Recovery From Acute Kidney Injury and CKD Following Heart Transplantation in Children, Adolescents, and Young Adults: A Retrospective Cohort Study

Risk factors and renal outcomes of AKI in children with secondary steroid-resistant nephrotic syndrome

BACKGROUND

Acute kidney injury (AKI) is increasingly prevalent in children with nephrotic syndrome (NS). It is associated with adverse outcomes in NS, especially steroid-resistant nephrotic syndrome (SRNS). The incidence, risk factors and outcomes of AKI in secondary SRNS remain undefined. The main objectives of this study were to determine the risk factors and prognosis of AKI in hospitalized children with secondary SRNS.

MATERIAL AND METHODS

This retrospective study was conducted from January 2014 to December 2019, involving 172 hospitalizations with secondary SRNS admitted to the First Affiliated Hospital of Sun Yat-sen University. AKI was defined and classified in accordance with the 2012 Kidney Disease Improving Global Outcomes (KDIGO) guidelines.

RESULTS

AKI was found in 67 (39.0%) of 172 hospitalizations with secondary SRNS. Average age of onset in our group is 4.4 (3.1, 6.7) years with AKI and 3.7 (1.8, 5.6) years without AKI. Urea nitrogen level is 5.9 (4.1, 10.0) mmol/L with AKI and 5.1 (3.7, 7.0) mmol/L. Uric acid level is 446.0 (340.0, 567.0) umol/L with AKI and 401.0 (303.0, 496.0) umol/L. 24-h urinary protein level is 4.14 (2.9, 6.5) g with AKI and 2.5 (1.3, 5.3) without AKI. Multivariate logistic regression revealed that infection (OR = 5.287; 95% confidence interval, 2.349 to 11.899; p < 0.001), age at onset (OR = 1.180; 95% confidence interval, 1.032 to 1.349; p = 0.015) and uric acid level (OR = 1.003; 95% confidence interval, 1.000 to 1.006; p = 0.031) were significantly associated with the development of AKI in children with secondary SRNS. Among 72 children with secondary SRNS, six went to end-stage kidney disease (ESKD). Children in the AKI group were more likely to progress to ESKD compared with children in the non-AKI group (p = 0.017) with a median follow-up of 48.5months.

CONCLUSION

AKI occurred in 39.0% of total hospitalizations associated with secondary SRNS. Risk factors including infection, age of onset, and uric acid level are associated with AKI in children with secondary SRNS. Furthermore, AKI was identified as a risk factor for the progression of secondary SRNS to ESKD.

Pattern and prognostic factors for kidney function progression in survivors of children with acute kidney injury: a cohort study

OBJECTIVE

To examine the pattern of kidney function progression after acute kidney injury (AKI) and identify the associated risk factors.

DESIGN

A prospective cohort study was conducted from June 2020 to June 2021 on children aged 1 month to <18 years admitted to the paediatric intensive care unit (PICU). Acute kidney disease (AKD) was defined as AKI persisting from 7 to 90 days after diagnosis. The natural history and prognostic factors of kidney function progression were determined.

RESULTS

Among the 253 admissions with a median (IQR) age of 4.9 (9.7) years, the AKI and AKD incidence was 41.9% and 52.2% respectively. The incidence of estimated glomerular filtration rate (eGFR) <90 mL/min/1.73 m2 was 6.7% at 90 days and 11.9% at latest follow-up. Severe and prolonged AKI and higher degree of nephrotoxic medication exposure were associated with AKD development. The severity and duration of AKI and AKD significantly predicted kidney function non-recovery. Children with both entities exhibited a higher peak-to-baseline serum creatinine level ratio at 90 days (1.6 vs 1.0, p<0.001), and a more pronounced decline in eGFR (21% vs 19%, p=0.028) during the follow-up period compared with those without AKI/AKD. They also had an increased risk of having eGFR <90 mL/min/1.73 m2 at 90 days (HR 14.9 (95% CI 1.8 to 124.0)) and latest follow-up (HR 3.8 (95% CI 1.1 to 13.1)).

CONCLUSIONS

AKI and AKD are prevalent among critically ill children and pose substantial risk for non-recovery of kidney function among PICU survivors. A structural follow-up visit for AKI survivors to monitor kidney function progression is advocated.

Epidemiology of acute kidney injury in children: a report from the 26th Acute Disease Quality Initiative (ADQI) consensus conference

The nephrology and critical care communities have seen an increase in studies exploring acute kidney injury (AKI) epidemiology in children. As a result, we now know that AKI is highly prevalent in critically ill neonates, children, and young adults. Furthermore, children who develop AKI experience greater morbidity and higher mortality. Yet knowledge gaps still exist that suggest a more comprehensive understanding of AKI will form the foundation for future efforts designed to improve outcomes. In particular, the areas of community acquired AKI, AKI in non-critically ill children, and cohorts from low-middle income countries have not been well studied. Longer-term functional outcomes and patient-centric metrics including social determinants of health, quality of life, and healthcare utilization should be the foci of the next phase of scholarship. Current definitions identify AKI-based upon evidence of dysfunction which serves as a proxy for injury; biomarkers capable of identifying injury as it occurs are likely to more accurately define populations with AKI. Despite the strength of the association, the causal and mechanistic relationships between AKI and poorer outcomes remain inadequately examined. A more robust understanding of the relationship represents a potential to identify therapeutic targets. Once established, a more comprehensive understanding of AKI epidemiology in children will allow investigation of preventive, therapeutic, and quality improvement interventions more effectively.

Intraoperative and Postoperative Hemodynamic Predictors of Acute Kidney Injury in Pediatric Heart Transplant Recipients

Acute kidney injury (AKI) is common after pediatric heart transplantation (HT) and is associated with inferior patient outcomes. Hemodynamic risk factors for pediatric heart transplant recipients who experience AKI are not well described. We performed a retrospective review of 99 pediatric heart transplant patients at Lucile Packard Children's Hospital Stanford from January 1, 2015, to December 31, 2019, in which clinical and demographic characteristics, intraoperative perfusion data, and hemodynamic measurements in the first 48 postoperative hours were analyzed as risk factors for severe AKI (Kidney Disease: Improving Global Outcomes [KDIGO] stage ≥ 2). Univariate analysis was conducted using Fisher's exact test, Chi-square test, and the Wilcoxon rank-sum test, as appropriate. Multivariable analysis was conducted using logistic regression. Thirty-five patients (35%) experienced severe AKI which was associated with lower intraoperative cardiac index ( p  = 0.001), higher hematocrit ( p  < 0.001), lower body temperature ( p  < 0.001), lower renal near-infrared spectroscopy ( p  = 0.001), lower postoperative mean arterial blood pressure (MAP: p  = 0.001), and higher central venous pressure (CVP; p  < 0.001). In multivariable analysis, postoperative CVP >12 mm Hg (odds ratio [OR] = 4.27; 95% confidence interval [CI]: 1.48-12.3, p  = 0.007) and MAP <65 mm Hg (OR = 4.9; 95% CI: 1.07-22.5, p  = 0.04) were associated with early severe AKI. Children with severe AKI experienced longer ventilator, intensive care, and posttransplant hospital days and inferior survival ( p  = 0.01). Lower MAP and higher CVP are associated with severe AKI in pediatric HT recipients. Patients, who experienced AKI, experienced increased intensive care unit (ICU) morbidity and inferior survival. These data may guide the development of perioperative renal protective management strategies to reduce AKI incidence and improve patient outcomes.

A novel acute kidney injury scoring system for renal and clinical outcomes in pediatric heart transplant patients

BACKGROUND

The development of acute kidney injury (AKI) has been associated with worse outcomes in children after heart transplantation. Our study compares the application of a cumulative six-point Kidney Diseases Improving Global Outcomes (KDIGO) AKI scoring system, utilizing both creatinine and urine output criteria that we term as the AKI-6 criteria, to traditional AKI staging as a predictor for clinical and renal outcomes in the pediatric heart transplant recipients.

METHODS

We conducted a retrospective single-center chart review on 155 pediatric patients who underwent heart transplantation from May 2014 to December 2021. The primary independent variable was the presence of severe AKI. Severe AKI by KDIGO was defined as Stage ≥2, whereas severe AKI by AKI-6 was defined as cumulative scores ≥4 or Stage 3 AKI based on either KDIGO criterion alone. Primary outcomes included actuarial survival and renal dysfunction by 1-year post-transplant, defined as an estimated glomerular filtration rate <60 mL/min/1.73 m2 .

RESULTS

In total, 140 (90%) patients developed AKI; 98 (63%) patients developed severe AKI by KDIGO, and 60 (39%) by AKI-6. Severe AKI by AKI-6 was associated with worse actuarial survival following heart transplantation compared with KDIGO (p = 0.01). Of the 143 patients with 1-year creatinine data, 6 (11%) patients out of 54 with severe AKI by AKI-6 had evidence of renal dysfunction (p = 0.01), compared with 6 (7%) patients out of 88 by KDIGO (p = 0.3).

CONCLUSIONS

AKI-6 scoring provides greater prognostic utility for actuarial survival and renal dysfunction by 1-year post-heart transplantation in pediatric patients than traditional KDIGO staging.

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.

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.

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.

Acute kidney disease predicts chronic kidney disease in pediatric non-kidney solid organ transplant patients

BACKGROUND

Acute kidney disease (AKD) is defined as impaired kidney function present for <90 days with or without an acute kidney injury (AKI) event. Adults with AKD have an increased risk for progression to chronic kidney disease (CKD) and mortality. There are no data on the epidemiology of AKD in children after transplant. The aim of this study was to evaluate the incidence and risk factors for AKI, AKD, and CKD in children after transplantation.

METHODS

This is a retrospective cohort study of all children undergoing non-kidney solid organ transplant between 2011 and 2019 at UPMC Children's Hospital of Pittsburgh. AKI and AKD were defined using the Kidney Disease Improving Global Outcomes criteria. Patients with a new estimated glomerular filtration rate <60 ml/min/1.73m² persisting for >3 months met criteria for new CKD. Variables associated with AKI, AKD, and CKD were analyzed.

RESULTS

Among 338 patients, 37.9% met criteria for severe AKI, 13% for AKD, and 8% for a new diagnosis of CKD. Stage 3 AKI was independently associated with AKD (OR: 5.35; 95% CI: 2.23-12.86). Severe AKI was not associated with new-onset CKD, whereas AKD was associated with new-onset CKD (OR: 29.74; CI: 11.22-78.82).

CONCLUSION

AKD may be superior to AKI in predicting risk of CKD in children after non-kidney solid organ transplantation.

Postoperative physiological parameters associated with severe acute kidney injury after pediatric heart transplant

BACKGROUND

The primary objective was to evaluate associations between perioperative clinical variables and postoperative hemodynamic indices after HT with the development of severe AKI. The secondary objective was to evaluate associations between UOP or creatinine as AKI indicators and morbidity after HT.

METHODS

Retrospective study of all patients who underwent HT 1/2016-11/2019 at a quaternary pediatric institution. Severe AKI was defined as KDIGO stage 2 or higher.

RESULTS

Of 94 HT patients, 73 met inclusion criteria; 45% of patients developed severe AKI. In univariate analysis, non-Hispanic Black race, preoperative AKI, longer CPB duration, lower weight, and peak lactate within 12 h post-HT were associated with severe AKI. CVP ≤12 h post-HT had a quadratic relationship, rather than linear, with severe AKI. PPV >18% was significantly associated with severe AKI but equated to noncontiguous 10 min of high variation over a 12-h period, and thus was deemed not clinically significant. In multivariate analysis, Black race, longer CPB duration, and higher CVP remained associated with severe AKI (c: 0.84, 95% CI 0.73-0.92). Severe AKI per creatinine, but not UOP criteria, was associated with longer duration of ventilation (p = .012) and longer intensive care unit length of stay (p = .003).

CONCLUSIONS

In pediatric HT patients, non-Hispanic Black race, longer CPB time, and higher postoperative CVP ≤12 h post-HT were associated with severe AKI. AKI based on creatinine, not UOP, was associated with postoperative HT morbidity.

Cardiovascular health in pediatric heart transplant patients

BACKGROUND

Ideal "cardiovascular health" (CVH)-optimal diet, exercise, nonsmoking, BMI, BP, lipids, and glucose-is associated with healthy longevity in adults. Pediatric heart transplant (HT) patients may be at risk for suboptimal CVH.

METHODS

Single-center retrospective study of HT patients 2003-2014 who survived 1 year post-transplant. Five CVH metrics were collected at listing, 1, 3 and 5 years post-transplant (diet and exercise were unavailable). CVH was scored by summing individual metrics: ideal = 2, intermediate = 1, and poor = 0 points; total scores of 8-10 points were considered high (favorable). CVH was compared between HT patients and the US pediatric population (GP) utilizing NHANES 2007-2016. Logistic regression was performed to examine the association of CVH 1 year post-transplant with a composite adverse outcome (death, re-listing, coronary vasculopathy, or chronic kidney disease) 3 years post-transplant.

RESULTS

We included 110 HT patients (median age at HT: 6 years [range 0.1-21]) and 19,081 NHANES participants. CVH scores among HT patients were generally high at listing (75%), 1 (74%), 3 (87%) and 5 (76%) years post-transplant and similar to GP, but some metrics (e.g., glucose) were worse among HT patients. Among HT patients, CVH was poorer with older age and non-Caucasian race/ethnicity. Per 1-point higher CVH score, the demographic-adjusted OR for adverse outcomes was 0.95 (95% CI, 0.7-1.4).

CONCLUSIONS

HT patients had generally favorable CVH, but some metrics were unfavorable and CVH varied by age and race/ethnicity. No significant association was detected between CVH and adverse outcomes in this small sample, but study in a larger sample is warranted.

Persistent Markers of Kidney Injury in Children Who Developed Acute Kidney Injury After Pediatric Cardiac Surgery: A Prospective Cohort Study

Background

Acute kidney injury (AKI) after pediatric cardiac surgery is common. Longer‐term outcomes and the incidence of chronic kidney disease after AKI are not well‐known.

Methods and Results

All eligible children (aged <16 years) who had developed AKI following cardiac surgery at our tertiary referral hospital were prospectively invited for a formal kidney assessment ≈5 years after AKI, including measurements of estimated glomerular filtration rate, proteinuria, α₁‐microglobulin, blood pressure, and kidney ultrasound. Longer‐term follow‐up data on kidney function were collected at the latest available visit. Among 571 patients who underwent surgery, AKI occurred in 113 (19.7%) over a 4‐year period. Fifteen of these (13.3%) died at a median of 31 days (interquartile range [IQR], 9–57) after surgery. A total of 66 patients participated in the kidney assessment at a median of 4.8 years (IQR, 3.9–5.7) after the index AKI episode. Thirty‐nine patients (59.1%) had at least 1 marker of kidney injury, including estimated glomerular filtration rate <90 mL/min per 1.73 m² in 9 (13.6%), proteinuria in 27 (40.9%), α₁‐microglobinuria in 5 (7.6%), hypertension in 13 (19.7%), and abnormalities on kidney ultrasound in 9 (13.6%). Stages 1 to 5 chronic kidney disease were present in 18 (27.3%) patients. Patients with CKD were more likely to have an associated syndrome (55.6% versus 20.8%, P=0.015). At 13.1 years (IQR, 11.2–14.0) follow‐up, estimated glomerular filtration rate <90 mL/min per 1.73 m² was present in 18 of 49 patients (36.7%), suggesting an average estimated glomerular filtration rate decline rate of −1.81 mL/min per 1.73 m² per year.

Conclusions

Children who developed AKI after pediatric cardiac surgery showed persistent markers of kidney injury. As chronic kidney disease is a risk factor for cardiovascular comorbidity, long‐term kidney follow‐up in this population is warranted.

Risk factors of renal replacement therapy after heart transplantation: a retrospective single-center study

BACKGROUND

Acute kidney injury (AKI) and renal replacement therapy (RRT) are common after heart transplantation (HT). The need for RRT has been reported to be one of the most important predictors of a poor prognosis after HT. Therefore, it is important to early identify risk factors of RRT after HT. However, in the heart transplantation setting, the risk factors are less well studied, and some of the conclusions are controversial. This study aimed to identify the clinical predictors of RRT after HT.

METHODS

This single-center, retrospective study from January 2010 to June 2021 analyzed risk factors (pre-, intra-, and postoperative characteristics) of 163 patients who underwent HT. The endpoint of the study was RRT within 7 days of HT. Risk factors were analyzed by multivariable logistic regression models.

RESULTS

Fifty-five (33.74%) recipients required RRT within 7 days of HT. Factors independently associated with RRT after HT were as follows: a baseline estimated glomerular filtration rate (eGFR) <60 mL/min per 1.73 m² [odds ratio (OR) =3.123; 95% confidence interval (CI): 1.183-8.244; P=0.022], a dose of intraoperative methylprednisolone >10 mg/kg (OR =3.197; 95% CI: 1.290-7.923; P=0.012), the use of mechanical circulatory support (MCS) during surgery (OR =4.903; 95% CI: 1.628-14.766; P=0.005), a cardiopulmonary bypass (CPB) time ≥5 hours (OR =3.929; 95% CI: 1.222-12.634; P=0.022), and postoperative serum total bilirubin (TBIL) ≥60 umol/L (OR =5.105; 95% CI: 1.868-13.952; P=0.001). Protective factors were higher postoperative serum albumin (OR =0.907; 95% CI: 0.837-0.983; P=0.017) and higher postoperative left ventricular ejection fraction (LVEF) (OR =0.908; 95% CI: 0.838-0.985; P=0.020).

CONCLUSIONS

A low preoperative eGFR, a high intraoperative dose of methylprednisolone, a long CPB time, the use of mechanical circulatory support, and a high postoperative TBIL were risk factors for RRT after HT. While a high postoperative serum albumin level and a high left ventricular ejection fraction were protective factors. Understanding these risk factors may help us identify high-risk patients and intervene early.

Impact of a clinical pathway on acute kidney injury in patients undergoing heart transplant

BACKGROUND

To evaluate the impact of a clinical pathway on the incidence and severity of acute kidney injury in patients undergoing heart transplant.

METHODS

This was a 2.5-year retrospective evaluation using 3 years of historical controls within a cardiac intensive care unit in an academic children's hospital. Patients undergoing heart transplant between May 27, 2014, and April 5, 2017 (pre-pathway) and May 1, 2017, and November 30, 2019 (pathway) were included. The clinical pathway focused on supporting renal perfusion through hemodynamic management, avoiding or delaying nephrotoxic medications, and providing pharmacoprophylaxis against AKI.

RESULTS

There were 57 consecutive patients included. There was an unadjusted 20% reduction in incidence of any acute kidney injury (p = .05) and a 17% reduction in Stage 2/3 acute kidney injury (p = .09). In multivariable adjusted analysis, avoidance of Stage 2/3 acute kidney injury was independently associated with the clinical pathway era (AOR -1.3 [95% CI -2.5 to -0.2]; p = .03), achieving a central venous pressure of or less than 12 mmHg (AOR -1.3 [95% CI -2.4 to -0.2]; p = .03) and mean arterial pressure above 60 mmHg (AOR -1.6 [95% CI -3.1 to -0.01]; p = .05) in the first 48 h post-transplant, and older age at transplant (AOR - 0.2 [95% CI -0.2 to -0.06]; p = .002).

CONCLUSIONS

This report describes a renal protection clinical pathway associated with a reduction in perioperative acute kidney injury in patients undergoing heart transplant and highlights the importance of normalizing perioperative central venous pressure and mean arterial blood pressure to support optimal renal perfusion.

Acute kidney injury and kidney recovery after cardiopulmonary bypass in children

BACKGROUND

Acute kidney injury (AKI) that improves in the pediatric intensive care unit (PICU) is associated with better outcomes compared to AKI that persists, but no study has investigated whether this also occurs in children undergoing cardiopulmonary bypass (CPB).

METHODS

A retrospective study of children ≤18 years who underwent CPB in three children's hospitals was conducted. Patients were classified into groups by kidney recovery after AKI according to Acute Disease Quality Initiative (ADQI) guidelines. Adjusted regression models evaluated associations between kidney recovery group and hospital outcomes.

RESULTS

Among 3620 children, AKI developed in 701 (19.4%): 610 transient AKI, 47 persistent AKI, and 44 acute kidney disease (AKD). Mortality increased with severity of kidney recovery group: 4.5% in the never developed AKI group, 8.9% in the transient AKI group, 25.5% in the persistent AKI group, and 31.8% in the AKD group (p <0.0001). In adjusted analysis, transient AKI (HR 1.4, CI 1.02, 2), persistent AKI (HR 22.4, CI 10.2, 49.2), and AKD (HR 3.7, CI 1.7, 7.9) had a greater hazard of mortality when compared to the never developed AKI group. Patients with transient AKI had a longer length of PICU stay than those with never developed AKI (HR 5.1, CI 2.9, 7.3).

CONCLUSIONS

Patterns of kidney recovery after AKI were associated with worse PICU outcomes in children after CPB compared to those who did not develop AKI, even after rapid AKI recovery. Identification of factors that increase risk for these AKI patterns is necessary for prevention of AKI during CPB in children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Acute kidney injury in the pediatric intensive care unit: outpatient follow-up

BACKGROUND

Few studies have characterized follow-up after pediatric acute kidney injury (AKI). Our aim was to describe outpatient AKI follow-up after pediatric intensive care unit (PICU) admission.

METHODS

Two-center retrospective cohort study (0-18 years; PICU survivors (2003-2005); noncardiac surgery; and no baseline kidney disease). Provincial administrative databases were used to determine outcomes.

EXPOSURE

AKI (KDIGO (Kidney Disease: Improving Global Outcomes) definitions).

OUTCOMES

post-discharge nephrology, family physician, pediatrician, and non-nephrology specialist visits. Regression was used to evaluate factors associated with the presence of nephrology follow-up (Cox) and the number of nephrology and family physician or pediatrician visits (Poisson), among AKI survivors.

RESULTS

Of n = 2041, 355 (17%) had any AKI; 64/355 (18%) had nephrology; 198 (56%) had family physician or pediatrician; and 338 (95%) had family physician, pediatrician, or non-nephrology specialist follow-up by 1 year post discharge. Only 44/142 (31%) stage 2-3 AKI patients had nephrology follow-up by 1 year. Inpatient nephrology consult (adjusted hazard ratio (aHR) 7.76 [95% confidence interval (CI) 4.89-12.30]), kidney admission diagnosis (aHR 4.26 [2.21-8.18]), and AKI non-recovery by discharge (aHR 2.65 [1.55-4.55]) were associated with 1-year nephrology follow-up among any AKI survivors.

CONCLUSIONS

Nephrology follow-up after AKI was uncommon, but nearly all AKI survivors had follow-up with non-nephrologist physicians. This suggests that AKI follow-up knowledge translation strategies for non-nephrology providers should be a priority.

IMPACT

Pediatric AKI survivors have high long-term rates of chronic kidney disease (CKD) and hypertension, justifying regular kidney health surveillance after AKI. However, there is limited pediatric data on follow-up after AKI, including the factors associated with nephrology referral and extent of non-nephrology follow-up. We found that only one-fifth of all AKI survivors and one-third of severe AKI (stage 2-3) survivors have nephrology follow-up within 1 year post discharge. However, 95% are seen by a family physician, pediatrician, or non-nephrology specialist within 1 year post discharge. This suggests that knowledge translation strategies for AKI follow-up should be targeted at non-nephrology healthcare providers.

Risk factors and occurrence of chronic kidney disease following acute kidney injury in Children

Background

Chronic kidney disease (CKD) is an irreversible progressive condition with diverse etiologies among which acute kidney injury (AKI) is increasingly being recognized as an important one.

Methods

This was a prospective observational study of pediatric intensive care unit (PICU) patients admitted with different etiologies, at a tertiary care hospital for children in Kashmir India, between October 2018 and September 2020. AKI was defined as an increase in absolute serum creatinine (SCr) ≥0.3 mg/dL or by a percentage increase in SCr 50% and/or by a decrease in urine output to <0.5 mL/kg/h for >6 hours (h). Besides analysis of AKI and associated PICU mortality, post-AKI patients after discharge were kept on follow-up for complete 1 year.

Results

From 119 enrolled patients with AKI with no preexisting risk factors, 5.6% (n = 8/119) developed CKD. The AKI-associated mortality rate after 48 h of PICU stay was 13.4% (n = 16/119). At time of discharge from hospital, elevated blood pressure (BP) (n = 5/8) and subnephrotic proteinuria (n = 3/8) were the statistically significant sequels of AKI (P value <0.001) for progression to CKD. After 3 months of follow-up, elevated BP (n = 7/8) and subnephrotic proteinuria (n = 3/8) were significantly associated with progression to CKD at 1 year (P < 0.005).

Conclusions

Occurrence of CKD after an attack of AKI was not uncommon and the risk of long-term consequences in the form of hypertension, proteinuria, and CKD is significant, which may be much higher than observed. It is prudent that all post-AKI PICU discharged patients must be monitored for the long-term consequences of AKI.

Using kinetic eGFR to identify acute kidney injury risk in children undergoing cardiac transplantation

BACKGROUND

Acute kidney injury (AKI) is common following pediatric cardiac transplantation. Since no treatments exist, strategies focus on early identification and prevention. Kinetic glomerular filtration rate (kGFR) was developed to assess renal function in the non-steady state. Although used to predict AKI in adults, kGFR has not been explored in children. Our study examines AKI and the ability of kGFR to identify AKI risk in pediatric heart transplant recipients.

METHODS

One hundred and seventy-five patients under 21 years who underwent cardiac transplantation at Lucile Packard Children's Hospital between September 2007-December 2017 were included. kGFR₁ was calculated using pre-operative and immediate post-operative creatinines; kGFR₂ was calculated with the first two post-operative creatinines. The primary outcome was AKI as defined by the Kidney Disease: Improving Global Outcomes criteria.

RESULTS

One hundred and thirty-one (75%) and 78 (45%) patients developed AKI and severe AKI, respectively; 5 (2.9%) required dialysis. kGFR was moderately associated with post-operative AKI risk. The adjusted area under the curve (AUC) for kGFR₁ was 0.72 (discovery) and 0.65 (validation). The AUC for kGFR₂ was 0.72 (discovery) and 0.68 (validation).

CONCLUSIONS

AKI is pervasive in children undergoing cardiac transplant, particularly in the 24 h after surgery. kGFR moderately identifies AKI risk and may represent a novel risk stratification technique.

IMPACT

Our research suggests that kGFR, a dynamic assessment of renal function that uses readily available laboratory values, can moderately identify AKI risk in children undergoing cardiac transplantation. Current published studies on kGFR are in adult populations; this study represents the first formal study of kGFR in a pediatric population. kGFR may serve as an early AKI indicator, allowing providers to implement preventative strategies sooner in a patient's clinical course.

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

BACKGROUND

AKI is common during pediatric hospitalizations and associated with adverse short-term outcomes. However, long-term outcomes among survivors of pediatric AKI who received dialysis remain uncertain.

METHODS

To determine the long-term risk of kidney failure (defined as receipt of chronic dialysis or kidney transplant) or death over a 22-year period for pediatric survivors of dialysis-treated AKI, we used province-wide health administrative databases to perform a retrospective cohort study of all neonates and children (aged 0-18 years) hospitalized in Ontario, Canada, from April 1, 1996, to March 31, 2017, who survived a dialysis-treated AKI episode. Each AKI survivor was matched to four hospitalized pediatric comparators without dialysis-treated AKI, on the basis of age, sex, and admission year. We reported the incidence of each outcome and performed Cox proportional hazards regression analyses, adjusting for relevant covariates.

RESULTS

We identified 1688 pediatric dialysis-treated AKI survivors (median age 5 years) and 6752 matched comparators. Among AKI survivors, 53.7% underwent mechanical ventilation and 33.6% had cardiac surgery. During a median 9.6-year follow-up, AKI survivors were at significantly increased risk of a composite outcome of kidney failure or death versus comparators. Death occurred in 113 (6.7%) AKI survivors, 44 (2.6%) developed kidney failure, 174 (12.1%) developed hypertension, 213 (13.1%) developed CKD, and 237 (14.0%) had subsequent AKI. AKI survivors had significantly higher risks of developing CKD and hypertension versus comparators. Risks were greatest in the first year after discharge and gradually decreased over time.

CONCLUSIONS

Survivors of pediatric dialysis-treated AKI are at higher long-term risks of kidney failure, death, CKD, and hypertension, compared with a matched hospitalized cohort.

Malaria-Associated Acute Kidney Injury in African Children: Prevalence, Pathophysiology, Impact, and Management Challenges

Acute kidney injury (AKI) is emerging as a complication of increasing clinical importance associated with substantial morbidity and mortality in African children with severe malaria. Using the Kidney Disease: Improving Global Outcomes (KDIGO) criteria to define AKI, an estimated 24–59% of African children with severe malaria have AKI with most AKI community-acquired. AKI is a risk factor for mortality in pediatric severe malaria with a stepwise increase in mortality across AKI stages. AKI is also a risk factor for post-discharge mortality and is associated with increased long-term risk of neurocognitive impairment and behavioral problems in survivors. Following injury, the kidney undergoes a process of recovery and repair. AKI is an established risk factor for chronic kidney disease and hypertension in survivors and is associated with an increased risk of chronic kidney disease in severe malaria survivors. The magnitude of the risk and contribution of malaria-associated AKI to chronic kidney disease in malaria-endemic areas remains undetermined. Pathways associated with AKI pathogenesis in the context of pediatric severe malaria are not well understood, but there is emerging evidence that immune activation, endothelial dysfunction, and hemolysis-mediated oxidative stress all directly contribute to kidney injury. In this review, we outline the KDIGO bundle of care and highlight how this could be applied in the context of severe malaria to improve kidney perfusion, reduce AKI progression, and improve survival. With increased recognition that AKI in severe malaria is associated with substantial post-discharge morbidity and long-term risk of chronic kidney disease, there is a need to increase AKI recognition through enhanced access to creatinine-based and next-generation biomarker diagnostics. Long-term studies to assess severe malaria-associated AKI’s impact on long-term health in malaria-endemic areas are urgently needed.

Cumulative Application of Creatinine and Urine Output Staging Optimizes the Kidney Disease: Improving Global Outcomes Definition and Identifies Increased Mortality Risk in Hospitalized Patients With Acute Kidney Injury

OBJECTIVES

Acute kidney injury is diagnosed according to creatinine and urine output criteria. Traditionally, both are applied, and a severity stage (1-3) is conferred based upon the more severe of the two; information from the other criteria is discarded. Physiologically, however, rising creatinine and oliguria represent two distinct types of renal dysfunction. We hypothesized that using the information from both criteria would more accurately characterize acute kidney injury severity and outcomes.

DESIGN

Prospective cohort study.

SETTING

Multicenter, international collaborative of ICUs.

PATIENTS

Three thousand four hundred twenty-nine children and young adults admitted consecutively to ICUs as part of the Assessment of the Worldwide Acute Kidney Injury, Renal Angina and Epidemiology Study.

MEASUREMENTS AND MAIN RESULTS

The Kidney Disease: Improving Global Outcomes creatinine and urine output acute kidney injury criteria were applied sequentially, and the two stages were summed, generating an Acute Kidney Injury (AKI) Score ranging from 1 to 6. The primary outcome was 28-day mortality; secondary outcomes were time until ICU discharge and nonrecovery from acute kidney injury. Models considered associations with AKI Score, assessing the relationship unadjusted and adjusted for covariates. Twenty-eight-day mortality and nonrecovery from acute kidney injury were modeled using logistic regression. For 28-day ICU discharge, competing risks analysis was performed. Although AKI Scores 1-3 had similar mortality to no Acute Kidney Injury, AKI Scores 4-6 were associated with increased mortality. Relative to No Acute Kidney Injury, AKI Scores 1-6 were less likely to be discharged from the ICU within 28 days. Relative to AKI Score 1, AKI Scores 2-6 were associated with higher risk of nonrecovery. Within the traditional Kidney Disease: Improving Global Outcomes Stage 3 acute kidney injury cohort, when compared with AKI Score 3, AKI Scores 4-6 had increased mortality, AKI Scores 5-6 had prolonged time to ICU discharge, and AKI Score 6 experienced higher nonrecovery rates.

CONCLUSIONS

Cumulative application of the creatinine and urine output criteria characterizes renal excretory and fluid homeostatic dysfunction simultaneously. This Acute Kidney Injury score more comprehensively describes the outcome implications of severe acute kidney injury than traditional staging methods.

Acute Kidney Injury in Pediatric Cardiac Intensive Care Children: Not All Admissions Are Equal: A Retrospective Study

OBJECTIVES

To describe the incidence, associated characteristics, and outcomes of the maximum severity of acute kidney injury (AKI) in a heterogeneous population of critically ill children with cardiac disease.

DESIGN

Retrospective cohort study.

SETTING

Pediatric cardiac intensive care unit (PCICU).

PARTICIPANTS

Patients admitted to the PCICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

From January 2018 to July 2020 all patients admitted to a tertiary PCICU were included. Only the first admission was considered. Neonates ≤seven days old were excluded. Of 742 patients, 53 were medical cases, 69 catheterization laboratory cases, and 620 surgical cases (with five subgroups). The median age was 2.47 years (interquartile range [IQR], 0.38-9.85 years), with a median Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery score of 2 (IQR, 1-3). Median PCICU length of stay was three days (IQR, 2-7 days), and 21 (2.8%) patients died. Any incidence of AKI occurred in 70% of patients, 26% of which were classified as mild (stage 1) and 43% as severe (stages 2 and 3). AKI was diagnosed by urine output criteria in 56%, serum creatinine in 28%, and both in 16% of patients. Severe AKI occurred in subgroups as follows: medical (38%), catheterization laboratory (45%), correction (35%), palliation (55%), transplantation (85%), mechanical assistance (70%), and redo surgery (58%). Severe AKI patients were significantly older (p = 0.004), had a higher Pediatric Index of Mortality 3 score (p = 0.0004), had a higher cumulative fluid balance (p < 0.0001), and had a longer cardiopulmonary bypass time (p < 0.0001). Early AKI (≤24 hours from admission) was the most frequent presentation, with a greater proportion of severe cases in the early group compared with the intermediate (>24 and ≤48 hours) and late (>48 hours) (p < 0.0001) groups. Presentation of late severe AKI had a higher mortality (odds ratio, 4.9; 95% confidence interval, 1.8-15; p = 0.001).

CONCLUSIONS

Severe AKI occurs in 43% of cardiac children and is diagnosed early, most often by urine output criteria. Severe AKI incidence varies significantly within subgroups of cardiac patients. Late AKI is associated with worse outcomes.

Acute Kidney Injury in Critically Ill Children Is Not all Acute: Lessons Over the Last 5 Years

Acute kidney injury (AKI) in the pediatric intensive care unit (PICU) is an important risk factor for increased morbidity and mortality during hospitalization. Over the past decade, accumulated data on children and young people indicates that acute episodes of kidney dysfunction can have lasting consequences on multiple organ systems and health outcomes. To date, there are no guidelines for follow-up of surviving children that may be at risk of long-term sequelae following AKI in the PICU. This narrative review aims to describe literature from the last 5 years on the risk of medium and long-term kidney and non-kidney outcomes after AKI in the PICU. More specifically, we will focus on outcomes in children and young people following AKI in the general PICU population and children undergoing cardiac surgery. These outcomes include mortality, hypertension, proteinuria, chronic kidney disease, and healthcare utilization. We also aim to highlight current gaps in knowledge in medium and long-term outcomes in this pediatric population. We suggest a framework for future research to develop evidence-based guidelines for follow-up of children surviving an episode of critical illness and AKI.

Acute kidney injury and chronic kidney disease after combined heart-liver transplant in patients with congenital heart disease: A retrospective case series

Although it is known that children undergoing heart transplantation are at increased risk for both AKI and CKD, renal function following CHLT remains understudied. All pediatric CHLT patients from 2006 to 2019 were included. The prevalence of AKI in the first 7 post-operative days, renal recovery at 30 post-operative days, and CKD were ascertained. AKI was defined as an increase in creatinine greater than 1.5 times baseline, and CKD, as an eCrCl less than 90 mL/min/1.73 m² . The need for RRT was also analyzed. 10 patients were included, with an average age of 20 years and an average listing time of 130 days. Preoperatively, the median eCrCl was 91.12 mL/min/m² (IQR 70.51, 127.75 min/mL/m² ). 5 (50%) patients had CKD, with 4 at stage 2 and 1 at stage 3. AKI occurred post-operatively in 3 of 9 (33%) patients: 2 at stage 1 and 1 at stage 2. 2 (67%) resolved by 7 days. Of the 5 patients who reached their 1-year follow-up, 1 (20%) had stage 3 CKD. Among 2 patients, neither had CKD at 5 years. One patient required RRT 2 weeks after CHLT. Despite an increased prevalence of preoperative CKD, patients undergoing CHLT have a lower AKI prevalence than those receiving an isolated heart or liver transplant. Of those with AKI, early renal recovery is common, although at 1 year CKD remains present in 20%. Among long-term survivors, normal renal function is achievable.

A coordinated approach to improving pediatric heart transplant waitlist outcomes: A summary of the ACTION November 2019 waitlist outcomes committee meeting

The number of children needing heart transplantation continues to rise. Although improvements in heart failure therapy, particularly durable mechanical support, have reduced waitlist mortality, the number of children who die while waiting for a suitable donor organ remains unacceptably high. Roughly, 13% of children and 25% of infants on the heart transplant waitlist will not survive to transplantation. With this in mind, the Advanced Cardiac Therapies Improving Outcomes Collaborative Learning Network (ACTION), through its Waitlist Outcomes Committee, convened a 2-day symposium in Ann Arbor, Michigan, from 2-3 November 2019, to better understand the factors that contribute to pediatric heart transplant waitlist mortality and to focus future efforts on improving the organ allocation rates for children needing heart transplantation. Using improvement science methodology, the heart failure-transplant trajectory was broken down into six key steps, after which modes of failure and opportunities for improvement at each step were discussed. As a result, several projects aimed at reducing waitlist mortality were initiated.

Acute kidney injury and chronic kidney disease after non-kidney solid organ transplantation

BACKGROUND

SOT is the treatment of choice for end-stage organ disease. Improved long-term survival after NKSOT has uncovered chronic morbidity including CKD. AKI is common after NKSOT and may be associated with long-term CKD.

METHODS

We performed a retrospective cohort study looking at AKI and CKD after pediatric heart (n = 109) or liver (n = 112) transplant. AKI was defined using KDIGO creatinine-based criteria. pAKI was AKI ≤ 7 days post-transplant; CKD_3-5 was eGFR < 60 mL/min/1.73 m² by modified Schwartz formula for > 3 months. We looked at the incidence of CKD_3-5 and the effect of perioperative pAKI on the slope of eGFR post-transplant.

RESULTS

pAKI was seen in 63% (n = 69) after heart and 38% (n = 43) after liver transplant. pAKI was associated with longer ICU and hospital stays. Cumulative incidence (95% CI) of CKD_3-5 at 60 months post-heart transplant was 40.9% (27.9%-57.1%) in patients with AKI vs 35.8% (17.1%-64.8%) in those without (P = NS). Post-liver transplant, the cumulative incidence of CKD_3-5 at 60 months was 0% in those without pAKI vs 10% (3.2%-29.3%) in those with (P = .01). Patients with pAKI had lower eGFR at last follow-up.

CONCLUSION

pAKI and CKD are common after NKSOT. Incidence of CKD is higher in those with pAKI. AKI episodes are associated with a drop in eGFR during follow-up. Identifying patients who have had AKI is an important first step in identifying those at risk of repeated AKI episodes. These patients would benefit from closer monitoring for CKD, lower nephrotoxic drug use, and follow-up with nephrology.

Kidney and blood pressure abnormalities 6 years after acute kidney injury in critically ill children: a prospective cohort study

BACKGROUND

Acute kidney injury (AKI) in pediatric intensive care unit (PICU) children may be associated with long-term chronic kidney disease or hypertension.

OBJECTIVES

To estimate (1) prevalence of kidney abnormalities (low estimated glomerular filtration rate (eGFR) or albuminuria) and blood pressure (BP) consistent with pre-hypertension or hypertension, 6 years after PICU admission; (2) if AKI is associated with these outcomes.

METHODS

Longitudinal study of children admitted to two Canadian PICUs (January 2005-December 2011). Exposures (retrospective): AKI or stage 2/3 AKI (KDIGO creatinine-based definition) during PICU. Primary outcome (single visit 6 years after admission): presence of (a) low eGFR (<90 ml/min/1.73 m²) or albuminuria (albumin to creatinine ratio >30 mg/g) (termed "CKD signs") or (b) BP consistent with ≥pre-hypertension (≥90th percentile) or hypertension (≥95th percentile).

RESULTS

Of 277 children, 25% had AKI. AKI and stage 2/3 AKI were associated with 2.2- and 6.6-fold higher adjusted odds, respectively, for the 6-year outcomes. Applying new hypertension guidelines attenuated associations; stage 2/3 AKI was associated with 4.5-fold higher adjusted odds for 6-year CKD signs or ≥elevated BP.

CONCLUSIONS

Kidney and BP abnormalities are common 6 years after PICU admission and associated with AKI. Other risk factors must be elucidated to develop follow-up recommendations and reduce cardiovascular risk.

Effects of hyperchloremia on renal recovery in critically ill children with acute kidney injury

BACKGROUND

Serum chloride derangements are associated with poor clinical outcomes, including acute kidney injury (AKI) and mortality. We sought to determine the association between persistent hyperchloremia and renal recovery in critically ill children with AKI.

METHODS

We performed a retrospective cohort study of all patients with day 2 AKI admitted to a large academic pediatric intensive care unit from January 2014 to December 2015. After applying exclusion criteria, 348 patients were categorized as (1) hyperchloremia on both day 2 and day 7 (PersistentCl), (2) hyperchloremia on day 2 with normochloremia on day 7 (RecoveredCl), (3) normochloremia on day 2 with hyperchloremia on day 7 (DelayedCl), and (4) no hyperchloremia on day 2 nor day 7 (NormalCl). Hyperchloremia was defined as ≥ 110 mEq/L. The primary outcome was renal recovery on day 7, defined as the absence of AKI criteria. Secondary outcomes included discharge renal recovery, mortality, duration of mechanical ventilation, and hospital length of stay.

RESULTS

Day 7 renal recovery rates for PersistentCl, RecoveredCl, DelayedCl, and NormalCl were 37%, 66%, 71%, and 52% respectively. PersistentCl had lower odds of day 7 renal recovery (aOR = 0.29; 95% CI, 0.14 to 0.60; p = 0.0009), lower odds of discharge renal recovery (aOR = 0.22; 95% CI, 0.11 to 0.48; p = 0.0001), and higher odds of mortality (aOR = 3.50; 95% CI, 1.11 to 11.10; p = 0.03) when compared with RecoveredCl after adjusting for confounders.

CONCLUSIONS

Persistent hyperchloremia is independently associated with impaired renal recovery as well as higher mortality. Prospective studies are indicated to determine if serum chloride represents a modifiable risk factor for poor outcomes. Graphical abstract.

Long-term complications of acute kidney injury in children

PURPOSE OF REVIEW

The current review will describe the current evidence and mechanisms of acute kidney injury (AKI) as a risk factor for long-term kidney complications, summarize the rationale for AKI follow-up and present an approach to monitoring children with AKI. Despite emerging evidence linking AKI with risk for long-term kidney and cardiovascular outcomes, many children who develop AKI are not followed for kidney disease development after hospital discharge. Better understanding of long-term complications after AKI and practical algorithms for follow-up will hopefully increase the rate and quality of post-AKI monitoring.

RECENT FINDINGS

Recent evidence shows that pediatric AKI is associated with long-term renal outcomes such as chronic kidney disease (CKD) and hypertension, both known to increase cardiovascular risk. The mechanism of AKI progression to CKD involves maladaptive regeneration of tubular epithelial and endothelial cells, inflammation, fibrosis and glomerulosclerosis. Many AKI survivors are not followed, and no guidelines for pediatric AKI follow-up have been published.

SUMMARY

Children who had AKI are at increased risk of long-term renal complications but many of them are not monitored for these complications. Recognizing long-term outcomes post-AKI and integration of follow-up programs may have a long-lasting positive impact on patient health.

Acute kidney injury in hospitalized children: consequences and outcomes

Over the past decade, the nephrology and critical care communities have adopted a consensus approach to diagnosing acute kidney injury (AKI) and, as a result, we have seen transformative changes in our understanding of pediatric AKI epidemiology. The data regarding outcomes among neonates and children who develop AKI have become far more robust and AKI has been clearly linked with an increased need for mechanical ventilation, longer inpatient stays, and higher mortality. Though AKI was historically thought to be self-limited, we now know that renal recovery is far from universal, particularly when AKI is severe; the absence of recovery from AKI also carries longitudinal prognostic implications. AKI survivors, especially those without full recovery, are at risk for chronic renal sequelae including proteinuria, hypertension, and chronic kidney disease. This review comprehensively describes AKI-related outcomes across the entire pediatric age spectrum, using the most rigorous studies to identify the independent effects of AKI events.

Long-term Mortality After Acute Kidney Injury in the Pediatric ICU

OBJECTIVES

(1) To evaluate the association between acute kidney injury (AKI) in the PICU and long-term mortality and (2) to determine the extent to which adding the urine output (UO)-defined AKI alters the association.

METHODS

A 2-center retrospective cohort study of children (≤18 years old) admitted to the PICU between 2003 and 2005 for noncardiac surgery, with follow-up until 2010. Patients with end stage renal disease, no provincial health insurance number, who died during hospitalization, or could not be linked to administrative data were excluded. One hospitalization per patient was included. AKI was defined by using serum creatinine criteria and/or UO criteria. Mortality was ascertained by using administrative data. Cox regression analysis was performed to evaluate the association between AKI and long-term mortality.

RESULTS

The study population included 2041 patients (55.7% male, mean admission age 6.5 ± 5.8 years). Of 2041 hospital survivors, 9 (0.4%) died within 30 days, 51 (2.5%) died within 1 year, and 118 (5.8%) died within 5 to 7 years postdischarge. AKI was independently associated with 5- to 7-year mortality (adjusted hazard ratio [95% confidence interval]: 3.10 [1.46-6.57] and 3.38 [1.63-7.02], respectively). Including UO did not strengthen the association.

CONCLUSIONS

AKI is associated with 5- to 7-year mortality. Because this is an observational study we cannot determine if AKI is causative of mortality or of the pathophysiology. However, patients with AKI represent a high-risk group. It is reasonable that these patients be considered for targeted follow-up until future researchers better elucidate these relationships.

Acute Kidney Injury in Critically Ill Children and Subsequent Chronic Kidney Disease

BACKGROUND

The progression from acute kidney injury (AKI) to chronic kidney disease (CKD) is not well understood in children.

OBJECTIVES

We aimed to develop a pediatric CKD definition using administrative data and use it to evaluate the association between AKI in critically ill children and CKD 5 years after hospital discharge.

DESIGN

Retrospective cohort study using chart collection and administrative data.

SETTING

Two-center study in Montreal, Canada.

PATIENTS

Children (≤18 years old) admitted to two pediatric intensive care units (ICUs) between 2003 and 2005. We a priori excluded patients with end-stage renal disease or no health care number. Only the first admission during the study period was included. We excluded patients who could not be linked to administrative data, did not survive hospitalization, or had preexisting renal disease.

MEASUREMENTS

Acute kidney injury was defined using Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Patients were defined as having CKD 5 years post-discharge if they had ≥1 CKD diagnostic code or ≥1 CKD-specific medication prescription.

METHODS

Chart data used to define the exposure (AKI) were merged with provincial administrative data used to define the outcome (CKD). Cox regression was used to evaluate the AKI-CKD association.

RESULTS

A total of 2235 (56% male) patients were included, and the median admission age was 3.7 years. A total of 464 (21%) patients developed AKI during pediatric ICU admission. At 5 years post-discharge, 43 (2%) patients had a CKD diagnosis. Patients with both stage 1 and stage 2-3 AKI had increased risk of a CKD diagnosis, with the adjusted hazard ratios (95% confidence intervals) of 2.2 (1.1-4.5) and 2.5 (1.1-5.7), respectively (P < .001).

LIMITATIONS

Results may not be generalizable to non-ICU patients. We were not able to control for post-discharge variables; future research should try to explore these additional potential risk factors further.

CONCLUSIONS

Acute kidney injury is associated with 5-year post-discharge CKD diagnosis defined by administrative health care data.

Renal injury and recovery in pediatric patients after ventricular assist device implantation and cardiac transplant

BACKGROUND

The use of ventricular assist devices (VADs) in children with heart failure may be of particular benefit to those with accompanying renal failure, as improved renal function is seen in some, but not all recipients. We hypothesized that persistent renal dysfunction at 7 days and/or 1 month after VAD implantation would predict chronic kidney disease (CKD) 1 year after heart transplantation (HT).

METHODS

Linkage analysis of all VAD patients enrolled in both the PEDIMACS and PHTS registries between 2012 and 2016. Persistent acute kidney injury (P-AKI), defined as a serum creatinine ≥1.5× baseline, was assessed at post-implant day 7. Estimated glomerular filtration rate (eGFR) was determined at implant, 30 days thereafter, and 12 months post-HT. Pre-implant eGFR, eGFR normalization (to ≥90 mL/min/1.73 m² ), and P-AKI were used to predict post-HT CKD (eGFR <90 mL/min/1.73 m² ).

RESULTS

The mean implant eGFR was 85.4 ± 46.5 mL/min/1.73 m² . P-AKI was present in 19/188 (10%). Mean eGFR at 1 month post-VAD implant was 131.1 ± 62.1 mL/min/1.73 m² , significantly increased above baseline (P < 0.001). At 1 year post-HT (n = 133), 60 (45%) had CKD. Lower pre-implant eGFR was associated with post-HT CKD (OR 0.99, CI: 0.97-0.99, P = 0.005); P-AKI was not (OR 0.96, CI: 0.3-3.0, P = 0.9). Failure to normalize renal function 30 days after implant was highly associated with CKD at 1 year post-transplant (OR 12.5, CI 2.8-55, P = 0.003).

CONCLUSIONS

Renal function improves after VAD implantation. Lower pre-implant eGFR and failure to normalize renal function during the support period are risk factors for CKD development after HT.

Postoperative Acute Kidney Injury in Young Adults With Congenital Heart Disease

BACKGROUND

There is an increasing number of young adults living with congenital heart disease (CHD). The goal of this study was to ascertain the frequency of acute kidney injury (AKI) as well as the risk factors and outcomes associated with AKI in young adults with CHD after a surgical procedure.

METHODS

This was a single-center retrospective cohort study including all patients 18 to 40 years of age with a diagnosis of CHD admitted to a quaternary care children's hospital cardiac intensive care unit postoperatively from 2004 to 2015. We defined AKI using the Kidney Disease Improving Global Outcomes criteria for serum creatinine. We explored potential susceptibilities and exposures for AKI using multivariable logistic regression and determined the association of AKI with duration of mechanical ventilation and length of stay using Poisson regression.

RESULTS

In 699 consecutively admitted patients AKI occurred in 13.2%. Suspected sepsis (odds ratio [OR], 2.87; 95% confidence interval [CI], 1.17 to 7.05), exposure to calcineurin inhibitors (OR, 5.80; 95% CI, 1.06 to 31.59), vancomycin (OR, 3.35; 95% CI, 1.11 to 10.14), and piperacillin-tazobactam (OR, 4.12; 95% CI, 1.23 to 13.78) increased the odds of AKI even after controlling for age, ejection fraction, recent cardiac catheterization, repeat cardiopulmonary bypass, bypass time, cross-clamp time, and other potential nephrotoxic medications. AKI was associated with a longer duration of mechanical ventilation (OR, 1.47; 95% CI, 1.15 to 1.89) and intensive care unit length of stay (OR, 1.50; 95% CI, 1.30 to 1.72).

CONCLUSIONS

AKI is common in young adults with CHD postoperatively and is associated with negative outcomes. The results highlight the importance future research and clinical efforts aimed at prevention and improved management of AKI in this patient group.

Big Data and Pediatric Acute Kidney Injury: The Promise of Electronic Health Record Systems

Over the last decade, our understanding of acute kidney injury (AKI) has evolved considerably. The development of a consensus definition standardized the approach to identifying and investigating AKI in children. As a result, pediatric AKI epidemiology has been refined and the consequences of renal injury are better established. Similarly, "big data" methodologies experienced a dramatic evolution and maturation, leading the critical care community to explore potential AKI/big data synergies. One such concept with tremendous potential is electronic health record (EHR) enabled informatics. Much of the promise surrounding these approaches is due to the unique position of the EHR which sits at the intersection of data accumulation and care delivery. EHR data is generated simply via the provision of routine clinical care and should be considered "big" from the standpoint of volume, variety, and velocity as a myriad of diverse elements accumulate rapidly in real time, spontaneously generating an immense dataset. This massive dataset interfaces directly with providers which creates tremendous opportunity. AKI can be diagnosed more accurately, AKI-related care can be optimized, and subsequent outcomes can be improved. Although applying big data concepts to the EHR has proven more challenging than originally thought, we have seen much success and continue to explore its potential. In this review article, we will discuss the EHR in the context of big data concepts, describe approaches applied to date, examine the challenges surrounding optimal application, and explore future directions.

Nephrotoxin exposure and acute kidney injury in critically ill children undergoing congenital cardiac surgery

BACKGROUND

Though acute kidney injury (AKI) is often multifactorial, investigators are now emphasizing the specific contribution of nephrotoxins. This study examines the epidemiology of nephrotoxin exposure and nephrotoxin-associated AKI among children undergoing congenital heart surgery (CHS).

METHODS

This is a retrospective cohort study of children admitted following CHS between June 1, 2014, and September 30, 2014. Nephrotoxins were defined according to the Nephrotoxic Injury Negated by Just-in-time-Action (NINJA) collaborative; high nephrotoxin exposure was defined as receipt of ≥ 3 nephrotoxins concurrently. AKI was diagnosed according to KDIGO creatinine criteria. Severe AKI was defined as KDIGO stage ≥ 2. Poisson models were used to compute adjusted relative risk (aRR) of high nephrotoxin exposure for AKI.

RESULTS

One hundred fifty-four children (median age 20.4 months, IQR 2.3-59.5) were included. One hundred thirty-one (85.1%) received at least one nephrotoxin; 32 (20.8%) received ≥ 3 nephrotoxins. The most commonly administered medications were ketorolac (n = 74, 48.1%), aspirin (n = 62, 40.3%), ibuprofen (n = 51, 33.1%), vancomycin (n = 39, 25.3%), piperacillin/tazobactam (n = 35, 22.7%), and enalapril (n = 14, 9.1%). AKI occurred more commonly in those exposed to ≥ 3 nephrotoxins (62.5 vs. 50.8%); this was not statistically significant after adjusting for confounders (aRR = 1.2, 95% CI 0.9-1.7). Severe AKI was similar between those with and without high nephrotoxin exposure (21.9 vs. 19.7%, p = 0.78).

CONCLUSIONS

Nephrotoxin use is common following pediatric CHS. While we found no association between high nephrotoxin exposure and AKI, this may be related to the multifactorial nature of AKI in this population. For many common nephrotoxins, less injurious agents exist and nephrotoxin exposure may represent a modifiable risk factor for AKI.

Pediatric acute kidney injury and the subsequent risk for chronic kidney disease: is there cause for alarm?

Acute kidney injury (AKI) is characterized clinically as an abrupt decline in renal function marked by reduced excretion of waste products, disordered electrolytes, and disrupted fluid homeostasis. The recent development of a standardized AKI definition has transformed our understanding of AKI epidemiology and outcomes. We now know that in the short term, children with AKI experience greater morbidity and mortality; additionally, observational studies have established that chronic renal sequelae are far more common after AKI events than previously realized. Many of these studies suggest that patients who develop AKI are at greater risk for the subsequent development of chronic kidney disease (CKD). The goal of this review is to critically evaluate the data regarding the association between AKI and CKD in children. Additionally, we describe best practice approaches for future studies, including the use of consensus AKI criteria, the application of rigorous definitions for CKD and renal sequelae, and the inclusion of non-AKI comparator groups. Finally, based upon existing data, we suggest an archetypal approach to follow-up care for the AKI survivors who may be at greater CKD risk, including children with more severe AKI, those who endure repeated AKI episodes, patients who do not experience full recovery, and those with pre-existing CKD.

Electronic Health Record-Enabled Big-Data Approaches to Nephrotoxin-Associated Acute Kidney Injury Risk Prediction

Nephrotoxin-associated acute kidney injury (NTx-AKI) has become one of the most common causes of AKI among hospitalized adults and children; across acute and intensive care populations, exposure to nephrotoxins accounts for 15-25% of AKI cases. Although some interventions have shown promise in observational studies, no treatments currently exist for NTx-AKI once it occurs. Thus, nearly all effective strategies are aimed at prevention. The primary obstacle to prevention is risk prediction and the determination of which patients are more likely to develop NTx-AKI when exposed to medications with nephrotoxic potential. Historically, traditional statistical modeling has been applied to previously recognized clinical risk factors to identify predictors of NTx-AKI. However, increased electronic health record adoption and the evolution of "big-data" approaches to predictive analytics may offer a unique opportunity to prevent NTx-AKI events. This article describes prior and current approaches to NTx-AKI prediction and offers three novel use cases for electronic health record-enabled NTx-AKI forecasting and risk profiling.

Healthcare Utilization after Acute Kidney Injury in the Pediatric Intensive Care Unit

BACKGROUND AND OBJECTIVES

Little is known about the long-term burden of AKI in the pediatric intensive care unit. We aim to evaluate if pediatric AKI is associated with higher health service use post-hospital discharge.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is a retrospective cohort study of children (≤18 years old) admitted to two tertiary centers in Montreal, Canada. Only the first admission per patient was included. AKI was defined in two ways: serum creatinine alone or serum creatinine and/or urine output. The outcomes were 30-day, 1-year, and 5-year hospitalizations, emergency room visits, and physician visits per person-time using provincial administrative data. Univariable and multivariable Poisson regression were used to evaluate AKI associations with outcomes.

RESULTS

A total of 2041 children were included (56% male, mean admission age 6.5±5.8 years); 299 of 1575 (19%) developed AKI defined using serum creatinine alone, and when urine output was included in the AKI definition 355 of 1622 (22%) children developed AKI. AKI defined using serum creatinine alone and AKI defined using serum creatinine and urine output were both associated with higher 1- and 5-year hospitalization risk (AKI by serum creatinine alone adjusted relative risk, 1.42; 95% confidence interval, 1.12 to 1.82; and 1.80; 1.54 to 2.11, respectively [similar when urine output was included]) and higher 5-year physician visits (adjusted relative risk, 1.26; 95% confidence interval, 1.14 to 1.39). AKI was not associated with emergency room use after adjustments.

CONCLUSIONS

AKI is independently associated with higher hospitalizations and physician visits postdischarge.

Is acute kidney injury a harbinger for chronic kidney disease?

PURPOSE OF REVIEW

Despite abundant evidence in adults, the relationship between acute kidney injury (AKI) and chronic kidney disease (CKD) remains unanswered in pediatrics. Obstacles to overcome include the challenges defining these entities and the lack of long-term follow-up studies. This review focuses on pediatric populations at high-risk for AKI, the evidence of the long-term effect of AKI on renal health, and biomarkers to detect renal disease.

RECENT FINDINGS

AKI in critically ill children and neonates is common and independently associated with adverse outcomes. Patients with diabetes and sickle cell disease along with neonates with necrotizing enterocolitis have been identified as high-risk for AKI. Preterm birth and neonates with AKI have signs of renal dysfunction early in childhood. Urinary biomarkers may identify AKI and CKD earlier than traditional biomarkers, but more work is necessary to determine their clinical utility. Promising technological advances including the ability to determine nephron number noninvasively will expand our ability to characterize the AKI to CKD transition.

SUMMARY

AKI is common and associated with poor outcomes. It is probable that AKI is a harbinger to CKD in pediatric populations. However, we currently lack the tools to definitely answer this question and more research is needed.

Acute Kidney Injury in Children

Acute kidney injury (AKI) has become one of the more common complications seen among hospitalized children. The development of a consensus definition has helped refine the epidemiology of pediatric AKI, and we now have a far better understanding of its incidence, risk factors, and outcomes. Strategies for diagnosing AKI have extended beyond serum creatinine, and the most current data underscore the diagnostic importance of oliguria as well as introduce the concept of urinary biomarkers of kidney injury. As AKI has become more widespread, we have seen that it is associated with a number of adverse consequences including longer lengths of stay and greater mortality. Though effective treatments do not currently exist for AKI once it develops, we hope that the diagnostic and definitional strides seen recently translate to the testing and development of more effective interventions.

Renal Function Follow-Up and Renal Recovery After Acute Kidney Injury in Critically Ill Children

OBJECTIVES

To evaluate factors associated with renal recovery from acute kidney injury in critically ill children and the extent to which serum creatinine is measured before discharge.

DESIGN

Retrospective cohort study.

SETTING

Two PICUs at tertiary centers in Montreal, QC, Canada.

PATIENTS

Children (< 18 yr old) admitted to the PICU between 2003 and 2005. Patients with end-stage renal disease, no healthcare number, died during admission, or admitted postcardiac surgery were excluded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Acute kidney injury was defined using internationally accepted criteria (Kidney Disease: Improving Global Outcomes). Two renal recovery outcomes commonly used in the literature were evaluated: hospital discharge serum creatinine less than 1.5 and less than 1.15 times baseline. Proportions of patients with 1) serum creatinine measurements between PICU and hospital discharge and 2) renal recovery were calculated. Univariate and multivariate analyses were performed to determine factors associated with serum creatinine monitoring and nonrecovery after acute kidney injury. Of 2,033 patients included, 829 (40.8%) had serum creatinine measurements between PICU and hospital discharge. The odds of having a discharge serum creatinine measurement increased with acute kidney injury severity (stages 1, 2, 3 adjusted odds ratio [95% CI]: 1.49 [1.03-2.15], 2.52 [1.40-4.54], 7.87 [3.16-19.60], respectively). Acute kidney injury recovery was 92.5% when defined as serum creatinine less than 1.5 times baseline versus 75.9% when defined as less than 1.15 times baseline (p < 0.001). Stage 3 acute kidney injury was associated with having a discharge serum creatinine greater than or equal to 1.5 times baseline (adjusted odds ratio = 3.51 [1.33-9.19]).

CONCLUSIONS

Less than half the PICU population had serum creatinine measured before hospital discharge. More severe acute kidney injury was associated with higher likelihood of serum creatinine monitoring and lower probability of acute kidney injury recovery. Future research should address knowledge translation on post-PICU acute kidney injury follow-up before hospital discharge.

Leveraging Big Data and Electronic Health Records to Enhance Novel Approaches to Acute Kidney Injury Research and Care

While acute kidney injury (AKI) has been poorly defined historically, a decade of effort has culminated in a standardized, consensus definition. In parallel, electronic health records (EHRs) have been adopted with greater regularity, clinical informatics approaches have been refined, and the field of EHR-enabled care improvement and research has burgeoned. Although both fields have matured in isolation, uniting the 2 has the capacity to redefine AKI-related care and research. This article describes how the application of a consistent AKI definition to the EHR dataset can accurately and rapidly diagnose and identify AKI events. Furthermore, this electronic, automated diagnostic strategy creates the opportunity to develop predictive approaches, optimize AKI alerts, and trace AKI events across institutions, care platforms, and administrative datasets.

Stop adding insult to injury-identifying and managing risk factors for the progression of acute kidney injury in children

Acute kidney injury (AKI) is common in children admitted to hospital. Whilst some recover normal kidney function following an acute kidney insult, a significant proportion experience long-term sequelae. The aim of this review is to summarize current understanding of the processes that can lead to sequelae following AKI. Kidney injury, repair, recovery and progression are described. Risk factors for progression are outlined, and potential strategies to stratify the risk of progression in children with AKI are discussed. Clinical management priorities to minimize sequelae are suggested. Looking ahead, novel therapeutic targets are discussed with the potential to accelerate adaptive repair and ameliorate the progression and sequelae of AKI in the future.