Use of height-independent baseline creatinine imputation method with renal angina index

Fifteen-year temporal changes in rates of acute kidney injury among children in Denmark

BACKGROUND

We aimed to examine temporal changes in the annual rate of acute kidney injury (AKI) in Danish children and associated changes in patient characteristics including potential underlying risk factors.

METHODS

In this population-based cohort study, we used plasma creatinine measurements from Danish laboratory databases to identify AKI episodes in children aged 0-17 years from 2007 to 2021. For each child, the first AKI episode per calendar year was included. We estimated the annual crude and sex- and age-standardized AKI rate as the number of children with an AKI episode divided by the total number of children as reported by census numbers. Using Danish medical databases, we assessed patient characteristics including potential risk factors for AKI, such as use of nephrotoxic medication, surgery, sepsis, and perinatal factors.

RESULTS

In total, 14,200 children contributed with 16,345 AKI episodes over 15 years. The mean annual AKI rate was 148 (95% CI: 141-155) per 100,000 children. From 2007 to 2021, the annual AKI rate demonstrated minor year-to-year variability without any discernible overall trend. The highest AKI rate was recorded in 2007 at 174 (95% CI: 161-187) per 100,000 children, while the lowest rate occurred in 2012 at 129 (95% CI: 118-140) per 100,000 children. In 2021, the AKI rate was 148 (95% CI: 141-155) per 100,000 children. Characteristics of children with AKI were similar throughout the study period.

CONCLUSION

The rate of AKI among Danish children was stable from 2007 to 2021 with little variation in patient characteristics over time.

Real-Time Acute Kidney Injury Risk Stratification-Biomarker Directed Fluid Management Improves Outcomes in Critically Ill Children and Young Adults

Introduction

Critically ill admitted patients are at high risk of acute kidney injury (AKI). The renal angina index (RAI) and urinary biomarker neutrophil gelatinase-associated lipocalin (uNGAL) can aid in AKI risk assessment. We implemented the Trial in AKI using NGAL and Fluid Overload to optimize CRRT Use (TAKING FOCUS 2; TF2) to personalize fluid management and continuous renal replacement therapy (CRRT) initiation based on AKI risk and patient fluid accumulation. We compared outcomes pre-TF2 and post-TF2 initiation.

Methods

Patients admitted from July 2017 were followed-up prospectively with the following: (i) an automated RAI result at 12 hours of admission, (ii) a conditional uNGAL order for RAI ≥8, and (iii) a CRRT initiation goal at 10% to 15% weight-based fluid accumulation.

Results

A total of 286 patients comprised 304 intensive care unit (ICU) RAI+ admissions; 178 patients received CRRT over the observation period (2014-2021). Median time from ICU admission to CRRT initiation was 2 days shorter (P < 0.002), and ≥15% pre-CRRT fluid accumulation rate was lower in the TF2 era (P < 0.02). TF2 ICU length of stay (LOS) after CRRT discontinuation and total ICU LOS were 6 and 11 days shorter for CRRT survivors (both P < 0.02). Survival rates to ICU discharge after CRRT discontinuation were higher in the TF2 era (P = 0.001). These associations persisted in each TF2 year; we estimate a conservative $12,500 health care cost savings per CRRT patient treated after TF2 implementation.

Conclusion

We suggest that automated clinical decision support (CDS) combining risk stratification and AKI biomarker assessment can produce durable reductions in pediatric CRRT patient morbidity.

External validation of the modified sepsis renal angina index for prediction of severe acute kidney injury in children with septic shock

BACKGROUND

Acute kidney injury (AKI) occurs commonly in pediatric septic shock and increases morbidity and mortality. Early identification of high-risk patients can facilitate targeted intervention to improve outcomes. We previously modified the renal angina index (RAI), a validated AKI prediction tool, to improve specificity in this population (sRAI). Here, we prospectively assess sRAI performance in a separate cohort.

METHODS

A secondary analysis of a prospective, multicenter, observational study of children with septic shock admitted to the pediatric intensive care unit from 1/2019 to 12/2022. The primary outcome was severe AKI (≥ KDIGO Stage 2) on Day 3 (D3 severe AKI), and we compared predictive performance of the sRAI (calculated on Day 1) to the original RAI and serum creatinine elevation above baseline (D1 SCr > Baseline +). Original renal angina fulfillment (RAI +) was defined as RAI ≥ 8; sepsis renal angina fulfillment (sRAI +) was defined as RAI ≥ 20 or RAI 8 to < 20 with platelets < 150 × 103/µL.

RESULTS

Among 363 patients, 79 (22%) developed D3 severe AKI. One hundred forty (39%) were sRAI + , 195 (54%) RAI + , and 253 (70%) D1 SCr > Baseline + . Compared to sRAI-, sRAI + had higher risk of D3 severe AKI (RR 8.9, 95%CI 5-16, p < 0.001), kidney replacement therapy (KRT) (RR 18, 95%CI 6.6-49, p < 0.001), and mortality (RR 2.5, 95%CI 1.2-5.5, p = 0.013). sRAI predicted D3 severe AKI with an AUROC of 0.86 (95%CI 0.82-0.90), with greater specificity (74%) than D1 SCr > Baseline (36%) and RAI + (58%). On multivariable regression, sRAI + retained associations with D3 severe AKI (aOR 4.5, 95%CI 2.0-10.2, p < 0.001) and need for KRT (aOR 5.6, 95%CI 1.5-21.5, p = 0.01).

CONCLUSIONS

Prediction of severe AKI in pediatric septic shock is important to improve outcomes, allocate resources, and inform enrollment in clinical trials examining potential disease-modifying therapies. The sRAI affords more accurate and specific prediction than context-free SCr elevation or the original RAI in this population.

Fluid Overload Precedes and Masks Cryptic Kidney Injury in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

Given the complex interrelatedness of fluid overload (FO), creatinine, acute kidney injury (AKI), and clinical outcomes, the association of AKI with poor outcomes in critically ill children may be underestimated due to definitions used. We aimed to disentangle these temporal relationships in a large cohort of children with acute respiratory distress syndrome (ARDS).

DESIGN

Retrospective cohort study.

SETTING

Quaternary care PICU.

PATIENTS

Seven hundred twenty intubated children with ARDS between 2011 and 2019.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Daily fluid balance, urine output (UOP), and creatinine for days 1-7 of ARDS were retrospectively abstracted. A subset of patients had angiopoietin 2 (ANGPT2) quantified on days 1, 3, and 7. Patients were classified as AKI by Kidney Disease Improving Global Outcomes (KDIGO) stage 2/3 then grouped by timing of AKI onset (early if days 1-3 of ARDS, late if days 4-7 of ARDS, persistent if both) for comparison of PICU mortality and ventilator-free days (VFDs). A final category of "Cryptic AKI" was used to identify subjects who met KDIGO stage 2/3 criteria only when creatinine was adjusted for FO. Outcomes were compared between those who had Cryptic AKI identified by FO-adjusted creatinine versus those who had no AKI. Conventionally defined AKI occurred in 26% of patients (early 10%, late 3%, persistent 13%). AKI was associated with higher mortality and fewer VFDs, with no differences according to timing of onset. The Cryptic AKI group (6% of those labeled no AKI) had higher mortality and fewer VFDs than patients who did not meet AKI with FO-adjusted creatinine. FO, FO-adjusted creatinine, and ANGPT2 increased 1 day prior to meeting AKI criteria in the late AKI group.

CONCLUSIONS

AKI was associated with higher mortality and fewer VFDs in pediatric ARDS, irrespective of timing. FO-adjusted creatinine captures a group of patients with Cryptic AKI with outcomes approaching those who meet AKI by traditional criteria. Increases in FO, FO-adjusted creatinine, and ANGPT2 occur prior to meeting conventional AKI criteria.

Derivation and evaluation of baseline creatinine equations for hospitalized children and adolescents: the AKI baseline creatinine equation

BACKGROUND

Acute kidney injury (AKI) definitions incorporate baseline creatinine (Cr_b) values, but Cr_b are frequently unknown in pediatrics. Our primary aim was to derive and validate a novel AKI Baseline Creatinine (ABC) estimation equation and compare it to existing methods of estimating Cr_b values.

METHODS

We conducted a single-center retrospective analysis of pediatric patients (0-25 years) admitted from 2012 to 2019. Included patients required at least one outpatient Cr_b prior to hospitalization (gold standard). Novel equations were developed with demographic and initial creatinine data. Existing methods included back-calculating Cr_b based on Schwartz, Full Age Spectrum (FAS), and CKiD-under-25 (U25) equations. To determine an optimal equation, we compared novel and existing equations to the gold standard.

RESULTS

The optimal simplified equation (ABC) included only age and had R² = 59.9% and 73.2% of values within 30% of true Cr_b. The precision increased significantly when the equation included age and minimum creatinine within initial 72 h (ABC-cr): R² = 75.4% and 86.5% of values within 30% of true Cr_b. The best performing existing equation was the age-based FAS, which had R² = 61.0% and 78.0% of values within 30% of true Cr_b. All other existing equations performed worse, some methods as low as 52.6% within 30% of true Cr_b.

CONCLUSIONS

The newly derived ABC equation is simple, and the ABC-cr equation can more accurately estimate Cr_b by ≥ 25% compared to previous methods. The potential applicability of these equations is vast, including faster recognition of AKI on initial patient contact and improved standardization of pediatric AKI definitions, enhancing health services research. A higher resolution version of the Graphical abstract is available as Supplementary information.

Risk Factors for Sepsis-Associated Acute Kidney Injury in the PICU: A Retrospective Cohort Study

OBJECTIVES

Acute kidney injury (AKI), particularly of greater severity and longer duration, is associated with increased morbidity and mortality in the pediatric population. AKI frequently occurs during sepsis, yet the knowledge of risk factors for sepsis-associated AKI in the PICU is limited. We aimed to identify risk factors for AKI that develops or persists after 72 hours from sepsis recognition in pediatric patients with severe sepsis.

DESIGN

Retrospective cohort study.

SETTING

PICU at an academic, tertiary-care center.

PATIENTS

Children greater than 1 month and less than or equal to 18 years with severe sepsis in the combined cardiac and medical/surgical PICU between December 1, 2013, and December 31, 2020, at the University of Virginia Children's Hospital.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The cohort included 124 patients with severe sepsis with 33 patients (27%) who were postcardiac surgery with cardiopulmonary bypass. AKI was defined by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. The primary outcome was severe AKI, defined as KDIGO stage 2 or 3 AKI present at any point between days 3 and 7 after sepsis recognition. Severe AKI was present in 25 patients (20%). Factors independently associated with severe AKI were maximum vasoactive-inotropic score (VIS) within 48 hours after sepsis recognition and fluid overload. The presence of severe AKI was associated with increased inhospital mortality.

CONCLUSIONS

In children with severe sepsis, the degree of hemodynamic support as measured by the VIS and the presence of fluid overload may identify patients at increased risk of developing severe AKI.

Integration of the Renal Angina Index and Urine Neutrophil Gelatinase Associated Lipocalin Improves Severe AKI Prediction in Critically Ill Children and Young Adults

Introduction

Acute kidney injury (AKI) occurs in one-fourth of children and young adults admitted to pediatric intensive care unit (PICU). Severe AKI (sAKI; Kidney Disease: Improving Global Outcomes stage 2 or 3) is associated with morbidity and mortality. An AKI risk stratification system, the Renal Angina Index (RAI) calculated at 12 hours of admission, exhibits excellent performance to rule out sAKI at 72 hours of admission. We found that integration of urine neutrophil gelatinase-associated lipocalin (NGAL) with RAI improves prediction of sAKI. We now report the first-year results after implementation of our prospective automated RAI-NGAL clinical decision support (CDS) program.

Methods

Patients 3 months to 25 years of age were eligible. Admission order sets have a conditional order for urine NGAL released when a 12-hour RAI ≥8. The primary outcome was sAKI any time at days 2 to 4 of admission. We assessed performance of the RAI and RAI+/NGAL to predict the primary outcome.

Results

A total of 1427 unique patients accounted for 1575 admissions. In 147 admissions, RAI was ≥8. RAI <8 had negative predictive value (NPV) of 0.98 (95% CI 0.97–0.99); RAI ≥ 8 had positive predictive value (PPV) of 0.37 (95% CI 0.30–0.46) to predict days 2 to 4 sAKI (area under the receiver operating characteristic curve [AUC-ROC] 0.88 [95% CI 0.84–0.92]). Of 147 RAI+ patients, 89 had NGAL available. RAI/NGAL combination improved PPV (0.64, 95% CI 0.50–0.79) without decrement in NPV (0.98, 95% CI 0.97–0.98).

Conclusion

AKI biomarker assessment directed by risk stratification improves prediction of sAKI in critically ill children and young adults. This CDS process has potential to enrich the population for interventional study, although improvement to adherence to CDS is needed.

Assessment of the renal angina index for the prediction of acute kidney injury in patients admitted to a European pediatric intensive care unit

BACKGROUND

Acute kidney injury (AKI) is associated with worse outcomes and increased morbidity and mortality in pediatric intensive care unit (PICU) patients. The renal angina index (RAI) has been proposed as an early prediction tool for AKI development.

OBJECTIVES

The objective was to evaluate outcomes of RAI-positive patients and to compare RAI performance with traditional AKI markers across different patient groups (medical/post-surgical). This was an observational retrospective study. All children admitted to a tertiary hospital PICU over a 3-year period were included. Electronic medical records were reviewed. Day 1 RAI was calculated, as was the presence and staging of day 3 AKI.

RESULTS

A total of 593 patients were included; 56% were male, the mean age was 55 months, and 17% had a positive RAI. This was associated with day 3 AKI development and worse outcomes, such as greater need for kidney replacement therapy, longer duration of mechanical ventilation, vasoactive support and PICU stay, and higher mortality. For all-stage kidney injury, RAI presented a sensitivity of 87.5% and a specificity of 88.1%. Prediction of day 3 all-stage AKI by RAI had an AUC=0.878; its performance increased for severe AKI (AUC = 0.93). RAI was superior to serum creatinine increase and KDIGO AKI staging on day 1 in predicting severe AKI development. The performance remained high irrespective of the type of admission.

CONCLUSIONS

The RAI is a simple and inexpensive tool that can be used with medical and post-surgical PICU patients to predict AKI development and anticipate complications, allowing for the adoption of preventive measures.

Recalibration of the Renal Angina Index for Pediatric Septic Shock

Introduction

Sepsis-associated acute kidney injury (AKI) is a common diagnosis in children that is associated with poor outcomes. The lack of therapeutic options once present makes early identification of at-risk patients essential. The renal angina index (RAI) has been previously validated to predict severe AKI in heterogeneous populations of critically ill children. The performance of this score specifically in children with septic shock is unknown.

Methods

A secondary analysis of a multicenter, prospective, observational study of 379 children with septic shock to determine the ability of the RAI to predict severe AKI at day 3, and to assess for the potential need for recalibration of the RAI in this unique subset of patients.

Results

At the original cutoff of ≥8, the RAI predicted day 3 severe AKI with an area under the receiving operating characteristic (AUROC) curve 0.90 (95% confidence interval [CI]: 0.86 to 93), 95% sensitivity, and 54% specificity. A Youden's index identified a higher optimal cutoff of ≥20 (sensitivity 83%, specificity 80%), and day 1 platelet count <150 × 10³/μl was an independent predictor of severe AKI (adjusted odds ratio: 3.2; 95% CI: 1.7 to 6.3; P < 0.001). Recalibration of the RAI to include platelet count and this new threshold restored the sensitivity of the original ≥8 threshold (95%), while improving its specificity (69%).

Conclusions

The RAI appears to be a sensitive and reliable tool for prediction of severe AKI in children with septic shock, although the use of a recalibrated sepsis-specific RAI using a higher cutoff and platelet count may be beneficial.

Re-evaluating Renal Angina Index: An Authentic, Evidence-Based Instrument for Acute Kidney Injury Assessment: Critical Appraisal

Background/Introduction: Renal angina index (RAI) used to calculate and accurately predict risk for the development of acute kidney injury (AKI) has been heavily explored. AKI is traditionally diagnosed by an increase in serum creatinine (SCr) concentration or oliguria, both of which are neither specific nor sensitive, especially among children. An RAI score may be calculated by combining objective signs of kidney dysfunction (such as SCr) and patient context, such as AKI risk factors, thus potentially serving as a more accurate indicator for AKI. Objective: Due to the propitious and novel nature of RAI, this editorial commentary aims to analyze the current literature on RAI and determine how well RAI serves as a predictor of AKI outcomes. Method: A comprehensive literature search was conducted in PubMed/Medline and Google Scholar between January 2012 and July 2020. Literature included the prognostic aspect of early prediction of AKI in the pediatric and adult population via RAI. Results: The initial literature search included 149 studies, and a total of 10 studies reporting the outcomes of interest were included. The overall sample size across these studies was 11,026. The predictive ability of RAI had a pooled (95% CI) sensitivity of 79.21%, specificity of 73.22%, and negative predictive value of 94.83%. Conclusion: RAI shows benefit in the prediction of AKI among adult and pediatric populations. However, there is a lack of sufficient data, and further prospective studies are needed in pediatric populations to use RAI as a principal AKI indicator among clinicians.

Identifying critically ill children at high risk of acute kidney injury and renal replacement therapy

Acute kidney injury (AKI), a common complication in paediatric intensive care units (PICU), is associated with increased morbidity and mortality. In this single centre, prospective, observational cohort study, neutrophil gelatinase-associated lipocalin in urine (uNGAL) and plasma (pNGAL) and renal angina index (RAI), and combinations of these markers, were assessed for their ability to predict severe (stage 2 or 3) AKI in children and young people admitted to PICU. In PICU children and young people had initial and serial uNGAL and pNGAL measurements, RAI calculation on day 1, and collection of clinical data, including serum creatinine measurements. Primary outcomes were severe AKI and renal replacement therapy (RRT). Secondary outcomes were length of stay, hospital acquired infection and mortality. The area under the Receiver Operating Characteristic (ROC) curves and Youden index was used to determine biomarker performance and identify optimum cut-off values. Of 657 children recruited, 104 met criteria for severe AKI (15∙8%) and 47 (7∙2%) required RRT. Severe AKI was associated with increased length of stay, hospital acquired infection, and mortality. The area under the curve (AUC) for severe AKI prediction for Day 1 uNGAL, Day 1 pNGAL and RAI were 0.75 (95% Confidence Interval [CI] 0∙69, 0∙81), 0∙64 (95% CI 0∙56, 0∙72), and 0.73 (95% CI 0∙65, 0∙80) respectively. The optimal combination of measures was RAI and day 1 uNGAL, giving an AUC of 0∙80 for severe AKI prediction (95% CI 0∙71, 0∙88). In this heterogenous PICU cohort, urine or plasma NGAL in isolation had poorer prediction accuracy for severe AKI than in previously reported homogeneous populations. However, when combined together with RAI, they produced good prediction for severe AKI.

Acute Kidney Injury: Diagnosis and Management

Pediatric medicine is growing in complexity and an increasing number of children with co-morbidities are exposed to potential renal damage. Initially ill-defined and thought to be mostly a transient phenomenon in children, acute kidney injury (AKI) has now emerged as a complex clinical syndrome independently associated with increased mortality and morbidity, including the development of chronic renal sequelae. Recent advances in molecular nephrology have better elucidated the early phase of AKI, where evidence of renal tissue damage is associated with adverse outcomes even without decrease in glomerular filtration rate, illustrating the flaws of the old paradigm based solely on an insensitive filtration marker, the serum creatinine. Prevention, prompt evaluation and early interventions are of essence to decrease AKI incidence and severity. Emerging data reveal that AKI is commonly encountered in hospitalized children, especially critically ill ones, hence the importance for all clinicians to be able to identify high risk patients, recognize AKI early and be comfortable with the initial medical management. In recent years, significant advances have been made in AKI definition and prediction, allowing early preventive measures in high risk children that are now proven to reduce AKI incidence. This review covers recent advances in the diagnosis, risk stratification, prevention and management of AKI in children.

PERSEVERE Biomarkers Predict Severe Acute Kidney Injury and Renal Recovery in Pediatric Septic Shock

Rationale: Acute kidney injury (AKI), a common complication of sepsis, is associated with substantial morbidity and mortality and lacks definitive disease-modifying therapy. Early, reliable identification of at-risk patients is important for targeted implementation of renal protective measures. The updated Pediatric Sepsis Biomarker Risk Model (PERSEVERE-II) is a validated, multibiomarker prognostic enrichment strategy to estimate baseline mortality risk in pediatric septic shock.Objectives: To assess the association between PERSEVERE-II mortality probability and the development of severe, sepsis-associated AKI on Day 3 (D3 SA-AKI) in pediatric septic shock.Methods: We performed secondary analysis of a prospective observational study of children with septic shock in whom the PERSEVERE biomarkers were measured to assign a PERSEVERE-II baseline mortality risk.Measurements and Main Results: Among 379 patients, 65 (17%) developed severe D3 SA-AKI. The proportion of patients developing severe D3 SA-AKI increased directly with increasing PERSEVERE-II risk category, and increasing PERSEVERE-II mortality probability was independently associated with increased odds of severe D3 SA-AKI after adjustment for age and illness severity (odds ratio, 1.4; 95% confidence interval, 1.2-1.7; P < 0.001). Similar associations were found between increasing PERSEVERE-II mortality probability and the need for renal replacement therapy. Lower PERSEVERE-II mortality probability was independently associated with increased odds of renal recovery among patients with early AKI. A newly derived model incorporating the PERSEVERE biomarkers and Day 1 AKI status predicted severe D3 SA-AKI with an area under the received operating characteristic curve of 0.95 (95% confidence interval, 0.92-0.98).Conclusions: Among children with septic shock, the PERSEVERE biomarkers predict severe D3 SA-AKI and identify patients with early AKI who are likely to recover.

Early Sequential Risk Stratification Assessment to Optimize Fluid Dosing, CRRT Initiation and Discontinuation in Critically Ill Children with Acute Kidney Injury: Taking Focus 2 Process Article

BACKGROUND

Acute Kidney Injury (AKI) is common in critically ill children and is associated with increased morbidity and mortality. Recognition and management of AKI is often delayed, predisposing patients to risk of clinically significant fluid accumulation (Fluid Overload (FO)). Early recognition and intervention in high risk patients could decrease fluid associated morbidity. We aim to assess an AKI Clinical Decision Algorithm (CDA) using a sequential risk stratification strategy integrating the Renal Angina Index (RAI), urine Neutrophil Gelatinase-Associated Lipocalin (NGAL) and the Furosemide Stress Test (FST) to optimize AKI and FO prediction and management in critically ill children.

METHODS/DESIGN

This single center prospective observational cohort study evaluates the AKI CDA in a Pediatric Intensive Care Unit (PICU). Every patient ≥ 3 months old has the risk score RAI calculated automatically at 12 hours of admission. Patients with a RAI ≥ 8 (fulfilling renal angina) have risk further stratified with a urine NGAL and, if positive (NGAL ≥ 150ng/mL), subsequently by their response to a standardized dose of furosemide (namely FST). RAI negative or NGAL negative patients are treated per usual care. FST-responders are managed conservatively, while non-responders receive fluid restrictive strategy and/or continuous renal replacement therapy (CRRT) at 10%-15% of FO. 2100 patients over 3 years will be evaluated to capture 210 patients with severe AKI (KDIGO Stage 2 or 3 AKI), 100 patients with >10% FO, and 50 requiring CRRT. Primary analyses: Standardizing a pediatric FST and assessing prediction accuracy of CDA for severe AKI, FO>10% and CRRT requirement in children. Secondary analyses in patients with AKI: Renal function return to baseline, RRT and mortality within 28 days.

DISCUSSION

This will be the first prospective evaluation of feasibility of AKI CDA, integrating individual prediction tools in one cohesive and comprehensive approach, and its prediction of FO>10% and AKI, as well as the first to standardize the FST in the pediatric population. This will increase knowledge on current AKI prediction tools and provide actionable insight for early interventions in critically ill children based on their level of risk.