after adjustment for AKI development. Cystatin C was associated with AKI in unadjusted analyses but not in analyses adjusted for creatinine.

CONCLUSION

Cystatin C and derived measures of kidney function at ICU admission are associated with an increased 90-day mortality. Increased AKI incidence does not fully explain this association.

The role of kidney injury biomarkers in COVID-19

The coronavirus disease-2019 (COVID-19) outbreak has been declared a global pandemic. COVID-19-associated acute kidney injury (COVID-19 AKI) is related to a high mortality rate and serves as an independent risk factor for hospital death in patients with COVID-19. Early diagnosis would allow for earlier intervention and potentially improve patient outcomes. The goal of early identification of AKI has been the primary impetus for AKI biomarker research, and several kidney injury biomarkers have been demonstrated to be beneficial in predicting COVID-19 AKI as well as disease progression in COVID-19. Furthermore, such data provide valuable insights into the molecular mechanisms underlying this complex and unique disease and serve as a molecular phenotyping tool that could be utilized to direct clinical intervention. This review focuses on a number of kidney injury biomarkers, such as CysC, NAGAL, KIM-1, L-FABP, IL-18, suPAR, and [TIMP-2] • [IGFBP7], which have been widely studied in common clinical settings, such as sepsis, cardiac surgery, and contrast-induced AKI. We explore the role of kidney injury biomarkers in COVID-19 and discuss what remains to be learned.

Accuracy of clinicians' ability to predict the need for renal replacement therapy: a prospective multicenter study

PURPOSE

Identifying patients who will receive renal replacement therapy (RRT) during intensive care unit (ICU) stay is a major challenge for intensivists. The objective of this study was to evaluate the performance of physicians in predicting the need for RRT at ICU admission and at acute kidney injury (AKI) diagnosis.

METHODS

Prospective, multicenter study including all adult patients hospitalized in 16 ICUs in October 2020. Physician prediction was estimated at ICU admission and at AKI diagnosis, according to a visual Likert scale. Discrimination, risk stratification and benefit of physician estimation were assessed. Mixed logistic regression models of variables associated with risk of receiving RRT, with and without physician estimation, were compared.

RESULTS

Six hundred and forty-nine patients were included, 270 (41.6%) developed AKI and 77 (11.8%) received RRT. At ICU admission and at AKI diagnosis, a model including physician prediction, the experience of the physician, SOFA score, serum creatinine and diuresis to determine need for RRT performed better than a model without physician estimation with an area under the ROC curve of 0.90 [95% CI 0.86-0.94, p < 0.008 (at ICU admission)] and 0.89 [95% CI 0.83-0.93, p = 0.0014 (at AKI diagnosis)]. In multivariate analysis, physician prediction was strongly associated with the need for RRT, independently of creatinine levels, diuresis, SOFA score and the experience of the doctor who made the prediction.

CONCLUSION

As physicians are able to stratify patients at high risk of RRT, physician judgement should be taken into account when designing new randomized studies focusing on RRT initiation during AKI.

ISCCM Guidelines on Acute Kidney Injury and Renal Replacement Therapy

Acute kidney injury (AKI) is a complex syndrome with a high incidence and considerable morbidity in critically ill patients. Renal replacement therapy (RRT) remains the mainstay of treatment for AKI. There are at present multiple disparities in uniform definition, diagnosis, and prevention of AKI and timing of initiation, mode, optimal dose, and discontinuation of RRT that need to be addressed. The Indian Society of Critical Care Medicine (ISCCM) AKI and RRT guidelines aim to address the clinical issues pertaining to AKI and practices to be followed for RRT, which will aid the clinicians in their day-to-day management of ICU patients with AKI.

How to cite this article

Mishra RC, Sodhi K, Prakash KC, Tyagi N, Chanchalani G, Annigeri RA, et al. ISCCM Guidelines on Acute Kidney Injury and Renal Replacement Therapy. Indian J Crit Care Med 2022;26(S2):S13-S42.

Delivering optimal renal replacement therapy to critically ill patients with acute kidney injury

Critical illness is often complicated by acute kidney injury (AKI). In patients with severe AKI, renal replacement therapy (RRT) is deployed to address metabolic dysfunction and volume excess until kidney function recovers. This review is intended to provide a comprehensive update on key aspects of RRT prescription and delivery to critically ill patients. Recently completed trials have enhanced the evidence base regarding several RRT practices, most notably the timing of RRT initiation and anticoagulation for continuous therapies. Better evidence is still needed to clarify several aspects of care including optimal targets for ultrafiltration and effective strategies for RRT weaning and discontinuation.

Neutrophil gelatinase-associated lipocalin as predictor of acute kidney injury requiring renal replacement therapy: A systematic review and meta-analysis

Background

Patients with severe acute kidney injury (AKI) may require renal replacement therapy (RRT), such as hemodialysis and peritoneal dialysis. Neutrophil gelatinase-associated lipocalin (NGAL) is a sensitive indicator for early diagnosis and recognition of AKI; however, its predictive value of AKI-associated need for RRT needs further evaluation.

Methods

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, relevant articles were systematically searched and selected from seven databases. The random effects model was applied to evaluate the predictive performance of NGAL for AKI requiring RRT. The Newcastle–Ottawa Scale (NOS) was used to assess the quality of each included study.

Results

A total of 18 studies including 1,787 patients with AKI and having an average NOS score of 7.67 were included in the meta-analysis. For plasma/serum NGAL, the pooled sensitivity and specificity with corresponding 95% confidence interval (CI) were 0.75 (95% CI: 0.68–0.81) and 0.76 (95% CI: 0.70–0.81), respectively. The pooled positive likelihood ratio (PLR) was 2.9 (95% CI: 2.1–4.1), and the pooled negative likelihood ratio (NLR) was 0.34 (95% CI: 0.25–0.46). Subsequently, the pooled diagnostic odds ratio (DOR) was 9 (95% CI: 5–16) using a random effects model, and the area under the curve (AUC) of summary receiver operating characteristic to summarize predictive accuracy was 0.82 (95% CI: 0.79–0.85). For urine NGAL, the pooled sensitivity, specificity, PLR, NLR, DOR, and AUC values were 0.78 (95% CI: 0.61–0.90), 0.77 (95% CI: 0.65–0.85), 3.4 (95% CI: 2.4–4.8), 0.28 (95% CI: 0.15–0.52), 12 (95% CI: 6–24), and 0.84 (95% CI: 0.80–0.87), respectively.

Conclusion

Plasma/serum and urine NGAL levels performed comparably well in predicting AKI requiring RRT. Our findings suggested that NGAL is an effective predictive biomarker for the AKI-associated need for RRT. Nevertheless, more pieces of high-quality evidence and future trials with larger sample sizes are needed for further improvement of patient outcomes.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022346595], identifier [CRD42022346595].

Comprehensive analysis of fifteen hub genes to identify a promising diagnostic model, regulated networks, and immune cell infiltration in acute kidney injury

BACKGROUND

Acute kidney injury is a common clinical problem with no sensitive and specific diagnostic biomarkers and definitive treatments. The underlying molecular mechanisms of acute kidney injury are unclear. Therefore, it is pivotal to explore the underlying mechanisms and screen for novel diagnostic biomarkers, and therapeutic targets.

METHODS

The present study identified 15 hub genes by WGCNA analysis. LASSO-based logistic regression analysis was used to select key features and construct a diagnostic model of AKI. In addition, GO and KEGG analyses were performed and TF-mRNA and miRNA-mRNA network analysis and immune infiltration analysis of hub genes were performed to reveal the underlying mechanisms of AKI.

RESULTS

A diagnostic model was constructed by LASSO-based logistic regression analysis and was validated by RT-qPCR based on 15 hub genes. GO and KEGG analyses revealed DEGs were enriched in oxidation-reduction process, cell adhesion, proliferation, migration, and metabolic process. The enriched TFs were BRD2, EP300, ETS1, MYC, SPI1, and ZNF263. The enriched miRNAs were miR-181c-5p, miR-218-5p, miR-485-5p, miR-532-5p and miR-6884-5p. The immune infiltration analysis showed that Macrophages M2 was decreasing significantly revealing a protective factor for further AKI treatment.

CONCLUSIONS

The present study identified 15 hub genes based on WGCNA. Development and validation of a potentially diagnostic model based on 15 hub genes. In addition, exploring the interaction between transcriptional factors and 15 hub genes, and miRNA-mRNA relationship pairs. Furthermore, immune infiltration analysis was performed by analyzing gene expression profiles of AKI. Our study provides some basis for further experimental studies.

Clinical Implementation of NGAL Testing to Improve Diagnostic Assessment of AKI Episodes in a Canadian Center

Background:

The differential diagnosis of acute kidney injury (AKI) episodes is often challenging. Novel AKI biomarkers have shown their utility to improve prognostic prediction and diagnostic assessment in various research populations but their implementation in standard clinical practice is still rarely reported.

Objective:

To report the differential diagnostic ability and associated clinical utility of the neutrophil gelatinase-associated lipocalin (NGAL) testing in a real-life setting of a heterogeneous AKI population.

Design:

This is a retrospective cohort study combined with a clinical audit using questionnaires distributed to consultant nephrologists following NGAL results.

Setting:

The first 250 consecutive patients with a confirmed AKI where an NGAL test (plasma NGAL [pNGAL] or urine NGAL [uNGAL]) was ordered from a large academic center in Montreal, Canada from January 2021 to August 2021.

Patients:

Patients were classified into 3 groups based on the final AKI etiology category (functional, intrarenal, and postrenal) following definitive adjudication by 2 independent nephrologists.

Methods:

The ability of plasma NGAL (pNGAL), urine NGAL (uNGAL), and uNGAL-to-creatinine ratio (uNGAL/Cr) to discriminate intrarenal from functional AKI etiologies was compared to standard urine chemistry (FENa) and proteinuria. A logistic regression was used to evaluate the association between intrarenal AKI and increased biomarker levels. The overall clinical utility and appreciation of the NGAL test was evaluated using a questionnaire completed prospectively by the consultant nephrologist at the time of receiving the NGAL result. The NGAL results were prospectively available to clinicians with a median time of 2.9 (1.3-7.4) hours from the initial order.

Results:

A total of 214 uNGAL and 44 pNGAL were ordered from 100 functional, 139 intrarenal and 11 postrenal AKI episodes after final adjudication. The discriminative ability of FENa (AUC 0.68 [95% CI: 0.61-0.75]) was lower than uNGAL (AUC 0.80 [95% CI: 0.73-0.86]) and uNGAL/Cr (AUC 0.83 [95% CI: 0.77-0.88]) but better than pNGAL (AUC 0.66 [95% CI: 0.48-0.85]). According to consultant nephrologists, the NGAL testing has led to a change in clinical management in 42% of cases.

Limitations:

Data reported came from a single center and NGAL was reserved for more complex cases, which limits generalizability. No biopsy has been performed for most AKI cases as the final adjudication was based on a retrospective review of the hospitalization episode.

Conclusions:

Neutrophil gelatinase-associated lipocalin testing can be successfully integrated as part of the diagnostic workup for AKI in clinical practice. The integration of tubular damage biomarkers to functional biomarkers can further improve the differential diagnostic assessment. However, the impact of such biomarkers on AKI management and associated outcomes still needs further validation.

Renal replacement therapy for acute kidney injury in burn patients, an international survey and a qualitative review of current controversies

BACKGROUND OF THE STUDY

Acute kidney injury (AKI) is a common complication in critically ill burn patients and is associated with a number of serious adverse outcomes. The clinical decision-making process related to the management of AKI in burn patients is complex and has not been sufficiently standardized. The main aim of this study was to explore the diagnostic approach and clinician's attitudes toward the management of AKI and RRT in burn patients around the world.

METHODS

The questionnaire was widely distributed among the members of International Society for Burn Injury (ISBI), who were invited to complete the survey. Data collection and report was compliant with the the Checklist for Reporting Results of Internet E-Surveys (CHERRIES) Web-survey guidelines. The survey form with multiple-choice questions was divided into 3 parts: a. physician and institutional demographics, b. AKI diagnostic information, c. technical aspects of RRT.

RESULTS

A total of 44 respondents worldwide submitted valuable data in the 2-month period. Of all respondents, 43.2% were from Europe, 30% from North America, 7% from South-East Asia 2.3% from Africa and 18.2% from other regions. 93.1% of participants declare that they use specific definitions to detect AKI, while 11.4% declare the use of renal ultrasonography for AKI diagnosis. CRRT appeared to be the most preferred option by 43.2% of participants, followed by intermittent hemodialysis (25%), and prolonged intermittent RRT (6.8%). The expertise to deliver a modality and the availability of resources were considered important factors when selecting the optimal RRT modality by 20.5% and 29.6% of respondents. The use of specific serum biomarkers for AKI diagnosis are stated by 16% of respondents; 25% of specialists refer to the use of biomarkers of AKI as a criterium for discontinuing the RRT. Femoral vena and right jugular vena were the most frequently used location for RRT temporary catheter placement, 54.6% of respondents declared using ultrasound guidance for catheter placement.

CONCLUSIONS

The majority of burn specialists use specific consensus classifications to detect acute kidney injury. Continuous renal replacement therapy appeared to be the most preferred option, while the expertise to deliver a particular modality and resources availability play a significant role in modality selection. The use of ultrasound and specific biomarkers for AKI evaluation is infrequent in routine clinical practice.

Diagnostic accuracy of renal angina index alone or in combination with biomarkers for predicting acute kidney injury in children

Early recognition of patients at risk for severe acute kidney injury (AKI) by renal angina index (RAI) may help in the early institution of preventive measures. Objective was to evaluate performance of RAI alone or in combination with biomarkers in predicting severe AKI (KDIGO stage 2 and 3 or equivalent) and receipt of kidney replacement therapy (KRT) in critically ill children. We searched PubMed, EMBASE, Web of Sciences, and CENTRAL for studies published till May 2021. Search terms included acute kidney injury, pediatrics, adolescent, renal angina index, and biomarker. Proceedings of relevant conferences and references of included studies were also scrutinized. Two reviewers independently assessed the study eligibility. Cohort and cross-sectional studies evaluating the diagnostic performance of RAI in predicting AKI or receipt of KRT in children were included. Eligible participants were the children less than 18 years with RAI assessment on day 0 ofadmission. We followed PRISMA-DTA guidelines and used the QUADAS-2 tool for quality assessment. A bivariate model for meta-analysis was used to calculate the summary estimates of diagnostic parameters. Major outcomes were the diagnostic accuracy of RAI (≥ 8) alone or with biomarkers in predicting severe AKI and KRT receipt. Diagnostic accuracy was reported using summary sensitivity, specificity, and area under the curve (AUC). Overall, 22 studies (24 reports, 14,001 participants) were included. RAI ≥ 8 on day 0 has summary sensitivity, specificity, and AUC of 0.86 (95% CI, 0.77-0.92), 0.77 (0.68-0.83), and 0.88 (0.85-0.91) respectively for prediction of severe AKI on day 3. In comparison, a combination of RAI and urinary neutrophil gelatinase-associated lipocalin (NGAL) showed summary sensitivity, specificity, and AUC of 0.76 (0.62-0.85), 0.89 (0.74-0.96), and 0.87 (0.84-0.90) respectively for predicting severe AKI. The sensitivity, specificity, and AUC of RAI for predicting receipt of KRT were 0.82 (0.71-0.90), 0.74 (0.66-0.81), and 0.85 (0.81-0.88) respectively. In meta-regression, only the study setting (sepsis vs. heterogenous) was associated with heterogeneity. We observed substantial heterogeneity among eligible studies. Five studies had concerns in patient selection, and seven studies also had applicability concerns in patient selection for this review. Moderate certainty evidence showed that RAI ≥ 8 has good predicting ability in recognizing children at risk of severe AKI and receipt of KRT. The combination of urinary NGAL and RAI further improves the predicting ability (low-certainty evidence). Further studies are required on the context-driven assessment of novel biomarkers in the early prediction of AKI in RAI-positive children. Systematic review registration number: CRD4202122268. A higher resolution version of the Graphical abstract is available as Supplementary information.

Soluble Urokinase-Type Plasminogen Activator Receptor Levels as a Predictor of Kidney Replacement Therapy in Septic Patients with Acute Kidney Injury: An Observational Study

The soluble urokinase-type plasminogen activator receptor (suPAR) is involved in the pathogenesis of acute kidney injury (AKI). Our goal was to establish the optimal suPAR cut-off point for predicting the need for kidney replacement therapy (KRT) use in sepsis patients and to analyze survival rates based on the suPAR level, AKI diagnosis, and the requirement for KRT. In total, 51 septic patients were included (82% septic shock; 96% mechanically ventilated, 35% KRT). Patients were stratified according to the AKI diagnosis and the need for KRT into three groups: AKI(+)/KRT(+), AKI(+)/KRT(−), and AKI(−)/KRT(−). A control group (N = 20) without sepsis and kidney failure was included. Sepsis patients had higher levels of the suPAR than control (13.01 vs. 4.05 ng/mL, p < 0.001). On ICU admission, the suPAR level was significantly higher in the AKI(+)/KRT(+) group than in the AKI(+)/KRT(−) and AKI(−)/KRT(−) groups (18.5 vs. 10.6 and 9.5 ng/mL, respectively; p = 0.001). The optimal suPAR cut-off point for predicting the need for KRT was established at 10.422 ng/mL (area under the curve 0.801, sensitivity 0.889, specificity 0.636). Moreover, patients AKI(+)/KRT(+) had the lowest probability of survival compared to patients AKI(+)/KRT(−) and AKI(−)/KRT(−) (p = 0.0003). The results indicate that the suPAR measurements may constitute an important element in the diagnosis of a patient with sepsis.

Identifying of miRNA–mRNA Regulatory Networks Associated with Acute Kidney Injury by Weighted Gene Co-Expression Network Analysis

Background

Acute kidney injury (AKI) is a clinical emergency characterized by a dramatic decline in renal function and the accumulation of metabolic waste products in the body, with a high morbidity and mortality rate. The pathogenesis of AKI remains unclear and there are no effective treatment options.

Methods

We aimed to identify critical genes involved in the pathogenesis of AKI and construct a miRNA–mRNA regulatory network using gene expression data downloaded from Gene Expression Omnibus (GSE85957) for 38 kidneys of AKI and 19 control rats and cisplatin treated kidneys of 3 AKI and 3 control rats. Data in GSE85957 were processed using weighted gene co-expression network analysis (WGCNA), and biological function analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used to analyze the functions associated with critical genes.

Results

Twenty-eight modules in the GSE85957 dataset were identified by WGCNA, of which 103 genes in the orange module and 30 genes in the black module were closely associated with AKI and dose. Biological function analysis of genes in the orange and black modules revealed that skeletal muscle cell differentiation, tissue development and organ development were involved in the pathological changes of AKI. Combining with our experimentally processed AKI rat kidney data, eight genes (Atf3, Egr1, Egr2, Fos, Fosb, Gdf15, Serpine1 and Nr1d1) were identified as potential biomarkers of AKI, and miRNA–mRNA regulatory networks were constructed based on the above eight critical genes. Further tissue validation revealed that Egr1 and Fos were highly expressed in AKI.

Conclusion

Our study identified potential biomarkers of AKI and constructed an associated miRNA–mRNA regulatory network, which may provide new insights into the molecular pathogenesis of AKI.

Combined serum free light chain predicts prognosis in acute kidney injury following cardiovascular surgery

Objectives

Increased polyclonal free light chains (FLCs) are found in inflammatory conditions. Inflammation is recognized in the progression of acute kidney injury (AKI). This study was aimed to determine whether polyclonal combined FLC (cFLC) was associated with prognosis of AKI patients.

Methods

This prospective cohort included 145 adults with hospital-acquired AKI following cardiovascular surgery between 2014 and 2016, according to the KDIGO creatinine criteria. The primary end point of the study was all-cause death during follow-up.

Results

The median of serum cFLC concentration in the cohort was 42.0 (31.9–60.3 mg/L) and levels of cFLC in patients with AKI stage 3 were higher than those in AKI stage 1 and stage 2. cFLC levels correlated significantly with renal function biomarkers, high sensitivity C-reactive protein (hsCRP), and sequential organ failure assessment (SOFA) score. Patients were organized into the following two groups: the low-cFLC group (cFLC <43.3 mg/L) and the high-cFLC group (cFLC ≥ 43.3 mg/L). A total of 17 (11.0%) patient deaths occurred within 90 d, 13 (18.8%) in the high-cFLC group. Kaplan–Meier analysis revealed that the two groups differed significantly with respect to 90-d survival (log-rank p = .012), and Cox regression analysis showed that an cFLC level ≥43.3 mg/L was significantly associated with a 5.0-fold increased risk of death (adjusted hazard ratio [HR], 5.95; 95% confidence interval [CI], 1.04– 33.91; p = .045) compared with an cFLC level <43.3 mg/L.

Conclusions

Serum cFLC levels were significantly elevated and might be an independent predictor of mortality in patients with AKI following cardiovascular surgery.

Protective role of antithrombin III in suppressing acute responses in a rat model of renal ischemia-reperfusion injury

Renal ischemia-reperfusion (IR) produces-induced injury and is characterized by restriction of blood supply to the kidney followed by restoration and re-oxygenation of the tissue. IR injury in the kidney contributes to pathological processes known as acute renal injury (ARI). Ischemia-perfusion injury (IRI) of the left renal artery has been demonstrated in Wistar rats. A total of 32 animals were divided into four groups: control group (SHAM), IR animals with induced ischemia-reperfusion, AT-IR animals treated by antithrombin III (AT) before IR, and AT-IR-AT animals with AT administered before and after IR. IR-induced hyperproteinemia, hyperalbuminemia, hyperglobulinemia, and a significantly low A/G ratio. Exogenous administration of AT prior to IR development effectively regulates protein fraction levels by establishing normoproteinemia. The preventive effect of AT regulates serum protein levels and reduces acute inflammation by reducing globulin and establishing physiological levels of A/G ratios. The therapeutic effect of AT given after IR is not effective compared to AT administered before IR. Protein fractions can serve as an important predictive marker for the prognosis and duration of acute inflammation. Serum globulin levels and the A/G ratio may serve as effective prognostic markers in acute inflammation caused by ischemia-reperfusion injury of the kidney. A strong correlation between globulin and the A/G ratio suggests novel markers associated with acute inflammation that can lead to chronic kidney disease.

Timing of renal-replacement therapy in intensive care unit-related acute kidney injury

PURPOSE OF REVIEW

The optimal timing of renal-replacement therapy (RRT) initiation for the management of acute kidney injury (AKI) in the intensive care unit (ICU) is frequently controversial. An earlier-strategy has biological rationale, even in the absence of urgent indications; however, a delayed-strategy may prevent selected patients from receiving RRT and avoid complications related to RRT.

RECENT FINDINGS

Previous studies assessing the optimal timing of RRT initiation found conflicting results, contributing to variation in clinical practice. The recent multinational trial, standard vs. accelerated initiation of renal replacement therapy in acute kidney injury (STARRT-AKI) found no survival benefit and a higher risk of RRT dependence with an accelerated compared to a standard RRT initiation strategy in critically ill patients with severe AKI. Nearly 40% of patients allocated to the standard-strategy group did not receive RRT. The Artificial Kidney Initiation in Kidney Injury-2 (AKIKI-2) trial further assessed delayed compared to more-delayed strategies for RRT initiation. The more-delayed strategy did not confer an increase in RRT-free days and was associated with a higher risk of death.

SUMMARY

Early preemptive initiation of RRT in critically ill patients with AKI does not confer clear clinical benefits. However, protracted delays in RRT initiation may be harmful.

The value of Neutrophil gelatinase-associated lipocalin and Neutrophil / Lymphocyte Ratio in the diagnosis of preeclampsia and its severity

Many hypotheses underlie the pathogenesis of preeclampsia. This study aims to evaluate Neutrophil gelatinase-associated lipocalin (a marker of immune hypothesis) and Neutrophil / Lymphocyte ratio (a marker of inflammation) in the diagnosis of preeclampsia and its severity and to determine the correlation between them.Study design : This randomized case-control study involved 132 pregnant women ; 88 were diagnosed with PE (divided into non-severe and severe groups), and 44 healthy pregnant women as a control group. Results : The mean serum level of NGL was significantly higher in PE (535.37 ± 158.61 ng / ml for severe PE, 522.5 ± 106.3 ng / ml for non-severe PE, and 161.96 ± 17.48 ng / ml for the control group). The ROC Curve NGL criteria of more than 204.4 ng / ml showed 100% sensitivity and specificity in both severe and non-severe cases versus control. The N / L ratio showed a significant difference (5.81 ± 5.24 for severe PE, 4.1 ± 3.41 for non-severe PE, and 3.89 ± 1.79 for the control group), but the ROC curve criterion was not significant. Both showed a non-significant positive correlation. Conclusion : NGL is an excellent diagnostic factor, whereas N / L might have lower diagnostic performance compared with NGL. Both are related independently to the pathophysiology of PE. J. Med. Invest. 68 : 321-325, August, 2021.

Neutrophil-to-lymphocyte ratio is a marker for acute kidney injury progression and mortality in critically ill populations: a population-based, multi-institutional study

Backgrounds

Neutrophil-to-lymphocyte ratio (NLR), a surrogate marker of systemic response to physiological stress, is used for prognosis prediction in many diseases. However, the usefulness of this marker for predicting acute kidney injury (AKI) progression is unclear.

Methods

This retrospective study was based on the Chang Gung Research Database. Patients admitted to the intensive care unit with a diagnosis of stage 1 or 2 AKI were identified. The primary outcome was a composite of progression to stage 3 AKI, requirement of renal replacement therapy, or 14-day in-hospital mortality. The association between NLR and the primary outcome was examined using a logistic regression model and multivariable analysis. The nonlinearity and cutoff points of this relationship were determined using a restricted cubic spline model.

Results

A total of 10,441 patients were enrolled. NLR level at the time of stage 1–2 AKI diagnosis was a marker of adverse outcomes. After adjustment for confounders, NLR was independently associated with the composite outcome of AKI progression, renal replacement therapy, or mortality. The restricted cubic spline model revealed a J-shaped curve, with the lowest odds ratio for an NLR between 7 and 38. Subgroup analysis revealed linear and J-shaped relationships between NLR and the primary outcome in patients admitted to the intensive care unit for medical reasons and for cardiovascular surgery, respectively.

Conclusions

NLR is an independent marker of AKI progression and in-hospital mortality. Because it is readily available in daily practice, it might be used for risk stratification in the AKI population.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40620-021-01162-3.

Cost-effectiveness of treatment optimisation with biomarkers for immunotherapy in solid tumours: a systematic review protocol

INTRODUCTION

The combination of biomarkers and drugs is the subject of growing interest both from regulators, physicians and companies. This study protocol of a systematic review is aimed to describe available literature evidences about the cost-effectiveness, cost-utility or net-monetary benefit of the use of biomarkers in solid tumour as tools for customising immunotherapy to identify what further research needs.

METHODS AND ANALYSIS

A systematic review of the literature will be carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines. PubMed and Embase will be queried from June 2010 to June 2021. The PICOS model will be applied: target population (P) will be patients with solid tumours treated with immune checkpoint inhibitors (ICIs); the interventions (I) will be test of the immune checkpoint predictive biomarkers; the comparator (C) will be any other targeted or non-targeted therapy; outcomes (O) evaluated will be health economic and clinical implications assessed in terms of incremental cost-effectiveness ratio, net health benefit, net monetary benefit, life years gained, quality of life, etc; study (S) considered will be economic evaluations reporting cost-effectiveness analysis, cost-utility analysis, net-monetary benefit. The quality of the evidence will be graded according to Grading of Recommendations Assessment, Development and Evaluation.

ETHICS AND DISSEMINATION

This systematic review will assess the cost-effectiveness implications of using biomarkers in the immunotherapy with ICIs, which may help to understand whether this approach is widespread in real clinical practice. This research is exempt from ethics approval because the work is carried out on published documents. We will disseminate this protocol in a related peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42020201549.

Clinical Implementation and Initial Experience of Neutrophil Gelatinase-Associated Lipocalin Testing for the Diagnostic and Prognostic Assessment of Acute Kidney Injury Events in Hospitalized Patients

INTRODUCTION

The use of novel kidney injury biomarkers has been shown to improve diagnostic assessment and prognostic prediction in various populations with acute kidney injury (AKI), but their use in a standard clinical practice have been rarely reported.

METHODS

We reported the clinical implementation of neutrophil gelatinase-associated lipocalin (NGAL) measurement for routine AKI diagnostic workup of patients receiving nephrology consultation in a tertiary academic centre. Specific focus was made on the diagnostic performance to discriminate functional ("pre-renal") from intra-renal AKI and to predict AKI progression.

RESULTS

Forty-five urine NGAL (uNGAL) and 25 plasma NGAL (pNGAL) samples in the first 50 consecutive patients were analysed. KDIGO Stage 1, 2, 3 AKI, and renal replacement therapy occurred in 10%, 40%, 50%, and 24% of cases, respectively. The uNGAL was lower in patients with transient AKI (<48 h) and no sign of urinary tract infections (37 [25-167] ng/mL) than sustained or progressive AKI (298 [74-1,308] ng/mL) (p = 0.016), while pNGAL did not discriminate transient (264 [100-373] ng/mL) from persistent AKI (415 [220-816] ng/mL) (p = 0.137). The median uNGAL level was 63 (35-1,123) ng/mL for functional/pre-renal AKI and 451 (177-1,315) ng/mL for intra-renal AKI (p = 0.043), while the pNGAL was 264 (114-468) and 415 (230-816) ng/mL (p = 0.235), respectively.

CONCLUSION

NGAL, as part of the routine workup, is useful for diagnostic and prognostic assessment of new-onset AKI in clinical practice. Interpretation of an increased NGAL level should be clinically evaluated in its clinical context, particularly considering concomitant infection (urinary or systemic). Clinical adoption of emerging AKI biomarkers as diagnostic tests in clinical practice should be further encouraged.

Biomarker-Based Management of AKI: Fact or Fantasy?

New biomarkers for acute kidney injury (AKI) have improved our understanding of the etiology and pathogenesis of AKI. Depending on their origin, function, and kinetic profile, biomarkers have a role in screening, diagnosis, prognostication, and monitoring of AKI. This offers opportunities to improve the management of AKI, but concerns and limitations remain. In this review, we summarize the current role of new AKI biomarkers in the management of AKI and outline some of the ongoing limitations and challenges.

Acute kidney injury and continuous renal replacement therapy: A nursing perspective for my shift today in the intensive care unit

Handover, clinical discussion, and care for patients in the Intensive Care Unit (ICU) require visual cues to a verbal "story" in an attempt to quickly understand the patient status. Continuous renal replacement therapy (CRRT) is often associated with sepsis or a toxic cause and "kidney attack" not apparent to the patient; "silent" with no pain, discomfort, or vital sign changes initially. Language, terminology, and definitions for this acute kidney injury (AKI) are a graded classification with guidelines. CRRT and dialysis techniques use the physiological principles of diffusion and or convection for solute removal providing a replacement for the basic kidney functions to sustain life until function returns. When to stop CRRT is based on clinical assessment of the patient overall status and urine production re-starting. The medical treatment is focused on the key interventions of resuscitation, remove the cause, support with CRRT or dialysis and monitor for recovery of function. CRRT requires a multidisciplinary team and quality process, local policies, education, and competency pathways to promote best outcomes and efficacy.