Predictive performance of urine neutrophil gelatinase-associated lipocalin for dialysis requirement and death following cardiac surgery in neonates and infants

Biomarker-based acute kidney injury sub-phenotypes refine risk assessment in children undergoing cardiac surgery

BACKGROUND

Pediatric cardiac surgery-associated acute kidney injury (CS-AKI) is common with variable association with outcomes, possibly because transient serum creatinine (SCr) elevations are unrelated to kidney disease. Sub-phenotypes of CS-AKI with biomarker integration may provide prognostic enrichment. This study aims to determine if combining early postoperative urine neutrophil gelatinase-associated lipocalin (uNGAL) and SCr into sub-phenotypes strengthens associations with AKI and outcomes. We hypothesized that patients with early subclinical (uNGAL + , SCr -) or damage (uNGAL + , SCr +) CS-AKI would have more postoperative day 2-4 KDIGO-defined AKI and worse clinical outcomes than patients with early functional AKI (uNGAL - , SCr +).

METHODS

Two-center prospective observational study evaluating combinations of early uNGAL (8-12 h from ICU admission, ≥ 150 ng/mL) and early postoperative (≤ 8 h of admission) KDIGO SCr-defined AKI to predict CS-AKI on postoperative days (POD) 2-4. Four CS-AKI phenotypes were derived (uNGAL - /SCr - ; uNGAL + /SCr - ; uNGAL - /SCr + and uNGAL + /SCr +). The primary outcome was POD2-4 KDIGO SCr-defined CS-AKI. Secondary outcomes included ventilator and intensive care unit-free days (maximum 28).

RESULTS

Four hundred seventy-six patients (median age 4.8 [IQR 1.4-30.4] months, 39% female) were included. POD2-4 AKI occurred in 44 (9.2%). 27% were uNGAL + /SCr - and 0.4% (n = 2) uNGAL + /SCr + . The adjusted odds of POD2-4 AKI was ninefold higher (aOR: 9.09, 95%CI: 3.84-21.53) in uNGAL + /SCr - when compared to uNGAL - /SCr - . uNGAL + /SCr - was associated with fewer ventilator-free (aOR: 0.30, 95%CI: 0.19-0.48) and ICU-free days (aOR: 0.41, 95%CI: 0.26-0.66) when compared to uNGAL - /SCr - .

CONCLUSION

Early postoperative uNGAL, regardless of SCr elevation, refines risk assessment for pediatric POD2-4 CS-AKI and associated morbidity, enabling earlier AKI identification and prognostics.

Urgent Implantation of Peritoneal Dialysis Catheter in Chronic Kidney Disease and Acute Kidney Injury-A Review

Acute kidney injury (AKI) and sudden exacerbation of chronic kidney disease (CKD) frequently necessitate urgent kidney replacement therapy (UKRT). Peritoneal dialysis (PD) is recognized as a viable modality for managing such patients. Urgent-start peritoneal dialysis (USPD) may be associated with an increased number of complications and is rarely utilized. This review examines recent literature investigating the clinical outcomes of USPD in CKD and AKI. Relevant research was identified through searches of the MEDLINE (PubMed), Scopus, Web of Science, and Google Scholar databases using MeSH terms and relevant keywords. Included studies focused on the emergency use of peritoneal dialysis in CKD or AKI and reported treatment outcomes. While no official recommendations exist for catheter implantation in USPD, the impact of the technique itself on outcomes was found to be less significant compared with the post-implantation factors. USPD represents a safe and effective treatment modality for AKI, although complications such as catheter malfunctions, leakage, and peritonitis were observed. Furthermore, USPD demonstrated efficacy in managing CKD, although it was associated with a higher incidence of complications compared to conventional-start peritoneal dialysis. Despite its cost-effectiveness, PD requires greater technical expertise from medical professionals. Close supervision and pre-planning for catheter insertion are essential for CKD patients. Whenever feasible, an urgent start should be avoided. Nevertheless, in emergency scenarios, USPD does remain a safe and efficient approach.

Cardiac Arrest in Children Following Cardiac Surgery: A Scoping Review of Contributing Factors

Nearly half of children experiencing cardiac arrest following cardiac surgery do not survive hospital discharge and patients who survive often experience significant neurological impairment. Additionally, increased resource utilization following cardiac arrest translates into adverse logistical and financial consequences. Although some studies have identified patient characteristics that increase the risk of cardiac arrest after pediatric cardiac surgery, modifiable risk factors, which could provide a foundation for effective prevention strategies, have been elusive. This scoping review explores the current knowledge surrounding risk factors associated with cardiac arrest in children following cardiac surgery and provides recommendations for future research.

Biomarkers of acute kidney injury after pediatric cardiac surgery: a meta-analysis of diagnostic test accuracy

Acute kidney injury (AKI) occurs frequently after cardiac surgery in children. Although current diagnostic criteria rely on serum creatinine and urine output, changes occur only after considerable loss of kidney function. This meta-analysis aimed to synthesize the knowledge on novel biomarkers and compare their ability to predict AKI. PubMed/MEDLINE, Embase, Scopus, and reference lists were searched for relevant studies published by March 2021. Diagnostic accuracy parameters were extracted and analyzed using hierarchical summary receiver operating characteristic (HSROC) method. Pooled estimates of the area under the curve (AUC) were calculated using conventional random-effects meta-analysis. Fifty-six articles investigating 49 biomarkers in 8617 participants fulfilled our eligibility criteria. Data from 37 studies were available for meta-analysis. Of the 10 biomarkers suitable for HSROC analysis, urinary neutrophil gelatinase-associated lipocalin (uNGAL) to creatinine (Cr) ratio yielded the highest diagnostic odds ratio (91.0, 95% CI 90.1-91.9), with a sensitivity of 91.3% (95% CI 91.2-91.3%) and a specificity of 89.7% (95% CI 89.6-89.7%). These results were confirmed in pooled AUC analysis, as uNGAL-to-Cr ratio and uNGAL were the only elaborately studied biomarkers (> 5 observations) with pooled AUCs ≥ 0.800. Liver fatty acid-binding protein (L-FABP), serum cystatin C (sCysC), serum NGAL (sNGAL), and interleukin-18 (IL-18) all had AUCs ≥ 0.700.

CONCLUSION

A variety of biomarkers have been proposed as predictors of cardiac surgery-associated AKI in children, of which uNGAL was the most prominent with excellent diagnostic qualities. However, more consolidatory evidence will be required before these novel biomarkers may eventually help realize precision medicine in AKI management.

WHAT IS KNOWN

• Acute kidney injury (AKI) occurs in about 30-60% of children undergoing cardiac surgery and is associated with increased in-hospital mortality and adverse short-term outcomes. However, in current clinical practice, AKI definitions and detection often rely on changes in serum creatinine and urine output, which are late and insensitive markers of kidney injury. • Although various novel biomarkers have been studied for the diagnosis of AKI in children after cardiac surgery, it remains unclear how these compare to one another in terms of diagnostic accuracy.

WHAT IS NEW

• Pooled analyses suggest that for the diagnosis of AKI in children who underwent cardiac surgery, NGAL is the most accurate among the most frequently studied biomarkers. • A number of other promising biomarkers have been reported, although they will require further research into their diagnostic accuracy and clinical applicability.

Biomarkers of acute kidney injury in pediatric cardiac surgery

Acute kidney injury (AKI) is characterized by a sudden decrease in kidney function. Children with congenital heart disease are a special group at risk of developing AKI. We performed a systematic review of the literature to search for studies reporting the usefulness of novel urine, serum, and plasma biomarkers in the diagnosis and progression of AKI and their association with clinical outcomes in children undergoing pediatric cardiac surgery. In thirty studies, we analyzed the capacity to predict AKI and poor outcomes of five biomarkers: Cystatin C, Neutrophil gelatinase-associated lipocalin, Interleukin-18, Kidney injury molecule-1, and Liver fatty acid-binding protein. In conclusion, we suggest the need for further meta-analyses with the availability of additional studies.

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.

Association between Elevated Urine Neutrophil Gelatinase-Associated Lipocalin and Postoperative Acute Kidney Injury in Neonates

OBJECTIVE

To examine the incidence of postoperative neonatal acute kidney injury (AKI) following general surgical procedures and to test the hypothesis that postoperative urine neutrophil gelatinase-associated lipocalin (uNGAL) concentrations predict AKI. The secondary objective was to evaluate for an association between AKI and hospital mortality.

STUDY DESIGN

Prospective observational study of infants undergoing abdominal and thoracic surgical procedures in the neonatal intensive care unit from October 2018 to March 2020. The primary outcome was incidence of neonatal AKI (defined by the neonatal modified Kidney Diseases Improving Global Outcomes criteria) following each procedure to postoperative day 5. Severe AKI was defined as stage 2 or 3 AKI. Urine samples were obtained pre- and postoperatively at 6 time points to evaluate for levels of uNGAL. Secondary outcomes were in-hospital mortality and length of stay.

RESULTS

Subjects (n = 141) underwent a total of 192 general surgical procedures during the study period. Neonatal AKI and severe AKI occurred following 36 (18%) and 15 (8%) procedures (n = 33 subjects). Percent change of uNGAL from 24 hours preoperatively to 24 hours postoperatively was greater in subjects with neonatal AKI (190.2% [IQR 0.0, 1666.7%] vs 0.7% [IQR -31.2%,140.2%], P = .0374). The strongest association of uNGAL and AKI occurred at 24 hours postoperatively (area under the receiver operator curves of 0.81, 95% CI 0.72, 0.89). Increased mortality risk was observed in subjects with any postoperative AKI (aOR 11.1 95% CI 2.0, 62.8, P = .0063) and severe AKI (aOR 13.8; 95% CI 3.0, 63.1, P = .0007).

CONCLUSION

Elevation in uNGAL 24 hours postoperative was associated with AKI. Neonates with postoperative AKI had increased mortality.

Early biochemical markers in the assessment of acute kidney injury in children after cardiac surgery

Our aim was to evaluate biochemical markers in plasma (NGAL, CysC) and urine (NGAL, KIM-1) in children's early onset of acute kidney injury after congenital heart defect surgery using cardiopulmonary bypass. This study prospectively included 100 children with congenital heart defects who developed AKI. Patients with acute kidney injury had significantly higher CysC levels 6 and 12 h after cardiac surgery and plasma NGAL levels 2 and 6 h after cardiac surgery. The best predictive properties for the development of acute kidney injury are the combination (+CysCpl or +NGALu) after 12 h and a combination (+CysCpl and +NGALu) 6 and 24 h after cardiac surgery. We showed that plasma CysC and urinary NGAL could reliably predict the development of acute kidney injury. Measurement of early biochemical markers in plasma and urine, individually and combination, may predict the development of cardiac surgery-associated acute kidney injury in children.

Patterns of Urinary Neutrophil Gelatinase-Associated Lipocalin and Acute Kidney Injury in Neonates Receiving Cardiopulmonary Bypass

Elevated urinary neutrophil gelatinase-associated lipocalin (uNGAL) predicts acute kidney injury (AKI) in children following cardiopulmonary bypass (CPB) during cardiac surgery, but little is known about uNGAL’s predictive ability in neonates in this setting. We sought to determine the relationship between AKI and post-CPB uNGAL in neonates in the first 72 post-operative hours. Methods: Urine samples for uNGAL analysis were collected at preoperative baseline and serially post-operatively from 76 neonates undergoing CPB. Mixed-effects regression models and logistic models assessed associations between uNGAL and AKI (controlling for sex, gestational age, CPB time, surgical complexity, and age at surgery). Receiver-operator curves were applied to define optimal uNGAL cut-off values for AKI diagnosis. Results: Between 0 and 4 h post-operatively, uNGAL values did not differ between neonates with and without AKI. After 4 h until 16 h post-operatively, significant time-wise separation occurred between uNGAL values of neonates with AKI and those without AKI. Odds ratios at each time point significantly exceeded unity, peaking at 10 h post-operatively (3.48 (1.58, 8.71)). Between 4 and 16 h post-operatively, uNGAL discriminated AKI from no-AKI, with a sensitivity of 0.63 (0.49, 0.75) and a specificity of 0.68 (0.62, 0.74) at a cut-off value of 100 ng/mL. Conclusion: After 4 h until 16 h post-operatively, elevated uNGAL is associated with AKI in neonates receiving CPB during cardiac surgery; however, this relationship is more complex than in older children.

Will urinary biomarkers provide a breakthrough in diagnosing cardiac surgery-associated AKI? - A systematic review

Introduction: Acute kidney injury following cardiac surgery is a dreaded complication contributing to early mortality. Diagnosing AKI using serum creatinine usually results in a delay. To combat this, certain kidney damage specific biomarkers were investigated to identify if they can serve as early predictors of cardiac surgery-associated AKI (CSA-AKI). This study systematically reviews three such biomarkers; NGAL, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and insulin-like growth factor binding protein-7 (IGFBP7) to identify if they can serve as early predictors of CSA-AKI.Methods: Systematic search was carried out on literature reporting the diagnostic ability of the three biomarkers from databases in accordance with PRISMA guidelines.Results: We found 43 articles reporting urinary-NGAL levels (n = 34 in adults, n = 9 in children) and 10 studies reporting TIMP-2 and IGFBP7 levels among adults. Interestingly, NGAL showed high diagnostic value in predicting AKI in children (seven among nine studies with AUROC > 0.8). The cell cycle arrest biomarkers, namely TIMP-2 and IGFBP7, showed high diagnostic value in predicting AKI in adults (five among ten studies with AUROC > 0.8).Conclusion: In predicting CSA-AKI; the diagnostic value of NGAL is high in the paediatric population while the diagnostic value of TIMP-2 and IGFBP7 is high in adults.

Renal replacement therapies for infants and children in the ICU

PURPOSE OF REVIEW

Pediatric acute kidney injury (AKI) in critically ill patients is associated with increased morbidity and mortality. Emerging data support that the incidence of pediatric AKI in the ICU is rising. For children with severe AKI, renal replacement therapy (RRT) can provide a lifesaving supportive therapy. The optimal timing to deliver and modality by which to deliver RRT remain a point of discussion within pediatric (and adult) literature. This review discusses the use of RRT for pediatric patients in the ICU. We discuss the most recent evidence-based methods for RRT with a focus on continuous RRT.

RECENT FINDINGS

The feasibility of dialyzing the smallest infants and more medically complex children in the ICU is dependent on the advancements in dialysis access and circuit technology. At present, data indicate that upward of 27% of children in the ICU develop AKI and 6% require RRT. Newer dialysis modalities including prolonged intermittent hemodialysis and continuous flow peritoneal dialysis as well as newer dialysis technologies such as the smaller volume circuits (e.g., Cardio-Renal Pediatric Dialysis Emergency Machine, Newcastle Infant Dialysis and Ultrafiltration System) have made the provision of dialysis safer and more effective for pediatric patients of a variety of sizes.

SUMMARY

Renal replacement in the ICU requires a multidisciplinary team approach that is facilitated by a pediatric nephrologist in conjunction with intensivists and skilled nursing staff. Although mortality rates for children on dialysis remain high, outcomes are improving with the support of the multidisciplinary team and dialysis technology advancements.

Cell-Cycle Arrest Biomarkers: Usefulness for Cardiac Surgery-Related Acute Kidney Injury in Neonates and Infants

OBJECTIVES

Cell cycle arrest urine biomarkers have recently been shown to be early indicators of acute kidney injury in various clinical settings in critically ill adults and children. The product of tissue inhibitor metalloproteinase -1 and insulin-like growth factor binding protein-7 concentrations/1,000 (TIMP-1) × (IGFBP-7) provides stratification of acute kidney injury-risk in adults with critical illness. The present study explores the predictive accuracy of (TIMP-1) × (IGFBP-7) measured early after cardiopulmonary bypass for cardiac surgery-related acute kidney injury in neonates and infants, a population in whom such data are not yet available.

DESIGN

Prospective, observational.

SETTING

A tertiary referral pediatric cardiac ICU.

PATIENTS

Fifty-seven neonates and 110 infants undergoing surgery with cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

(TIMP-1) × (IGFBP-7) was measured on the NephroCheck (Astute Medical, San Diego, CA) platform preoperatively, less than 1 hour of cardiopulmonary bypass and 1-3 hours of cardiopulmonary bypass. The incidence of postoperative acute kidney injury, dialysis, and/or death were compared among quintiles of postoperative (TIMP-1) × (IGFBP-7). Multivariable regression was used to assess the added predictive value for renal events of (TIMP-1) × (IGFBP-7) over clinical models. Basal (TIMP-1) × (IGFBP-7) increased with age at surgery (regression coefficient = 0.004 ± 0.001; p = 0.005). (TIMP-1) × (IGFBP-7) increased after cardiopulmonary bypass. Neonates had lower postoperative (TIMP-1) × (IGFBP-7) compared with older infants, despite undergoing longer surgeries and experiencing a higher incidence of postoperative renal events. (TIMP-1) × (IGFBP-7) was not associated with acute kidney injury, dialysis, and/or death and was not a predictor of the aforementioned events when added to a clinical acute kidney injury model including age, duration of cardiopulmonary bypass, and mechanical ventilation prior to surgery.

CONCLUSIONS

These findings question the usefulness of (TIMP-1) × (IGFBP-7) for the prediction of cardiac surgery-related acute kidney injury in neonates and infants when measured within 3 hours of cardiopulmonary bypass.

Plasma Neutrophil Gelatinase-Associated Lipocalin Is Associated With Acute Kidney Injury and Clinical Outcomes in Neonates Undergoing Cardiopulmonary Bypass

OBJECTIVES

Acute kidney injury is a frequent complication following neonatal cardiac surgery and is associated with significant morbidity and mortality. The objectives of this study were to determine if plasma neutrophil gelatinase-associated lipocalin levels were associated with acute kidney injury and clinical outcomes in neonates with congenital heart disease undergoing cardiopulmonary bypass.

DESIGN

Retrospective single-center observational study.

SETTING

A pediatric cardiac ICU within a tertiary-care academic hospital.

PATIENTS

Patients age less than 30 days undergoing cardiac surgery requiring cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma neutrophil gelatinase-associated lipocalin peaked at 12 hours postcardiopulmonary bypass and more than doubled compared with preoperative levels. Higher preoperative and 24-hour postoperative neutrophil gelatinase-associated lipocalin levels were associated with acute kidney injury (r = 0.30, r = 0.49), longer duration of mechanical ventilation (r = 0.40, r = 0.51), ICU (r = 0.32, r = 0.33) and hospital lengths of stay (r = 0.28, r = 0.32), and total hospital charges (r = 0.35, r = 0.30; all p values < 0.05).

CONCLUSIONS

Both preoperative and 24-hour postoperative plasma neutrophil gelatinase-associated lipocalin levels are associated with acute kidney injury and worse clinical outcomes in neonates undergoing cardiac surgery. Plasma neutrophil gelatinase-associated lipocalin levels may have a role in risk stratification for predicting postoperative renal dysfunction as well as providing a potential clinical trajectory in the postoperative period.

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.

Urinary calprotectin, kidney injury molecule-1, and neutrophil gelatinase-associated lipocalin for the prediction of adverse outcome in pediatric acute kidney injury

Early identification of patients with acute kidney injury (AKI) being at high risk for adverse outcome can influence medical treatment. This study compares urinary calprotectin, kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) for their performance in predicting mortality and need for renal replacement therapy (RRT) in pediatric AKI patients. Urinary biomarker concentrations were assessed prospectively in 141 subjects aged 0-18 years including 55 patients with established AKI according to pediatric Risk, Injury, Failure, Loss, and End-stage kidney disease (pRIFLE) criteria, 27 patients without AKI, and 59 healthy children. Within the AKI group, receiver operating characteristic (ROC) curve analysis revealed moderate to poor performance of calprotectin and KIM-1 in the prediction of 30-day mortality (calprotectin area under the curve (AUC) 0.55; KIM-1 AUC 0.55) and 3-month mortality (calprotectin AUC 0.61; KIM-1 AUC 0.60) and fair performance in the prediction of RRT requirement (calprotectin AUC 0.72; KIM-1 AUC 0.71). Urinary NGAL showed good performance in predicting 30-day (AUC 0.79) and 3-month (AUC 0.81) mortality and moderate performance in predicting RRT (AUC 0.61).

CONCLUSIONS

Whereas urinary calprotectin and KIM-1 can be useful for the prediction of RRT, urinary NGAL has a good diagnostic performance in predicting mortality in pediatric patients with AKI of heterogeneous etiology. What is known: • There is increasing evidence that urinary biomarkers like neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) are valuable for the prediction of adverse outcome in adult acute kidney injury (AKI), whereas data on pediatric AKI is scarce. What is new: • Urinary calprotectin and KIM-1 do not predict mortality in our heterogeneous pediatric AKI cohort, but they show moderate performance in the prediction of dialysis. • Urinary NGAL is a good predictor of mortality performing better than pRIFLE stage, eGFR, or creatinine, but it shows moderate performance in the prediction of dialysis.

Clinical significance of NGAL and KIM-1 for acute kidney injury in patients with scrub typhus

Background

The aim of this study is to investigate the clinical significance of neutrophil gelatinase–associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) for acute kidney injury (AKI) in patients with scrub typhus.

Methods

From 2014 to 2015, 145 patients were diagnosed with scrub typhus. Of these, we enrolled 138 patients who were followed up until renal recovery or for at least 3 months. We measured serum and urine NGAL and KIM-1 levels and evaluated prognostic factors affecting scrub typhus–associated AKI.

Results

Of the 138 patients, 25 had scrub typhus–associated AKI. The incidence of AKI was 18.1%; of which 11.6%, 4.3%, and 2.2% were classified as risk, injury, and failure, respectively, according to RIFLE criteria. Compared with patients in the non-AKI group, patients in the AKI group were older and showed higher total leukocyte counts and hypoalbuminemia or one or more comorbidities such as hypertension (72% vs 33%, p<0.01), diabetes (40% vs 14%, p<0.01), or chronic kidney disease (32% vs 1%, p<0.01). In addition, serum NGAL values (404± 269 vs 116± 78 ng/mL, P<0.001), KIM-1 values (0.80± 0.52 vs 0.33± 0.68 ng/mL, P<0.001), urine NGAL/creatinine values (371± 672 vs 27± 39 ng/mg, P<0.001) and urine KIM-1/creatinine values (4.04± 2.43 vs 2.38± 1.89 ng/mg, P<0.001) were higher in the AKI group than in the non-AKI group. By multivariate logistic regression, serum NGAL and the presence of chronic kidney disease were significant predictors of AKI.

Conclusion

Serum NGAL might be an additive predictor for scrub typhus–associated AKI.

Oliguria and Biomarkers of Acute Kidney Injury: Star Struck Lovers or Strangers in the Night?

Oliguria is a common phenomenon that is found in hospitalized patients . Although a rapid reduction in urine excretion rate may reflect a precipitous fall in the glomerular filtration rate, in many cases it may not. Given the common physiological finding of oliguria, we explore the relationship between the functional biomarker of renal injury (oliguria) with the increasing number of markers of renal injury to see if this combination may aid in risk stratification. © 2016 S. Karger AG, Basel.

Fluid Management: Pharmacologic and Renal Replacement Therapies

OBJECTIVES

Focusing on critically ill children with cardiac disease, we will review common causes of fluid perturbations, clinical recognition, and strategies to minimize and treat fluid-related complications.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSIONS

Meticulous fluid management is vital in critically ill children with cardiac disease. Fluid therapy is important to maintain adequate blood volume and perfusion pressure in order to support cardiac output, tissue perfusion, and oxygen delivery. However, fluid overload and acute kidney injury are common and are associated with increased morbidity and mortality. Understanding the etiologies for disturbances in volume status and the pathophysiology surrounding those conditions is crucial for providing optimal care.

Structural equation modelling exploration of the key pathophysiological processes involved in cardiac surgery-related acute kidney injury in infants

Background

Uncertainties about the pathophysiological processes resulting in cardiac surgery-related acute kidney injury (AKI) in infants concern the relative impact of the most prominent risk factors, the clinical relevance of changes in glomerular filtration rate vs tubular injury, and the usefulness of available diagnostic tools. Structural equation modelling could allow for the assessment of these complex relationships.

Methods

A structural model was specified using data from a prospective observational cohort of 200 patients <1 year of age undergoing cardiopulmonary bypass surgery. It included four latent variables: AKI, modelled as a construct of perioperative creatinine variation, of oliguria and of urine neutrophil gelatinase-associated lipocalin (uNGAL) concentrations; the cardiopulmonary bypass characteristics; the occurrence of a post-operative low cardiac output syndrome and the post-operative outcome.

Results

The model showed a good fit, and all path coefficients were statistically significant. The bypass was the most prominent risk factor, with a path coefficient of 0.820 (95 % CI 0.527–0.979), translating to a 67.2 % explanation for the risk of AKI. A strong relationships was found between AKI and early uNGAL excretion, and between AKI and the post-operative outcome, with path coefficients of 0.611 (95 % CI 0.347–0.777) and 0.741 (95 % CI 0.610–0.988), respectively. The path coefficient between AKI and a >50 % increase in serum creatinine was smaller, with a path coefficient of 0.443 (95 % CI 0.273–0.596), and was intermediate for oliguria, defined as urine output <0.5 ml kg⁻¹ h⁻¹, with a path coefficient of 0.495 (95 % CI 0.250–0.864). A path coefficient of −0.229 (95 % CI −0.319 to 0.060) suggested that the risk of AKI during the first year of life did not increase with younger age at surgery.

Conclusions

These findings suggest that cardiac surgery-related AKI in infants is a translation of tubular injury, predominately driven by the cardiopulmonary bypass, and linked to early uNGAL excretion and to post-operative outcome.

Trial registration

ClinicalTrials.gov identifier NCT01219998. Registered 11 October 2010.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1350-1) contains supplementary material, which is available to authorized users.

PROGRESSION OF CHRONIC KIDNEY DISEASE AFTER ACUTE KIDNEY INJURY

The incidence of chronic kidney disease (CKD) in children and adults is increasing. Cardiologists have become indispensable members of the care provider team for children with CKD. This is partly due to the high incidence of CKD in children and adults with congenital heart disease, with current estimates of 30-50%. In addition, the high incidence of acute kidney injury (AKI) due to cardiac dysfunction or following pediatric cardiac surgery that may progress to CKD is also well documented. It is now apparent that AKI and CKD are uniquely intertwined as interconnected syndromes. Furthermore, the well-known long-term cardiovascular morbidity and mortality associated with CKD require the joint attention of both nephrologists and cardiologists. Children with both congenital heart disease and CKD are increasingly surviving to adulthood, with synergistically negative medical, financial, and quality of life impact. An improved understanding of the epidemiology, mechanisms, early diagnosis, and preventive measures is of importance to cardiologists, nephrologists, scientists, economists, and policy makers alike. Herein, we report the current definitions, epidemiology, and complications of CKD in children, with an emphasis on children with congenital heart disease. We then focus on the clinical and experimental evidence for the progression of CKD after episodes of AKI commonly encountered in children with heart disease, and explore the role of novel biomarkers for the prediction of CKD progression.

Early detection of acute kidney injury after pediatric cardiac surgery

Acute kidney injury (AKI) is increasingly recognized as a common problem in children undergoing cardiac surgery, with well documented increases in morbidity and mortality in both the short and the long term. Traditional approaches to the identification of AKI such as changes in serum creatinine have revealed a large incidence in this population with significant negative impact on clinical outcomes. However, the traditional diagnostic approaches to AKI diagnosis have inherent limitations that may lead to under-diagnosis of this pathologic process. There is a dearth of randomized controlled trials for the prevention and treatment of AKI associated with cardiac surgery, at least in part due to the paucity of early predictive biomarkers. Novel non-invasive biomarkers have ushered in a new era that allows for earlier detection of AKI. With these new diagnostic tools, a more consistent approach can be employed across centers that may facilitate a more accurate representation of the actual prevalence of AKI and more importantly, clinical investigation that may minimize the occurrence of AKI following pediatric cardiac surgery. A thoughtful management approach is necessary to mitigate the effects of AKI after cardiac surgery, which is best accomplished in close collaboration with pediatric nephrologists. Long-term surveillance for improvement in kidney function and potential development of chronic kidney disease should also be a part of the comprehensive management strategy.

Clinical Factors Associated with Dose of Loop Diuretics After Pediatric Cardiac Surgery: Post Hoc Analysis

A post hoc analysis of a randomized controlled trial comparing the clinical effects of furosemide and ethacrynic acid was conducted. Infants undergoing cardiac surgery with cardiopulmonary bypass were included in order to explore which clinical factors are associated with diuretic dose in infants with congenital heart disease. Overall, 67 patients with median (interquartile range) age of 48 (13-139) days were enrolled. Median diuretic dose was 0.34 (0.25-0.4) mg/kg/h at the end of postoperative day (POD) 0 and it significantly decreased (p = 0.04) over the following PODs; during this period, the ratio between urine output and diuretic dose increased significantly (p = 0.04). Age (r -0.26, p = 0.02), weight (r -0.28, p = 0.01), cross-clamp time (r 0.27, p = 0.03), administration of ethacrynic acid (OR 0.01, p = 0.03), and, at the end of POD0, creatinine levels (r 0.3, p = 0.009), renal near-infrared spectroscopy saturation (-0.44, p = 0.008), whole-blood neutrophil gelatinase-associated lipocalin levels (r 0.30, p = 0.01), pH (r -0.26, p = 0.02), urinary volume (r -0.2755, p = 0.03), and fluid balance (r 0.2577, p = 0.0266) showed a significant association with diuretic dose. At multivariable logistic regression cross-clamp time (OR 1.007, p = 0.04), use of ethacrynic acid (OR 0.2, p = 0.01) and blood pH at the end of POD0 (OR 0.0001, p = 0.03) was independently associated with diuretic dose. Early resistance to loop diuretics continuous infusion is evident in post-cardiac surgery infants: Higher doses are administered to patients with lower urinary output. Independently associated variables with diuretic dose in our population appeared to be cross-clamping time, the administration of ethacrynic acid, and blood pH.

Urinary KIM-1 in children undergoing nephrotoxic antineoplastic treatment: a prospective cohort study

BACKGROUND

Acute kidney injury (AKI) is a significant complication in patients with cancer, and nephrotoxic drugs are among the most common causes of AKI. To date, there is no study evaluating the potential role of renal biomarkers in children receiving nephrotoxic chemotherapy.

METHODS

A prospective study was conducted in children receiving methotrexate (MTX) or platinum-based treatment. Urinary kidney injury molecule-1 (KIM-1) was measured 24 h after the initiation of the chemotherapy infusion, and serum creatinine (sCr) was measured prior to drug infusion and at 24, 48, 72, and 96 h, 1 and 2 weeks, and 3 months post-initiation of treatment.

RESULTS

A total of 64 children were evaluated, of whom 21 (32.8%) developed AKI. The majority had AKI stage 1 (n = 12, 57.1%) and only one developed AKI stage 3. Median values of urinary KIM-1 were higher in patients with AKI than in those without AKI [10.7, interquartile range (IQR) 1.6-17.9 vs. 4.3 (IQR 1.3-6.1) ng/mg creatinine; p < 0.01]. Urinary KIM-1 showed good discrimination for AKI in patients receiving nephrotoxic chemotherapy, with an area under the receiver operator characteristic curve for AKI up to 1 week later of 0.82 (95% confidence interval 0.66-0.95). Even when measured only 24 h after drug infusion, urinary KIM-1 still showed good discrimination to predict persistent renal impairment three months later.

CONCLUSION

Urinary KIM-1 measured 24 h after the start of drug infusion has the potential to detect early AKI in pediatric patients treated with MTX or platinum-class drugs.

Umbilical neutrophil gelatinase-associated lipocalin level as an early predictor of acute kidney injury in neonates with hypoplastic left heart syndrome

Acute kidney injury (AKI) is a primarily described complication after unbalanced systemic perfusion in neonates with congenital heart defects, including hypoplastic left heart syndrome (HLHS). The aim of the study was to compare the umbilical NGAL concentrations between neonates born with HLHS and healthy infants, as well as to analyze whether the determination of NGAL level could predict AKI in neonates with prenatally diagnosed HLHS. Twenty-one neonates with prenatally diagnosed HLHS were enrolled as study group and 30 healthy neonates served as controls. Perinatal characteristics and postnatal parameters were extracted from the hospital neonatal database. In umbilical cord blood, we determined plasma NGAL concentrations, acid base balance, and lactate and creatinine levels. In neonates with HLHS, complications (respiratory insufficiency, circulatory failure, NEC, IVH, and AKI) were recorded until the day of cardiosurgery. We observed in neonates with HLHS higher umbilical NGAL levels compared to controls. Among 8 neonates with HLHS and diagnosed AKI stage 1, we observed elevated NGAL levels in comparison to those newborns without AKI. Umbilical NGAL could predict, with high sensitivity and specificity, AKI development in study neonates. We suggest that the umbilical blood NGAL concentration may be an early marker to predict AKI in neonates with HLHS.