Long-Term Kidney Outcomes Following Dialysis-Treated Childhood Acute Kidney Injury: A Population-Based Cohort Study

Furosemide stress test to predict acute kidney injury progression in critically ill children

BACKGROUND

Furosemide stress test (FST) is a novel functional biomarker for predicting severe acute kidney injury (AKI); however, pediatric studies are limited.

METHODS

Children 3 months to 18 years of age admitted to the intensive care unit (ICU) of a tertiary care hospital from Nov 2019 to July 2021 were screened and those who developed AKI stage 1 or 2 within 7 days of admission underwent FST (intravenous furosemide 1 mg/kg). Urine output was measured hourly for the next 6 h; a value > 2 ml/kg within the first 2 h was deemed furosemide responsive. Other biomarkers like plasma neutrophil gelatinase-associated lipocalin (NGAL) and proenkephalin (PENK) were also evaluated.

RESULTS

Of the 480 admitted patients, 51 developed AKI stage 1 or 2 within 7 days of admission and underwent FST. Nine of these patients were furosemide non-responsive. Thirteen (25.5%) patients (eight of nine from FST non-responsive group) developed stage 3 AKI within 7 days of FST, nine (17.6%) of whom (seven from non-responsive group) required kidney support therapy (KST). FST emerged as a good biomarker for predicting stage 3 AKI and need for KST with area-under-the-curve (AUC) being 0.93 ± 0.05 (95% CI 0.84-1.0) and 0.96 ± 0.03 (95% CI 0.9-1.0), respectively. FST outperformed NGAL and PENK in predicting AKI stage 3 and KST; however, the combination did not improve the diagnostic accuracy.

CONCLUSIONS

Furosemide stress test is a simple, inexpensive, and robust biomarker for predicting stage 3 AKI and KST need in critically ill children. Further research is required to identify the best FST cut-off in children.

Characteristics and outcomes of children ≤ 10 kg receiving continuous kidney replacement therapy: a WE-ROCK study

BACKGROUND

Continuous kidney replacement therapy (CKRT) is often used for acute kidney injury (AKI) or fluid overload (FO) in children ≤ 10 kg. Intensive care unit (ICU) mortality in children ≤ 10 kg reported by the prospective pediatric CRRT (ppCRRT, 2001-2003) registry was 57%. We aimed to evaluate characteristics associated with ICU mortality using a contemporary registry.

METHODS

The Worldwide Exploration of Renal Replacement Outcomes Collaborative in Kidney Disease (WE-ROCK) registry is a retrospective, multinational, observational study of children and young adults aged 0-25 years receiving CKRT (2015-2021) for AKI or FO. This analysis included patients ≤ 10 kg at hospital admission.

PRIMARY AND SECONDARY OUTCOMES

ICU mortality and major adverse kidney events at 90 days (MAKE-90) defined as death, persistent kidney dysfunction, or dialysis within 90 days, respectively.

RESULTS

A total of 210 patients were included (median age 0.53 years (IQR, 0.1, 0.9)). ICU mortality was 46.5%. MAKE-90 occurred in 150/207 (72%). CKRT was initiated at a median 3 days (IQR 1, 9) after ICU admission and lasted a median 6 days (IQR 3, 16). On multivariable analysis, pediatric logistic organ dysfunction score (PELOD-2) at CKRT initiation was associated with increased odds of ICU mortality (aOR 2.64, 95% CI 1.68-4.16), and increased odds of MAKE-90 (aOR 2.2, 95% CI 1.31-3.69). Absence of comorbidity was associated with lower MAKE-90 (aOR 0.29, 95%CI 0.13-0.65).

CONCLUSIONS

We report on a contemporary cohort of children ≤ 10 kg treated with CKRT for acute kidney injury and/or fluid overload. ICU mortality is decreased compared to ppCRRT. The extended risk of death and morbidity at 90 days highlights the importance of close follow-up.

Pediatric acute kidney injury and adverse health outcomes: using a foundational framework to evaluate a causal link

Acute kidney injury (AKI) is a major global health problem, expensive to manage, and its associations with negative pediatric health outcomes have been clearly demonstrated. One of the most fundamental questions to consider as we use previous epidemiological information to advance research and care paradigms is the strength of the causal link between pediatric AKI and health outcomes. In this review, we apply the foundational framework of the Bradford Hill criteria to evaluate the extent to which a causal link exists between AKI and the associated adverse outcomes in children. Available data in children support a causal link between AKI and short-term outcomes including mortality, length of stay, and ventilation time. Clarifying the causal nature of longer term associations requires further high-quality observational studies in children, careful consideration of what defines the most meaningful and measurable longer term outcomes after pediatric AKI, and integration of evolving biological data related to mechanisms of disease. Preventing or mitigating AKI should lead to improved outcomes. Demonstrating such reversibility will solidify confidence in the causal relationship, improve child health, and highlight an aspect which is highly relevant to clinicians, scientists, and policy makers.

Kidney and blood pressure outcomes 11 years after pediatric critical illness and longitudinal impact of AKI: a prospective cohort study

BACKGROUND

Acute kidney injury (AKI) is common in critically ill children and associated with adverse short-term outcomes; however, long-term outcomes are not well described.

METHODS

This longitudinal prospective cohort study examined the prevalence of chronic kidney disease (CKD) and hypertension (HTN) 11 vs. 6 years after pediatric intensive care unit (PICU) admission and association with AKI. We examined children (age < 19 years) without pre-existing kidney disease 11 ± 1.5 years after PICU admission at a single center. AKI was defined using serum creatinine criteria. The primary outcome was a composite of CKD or HTN. CKD was defined as estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73 m2 or albuminuria. Multivariable analyses compared outcomes at 11- vs. 6-year follow-up and association with AKI during PICU admission.

RESULTS

Of 96 children evaluated 11 years after PICU admission, 16% had evidence of CKD or HTN (vs. 28% at 6 years, p < 0.05). Multivariable analysis did not show improvement in outcomes from 6- to 11-year follow-up. eGFR decreased from 6- to 11-year follow-up (adjusted coefficient - 11.7, 95% CI - 17.6 to - 5.9) and systolic and diastolic blood pressures improved. AKI was associated with composite outcome at 6-year (adjusted odds ratio (aOR) 12.7, 95% CI 3.2-51.2, p < 0.001), but not 11-year follow-up (p = 0.31). AKI was associated with CKD (aOR 10.4, 95% CI 3.1-34.7) at 11 years.

CONCLUSIONS

This study provides novel data showing that adverse kidney and blood pressure outcomes remain highly prevalent 10 years after critical illness in childhood. The association with AKI wanes over time.

Long-Term Kidney Outcomes after Pediatric Acute Kidney Injury

Key Points

Among 4173 children with AKI, 18% had major adverse kidney events (death, kidney failure, or CKD) during a median 10-year follow-up. AKI survivors were at 2–4 times higher risk of major adverse kidney events, hypertension, and subsequent AKI versus matched hospitalized comparators. This justifies improved surveillance after pediatric AKI to detect CKD and hypertension early and improve long-term kidney health.

Background

AKI is common in hospitalized children. Pediatric AKI receiving acute KRT is associated with long-term CKD, hypertension, and death. We aim to determine the outcomes after AKI in children who did not receive acute KRT because these remain uncertain.

Methods

Retrospective cohort study of all hospitalized children (0–18 years) surviving AKI without acute KRT between 1996 and 2020 in Ontario, Canada, identified by validated diagnostic codes in provincial administrative health databases. Children with prior KRT, CKD, or AKI were excluded. Cases were matched with up to four hospitalized comparators without AKI by age, neonatal status, sex, intensive care unit admission, cardiac surgery, malignancy, hypertension, hospitalization era, and a propensity score for AKI. Patients were followed until death, provincial emigration, or censoring in March 2021. The primary outcome was long-term major adverse kidney events (a composite of all-cause mortality, long-term KRT, or incident CKD).

Results

We matched 4173 pediatric AKI survivors with 16,337 hospitalized comparators. Baseline covariates were well-balanced following propensity score matching. During a median 9.7-year follow-up, 18% of AKI survivors developed long-term major adverse kidney event versus 5% of hospitalized comparators (hazard ratio [HR], 4.0; 95% confidence interval [CI], 3.6 to 4.4). AKI survivors had higher rates of long-term KRT (2% versus <1%; HR, 11.7; 95% CI, 7.5 to 18.4), incident CKD (16% versus 2%; HR, 7.9; 95% CI, 6.9 to 9.1), incident hypertension (17% versus 8%; HR, 2.3; 95% CI, 2.1 to 2.6), and AKI during subsequent hospitalization (6% versus 2%; HR, 3.7; 95% CI, 3.1 to 4.5), but no difference in all-cause mortality (3% versus 3%; HR, 0.9; 95% CI, 0.7 to 1.1).

Conclusions

Children surviving AKI without acute KRT were at higher long-term risk of CKD, long-term KRT, hypertension, and subsequent AKI versus hospitalized comparators.

Outcome 10 years after Shiga toxin-producing E. coli (STEC)-associated hemolytic uremic syndrome: importance of long-term follow-up

BACKGROUND

Hemolytic uremic syndrome (HUS) is an important cause of acute kidney injury in children. HUS is known as an acute disease followed by complete recovery, but patients may present with kidney abnormalities after long periods of time. This study evaluates the long-term outcome of Shiga toxin-producing Escherichia coli-associated HUS (STEC-HUS) in pediatric patients, 10 years after the acute phase of disease to identify risk factors for long-term sequelae.

METHODS

Over a 6-year period, 619 patients under 18 years of age with HUS (490 STEC-positive, 79%) were registered in Austria and Germany. Long-term follow-up data of 138 STEC-HUS-patients were available after 10 years for analysis.

RESULTS

A total of 66% (n = 91, 95% CI 0.57-0.73) of patients fully recovered showing no sequelae after 10 years. An additional 34% (n = 47, 95% CI 0.27-0.43) presented either with decreased glomerular filtration rate (24%), proteinuria (23%), hypertension (17%), or neurological symptoms (3%). Thirty had sequelae 1 year after STEC-HUS, and the rest presented abnormalities unprecedented at the 2-year (n = 2), 3-year (n = 3), 5-year (n = 3), or 10-year (n = 9) follow-up. A total of 17 patients (36.2%) without kidney abnormalities at the 1-year follow-up presented with either proteinuria, hypertension, or decreased eGFR in subsequent follow-up visits. Patients needing extracorporeal treatments during the acute phase were at higher risk of presenting symptoms after 10 years (p < 0.05).

CONCLUSIONS

Patients with STEC-HUS should undergo regular follow-up, for a minimum of 10 years following their index presentation, due to the risk of long-term sequelae of their disease. An initial critical illness, marked by need of kidney replacement therapy or plasma treatment may help predict poor long-term outcome.

Systematic Review and Meta-Analysis of the Incidence of Chronic Kidney Disease After Pediatric Critical Illness

OBJECTIVE

Survivors of pediatric critical illnesses are at risk of significant long-term organ sequelae. Chronic kidney disease (CKD) is a complication of critical illness (and ICU interventions) associated with growth impairment, cardiovascular disease, and early death. Our objective was to synthesize the evidence on the incidence of CKD among survivors of pediatric critical illness.

DATA SOURCES

MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Register of Controlled Trials from inception to February 2024.

STUDY SELECTION

Observational studies reporting the incidence of de novo CKD among survivors of pediatric critical illness.

DATA EXTRACTION

Two reviewers independently extracted data on study design, setting, population, demographics, diagnostic criteria, and outcome.

DATA SYNTHESIS

Meta-analysis was used to describe the incidence of CKD among survivors, risk of bias (RoB) assessed using the Joanna Briggs Institute Tool, and strength and reliability of evidence assessed with GRADE (Grading of Recommendations, Assessment, Development, and Evaluations). CKD was quantified as an estimated glomerular filtration rate (eGFR) less than 90 mL/min/1.73 m2 (outcome 1), eGFR less than 60 mL/min/1.73 m2 (outcome 2), and end-stage renal disease (ESRD) as eGFR less than 15 mL/min per 1.73 m2 (outcome 3). Twelve studies (3642 patients) met selection criteria and reported at least one measure of CKD. The median duration of follow-up was 2, 3.6, and 5 years, respectively, for outcomes 1, 2, and 3. For each threshold, the pooled estimate of CKD incidence was 24% (95% CI, 16-32%) for eGFR less than 90, 14% (95% CI, 6-23%) less than 60, and 4% (95% CI, 0-7%) for ESRD. The overall quality assessment indicated a moderate RoB.

CONCLUSIONS

Among a heterogenous population of pediatric critical illness survivors, an important minority of survivors developed CKD or ESRD. This study highlights the importance of diagnostic criteria for reporting, a greater focus on postcritical care surveillance and follow-up to identify those with CKD. Further study would facilitate the delineation of high-risk groups and strategies for improved outcomes.

Sensing Dying Cells in Health and Disease: The Importance of Kidney Injury Molecule-1

Kidney injury molecule-1 (KIM-1), also known as T-cell Ig and mucin domain-1 (TIM-1), is a widely recognized biomarker for AKI, but its biological function is less appreciated. KIM-1/TIM-1 belongs to the T-cell Ig and mucin domain family of conserved transmembrane proteins, which bear the characteristic six-cysteine Ig-like variable domain. The latter enables binding of KIM-1/TIM-1 to its natural ligand, phosphatidylserine, expressed on the surface of apoptotic cells and necrotic cells. KIM-1/TIM-1 is expressed in a variety of tissues and plays fundamental roles in regulating sterile inflammation and adaptive immune responses. In the kidney, KIM-1 is upregulated on injured renal proximal tubule cells, which transforms them into phagocytes for clearance of dying cells and helps to dampen sterile inflammation. TIM-1, expressed in T cells, B cells, and natural killer T cells, is essential for cell activation and immune regulatory functions in the host. Functional polymorphisms in the gene for KIM-1/TIM-1, HAVCR1 , have been associated with susceptibility to immunoinflammatory conditions and hepatitis A virus-induced liver failure, which is thought to be due to a differential ability of KIM-1/TIM-1 variants to bind phosphatidylserine. This review will summarize the role of KIM-1/TIM-1 in health and disease and its potential clinical applications as a biomarker and therapeutic target in humans.

Patterns of Multiple Organ Dysfunction and Renal Recovery in Critically Ill Children and Young Adults Receiving Continuous Renal Replacement Therapy

OBJECTIVES

Acute kidney injury requiring dialysis (AKI-D) commonly occurs in the setting of multiple organ dysfunction syndrome (MODS). Continuous renal replacement therapy (CRRT) is the modality of choice for AKI-D. Mid-term outcomes of pediatric AKI-D supported with CRRT are unknown. We aimed to describe the pattern and impact of organ dysfunction on renal outcomes in critically ill children and young adults with AKI-D.

DESIGN

Retrospective cohort.

SETTING

Two large quarternary care pediatric hospitals.

PATIENTS

Patients 26 y old or younger who received CRRT from 2014 to 2020, excluding patients with chronic kidney disease.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Organ dysfunction was assessed using the Pediatric Logistic Organ Dysfunction-2 (PELOD-2) score. MODS was defined as greater than or equal to two organ dysfunctions. The primary outcome was major adverse kidney events at 30 days (MAKE30) (decrease in estimated glomerular filtration rate greater than or equal to 25% from baseline, need for renal replacement therapy, and death). Three hundred seventy-three patients, 50% female, with a median age of 84 mo (interquartile range [IQR] 16-172) were analyzed. PELOD-2 increased from 6 (IQR 3-9) to 9 (IQR 7-12) between ICU admission and CRRT initiation. Ninety-seven percent of patients developed MODS at CRRT start and 266 patients (71%) had MAKE30. Acute kidney injury (adjusted odds ratio [aOR] 3.55 [IQR 2.13-5.90]), neurologic (aOR 2.07 [IQR 1.15-3.74]), hematologic/oncologic dysfunction (aOR 2.27 [IQR 1.32-3.91]) at CRRT start, and progressive MODS (aOR 1.11 [IQR 1.03-1.19]) were independently associated with MAKE30.

CONCLUSIONS

Ninety percent of critically ill children and young adults with AKI-D develop MODS by the start of CRRT. Lack of renal recovery is associated with specific extrarenal organ dysfunction and progressive multiple organ dysfunction. Currently available extrarenal organ support strategies, such as therapeutic plasma exchange lung-protective ventilation, and other modifiable risk factors, should be incorporated into clinical trial design when investigating renal recovery.

Programs and processes for advancing pediatric acute kidney support therapy in hospitalized and critically ill children: a report from the 26th Acute Disease Quality Initiative (ADQI) consensus conference

Pediatric acute kidney support therapy (paKST) programs aim to reliably provide safe, effective, and timely extracorporeal supportive care for acutely and critically ill pediatric patients with acute kidney injury (AKI), fluid and electrolyte derangements, and/or toxin accumulation with a goal of improving both hospital-based and lifelong outcomes. Little is known about optimal ways to configure paKST teams and programs, pediatric-specific aspects of delivering high-quality paKST, strategies for transitioning from acute continuous modes of paKST to facilitate rehabilitation, or providing effective short- and long-term follow-up. As part of the 26th Acute Disease Quality Initiative Conference, the first to focus on a pediatric population, we summarize here the current state of knowledge in paKST programs and technology, identify key knowledge gaps in the field, and propose a framework for current best practices and future research in paKST.

Continuous renal replacement therapy in neonates and children: what does the pediatrician need to know? An overview from the Critical Care Nephrology Section of the European Society of Paediatric and Neonatal Intensive Care (ESPNIC)

Continuous renal replacement therapy (CRRT) is the preferred method for renal support in critically ill and hemodynamically unstable children in the pediatric intensive care unit (PICU) as it allows for gentle removal of fluids and solutes. The most frequent indications for CRRT include acute kidney injury (AKI) and fluid overload (FO) as well as non-renal indications such as removal of toxic metabolites in acute liver failure, inborn errors of metabolism, and intoxications and removal of inflammatory mediators in sepsis. AKI and/or FO are common in critically ill children and their presence is associated with worse outcomes. Therefore, early recognition of AKI and FO is important and timely transfer of patients who might require CRRT to a center with institutional expertise should be considered. Although CRRT has been increasingly used in the critical care setting, due to the lack of standardized recommendations, wide practice variations exist regarding the main aspects of CRRT application in critically ill children.     Conclusion: In this review, from the Critical Care Nephrology section of the European Society of Paediatric and Neonatal Intensive Care (ESPNIC), we summarize the key aspects of CRRT delivery and highlight the importance of adequate follow up among AKI survivors which might be of relevance for the general pediatric community. What is Known: • CRRT is the preferred method of renal support in critically ill and hemodynamically unstable children in the PICU as it allows for gentle removal of fluids and solutes. • Although CRRT has become an important and integral part of modern pediatric critical care, wide practice variations exist in all aspects of CRRT. What is New: • Given the lack of literature on guidance for a general pediatrician on when to refer a child for CRRT, we recommend timely transfer to a center with institutional expertise in CRRT, as both worsening AKI and FO have been associated with increased mortality. • Adequate follow-up of PICU patients with AKI and CRRT is highlighted as recent findings demonstrate that these children are at increased risk for adverse long-term outcomes.

Machine learning prediction model of major adverse outcomes after pediatric congenital heart surgery-a retrospective cohort study

BACKGROUND

Major adverse postoperative outcomes (APOs) can greatly affect mortality, hospital stay, care management and planning, and quality of life. This study aimed to evaluate the performance of five machine learning (ML) algorithms for predicting four major APOs after pediatric congenital heart surgery and their clinically meaningful model interpretations.

METHODS

Between August 2014 and December 2021, 23,000 consecutive pediatric patients receiving congenital heart surgery were enrolled. Based on the split date of 1 January 2019, we selected 13,927 participants for the training cohort, and 9,073 participants for the testing cohort. Four predefined major APOs including low cardiac output syndrome (LCOS), pneumonia, renal failure, and deep venous thrombosis (DVT) were investigated. 39 clinical and laboratory features were inputted in five ML models: light gradient boosting machine (LightGBM), logistic regression (LR), support vector machine, random forest, and CatBoost. The performance and interpretations of ML models were evaluated using the area under the receiver operating characteristic curve (AUC) and Shapley Additive Explanations (SHAP).

RESULTS

In the training cohort, CatBoost algorithms outperformed others with the mean AUCs of 0.908 for LCOS and 0.957 for renal failure, while LightGBM and LR achieved the best mean AUCs of 0.886 for pneumonia and 0.942 for DVT, respectively. In the testing cohort, the best-performing ML model for each major APOs with the following mean AUCs: LCOS (LightGBM), 0.893 (95% confidence interval (CI), 0.884-0.895); pneumonia (LR), 0.929 (95% CI, 0.926-0.931); renal failure (LightGBM), 0.963 (95% CI, 0.947-0.979), and DVT (LightGBM), 0.970 (95% CI, 0.953-0.982). The performance of ML models using only clinical variables was slightly lower than those using combined data, with the mean AUCs of 0.873 for LCOS, 0.894 for pneumonia, 0.953 for renal failure, and 0.933 for DVT. The SHAP showed that mechanical ventilation time was the most important contributor of four major APOs.

CONCLUSIONS

In pediatric congenital heart surgery, the established ML model can accurately predict the risk of four major APOs, providing reliable interpretations for high-risk contributor identification and informed clinical decisions making.

Adults are just big kids: pediatric considerations for adult critical care nephrology

PURPOSE OF REVIEW

In recent years, there has been growing attention to pediatric kidney health, especially pediatric acute kidney injury (AKI). However, there has been limited focus on the role of pediatric AKI on adult kidney health, specifically considerations for the critical care physician.

RECENT FINDINGS

We summarize what is known in the field of pediatric AKI to inform adult medical care including factors throughout the early life course, including perinatal, neonatal, and pediatric exposures that impact survivor care later in adulthood.

SUMMARY

The number of pediatric AKI survivors continues to increase, leading to a higher burden of chronic kidney disease and other long-term co-morbidities later in life. Adult medical providers should consider pediatric history and illnesses to inform the care they provide. Such knowledge may help internists, nephrologists, and intensivists alike to improve risk stratification, including a lower threshold for monitoring for AKI and kidney dysfunction in their patients.

Early recognition and prevention of acute kidney injury in hospitalised children

Acute kidney injury is common in hospitalised children and is associated with poor patient outcomes. Once acute kidney injury occurs, effective therapies to improve patient outcomes or kidney recovery are scarce. Early identification of children at risk of acute kidney injury or at an early injury stage is essential to prevent progression and mitigate complications. Paediatric acute kidney injury is under-recognised by clinicians, which is a barrier to optimisation of inpatient care and follow-up. Acute kidney injury definitions rely on functional biomarkers (ie, serum creatinine and urine output) that are inadequate, since they do not account for biological variability, analytical issues, or physiological responses to volume depletion. Improved predictive tools and diagnostic biomarkers of kidney injury are needed for earlier detection. Novel strategies, including biomarker-guided care algorithms, machine-learning methods, and electronic alerts tied to clinical decision support tools, could improve paediatric acute kidney injury care. Clinical prediction models should be studied in different paediatric populations and acute kidney injury phenotypes. Research is needed to develop and test prevention strategies for acute kidney injury in hospitalised children, including care bundles and therapeutics.

Acute Kidney Injury: Gaps and Opportunities for Knowledge and Growth

Acute kidney injury (AKI) occurs frequently in hospitalized patients, regardless of age or prior medical history. Increasing awareness of the epidemiologic problem of AKI has directly led to increased study of global recognition, diagnostic tools, both reactive and proactive management, and analysis of long-term sequelae. Many gaps remain, however, and in this article we highlight opportunities to add significantly to the increasing bodies of evidence surrounding AKI. Practical considerations related to initiation, prescription, anticoagulation, and monitoring are discussed. In addition, the importance of AKI follow-up evaluation, particularly for those surviving the receipt of renal replacement therapy, is highlighted as a push for global equity in the realm of critical care nephrology is broached. Addressing these gaps presents an opportunity to impact patient care directly and improve patient outcomes.

Long-term outcomes of acute kidney injury in children

PURPOSE OF REVIEW

Acute kidney injury (AKI) affects up to 35% of all critically ill children and is associated with substantial short-term morbidity and mortality. However, the link between paediatric AKI and long-term adverse outcomes remains incompletely understood. This review highlights the most recent clinical data supporting the role of paediatric AKI as a risk factor for long-term kidney and cardiovascular consequences. In addition, it stresses the need for long-term surveillance of paediatric AKI survivors.

RECENT FINDINGS

Recent large-scale studies have led to an increasing understanding that paediatric AKI is a significant risk factor for adverse outcomes such as hypertension, cardiovascular disease and chronic kidney disease (CKD) over time. These long-term sequelae of paediatric AKI are most often observed in vulnerable populations, such as critically ill children, paediatric cardiac surgery patients, children who suffer from severe infections and paediatric cancer patients.

SUMMARY

A growing body of research has shown that paediatric AKI is associated with long-term adverse outcomes such as CKD, hypertension and cardiovascular disease. Although therapeutic pathways tailored to individual paediatric AKI patients are yet to be validated, we provide a framework to guide monitoring and prevention in children at the highest risk for developing long-term kidney dysfunction.

Incidence of Acute Kidney Injury in Hospitalized Children: A Meta-analysis

BACKGROUND AND OBJECTIVES

There is limited literature on the incidence of acute kidney injury (AKI) and associated mortality in hospitalized children. To systematically assess the worldwide incidence of AKI in hospitalized children to inform policymakers regarding appropriate health resource allocation.

METHODS

Three different databases were searched (PubMed, Embase, Web of Sciences) from March 2012 to January 2022 without language or geographical restrictions. We included cohort and cross-sectional studies that reported AKI incidence in hospitalized children. Eligible studies had at least 100 participants and used the standard Kidney Disease Improving Global Outcomes criteria to define AKI. Two authors extracted data on the study and patients' characteristics and outcomes (incidence and AKI-associated mortality) and performed the risk of bias assessment. We used a random-effects meta-analysis to generate pooled estimates.

RESULTS

We included 94 studies (202 694 participants) from 26 countries. The incidence of any AKI was 26% (95% confidence interval: 22-29), and that of moderate-severe AKI was 14% (11-16). The incidence of AKI was similar in high-income 27% (23-32), low-middle-income 25% (13-38), and low-income 24% (12-39) countries. Overall, AKI-associated mortality was observed in 11% (9-13) of the pediatric population. AKI-associated mortality rate was highest at 18% (11-25) and 22% (9-38) in low-income and low-middle-income countries, respectively.

CONCLUSIONS

AKI was observed in one-quarter of the hospitalized children and is associated with increased mortality risk. Low-income and low-middle-income countries had observed higher mortality rates compared with high-income countries despite a similar AKI burden.

Long-term Health Care Utilization and Associated Costs After Dialysis-Treated Acute Kidney Injury in Children

RATIONALE & OBJECTIVE

Acute kidney injury (AKI) is common among hospitalized children and is associated with increased hospital length of stay and costs. However, there are limited data on postdischarge health care utilization after AKI hospitalization. Our objectives were to evaluate health care utilization and physician follow-up patterns after dialysis-treated AKI in a pediatric population.

STUDY DESIGN

Retrospective cohort study, using provincial health administrative databases.

SETTING & PARTICIPANTS

All children (0-18 years) hospitalized between 1996 and 2017 in Ontario, Canada. Excluded individuals comprised non-Ontario residents; those with metabolic disorders or poisoning; and those who received dialysis or kidney transplant before admission, a kidney transplant by 104 days after discharge, or were receiving dialysis 76-104 days from dialysis start date.

EXPOSURE

Episodes of dialysis-treated AKI, identified using validated health administrative codes. AKI survivors were matched to 4 hospitalized controls without dialysis-treated AKI by age, sex, and admission year.

OUTCOME

Our primary outcome was postdischarge hospitalizations, emergency department visits, and outpatient physician visits. Secondary outcomes included outpatient visits by physician type and composite health care costs.

ANALYTICAL APPROACH

Proportions with≥1 event and rates (per 1,000 person-years). Total and median composite health care costs. Adjusted rate ratios using negative binomial regression models.

RESULTS

We included 1,688 pediatric dialysis-treated AKI survivors and 6,752 matched controls. Dialysis-treated AKI survivors had higher rehospitalization and emergency department visit rates during the analyzed follow-up periods (0-1, 0-5, and 0-10 years postdischarge, and throughout follow-up), and higher outpatient visit rates in the 0-1-year follow-up period. The overall adjusted rate ratio for rehospitalization was 1.46 (95% CI, 1.25-1.69; P<0.0001) and for outpatient visits was 1.16 (95% CI, 1.09-1.23; P=0.01). Dialysis-treated AKI survivors also had higher health care costs. Nephrologist follow-up was infrequent among dialysis-treated AKI survivors (18.6% by 1 year postdischarge).

LIMITATIONS

Potential miscoding of study exposures or outcomes. Residual uncontrolled confounding. Data for health care costs and emergency department visits was unavailable before 2006 and 2001, respectively.

CONCLUSIONS

Dialysis-treated AKI survivors had greater postdischarge health care utilization and costs versus hospitalized controls. Strategies are needed to improve follow-up care for children after dialysis-treated AKI to prevent long-term complications.

Long-Term Consequences of Acute Kidney Injury After Pediatric Cardiac Surgery: A Systematic Review

OBJECTIVE

The objective of this study was to evaluate the available data on long-term kidney dysfunction, hypertension, and mortality after cardiac surgery-associated acute kidney injury (AKI) in the pediatric population.

STUDY DESIGN

PubMed/MEDLINE, Embase, Scopus, and reference lists of relevant articles were searched for eligible studies published from inception through March 2022. Long-term outcomes after pediatric cardiac surgery complicated by AKI and those without were investigated.

RESULTS

We identified 14 studies published between 2013 and 2022 that included a total of 6701 patients (AKI: 1376 patients; no AKI: 5325 patients). These studies used different well-established classifications to define AKI. All the studies suggested that AKI after heart surgery is common in the pediatric patient population and reported a potential link between cardiac surgery-associated AKI and important clinical outcomes. However, only 4 out of 11 studies found a strong association between (absence of recovery from) cardiac surgery-associated AKI and risk of developing chronic kidney disease, and 3 out of 5 studies found a significant increase in mortality rates for pediatric patients who developed AKI after cardiac surgery. Only 1 out of 4 studies found an association between AKI and hypertension at 12 months postoperatively, but found no association at later follow-up times.

CONCLUSIONS

Although there is a trend, evidence on the long-term consequences of cardiac surgery-associated AKI in the pediatric population is mixed. Genetic syndromes, preexisting kidney disease, univentricular or cyanotic heart conditions, and/or high-complexity surgery may be more important for the development of kidney dysfunction by adolescence and early adulthood. Regardless, these children may benefit from a long-term kidney follow-up.

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

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

Hemodynamic instability during connection to continuous kidney replacement therapy in critically ill pediatric patients

BACKGROUND

Emerging data suggest evidence of organ hypoperfusion during continuous kidney replacement therapy (CKRT). To facilitate kidney and global recovery, we must understand the hemodynamic risks associated with CKRT. We aimed to investigate frequency of hemodynamic instability and association with patient outcomes in pediatric CKRT.

METHODS

In a single-center study of CKRT patients between September 2016 and October 2018, we collected hemodynamic data using archived high-resolution physiologic data before and after connection. Primary outcome was hypotension defined as ≥ 20% decrease in baseline mean arterial pressure (MAP) for ≥ 2 consecutive minutes in the 60 min following connection. Secondary outcomes were tachycardia (≥ 20% increase in heart rate (HR)) and hemodynamic interventions.

RESULTS

Seventy-one patients median age 54 months (IQR 7-144), weight 16.7 kg (IQR 8-41), on hemodiafiltration had 304 filter connections, 4 (IQR 1-7) filters per patient; the median duration of CKRT was 9 days (IQR 3-20). The most common CKRT indication was AKI with fluid overload (48/71, 69%). There were 78 (27%) hypotension and 42 (14%) tachycardia events; cumulative duration of hypotension was 14 min IQR (3-31.75). Teams provided intervention in 17/304 (6%) of connections. Pediatric Logistic Organ Dysfunction 2 was the only independent predictor of hypotension (aOR 2.12 (CI 1.02-4.41)).

CONCLUSIONS

One in four and one in six pediatric CKRT filter connections were complicated by hypotension and tachycardia, respectively. Higher illness severity at CKRT initiation was independently associated with hypotension. Impact of CKRT-associated hemodynamic instability on global patient outcomes requires further targeted study. A higher resolution version of the Graphical abstract is available as Supplementary information.

Consensus-Based Recommendations on Priority Activities to Address Acute Kidney Injury in Children: A Modified Delphi Consensus Statement

IMPORTANCE

Increasing evidence indicates that acute kidney injury (AKI) occurs frequently in children and young adults and is associated with poor short-term and long-term outcomes. Guidance is required to focus efforts related to expansion of pediatric AKI knowledge.

OBJECTIVE

To develop expert-driven pediatric specific recommendations on needed AKI research, education, practice, and advocacy.

EVIDENCE REVIEW

At the 26th Acute Disease Quality Initiative meeting conducted in November 2021 by 47 multiprofessional international experts in general pediatrics, nephrology, and critical care, the panel focused on 6 areas: (1) epidemiology; (2) diagnostics; (3) fluid overload; (4) kidney support therapies; (5) biology, pharmacology, and nutrition; and (6) education and advocacy. An objective scientific review and distillation of literature through September 2021 was performed of (1) epidemiology, (2) risk assessment and diagnosis, (3) fluid assessment, (4) kidney support and extracorporeal therapies, (5) pathobiology, nutrition, and pharmacology, and (6) education and advocacy. Using an established modified Delphi process based on existing data, workgroups derived consensus statements with recommendations.

FINDINGS

The meeting developed 12 consensus statements and 29 research recommendations. Principal suggestions were to address gaps of knowledge by including data from varying socioeconomic groups, broadening definition of AKI phenotypes, adjudicating fluid balance by disease severity, integrating biopathology of child growth and development, and partnering with families and communities in AKI advocacy.

CONCLUSIONS AND RELEVANCE

Existing evidence across observational study supports further efforts to increase knowledge related to AKI in childhood. Significant gaps of knowledge may be addressed by focused efforts.

Trajectory of kidney recovery in pediatric patients requiring continuous kidney replacement therapy for acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is commonly seen in the PICU and is associated with poor short-term and long-term outcomes, especially in patients who required continuous kidney replacement therapy (CKRT). However, as the trajectory of kidney recovery in these patients remain uncertain, determination of the timing to convert to permanent kidney replacement therapy (KRT) remains a major challenge. We aimed to examine the frequency and timing of kidney recovery in pediatric AKI survivors that required CKRT.

METHODS

We performed a retrospective study of patients under 18 years old who received CKRT for AKI in a tertiary-care PICU over 6 years. Primary outcomes were the rate of KRT withdrawal due to kidney recovery and KRT-dependent days for those who survived to hospital discharge. Secondary outcomes were all-cause mortality, dialysis dependence, and occurrences of estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73m² and eGFR < 60 mL/min/1.73m² one year after initiation of the index CKRT in survivors.

RESULTS

Thirty-nine patients were included. Of the 28 children who survived to hospital discharge, 26 (93%) withdrew from dialysis due to kidney recovery, all within 30 days. Twenty-three patients were followed up. One had died, five had an eGFR of 60 mL/min/1.73m² or more but less than 90 mL/min/1.73m², and two had an eGFR < 60 mL/min/1.73m², of which one required peritoneal dialysis.

CONCLUSIONS

Over 90% of the survivors withdrew CKRT within 30 days. However, the frequency of abnormal eGFR one year after initiation of CKRT in survivors exceeded 30% and supports the recommendation of post-AKI follow-up.

Acute Kidney Disease in Hospitalized Pediatric Patients With Acute Kidney Injury in China

Objective

The epidemiology and outcomes of acute kidney disease (AKD) after acute kidney injury (AKI) in hospitalized children are poorly described. The aim of this study is to investigate the prevalence, predictive factors, and clinical outcomes of AKD in hospitalized children with AKI.

Methods

Children (1 month-18 years) with AKI during hospitalization in the Second Xiangya Hospital from January 2015 to December 2020 were identified. AKD was defined based on the consensus report of the Acute Disease Quality Initiative 16 workgroup. The endpoints include adverse outcomes in 30 and 90 days. Multivariable logistic regression analyses were used to estimate the odds ratio of 30- and 90-day adverse outcomes associated with AKD and identify the risk factors of AKD.

Results

AKD was developed in 42.3% (419/990) of the study patients, with 186 in AKD stage 1, 107 in AKD stage 2, and 126 in AKD stage 3. Pediatric patients with AKD stages 2-3 had significantly higher rates of developing 30- and 90-day adverse outcomes than those with AKD stage 0 and 1. The adjusted odds ratio of AKD stage 2-3 was 12.18 (95% confidence interval (CI), 7.38 - 20.09) for 30-day adverse outcomes and decreased to 2.49 (95% CI, 1.26 - 4.91) for 90-day adverse outcomes. AKI stages 2 and 3, as well as glomerulonephritis, were the only predictive factors for AKD stage 2-3.

Conclusion

AKD is frequent among hospitalized pediatric AKI patients. AKD stage 2-3 represents a high-risk subpopulation among pediatric AKI survivors and is independently associated with 30- and 90-day adverse outcomes. Awareness of the potential risks associated with AKD stage 2-3 and its risk factors may help improve outcomes through careful monitoring and timely intervention.

Pathophysiology of Acute Kidney Injury in Malaria and Non-Malarial Febrile Illness: A Prospective Cohort Study

Acute kidney injury (AKI) is a life-threatening complication. Malaria and sepsis are leading causes of AKI in low-and-middle-income countries, but its etiology and pathogenesis are poorly understood. A prospective observational cohort study was conducted to evaluate pathways of immune and endothelial activation in children hospitalized with an acute febrile illness in Uganda. The relationship between clinical outcome and AKI, defined using the Kidney Disease: Improving Global Outcomes criteria, was investigated. The study included 967 participants (mean age 1.67 years, 44.7% female) with 687 (71.0%) positive for malaria by rapid diagnostic test and 280 (29.1%) children had a non-malarial febrile illness (NMFI). The frequency of AKI was higher in children with NMFI compared to malaria (AKI, 55.0% vs. 46.7%, p = 0.02). However, the frequency of severe AKI (stage 2 or 3 AKI) was comparable (12.1% vs. 10.5%, p = 0.45). Circulating markers of both immune and endothelial activation were associated with severe AKI. Children who had malaria and AKI had increased mortality (no AKI, 0.8% vs. AKI, 4.1%, p = 0.005), while there was no difference in mortality among children with NMFI (no AKI, 4.0% vs. AKI, 4.6%, p = 0.81). AKI is a common complication in children hospitalized with acute infections. Immune and endothelial activation appear to play central roles in the pathogenesis of AKI.

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

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