Evaluation of new acute kidney injury biomarkers in a mixed intensive care unit

Predictive Performance of Neutrophil Gelatinase Associated Lipocalin, Liver Type Fatty Acid Binding Protein, and Cystatin C for Acute Kidney Injury and Mortality in Severely Ill Patients

Background

Acute kidney injury (AKI) is a common condition in severely ill patients associated with poor outcomes. We assessed the associations between urinary neutrophil gelatinase-associated lipocalin (uNGAL), urinary liver-type fatty acid-binding protein (uLFABP), and urinary cystatin C (uCysC) concentrations and patient outcomes.

Methods

We assessed the predictive performances of uNGAL, uLFABP, and uCysC measured in the early phase of intensive care unit (ICU) management and at discharge from the ICU in severely ill patients for short- and long-term outcomes. The primary outcome was the occurrence of AKI during ICU stay; secondary outcomes were 28-day and 1-yr allcause mortality.

Results

In total, 1,759 patients were admitted to the ICU, and 728 (41.4%) developed AKI. Median (interquartile range, IQR) uNGAL, uLFABP, and uCysC concentrations on admission were 147.6 (39.9-827.7) ng/mL, 32.4 (10.5-96.0) ng/mL, and 0.33 (0.12-2.05) mg/L, respectively. Biomarker concentrations on admission were higher in patients who developed AKI and associated with AKI severity. Three hundred fifty-six (20.3%) and 647 (37.9%) patients had died by 28 days and 1-yr, respectively. Urinary biomarker concentrations at ICU discharge were higher in non-survivors than in survivors. The areas under the ROC curve (95% confidence interval) of uLFABP for the prediction of AKI, 28-day mortality, and 1-yr mortality (0.70 [0.67-0.72], 0.63 [0.59-0.66], and 0.57 [0.51-0.63], respectively) were inferior to those of the other biomarkers.

Conclusions

uNGAL, uLFABP, and uCysC concentrations on admission were associated with poor outcomes. However, their predictive performance, individually and in combination, was limited. Further studies are required to confirm our results.

Urinary liver-type fatty acid-binding protein levels may be associated with the occurrence of acute kidney injury induced by trauma

Introduction

Acute kidney injury (AKI), with a fatality rate of 8.6%, is one of the most common types of multiorgan failure in the intensive care unit (ICU). Thus, AKI should be diagnosed early, and early interventions should be implemented. Urinary liver-type fatty acid-binding protein (L-FABP) could aid in the diagnosis of AKI.

Methods

In this prospective, single-center, observational study, we included 100 patients with trauma. Urinary L-FABP levels were measured using a semi-quantitative rapid assay kit 6 and 12 h after injury. Negative, weakly positive, and strongly positive urinary L-FABP levels were examined using two protocols. Using protocol 1, measurements were performed at 6 h after injury negative levels were considered "negative," and weakly positive and strongly positive levels were considered "positive." Using protocol 2, strongly positive levels at 6 h after injury were considered "positive," and negative or weakly positive levels at 6 h after injury were considered "positive" if they were weakly positive or positive at 12 h after injury.

Results

Fifteen patients were diagnosed with AKI. Using protocol 1, the odds ratio (OR) was 20.55 (p = 0.001) after adjustment for the injury severity score (ISS), contrast media use, and shock index. When the L-FABP levels at 6 and 12 h were similarly adjusted for those three factors, the OR was 18.24 (p < 0.001). The difference in ORs for protocols 1 and 2 was 1.619 (p = 0.04).

Discussion

Associations between urinary L-FABP and AKI can be examined more precisely by performing measurements at 6 and 12 h after injury than only one time at 6 h.

Review of the limitations of current biomarkers in acute kidney injury clinical practices

Acute kidney injury is a prevalent disease in hospitalized patients and is continuously increasing worldwide. Various efforts have been made to define and classify acute kidney injury to understand the progression of this disease. Furthermore, deviations from structure and kidney function and the current diagnostic guidelines are not adequately placed due to baseline serum creatinine values, which are rarely known and estimated based on glomerular function rate, resulting in misclassification of acute kidney injury staging. Hence, the current guidelines are still developing to improve and understand the clinical implications of risk factors and earlier predictive biomarkers of acute kidney injury. Yet, studies have indicated disadvantages and limitations with the current acute kidney injury biomarkers, including lack of sensitivity and specificity. Therefore, the present narrative review brings together the most current evidenced-based practice and literature associated with the limitations of the gold standard for acute kidney injury diagnoses, the need for novel acute kidney injury biomarkers, and the process for biomarkers to be qualified for diagnostic use under the following sections and themes. The introduction section situates the anatomy and normal and abnormal kidney functions related to acute kidney injury disorders. Guidelines in providing acute kidney injury definitions and classification are then considered, followed by a discussion of the disadvantages of standard markers used to diagnose acute kidney injury. Characteristics of an ideal acute kidney injury biomarker are discussed concerning sensitivity, specificity, and anatomic location of injury. A particular focus on the role and function of emerging biomarkers is discussed in relation to their applications and significance to the prognosis and severity of acute kidney injury. Findings show emerging markers are early indicators of acute kidney injury prediction in different clinical settings. Finally, the process required for a biomarker to be applied for diagnostic use is explained.

From Acute to Chronic: Unraveling the Pathophysiological Mechanisms of the Progression from Acute Kidney Injury to Acute Kidney Disease to Chronic Kidney Disease

This article provides a thorough overview of the biomarkers, pathophysiology, and molecular pathways involved in the transition from acute kidney injury (AKI) and acute kidney disease (AKD) to chronic kidney disease (CKD). It categorizes the biomarkers of AKI into stress, damage, and functional markers, highlighting their importance in early detection, prognosis, and clinical applications. This review also highlights the links between renal injury and the pathophysiological mechanisms underlying AKI and AKD, including renal hypoperfusion, sepsis, nephrotoxicity, and immune responses. In addition, various molecules play pivotal roles in inflammation and hypoxia, triggering maladaptive repair, mitochondrial dysfunction, immune system reactions, and the cellular senescence of renal cells. Key signaling pathways, such as Wnt/β-catenin, TGF-β/SMAD, and Hippo/YAP/TAZ, promote fibrosis and impact renal function. The renin-angiotensin-aldosterone system (RAAS) triggers a cascade leading to renal fibrosis, with aldosterone exacerbating the oxidative stress and cellular changes that promote fibrosis. The clinical evidence suggests that RAS inhibitors may protect against CKD progression, especially post-AKI, though more extensive trials are needed to confirm their full impact.

Role of Semaphorin 3A in Kidney Development and Diseases

Kidney diseases are worldwide public health problems affecting millions of people. However, there are still limited therapeutic options against kidney diseases. Semaphorin 3A (SEMA3A) is a secreted and membrane-associated protein, which regulates diverse functions, including immune regulation, cell survival, migration and angiogenesis, thus involving in the several pathogeneses of diseases, including eyes and neurons, as well as kidneys. SEMA3A is expressed in podocytes and tubular cells in the normal adult kidney, and recent evidence has revealed that excess SEMA3A expression and the subsequent signaling pathway aggravate kidney injury in a variety of kidney diseases, including nephrotic syndrome, diabetic nephropathy, acute kidney injury, and chronic kidney disease. In addition, several reports have demonstrated that the inhibition of SEMA3A ameliorated kidney injury via a reduction in cell apoptosis, fibrosis and inflammation; thus, SEMA3A may be a potential therapeutic target for kidney diseases. In this review article, we summarized the current knowledge regarding the role of SEMA3A in kidney pathophysiology and their potential use in kidney diseases.

Urinary neutrophil gelatinase-associated lipocalin and plasma IL-6 in discontinuation of continuous venovenous hemodiafiltration for severe acute kidney injury: a multicenter prospective observational study

BACKGROUND

Patients with severe acute kidney injury (AKI) who require continuous venovenous hemodiafiltration (CVVHDF) in intensive care unit (ICU) are at high mortality risk. Little is known about clinical biomarkers for risk prediction, optimal initiation, and optimal discontinuation of CVVHDF.

METHODS

This prospective observational study was conducted in seven university-affiliated ICUs. For urinary neutrophil gelatinase-associated lipocalin (NGAL) and plasma IL-6 measurements, samples were collected at initiation, 24 h, 48 h after, and CVVHDF discontinuation in adult patients with severe AKI. The outcomes were deaths during CVVHDF and CVVHDF dependence.

RESULTS

A total number of 133 patients were included. Twenty-eight patients died without CVVHDF discontinuation (CVVHDF nonsurvivors). Urinary NGAL and plasma IL-6 at the CVVHDF initiation were significantly higher in CVVHDF nonsurvivors than in survivors. Among 105 CVVHDF survivors, 70 patients were free from renal replacement therapy (RRT) or death in the next 7 days after discontinuation (success group), whereas 35 patients died or needed RRT again (failure group). Urinary NGAL at CVVHDF discontinuation was significantly lower in the success group (93.8 ng/ml vs. 999 ng/ml, p < 0.01), whereas no significant difference was observed in plasma IL-6 between the groups. Temporal elevations of urinary NGAL levels during the first 48 h since CVVHDF initiation were observed in CVVHDF nonsurvivors and those who failed in CVVHDF discontinuation.

CONCLUSIONS

Urinary NGAL at CVVHDF initiation and discontinuation was associated with mortality and RRT dependence, respectively. The serial changes of urinary NGAL might also help predict the prognosis of patients with AKI on CVVHDF.

Application of urinary biomarkers for diagnosing acute kidney injury in critically ill patients without baseline renal function data

PURPOSE

Estimating the baseline renal function of patients without prior creatinine measurement is crucial for diagnosing acute kidney injury (AKI). This study aimed to incorporate AKI biomarkers into a new AKI diagnosis rule when no premorbid baseline is available.

METHODS

This prospective observational study was conducted in an adult intensive care unit (ICU). Urinary neutrophil gelatinase-associated lipocalin (NGAL) and L-type fatty acid-binding protein (L-FABP) were measured at ICU admission. An AKI diagnostic rule was composed by classification and regression tree (CART) analysis.

RESULTS

A total of 243 patients were enrolled. In the development cohort, CART analysis composed a decision tree for AKI diagnosis selecting serum creatinine and urinary NGAL at ICU admission as predictors. In the validation cohort, the novel decision rule was superior to the imputation strategy based on Modification of Diet in Renal Disease (MDRD) equation regarding misclassification rate (13.0% vs. 29.6%, p = 0.002). Decision curve analysis demonstrated that the net benefit of the decision rule exceeded the MDRD approach in a threshold probability range of 25% and higher.

CONCLUSIONS

The novel diagnostic rule incorporating serum creatinine and urinary NGAL at ICU admission showed superiority to the MDRD approach in AKI diagnosis without baseline renal function data.

Acute Kidney Injury Is Associated with Higher Serum Cys-C and NGAL Concentrations, and Risk of Mortality in Premature Calves with Respiratory Distress Syndrome

The purpose of the present study was to establish the development of acute kidney injury (AKI) and evaluate the usefulness of kidney-specific biomarkers in diagnosing AKI in premature calves with respiratory distress syndrome (RDS). Ten-term healthy and 70 premature calves with RDS were enrolled. Clinical examination, blood gases, and chemical analysis were performed at admission and 72 h. Serum concentrations of blood urea nitrogen (BUN), creatinine (Cre), phosphorus (P), cystatin-C (Cys-C), neutrophil gelatinase-associated lipocalin (NGAL), uromodulin (UMOD), and liver-type fatty acid-binding protein (L-FABP) were measured to evaluate kidney injury. Our findings showed that 38.5% of the premature calves with RDS developed AKI. The RDS-AKI group had a 4-fold higher mortality risk than the RDS-non-AKI group. Cys-C, with 90% and 89% specificity, and NGAL, with 100% sensitivity and 85% specificity, were the most reliable biomarkers to determine AKI in premature calves. The usefulness of any biomarker to predict mortality was not found to be convincing. In conclusion, AKI can develop as a consequence of hypoxia in premature calves and may increase the risk of mortality. In addition, serum Cys-C and NGAL concentrations may be useful in the diagnosis of AKI in premature calves with RDS.

The value of urinary interleukin-18 in predicting acute kidney injury: a systematic review and meta-analysis

Aims

The aim of this study was to systematically review relevant studies to evaluate the value of urinary interleukin-18 (uIL-18) in predicting acute kidney injury (AKI).

Methods

A comprehensive search of PubMed, Medline, Embase, and Cochrane Library was conducted for literature published up to 1 August 2022. Quality Assessment Tool for Diagnostic Accuracy Studies-2 (QUADAS-2) was applied to assess the literature quality. Then, relevant data were extracted from each eligible study and a random-effects regression model was utilized to pool sensitivity, specificity, and construct summary receiver operating characteristic (SROC) and area under curve (AUC).

Results

Twenty-six studies with 7183 patients were enrolled and relevant information was extracted. The estimated sensitivity and specificity of uIL-18 in the diagnosis of AKI were 0.64 (95% confidence interval (CI): 0.54–0.73) and 0.77 (95%CI: 0.71–0.83), respectively. The pooled diagnostic odds ratio (DOR) was 6.08 (95%CI: 3.63–10.18), and the AUC of uIL-18 in predicting AKI was 0.78 (95%CI: 0.74–0.81). Subgroup analysis showed that uIL-18 in pediatric patients was more effective in predicting AKI than in adults (DOR: 7.33 versus 5.75; AUC: 0.81 versus 0.77).

Conclusions

Urinary IL-18 could be a relatively good biomarker with moderate predictive value for AKI, especially in pediatric patients. However, further research and clinical settings are still needed to validate our findings.

Comparative accuracy of biomarkers for the prediction of hospital-acquired acute kidney injury: a systematic review and meta-analysis

Background

Several biomarkers have been proposed to predict the occurrence of acute kidney injury (AKI); however, their efficacy varies between different trials. The aim of this study was to compare the predictive performance of different candidate biomarkers for AKI.

Methods

In this systematic review, we searched PubMed, Medline, Embase, and the Cochrane Library for papers published up to August 15, 2022. We selected all studies of adults (> 18 years) that reported the predictive performance of damage biomarkers (neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), liver-type fatty acid-binding protein (L-FABP)), inflammatory biomarker (interleukin-18 (IL-18)), and stress biomarker (tissue inhibitor of metalloproteinases-2 × insulin-like growth factor-binding protein-7 (TIMP-2 × IGFBP-7)) for the occurrence of AKI. We performed pairwise meta-analyses to calculate odds ratios (ORs) and 95% confidence intervals (CIs) individually. Hierarchical summary receiver operating characteristic curves (HSROCs) were used to summarize the pooled test performance, and the Grading of Recommendations, Assessment, Development and Evaluations criteria were used to appraise the quality of evidence.

Results

We identified 242 published relevant studies from 1,803 screened abstracts, of which 110 studies with 38,725 patients were included in this meta-analysis. Urinary NGAL/creatinine (diagnostic odds ratio [DOR] 16.2, 95% CI 10.1–25.9), urinary NGAL (DOR 13.8, 95% CI 10.2–18.8), and serum NGAL (DOR 12.6, 95% CI 9.3–17.3) had the best diagnostic accuracy for the risk of AKI. In subgroup analyses, urinary NGAL, urinary NGAL/creatinine, and serum NGAL had better diagnostic accuracy for AKI than urinary IL-18 in non-critically ill patients. However, all of the biomarkers had similar diagnostic accuracy in critically ill patients. In the setting of medical and non-sepsis patients, urinary NGAL had better predictive performance than urinary IL-18, urinary L-FABP, and urinary TIMP-2 × IGFBP-7: 0.3. In the surgical patients, urinary NGAL/creatinine and urinary KIM-1 had the best diagnostic accuracy. The HSROC values of urinary NGAL/creatinine, urinary NGAL, and serum NGAL were 91.4%, 85.2%, and 84.7%, respectively.

Conclusions

Biomarkers containing NGAL had the best predictive accuracy for the occurrence of AKI, regardless of whether or not the values were adjusted by urinary creatinine, and especially in medically treated patients. However, the predictive performance of urinary NGAL was limited in surgical patients, and urinary NGAL/creatinine seemed to be the most accurate biomarkers in these patients. All of the biomarkers had similar predictive performance in critically ill patients.

Trial registrationCRD42020207883, October 06, 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04223-6.

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.

A case of severe generalized pustular psoriasis successfully treated with IL-17A monoclonal antibody and granulocyte removal therapy

Background

Generalized pustular psoriasis (GPP) usually presents with fever, generalized flushing, and multiple sterile pustules on the skin, which histopathologically form subcorneal pustules characterized by Kogoj spongiform pustules. Granulocyte/monocyte adsorption apheresis (GMA) was approved in Japan in 2012. The use of biologics for psoriasis treatment is increasing. Several case reports have evaluated the combination of GMA and cyclosporine (CyA) for GPP. However, very few English reports on combining biologics and GMA in treating GPP exist.

Case presentation

A 79-year-old man with a history of hypertension, diabetes mellitus, chronic kidney disease, and atrial fibrillation was admitted. He had been consulting a dermatologist for psoriasis vulgaris (PV) since the age of 44. The patient was diagnosed with severe GPP and treated with 300 mg secukinumab (SEC) on day 3. SEC is a fully human monoclonal IgG1 antibody that targets IL-17A. Five doses were administered. In addition, GMA was administered once a week, three times from day 4. After the first administration of GMA, the inflammatory response and skin condition improved markedly. The patient was discharged from the hospital on day 34.

Conclusions

The present study is the first English-written report on the combined administration of SEC and GMA both instituted since admission for severe GPP, with immediate patient response to treatment. Notably, IL-17A plays a vital role in the pathogenesis of GPP. GMA can eliminate activated leukocytes, and the early introduction of combined IL-17 monoclonal antibody and GMA may allow disease suppression in patients with severe GPP, thus avoiding progression to multiorgan failure. Further studies may verify the effects of IL-17 monoclonal antibodies and GMA on severe GPP.

Biomarkers for early detection and predicting outcomes in acute kidney injury

The current diagnosis of acute kidney injury relies on the measurement of serum creatinine levels and urine output. However, both measures are subject to considerable limitations; for example, change in serum creatinine levels ideally requires a knowledge of baseline function that is often not available. Furthermore, creatinine levels are influenced by many factors including diet, drug therapy, muscle mass, gender and ethnicity, which may lead to underestimation of the extent of renal dysfunction. Similarly, urine output lacks both specificity and sensitivity as a marker of acute kidney injury given that oliguria may be an appropriate physiological response to a multitude of stressors and that output may be maintained until significant renal damage has already occurred.

Given the well-documented consequences of acute kidney injury and the considerable burden associated with its development, much attention has focused on early identification of patients at high risk to try and improve outcomes. Many studies have focused on the identification of candidate molecules that may enable the early detection of individuals at risk of developing acute kidney injury, including constitutive proteins associated with kidney damage, as well as molecules upregulated in response to injury, non-renal products that may be filtered, reabsorbed or secreted by the kidney, and markers of renal stress. Such biomarkers may also aid stratification for adverse events, such as the need for kidney replacement therapy or progression to chronic kidney disease and end-stage kidney disease. This article discusses some of these novel biomarkers and assesses the role they may have in the understanding, management, diagnosis and prognostication of acute kidney injury.

Small, short-term, point-of-care creatinine changes as predictors of acute kidney injury in critically ill patients

PURPOSE

To assess short-term creatinine changes as predictors of acute kidney injury (AKI) when used alone and in combination with AKI risk factors.

METHODS

In this prospective cohort study, we identified all creatinine measurements from frequent point-of-care arterial blood gas measurements from ICU admission until AKI. We evaluated the predictive value of small changes between these creatinine measurements for AKI development, alone and with AKI risk factors.

RESULTS

Of 377 patients with 3235 creatinine measurements, generating 15,075 creatinine change episodes, 215 (57%) patients developed AKI, and 68 (18%) developed stage 2 or 3 AKI. In isolation, a creatinine increase over 4.1-7.3 h had a 0.65 area under the curve for predicting stage 2 or 3 AKI within 3-37.7 h. Combining creatinine increases of ≥1 μmol/L/h (≥0.0113 mg/dL/h) over 4-5.8 h with three AKI risk factors (cardiac surgery, use of vasopressors, chronic liver disease) had 83% sensitivity, 79% specificity and 0.87 area under the curve for stage 2 or 3 AKI occurring 8.7-25.6 h later.

CONCLUSION

In combination with key risk factors, frequent point-of-care creatinine assessment on arterial blood gases to detect small, short-term creatinine changes provides a robust, novel, low-cost, and rapid method for predicting AKI in critically ill patients.

Variations of urinary N-acetyl-β-D-glucosaminidase levels and its performance in detecting acute kidney injury under different thyroid hormones levels: a prospectively recruited, observational study

OBJECTIVE

Changes in thyroid function will be accompanied by changes in urinary N-acetyl-β-D-glucosaminidase (uNAG) levels. Therefore, whether thyroid hormones interfere the ability of uNAG in detecting acute kidney injury (AKI) has raised concern in patients with critical illness.

DESIGN

A prospectively recruited, observational study was performed.

SETTING

Adults admitted to the intensive care unit of a grade A tertiary hospital in China.

PARTICIPANTS

A total of 1919 critically ill patients were enrolled in the study.

MAIN OUTCOME MEASURES

To investigate the variations of the ability of uNAG to detect AKI in patients with critical illness under different thyroid hormones levels (differences in area under the curve (AUC) for uNAG diagnosis and prediction of AKI with different thyroid hormones levels).

RESULTS

The bivariate correlation analysis revealed that FT3 and TT3 levels were independently associated with uNAG levels (p<0.001). FT3 and uNAG also showed correlation in multivariable linear regression analysis (p<0.001). After stratification according to the levels of FT3 or TT3, significant variation was observed in the uNAG levels with different quartiles (p<0.05). However, in patients with varying FT3 and TT3 levels, no significant difference was found in the AUCs of uNAG to detect AKI (p>0.05).

CONCLUSIONS

Even if uNAG levels varied with FT3 and TT3 levels, these hormones did not interfere with uNAG's ability to detect AKI in patients with critical illness.

Biomarkers for assessing acute kidney injury for people who are being considered for admission to critical care: a systematic review and cost-effectiveness analysis

BACKGROUND

Acute kidney injury is a serious complication that occurs in the context of an acute critical illness or during a postoperative period. Earlier detection of acute kidney injury may facilitate strategies to preserve renal function, prevent further disease progression and reduce mortality. Acute kidney injury diagnosis relies on a rise in serum creatinine levels and/or fall in urine output; however, creatinine is an imperfect marker of kidney function. There is interest in the performance of novel biomarkers used in conjunction with existing clinical assessment, such as NephroCheck^® (Astute Medical, Inc., San Diego, CA, USA), ARCHITECT^® urine neutrophil gelatinase-associated lipocalin (NGAL) (Abbott Laboratories, Abbott Park, IL, USA), and urine and plasma BioPorto NGAL (BioPorto Diagnostics A/S, Hellerup, Denmark) immunoassays. If reliable, these biomarkers may enable earlier identification of acute kidney injury and enhance management of those with a modifiable disease course.

OBJECTIVE

The objective was to evaluate the role of biomarkers for assessing acute kidney injury in critically ill patients who are considered for admission to critical care.

DATA SOURCES

Major electronic databases, conference abstracts and ongoing studies were searched up to June 2019, with no date restrictions. MEDLINE, EMBASE, Health Technology Assessment Database, Cumulative Index to Nursing and Allied Health Literature, Cochrane Central Register of Controlled Trials, Web of Science, World Health Organization Global Index Medicus, EU Clinical Trials Register, International Clinical Trials Registry Platform and ClinicalTrials.gov were searched.

REVIEW METHODS

A systematic review and meta-analysis were conducted to evaluate the performance of novel biomarkers for the detection of acute kidney injury and prediction of other relevant clinical outcomes. Random-effects models were adopted to combine evidence. A decision tree was developed to evaluate costs and quality-adjusted life-years accrued as a result of changes in short-term outcomes (up to 90 days), and a Markov model was used to extrapolate results over a lifetime time horizon.

RESULTS

A total of 56 studies (17,967 participants), mainly prospective cohort studies, were selected for inclusion. No studies addressing the clinical impact of the use of biomarkers on patient outcomes, compared with standard care, were identified. The main sources of bias across studies were a lack of information on blinding and the optimal threshold for NGAL. For prediction studies, the reporting of statistical details was limited. Although the meta-analyses results showed the potential ability of these biomarkers to detect and predict acute kidney injury, there were limited data to establish any causal link with longer-term health outcomes and there were considerable clinical differences across studies. Cost-effectiveness results were highly uncertain, largely speculative and should be interpreted with caution in the light of the limited evidence base. To illustrate the current uncertainty, 15 scenario analyses were undertaken. Incremental quality-adjusted life-years were very low across all scenarios, ranging from positive to negative increments. Incremental costs were also small, in general, with some scenarios generating cost savings with tests dominant over standard care (cost savings with quality-adjusted life-year gains). However, other scenarios generated results whereby the candidate tests were more costly with fewer quality-adjusted life-years, and were thus dominated by standard care. Therefore, it was not possible to determine a plausible base-case incremental cost-effectiveness ratio for the tests, compared with standard care.

LIMITATIONS

Clinical effectiveness and cost-effectiveness results were hampered by the considerable heterogeneity across identified studies. Economic model predictions should also be interpreted cautiously because of the unknown impact of NGAL-guided treatment, and uncertain causal links between changes in acute kidney injury status and changes in health outcomes.

CONCLUSIONS

Current evidence is insufficient to make a full appraisal of the role and economic value of these biomarkers and to determine whether or not they provide cost-effective improvements in the clinical outcomes of acute kidney injury patients.

FUTURE WORK

Future studies should evaluate the targeted use of biomarkers among specific patient populations and the clinical impact of their routine use on patient outcomes and management.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019147039.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Evidence Synthesis programme and will be published in full in Health Technology Assessment; Vol. 26, No. 7. See the NIHR Journals Library website for further project information.

Accuracy of Liver-Type Fatty Acid-Binding Protein in Predicting Acute Kidney Injury: A Meta-Analysis

BACKGROUND

Liver-type fatty acid-binding protein (L-FABP) is a promising biomarker for the early prediction of acute kidney injury (AKI). However, the clinical utility of L-FABP in different populations or settings remains unclear. We present a meta-analysis of studies evaluating the performance of L-FABP in AKI prediction.

METHODS

We performed a literature search in MEDLINE, EMBASE, and Cochrane library, using search terms "acute kidney injury" and "L-FABP." Studies investigating the performance characteristics of L-FABP for the early diagnosis of AKI were included. Data about patient characteristics, diagnostic criteria of AKI, quantitative data required for construction of a 2 × 2 table (number of participants, sensitivity, specificity, and case number), study settings, and outcomes were extracted. The bivariable model was applied to calculate the estimated sensitivity and specificity of L-FABP. A summary ROC curve was created by plotting the true-positive rate against the false-positive rate at various cutoff values from different studies.

RESULTS

We found 27 studies reporting measurement of urine (n = 25 studies) or plasma (n = 2 studies) L-FABP. Overall, the estimated sensitivity was 0.74 (95% CI: 0.69-0.80) and specificity was 0.78 (95% CI: 0.71-0.83). L-FABP demonstrated a stable area under the ROC of 0.82 (95% CI: 0.79-0.85) in variable clinical settings including intensive care unit, surgery, and contrast-induced AKI. In subgroup analysis excluding pediatric and post radiocontrast exposure cohorts, L-FABP had comparative diagnostic performance with neutrophil gelatinase associated lipocalin (NGAL).

CONCLUSIONS

Despite broad prevalence, L-FABP is a clinically useful marker with moderate accuracy in variable clinical settings as demonstrated in our subgroup analysis. Except for pediatric patients and those post-radiocontrast exposure, L-FABP has comparable discriminative capability as NGAL.

Prediction and visualization of acute kidney injury in intensive care unit using one-dimensional convolutional neural networks based on routinely collected data

BACKGROUND

Acute kidney injury (AKI) occurs frequently in in-hospital patients, especially in the intensive care unit (ICU), due to various etiologies including septic shock. It is clinically important to identify high-risk patients at an early stage and perform the appropriate intervention.

METHODS

We proposed a system to predict AKI using one-dimensional convolutional neural networks (1D-CNN) with the real-time calculation of the probability of developing AKI, along with the visualization of the rationale behind prediction using score-weighted class activation mapping and guided backpropagation. The system was applied to predicting developing AKI based on the KDIGO guideline in time windows of 24 to 48 h using data of 0 to 24 h after admission to ICU.

RESULTS

The comparison result of multiple algorithms modeling time series data indicated that the proposed 1D-CNN model achieved higher performance compared to the other models, with the mean area under the receiver operating characteristic curve of 0.742 ± 0.010 for predicting stage 1, and 0.844 ± 0.029 for stage 2 AKI using the input of the vital signs, the demographic information, and serum creatinine values. The visualization results suggested the reasonable interpretation that time points with higher respiratory rate, lower blood pressure, as well as lower SpO2, had higher attention in terms of predicting AKI, and thus important for prediction.

CONCLUSIONS

We presumed the proposed system's potential usefulness as it could be applied and transferred to almost any ICU setting that stored the time series data corresponding to vital signs.

Urinary liver-type fatty acid-binding protein variation as a predictive value of short-term mortality in intensive care unit patients

BACKGROUND

Predicting the prognosis of intensive care unit (ICU) patients is crucial because it may lead to patient stratification that would in turn help in appropriately distributing limited medical resources. This study, therefore, aimed to investigate the use of the urinary liver-type fatty acid-binding protein (L-FABP) semi-quantitative kit in rapidly predicting the prognosis of patients admitted to the ICU.

METHODS

We conducted a single-center, prospective, observational study wherein 100 consecutive patients admitted to the ICU with an indwelling bladder catheter were enrolled between April and October 2020. Urine specimens were collected at the time of admission (T1) and after 6 h (T2), and urinary L-FABP levels were semi-quantitatively measured. Based on the results, an L-FABP variation was defined as the change in L-FABP (negative, weakly positive, or strongly positive) from T1 to T2. Patients were divided into three groups (L-FABP decreased group, unchanged group, or increased group), following which we compared their 14-day mortality.

RESULTS

Finally, a total of 79 patients were included in the analysis. In multivariate analysis, urinary L-FABP variation [Odds ratio (OR) = 14.327, 95% confidence interval (CI) = 1.819-112.868, p = 0.01] and lactate (OR = 1.234, 95%CI = 1.060-1.437, p = 0.01) were significantly associated with 14-day mortality.

CONCLUSION

Urinary L-FABP variation at 6 h after admission was significantly associated with 14-day mortality.

First Experience Addressing the Prognostic Utility of Novel Urinary Biomarkers in Patients With COVID-19

Urine 11-dehydro-thromboxane B₂ (u11-dh-TxB₂), 8-hydroxy-2’-deoxyguanosine (8-OHdG), and liver-type fatty acid binding protein levels (L-FABP) at the time of hospitalization were higher in coronavirus disease 2019 (COVID-19) patients with adverse events vs without events. Higher u11-dh-TxB₂ and L-FABP levels were associated with longer hospitalization, more thrombotic events, and greater mortality, providing evidence for potential utility as early prognostic biomarkers for COVID-19.

Urinary cytokines correlate with acute kidney injury in critically ill COVID-19 patients

Background

Acute kidney injury is common in COVID-19 patients admitted to the ICU. Urinary biomarkers are a non-invasive way of assaying renal damage, and so far, urinary cytokines are not fully investigated. The current study aimed to assess urinary cytokine levels in COVID-19 patients.

Methods

Urine was collected from COVID-19 patients (n = 29) in intensive care and compared to a preoperative group of patients (n = 9) with no critical illness. 92 urinary cytokines were analyzed in multiplex using the Olink Target 96 inflammation panel and compared to clinical characteristics, and urinary markers of kidney injury.

Results

There were strong correlations between proinflammatory cytokines and between urinary cytokines and urinary kidney injury markers in 29 COVID-19 patients. Several cytokines were correlated to kidney injury, 31 cytokines to AKI stage and 19 cytokines correlated to maximal creatinine.

Conclusions

Urinary inflammatory cytokines from a wide range of immune cell lineages were significantly upregulated during COVID-19 and the upregulation correlated with acute kidney injury as well as urinary markers of kidney tissue damage.

An acute phase protein α1-acid glycoprotein mitigates AKI and its progression to CKD through its anti-inflammatory action

The molecular mechanism for acute kidney injury (AKI) and its progression to chronic kidney disease (CKD) continues to be unclear. In this study, we investigated the pathophysiological role of the acute phase protein α1-acid glycoprotein (AGP) in AKI and its progression to CKD using AGP KO mice. Plasma AGP levels in WT mice were increased by about 3.5-fold on day 1-2 after renal ischemia-reperfusion (IR), and these values then gradually decreased to the level before renal IR on day 7-14. On day 1 after renal IR, the AGP KO showed higher renal dysfunction, tubular injury and renal inflammation as compared with WT. On day 14, renal function, tubular injury and renal inflammation in WT had recovered, but the recovery was delayed, and renal fibrosis continued to progress in AGP KO. These results obtained from AGP KO were rescued by the administration of human-derived AGP (hAGP) simultaneously with renal IR. In vitro experiments using RAW264.7 cells showed hAGP treatment suppressed the LPS-induced macrophage inflammatory response. These data suggest that endogenously induced AGP in early renal IR functions as a renoprotective molecule via its anti-inflammatory action. Thus, AGP represents a potential target molecule for therapeutic development in AKI and its progression CKD.

Direct hemoperfusion using a polymyxin B-immobilized polystyrene column for COVID-19

Objective

To evaluate the efficacy and safety of direct hemoperfusion using a polymyxin B‐immobilized polystyrene column (PMX‐DHP) in severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2)‐positive pneumonia patients.

Methods

This study was a case series conducted at a designated infectious diseases hospital. Twelve SARS‐CoV‐2‐positive patients with partial pressure of arterial oxygen/percentage of inspired oxygen (P/F) ratio < 300 were treated with PMX‐DHP on two consecutive days each during hospitalization. We defined day 1 as the first day when PMX‐DHP was performed. PMX‐DHP efficacy was assessed on days 7 and 14 after the first treatment based on eight categories. Subsequently, improvement in P/F ratio and urinary biomarkers on days 4 and 8, malfunctions, and ventilator and extracorporeal membrane oxygenation avoidance rates were also evaluated.

Results

On day 14 after the first treatment, disease severity decreased in 58.3% of the patients. P/F ratio increased while urine β2‐microglobulin decreased on days 4 and 8. Cytokine measurement pre‐ and post‐PMX‐DHP revealed decreased levels of interleukin‐6 and the factors involved in vascular endothelial injury, including vascular endothelial growth factor. Twenty‐two PMX‐DHPs were performed, of which seven and five PMX‐DHPs led to increased inlet pressure and membrane coagulation, respectively. When the membranes coagulated, the circuitry needed to be reconfigured. Circuit problems were usually observed when D‐dimer and fibrin degradation product levels were high before PMX‐DHP.

Conclusions

Future studies are expected to determine the therapeutic effect of PMX‐DHP on COVID‐19. Because of the relatively high risk of circuit coagulation, coagulation capacity should be assessed beforehand.

The effect of recombinant human soluble thrombomodulin on renal function and mortality in septic disseminated intravascular coagulation patients with acute kidney injury: a retrospective study

Background

Clinical evidence showing the effectiveness of recombinant human soluble thrombomodulin (rhTM) for treating sepsis-induced disseminated intravascular coagulation (DIC) and organ dysfunction (particularly renal injury) is limited because of differences in the inclusion criteria and disease severity among patients. This study aimed to assess the association between rhTM and outcomes in septic DIC patients with acute kidney injury (AKI).

Methods

This retrospective observational study analyzed the data of patients who were admitted to the intensive care unit (ICU) of a single center between January 2012 and December 2018, and diagnosed with sepsis-induced DIC and AKI. Data were extracted as follows: patients’ characteristics; DIC score, as calculated by the Japanese Association for Acute Medicine and the International Society of Thrombosis and Hemostasis criteria; serum creatinine levels; and ICU and 28-day mortality rates. The primary outcome was the dependence on renal replacement therapy (RRT) at ICU discharge. The propensity score (PS) was calculated using the following variables: age, sex, septic shock at admission, DIC score, and KDIGO classification. Subsequently, logistic regression analysis was performed using the PS to evaluate the outcome.

Results

In total, 97 patients were included in this study. Of these, 52 (53.6%) patients had received rhTM. The dependence on RRT at ICU discharge was significantly lower in the rhTM than in the non-rhTM group (odds ratio [OR], 0.43; 95% confidence interval [CI], 0.19–0.97; P = 0.043). The serum creatinine levels at ICU discharge (OR, 0.31; 95% CI, 0.13–0.72; P = 0.007) and hospital discharge (OR, 0.25; 95% CI, 0.11–0.60; P = 0.002, respectively), and the 28-day mortality rate (OR, 0.40; 95% CI, 0.17–0.93; P = 0.033) were significantly lower in the rhTM than in the non-rhTM group. Moreover, the Kaplan–Meier survival curve revealed significantly lower mortality rates in the rhTM than in the non-rhTM group (P = 0.009). No significant differences in the DIC score and AKI severity were observed between the groups.

Conclusions

Among sepsis-induced DIC patients with AKI, rhTM administration was associated with lower dependence on RRT at ICU discharge, improvement in renal function, and lower 28-day mortality rate.

Calprotectin and Neutrophil Gelatinase-Associated Lipocalin As Biomarkers of Acute Kidney Injury in Acute Coronary Syndrome

BACKGROUND

Acute kidney injury (AKI) is increasingly being seen in patients with acute coronary syndromes (ACS) and it is associated with higher short-term and long-term morbidity and mortality. Therefore, it is of paramount importance to identify those ACS patients at risk for the development of AKI. The objective of this study was to evaluate two different plasma biomarkers calprotectin and neutrophil gelatinase-associated lipocalin (NGAL) in early detecting the development of AKI in ACS patients.

METHODS

172 ACS patients admitted to the Coronary Care Unit in Yantai Yuhuangding Hospital were prospectively enrolled. Their blood samples were obtained on admission and subjected to enzyme-linked immunosorbent assay to determine the levels of novel biomarkers. The clinical data and biomarkers were recorded and analyzed.

RESULTS

In this study, 23 (13.4%) patients had a diagnosis of AKI. Statistical analysis demonstrated that in ACS patients with AKI, the following two biomarkers were significantly higher than these without AKI: plasma calprotectin (5942.26 ± 1955.88 ng/mL vs. 3210.29 ± 1833.60 ng/mL, p < 0.001) and plasma NGAL (164.91 ± 43.63 ng/mL vs. 122.48 ± 27.33 ng/mL, p < 0.001). Plasma calprotectin and NGAL could discriminate the development of AKI respectively with an area under the ROC curve (AUC) of 0.864 and 0.850. A combination of the two plasma biomarkers calprotectin and NGAL could early discriminate AKI in ACS patients with an AUC of 0.898.

CONCLUSIONS

This study demonstrated a promising panel of plasma calprotectin and NGAL as early diagnostic biomarkers for AKI in ACS patients.

The need for disruptive innovation in acute kidney injury

Acute kidney injury (AKI) is a threatening medical condition associated with poor outcomes at different settings. The development of standardized diagnostic criteria and new biomarkers addressed significant clinical impacts of AKI and the need for an early AKI detection, respectively. There have been some breakthroughs in understanding the pathogenesis of AKI through basic research; however, treatments against AKI aside from renal replacement therapy (RRT) have not shown adequate successful results. Biomarkers that could identify good responders to certain treatment are expected to facilitate translation of basic research findings. Most patients with severe AKI treated with RRT died due to multiple-organ failure, not renal dysfunction. Hence, it is essential to identify other organ dysfunctions induced by AKI as organ crosstalk. Also, a multidisciplinary approach of critical care nephrology is needed to evaluate a complex organ crosstalk in AKI. For disruptive innovation for AKI, we further explore these new aspects of AKI, which previously were considered outside the scope of nephrology.

Urinary biomarkers of kidney tubule injury, risk of acute kidney injury, and mortality in patients with acute ischaemic stroke treated at a stroke care unit

BACKGROUND AND PURPOSE

Urinary liver-type fatty-acid binding protein (L-FABP), which is a biomarker of kidney tubule injury, has been studied extensively and established as a risk marker of acute kidney injury (AKI). The aim of this study was to investigate whether kidney tubule injury is associated with the development of AKI and mortality in patients with acute ischaemic stroke.

METHODS

Acute ischaemic stroke patients hospitalized in the stroke care unit (SCU) within 24 h after symptom onset were prospectively investigated. AKI was defined on the basis of Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Baseline urinary L-FABP was measured on admission. We evaluated the associations among urinary L-FABP, incidence of AKI, and 90-day mortality adjusted for renal function, albuminuria and other potentially predictive variables, using multivariable analysis.

RESULTS

In total, 527 acute ischaemic stroke patients (342 men, median age 74 years) were enrolled in the study. Twenty-seven patients (5.1%) experienced AKI within 7 days of admission. In the univariate analysis, high urinary L-FABP level had positive associations with AKI [53.8 μg/g creatinine (Cr) vs. 3.9 μg/g Cr; P < 0.001] and 90-day mortality (15.5 μg/g Cr vs. 4.0 μg/g Cr; P < 0.001). In the multivariate analysis, elevated urinary L-FABP level (per 10-μg/g Cr increase) was independently associated with AKI (odds ratio 1.225, 95% confidence interval (CI) 1.083-1.454; P = 0.003) and 90-day mortality (hazard ratio 1.091, 95% CI 1.045-1.138; P < 0.001).

CONCLUSION

Urinary biomarkers of kidney tubule injury are independently associated with the development of AKI and 90-day mortality in patients with acute ischaemic stroke treated at the SCU.

Evaluation of Coronavirus Disease 2019 Severity Using Urine Biomarkers

Subjects

Early detection of coronavirus disease 2019 in patients likely to develop severe manifestations enables appropriate interventions, including rapid ICU admission. This study was conducted to determine whether noninvasive urine biomarkers can predict the clinical severity of coronavirus disease 2019.

Interventions

Not applicable.

Measurements and Main Results

This is single-center study, national center hospital designated for infectious disease. Fifty-eight patients who tested positive for severe acute respiratory syndrome coronavirus 2 in respiratory specimens through real-time reverse transcription-polymerase chain reaction were retrospectively studied. Urinary β2-microglobulin, liver-type fatty acid-binding protein were serially measured. Serum interferon-γ and monocyte chemotactic protein-1 were also evaluated. The 58 patients were assigned into three groups. Patients requiring intensive care were assigned to the severe group (n = 12). Patients treated with oxygen were assigned to the moderate group (n = 13). Other patients were assigned to the mild group (n = 33). Urine tests revealed that low β2-microglobulin and liver-type fatty acid-binding protein levels were associated with mild disease, whereas high levels were associated with severe disease. In severe cases, liver-type fatty acid-binding protein tended to be persistently high. The resulting cutoff values were β2-microglobulin; severe versus moderate + mild: 2,457 μg/dL (specificity 76.9% and sensitivity 90.0%, area under the receiver operating characteristic curve 85.9%), liver-type fatty acid-binding protein; severe versus moderate + mild: 22.0 μg/gCre (specificity 84.6% and sensitivity 90%, area under the receiver operating characteristic curve 91.8%). Urinary β2-microglobulin and serum interferon-γ/monocyte chemotactic protein-1 showed a similar trend.

Conclusions

Evaluating urinary biomarkers such as β2-microglobulin and liver-type fatty acid-binding protein may allow determination of coronavirus disease 2019 patients with active cytokines and recognition of patients likely to become critically ill and requiring careful observation and early intervention.

Diagnostics, Risk Factors, Treatment and Outcomes of Acute Kidney Injury in a New Paradigm

Acute kidney injury (AKI) is a common clinical condition among patients admitted in the hospitals. The condition is associated with both increased short-term and long-term mortality. With the development of a standardized definition for AKI and the acknowledgment of the impact of AKI on patient outcomes, there has been increased recognition of AKI. Two advances from past decades, the usage of computer decision support and the discovery of AKI biomarkers, have the ability to advance the diagnostic method to and further management of AKI. The increasingly widespread use of electronic health records across hospitals has substantially increased the amount of data available to investigators and has shown promise in advancing AKI research. In addition, progress in the finding and validation of different forms of biomarkers of AKI within diversified clinical environments and has provided information and insight on testing, etiology and further prognosis of AKI, leading to future of precision and personalized approach to AKI management. In this this article, we discussed the changing paradigms in AKI: from mechanisms to diagnostics, risk factors, and management of AKI.

Design of a Multiplexed Analyte Biosensor using Digital Barcoded Particles and Impedance Spectroscopy

Multiplexing allows quantifying multiple analytes in a single step, providing advantages over individual testing through shorter processing time, lower sample volume, and reduced cost per test. Currently, flow cytometry is the gold standard for biomedical multiplexing, but requires technical training, extensive data processing, and expensive operational and capital costs. To solve this challenge, we designed digital barcoded particles and a microfluidic architecture for multiplexed analyte quantification. In this work, we simulate and model non-fluorescence-based microfluidic impedance detection with a single excitation and detection scheme using barcoded polymer microparticles. Our barcoded particles can be designed with specific coding regions and generate numerous distinct patterns enabling digital barcoding. We found that signals based on adhered microsphere position and relative orientation were evaluated and separated based on their associated electrical signatures and had a 7 µm microsphere limit of detection. Our proposed microfluidic system can enumerate micron-sized spheres in a single assay using barcoded particles of various configurations. As representation of blood cells, the microsphere concentrations may provide useful information on disease onset and progression. Such sensors may be used for diagnostic and management of common critical care diseases like sepsis, acute kidney injury, urinary tract infections, and HIV/AIDS.

Urinary Liver-Type Fatty-Acid-Binding Protein Predicts Long-Term Adverse Outcomes in Medical Cardiac Intensive Care Units

We prospectively investigated the prognostic value of urinary liver-type fatty-acid-binding protein (L-FABP) levels on hospital admission, both independently and in combination with serum creatinine-defined acute kidney injury (AKI), to predict long-term adverse outcomes in 1119 heterogeneous patients (mean age; 68 years) treated at medical (non-surgical) cardiac intensive care units (CICUs). Patients with stage 5 chronic kidney disease were excluded from the study. Of these patients, 47% had acute coronary syndrome and 38% had acute decompensated heart failure. The creatinine-defined AKI was diagnosed according to the "Kidney Disease: Improving Global Outcomes" criteria. The primary endpoint was a composite of all-cause death or progression to end-stage kidney disease, indicating the initiation of maintenance dialysis therapy or kidney transplantation. Creatinine-defined AKI occurred in 207 patients, with 44 patients having stage 2 or 3 disease. During a mean follow-up period of 41 months after enrollment, the primary endpoint occurred in 242 patients. Multivariate Cox regression analyses revealed L-FABP levels as independent predictors of the primary endpoint (p < 0.001). Adding L-FABP to a baseline model with established risk factors further enhanced reclassification and discrimination beyond that of the baseline model alone, for primary-endpoint prediction (both; p < 0.01). On Kaplan-Meier analyses, increased L-FABP (≥4th quintile value of 9.0 ng/mL) on admission or presence of creatinine-defined AKI, correlated with an increased risk of the primary endpoint (p < 0.001). Thus, urinary L-FABP levels on admission are potent and independent predictors of long-term adverse outcomes, and they might improve the long-term risk stratification of patients admitted at medical CICUs, when used in combination with creatinine-defined AKI.

Clinical Survey of Decreased Blood Flow Rate in Continuous Renal Replacement Therapy: A Retrospective Observational Study

Background

Continuous renal replacement therapy (CRRT) is an essential procedure for patients with acute kidney injury in intensive care. It is important to maintain an adequate blood flow rate during CRRT. Several previous studies have reported the relationships between blood flow rate and filter lifespan, or circuit life, in CRRT. Here, we aim at elucidating the incidence and factors associated with a decreased blood flow rate in CRRT.

Methods

This is a retrospective observational study. From January 2014 to June 2017, 119 patients who underwent CRRT in the intensive care unit were enrolled. The definition of a decreased blood flow rate included situations in which the medical staff needed to decrease the blood flow volume. We statistically analyzed the association of the decreased blood flow rate with patients' clinical characteristics.

Results

Of 119 patients, 52 required a decreased blood flow rate during CRRT. Almost half of the cases occurred within one day of starting CRRT. None of the clinical factors (age, sex, height, sequential organ failure assessment (SOFA) score, catheter position, systemic infection, albumin, hemoglobin, and activating coagulation time) were significantly associated with decreased blood flow rate.

Conclusions

A decreased blood flow rate often occurs during CRRT. Clinical factors significantly associated with the occurrence of the decreased blood flow rate were not detected in the current study. Further investigation regarding the occurrence of a decreased blood flow is warranted.

Preactivated and disaggregated shape-changed platelets protect kidney against from ischemia-reperfusion injury in rat through attenuating inflammation reaction

This study tested the hypothesis that preactivated and disaggregated shape-changed platelet (PreD-SCP) therapy significantly protected rat kidney from ischemia-reperfusion (IR) injury. Adult-male Sprague-Dawley rats (n = 24) were equally categorized into Groups 1 (sham-operated control [SC]), 2 (SC + PreD-SCP), 3 (IR only), and 4 (IR + PreD-SCP). By 72 hr after IR procedure, the circulatory levels of creatinine, blood urine nitrogen and inflammatory biomarkers (interleukin [IL]-6/tumor necrosis factor [TNF]-α), and ratio of urine protein to urine creatinine were significantly higher in Group 3 than in other groups and significantly higher in Group 4 than in Groups 1 and 2, but they showed no different between Groups 1 and 2 (all p < .001). The microscopic findings showed that the expressions of kidney injury score, cellular inflammation (MMP-9/CD14//F4/80), and fibrotic area were identical to the circulatory inflammation, whereas the integrity of podocyte components (ZO-1/synaptopodin/podocin) exhibited an opposite to circulatory inflammation among the four groups (all p < .0001). The protein expressions of inflammatory (TNF-α/IL-1ß/NF-κB/iNOS/TRAF6/MyD88/TLR-4), apoptotic/cell death (mitochondrial Bax/cleaved caspase-3/p-53), oxidized protein, mitogen-activated protein kinase family (p-38/p-JNK/p-c-JUN), and mitochondrial-damaged biomarkers displayed a similar pattern, whereas the antiapoptotic (Bcl-2/Bcl-XL) and integrity of mitochondrial biomarkers followed an opposite trend to circulatory inflammation among the four groups (all p < .001). PreD-SCP therapy effectively protected the kidney against IR injury.

The Potential for Renal Injury Elicited by Physical Work in the Heat

An epidemic of chronic kidney disease (CKD) is occurring in laborers who undertake physical work in hot conditions. Rodent data indicate that heat exposure causes kidney injury, and when this injury is regularly repeated it can elicit CKD. Studies in humans demonstrate that a single bout of exercise in the heat increases biomarkers of acute kidney injury (AKI). Elevations in AKI biomarkers in this context likely reflect an increased susceptibility of the kidneys to AKI. Data largely derived from animal models indicate that the mechanism(s) by which exercise in the heat may increase the risk of AKI is multifactorial. For instance, heat-related reductions in renal blood flow may provoke heterogenous intrarenal blood flow. This can promote localized ischemia, hypoxemia and ATP depletion in renal tubular cells, which could be exacerbated by increased sodium reabsorption. Heightened fructokinase pathway activity likely exacerbates ATP depletion occurring secondary to intrarenal fructose production and hyperuricemia. Collectively, these responses can promote inflammation and oxidative stress, thereby increasing the risk of AKI. Equivalent mechanistic evidence in humans is lacking. Such an understanding could inform the development of countermeasures to safeguard the renal health of laborers who regularly engage in physical work in hot environments.

Clinical significance of urinary L-FABP in the emergency department

BACKGROUND

This study's aim is to measure liver-type fatty acid-binding protein (L-FABP) levels in urine using a rapid semiquantitative assay kit in the emergency department and to investigate whether the onset of acute kidney injury (AKI) after hospitalization can be predicted.

METHODS

This was a prospective observation study. Patients transferred to the emergency and critical care center were divided into two groups: urinary L-FABP negative and positive groups. The status and severity of AKI were evaluated for the respective patients based on the Kidney Disease: Improving Global Outcome (KDIGO) classification. We compared the proportion of AKI patients in the two groups.

RESULTS

In the urine L-FABP-positive group, many patients had a significant onset of AKI (p < 0.001). After excluding patients who were diagnosed as AKI for creatinine level at admission, urinary L-FABP could predict the onset of AKI after admission (p < 0.001).

CONCLUSION

By measuring urinary L-FABP concentration using a rapid semiquantitative assay kit, there is the possibility that the onset of AKI after admission can be predicted from immediately after a patient is transported by ambulance.

Potential Prognostic Markers of Acute Kidney Injury in the Early Phase of Acute Pancreatitis

Acute kidney injury (AKI) is a serious complication of acute pancreatitis (AP), which occurs in up to 70% of patients with severe AP and significantly increases the risk of mortality. At present, AKI is diagnosed based on dynamic increase in serum creatinine and decreased urine output; however, there is a need for earlier and more accurate biomarkers. The aim of the study was to review current evidence on the laboratory tests that were studied as the potential biomarkers of AKI in AP. We also briefly summarized the knowledge coming from the studies including sepsis or ICU patients since severe acute pancreatitis is associated with systemic inflammation and organ failure. Serum cystatin C and serum or urine NGAL have been shown to predict or diagnose AKI in AP; however, this evidence come from the single center studies of low number of patients. Other markers, such as urinary kidney injury molecule-1, cell cycle arrest biomarkers (tissue inhibitor metalloproteinase-2 and urine insulin-like growth factor-binding protein 7), interleukin-18, liver-type fatty acid-binding protein, or calprotectin have been studied in other populations suffering from systemic inflammatory states. In AP, the potential markers of AKI may be significantly influenced by either dehydration or inflammation, and the impact of these factors may be difficult to distinguish from kidney injury. The subject of AKI complicating AP is understudied. More studies are needed, for both exploratory (to choose the best markers) and clinical (to evaluate the diagnostic accuracy of the chosen markers in real clinical settings).

[Acute kidney injury: from creatinine to KIM‑1?]

In addition to the early detection of an acute kidney injury (AKI), several problems or questions have to be addressed. These include the identification of the etiology, the severity (functional or structural), the prognosis (recovery or transition to chronic renal failure), the course of the disease (dialysis or not), and the identification of specific treatment options for AKI. The following article provides an overview of established and new AKI biomarkers as well as an outlook on the potential of future biomarker-associated models of AKI.

Impact of blood glucose levels on the accuracy of urinary N-acety-β-D-glucosaminidase for acute kidney injury detection in critically ill adults: a multicenter, prospective, observational study

BACKGROUND

The performance of urinary N-acetyl-β-D-glucosaminidase (uNAG) for the detection of acute kidney injury (AKI) was controversial. uNAG is positively correlated with blood glucose levels. Hyperglycemia is common in the critically ill adults. The influence of blood glucose levels on the accuracy of uNAG in AKI detection has not yet been reported. The present study evaluated the effect of blood glucose levels on the diagnostic accuracy of uNAG to detect AKI.

METHODS

A total of 1585 critically ill adults in intensive care units at three university hospitals were recruited in this prospective observational study. uNAG, serum glucose, and glycosylated hemoglobin (HbA1c) were measured at ICU admission. Patients were categorized based on the history of diabetes and blood glucose levels. The performance of uNAG to detect AKI in different groups was assessed by the area under the receiver operator characteristic curve.

RESULTS

Four hundred and twelve patients developed AKI, of which 109 patients were severe AKI. uNAG was significantly correlated with the levels of serum glucose (P < 0.001) and HbA1c (P < 0.001). After stratification based on the serum glucose levels, no significant difference was observed in the AUC of uNAG in detecting AKI between any two groups (P > 0.05). Stratification for stress hyperglycemic demonstrated similar results.However, among non-diabetic patients, the optimal cut-off value of uNAG for detecting AKI was higher in stress hyperglycemic patients as compared to those without stress hyperglycemia.

CONCLUSIONS

The blood glucose levels did not significantly affect the performance of uNAG for AKI detection in critically ill adults. However, the optimal cut-off value of uNAG to detect AKIwas affected by stress hyperglycemia in non-diabetic patients.

Urinary and Serum Biomarkers for Prediction of Acute Kidney Injury in Patients Undergoing Liver Transplantation

Acute kidney injury (AKI) is a frequent and serious complication of orthotopic liver transplantation (OLT), with a significant impact on mortality, graft survival, and chronic kidney disease. Currently, the diagnosis of AKI is based on changes in serum creatinine, which is a late marker, usually rising when there is already significant damage to the renal parenchyma. During the last 2 decades, various biomarkers have been studied in many clinical situations, mostly after cardiac surgery, in drug-induced AKI, or in sepsis. The present article summarizes the data on those biomarkers that have been evaluated for the prediction of AKI in patients undergoing OLT.

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

BACKGROUND

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

OBJECTIVES

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

DATA SOURCES

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

REVIEW METHODS

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

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

STUDY REGISTRATION

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

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Association between serum levels of interleukin-6 on ICU admission and subsequent outcomes in critically ill patients with acute kidney injury

Background

Exacerbated inflammatory response is considered one of the key elements of acute kidney injury (AKI). Interleukin-6 (IL-6) is an inflammatory cytokine that plays important roles in the inflammatory response and may be useful for predicting the clinical outcomes in patients with AKI. However, supporting evidence adapted to the current KDIGO criteria is lacking.

Methods

AKI patients admitted to the ICU between Jan 2011 and Dec 2015 were retrospectively screened. Patients were assigned to three groups by admission IL-6 tertiles. Associations between IL-6 on ICU admission and in-hospital 90-day mortality, short-term/long-term renal function were analyzed.

Results

Patients (n = 646) were divided into low (1.5–150.2 pg/mL), middle (152.0–1168 pg/mL), and high (1189-2,346,310 pg/mL) IL-6 on ICU admission groups. Patients in the high IL-6 group had higher in-hospital 90-day mortality (low vs. middle vs. high, P = 0.0050), lower urine output (low vs. middle vs. high, P < 0.0001), and an increased probability of persistent of anuria for ≥12 h (low vs. middle vs. high, P < 0.0001) within 72 h after ICU admission. In contrast, the high IL-6 group had a lower incidence of persistent AKI at 90 days after the ICU admission in survivors (low vs. middle vs. high, P = 0.013).

Conclusions

Serum levels of IL-6 on ICU admission may predict short-term renal function and mortality in AKI patients and were associated with renal recovery in survivors.

The Japanese clinical practice guideline for acute kidney injury 2016

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

The Japanese Clinical Practice Guideline for acute kidney injury 2016

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

Biomarkers in acute kidney injury (AKI)

Acute kidney injury is common in critically ill patients and portends a significant impact on mortality, progressive chronic kidney disease, and cardiovascular disease and mortality. Though most physicians alter therapy depending on changes in serum creatinine, this often represents delayed intervention. Various AKI biomarkers have been discovered and validated to improve timely detection, differentiation and stratification into risk groups for progressive renal decline, need for renal replacement therapy or death. This chapter will review AKI biomarkers validated over the past decade. We also describe the clinical performance of the biomarkers. We suggest that using AKI biomarkers to complement serum creatinine (or cystatin C) and urine output will better integrate patient care through earlier recognition and clinical outcome prediction after AKI.