Subclinical Kidney Injury in Children Receiving Nonsteroidal Anti-Inflammatory Drugs After Cardiac Surgery

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

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

Efficacy and Safety of NSAIDs in Infants: A Comprehensive Review of the Literature of the Past 20 Years

Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used in infants, children, and adolescents worldwide; however, despite sufficient evidence of the beneficial effects of NSAIDs in children and adolescents, there is a lack of comprehensive data in infants. The present review summarizes the current knowledge on the safety and efficacy of various NSAIDs used in infants for which data are available, and includes ibuprofen, dexibuprofen, ketoprofen, flurbiprofen, naproxen, diclofenac, ketorolac, indomethacin, niflumic acid, meloxicam, celecoxib, parecoxib, rofecoxib, acetylsalicylic acid, and nimesulide. The efficacy of NSAIDs has been documented for a variety of conditions, such as fever and pain. NSAIDs are also the main pillars of anti-inflammatory treatment, such as in pediatric inflammatory rheumatic diseases. Limited data are available on the safety of most NSAIDs in infants. Adverse drug reactions may be renal, gastrointestinal, hematological, or immunologic. Since NSAIDs are among the most frequently used drugs in the pediatric population, safety and efficacy studies can be performed as part of normal clinical routine, even in young infants. Available data sources, such as (electronic) medical records, should be used for safety and efficacy analyses. On a larger scale, existing data sources, e.g. adverse drug reaction programs/networks, spontaneous national reporting systems, and electronic medical records should be assessed with child-specific methods in order to detect safety signals pertinent to certain pediatric age groups or disease entities. To improve the safety of NSAIDs in infants, treatment needs to be initiated with the lowest age-appropriate or weight-based dose. Duration of treatment and amount of drug used should be regularly evaluated and maximum dose limits and other recommendations by the manufacturer or expert committees should be followed. Treatment for non-chronic conditions such as fever and acute (postoperative) pain should be kept as short as possible. Patients with chronic conditions should be regularly monitored for possible adverse effects of NSAIDs.

Advances in the study of subclinical AKI biomarkers

Acute kidney injury (AKI) is a prevalent and serious illness in all clinical departments, with a high morbidity and death rate, particularly in intensive care units, where prevention and treatment are crucial. As a result, active prevention, early detection, and timely intervention for acute kidney injury are critical. The current diagnostic criteria for acute kidney injury are an increase in serum creatinine concentration and/or a decrease in urine output, although creatinine and urine output merely reflect changes in kidney function, and AKI suggests injury or damage, but not necessarily dysfunction. The human kidney plays a crucial functional reserve role, and dysfunction is only visible when more than half of the renal mass is impaired. Tubular damage markers can be used to detect AKI before filtration function is lost, and new biomarkers have shown a new subset of AKI patients known as "subclinical AKI." Furthermore, creatinine and urine volume are only marginally effective for detecting subclinical AKI. As a result, the search for new biomarkers not only identifies deterioration of renal function but also allows for the early detection of structural kidney damage. Several biomarkers have been identified and validated. This study discusses some of the most promising novel biomarkers of AKI, including CysC, NGAL, KIM-1, lL-18, L-FABP, IGFBP7, TIMP-2, Clusterin, and Penkid. We examine their performance in the diagnosis of subclinical AKI, limitations, and future clinical practice directions.

Role of urinary NGAL and microalbuminuria in the detection of subclinical acute kidney injury in pediatric intensive care unit and diabetic children

Subclinical Acute Kidney Injury (AKI) describes patients who did not fulfill the classical criteria for AKI diagnosis but showed elevated levels of new biomarkers reflecting tubular injury. One of these biomarkers is Neutrophil Gelatinase-Associated Lipocalin (NGAL). The aim of this study is to investigate the role of urinary NGAL and microalbuminuria as non-invasive biomarkers in the detection of subclinical AKI. Analysis of urinary NGAL and microalbuminuria in 91 subjects [30 pediatric intensive care unit (PICU) patients, 31 diabetic patients and 30 healthy controls] recruited from Cairo University Pediatric Hospital was done. Our study revealed that urinary NGAL was significantly higher in the PICU group followed by the diabetic group and lowest in the controls group (p=0.022). A positive correlation was found between urinary NGAL and microalbuminuria in the PICU group (Rvalue= 0.585, p-value=0.001). In diabetic group, a positive correlation was found between urinary NGAL and fasting blood glucose, 2 hours post prandial and HbA1C (R-value=0.421; pvalue= 0.021; R-value=0.426; p-value=0.019; R-value=0.438; pvalue= 0.018 respectively). Urinary NGAL may be a potential biomarker to detect subclinical AKI before actual functional renal damage leading to early intervention and reduction of mortality.

Acute kidney injury associated with non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are ones of the commonly prescribed drugs worldwide. They primarily inhibit cyclooxygenase (COX) enzyme which is responsible for conversion of phospholipids to various prostaglandins (PGs). Disruption in PGs production affects the kidneys in several ways, including vasoconstriction that may result in ischemic acute kidney injury (AKI) in at-risk patients. They also impair salt and water excretion, leading to edema and hypertension. Other complications include hyperkalemia, hyponatremia, nephrotic syndrome, acute interstitial nephritis and chronic kidney disease progression. AKI from NSAIDs is usually reversible with favorable prognosis after discontinuation of NSAIDs. Avoidance of NSAIDs exposure is extremely important, especially among high-risk patients.

Neutrophil gelatinase-associated lipocalin is elevated in children with acute kidney injury and sickle cell anemia, and predicts mortality

Urine neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker of acute kidney injury that has been adapted to a urine dipstick test. However, there is limited data on its use in low-and-middle-income countries where diagnosis of acute kidney injury remains a challenge. To study this, we prospectively enrolled 250 children with sickle cell anemia aged two to 18 years encompassing 185 children hospitalized with a vaso-occlusive pain crisis and a reference group of 65 children attending the sickle cell clinic for routine care follow up. Kidney injury was defined using serial creatinine measures and a modified-Kidney Disease Improving Global Outcome definition for sickle cell anemia. Urine NGAL was measured using the NGAL dipstick and a laboratory reference. The mean age of children enrolled was 8.9 years and 42.8% were female. Among hospitalized children, 36.2% had kidney injury and 3.2% died. Measured urine NGAL levels by the dipstick were strongly correlated with the standard enzyme-linked immunosorbent assay for urine NGAL (hospitalized children, 0.71; routine care reference, 0.88). NGAL levels were elevated in kidney injury and significantly increased across injury stages. Hospitalized children with a high-risk dipstick test (300ng/mL and more) had a 2.47-fold relative risk of kidney injury (95% confidence interval 1.68 to 3.61) and 7.28 increased risk of death (95% confidence interval 1.10 to 26.81) adjusting for age and sex. Thus, urine NGAL levels were found to be significantly elevated in children with sickle cell anemia and acute kidney injury and may predict mortality.

Association of Ibuprofen Prescription With Acute Kidney Injury Among Hospitalized Children in China

IMPORTANCE

Ibuprofen is widely used in children worldwide, especially in those with cancer, fever, or trauma. However, large and high-quality studies of the association between ibuprofen and acute kidney injury (AKI) in children have been lacking.

OBJECTIVE

To examine the association between the use of ibuprofen and the risk of hospital-acquired AKI in hospitalized children in China.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study analyzed the cohort of the Epidemiology of AKI in Chinese Hospitalized Patients (EACH) study, a large, multicenter retrospective study of 3 044 023 patients who were admitted to 1 of 25 academic medical centers in China between January 1, 2013, and December 31, 2015. Patient-level data were obtained from the electronic health record system of the participating centers. Hospitalized children aged 1 month to 18 years who had prescriptions and a certain number of serum creatinine (SCr) tests were included. Children with end-stage renal disease, community-acquired AKI, low baseline SCr level (<10 μmol/L), high standardized baseline SCr level (>4 times the sex- and age-specific reference value), or missing diagnosis code were excluded. Data analysis was conducted from January 1, 2020, to August 30, 2020.

EXPOSURES

Exposure to ibuprofen was coded as a time-dependent dichotomous variable.

MAIN OUTCOMES AND MEASURES

Baseline SCr level was calculated for each patient as the mean of all available SCr values between the 30 days prior to admission and the first SCr testing within the first 3 days of hospitalization. Acute kidney injury was defined as an increase in SCr level of 26.5 μmol/L or higher within 48 hours or by 50% or more over the baseline value, according to the Kidney Disease: Improving Global Outcomes guidelines.

RESULTS

Among the 50 420 children (mean [SD] age, 5.0 [5.2] years; 30 640 boys [60.8%]) included in this study, 5526 (11.0%) used ibuprofen and 3476 (6.9%) developed hospital-acquired AKI during hospitalization. Ibuprofen use was associated with a statistically significantly increased risk of hospital-acquired AKI (hazard ratio [HR], 1.23; 95% CI, 1.14-1.34) after adjusting for confounders. Ibuprofen use was associated with a greater hazard in children who had chronic kidney disease vs those without (HR, 2.31 [95% CI, 1.73-3.10] vs 1.19 [95% CI, 1.09-1.29]), required intensive care vs those without this need (HR, 1.47 [95% CI, 1.24-1.75] vs 1.18 [95% CI, 1.07-1.29]), or were older vs younger (>10 years and >1 year to 10 years vs 1 month to 1 year) (HR, 1.64 [95% CI, 1.32-2.05]; 1.36 [95% CI, 1.23-1.52] vs 0.99 [95% CI, 0.86-1.13]). Dose-response analysis suggested that the association of ibuprofen with the risk of hospital-acquired AKI was dose-dependent.

CONCLUSIONS AND RELEVANCE

This study found that ibuprofen was widely used and associated with an increased risk of hospital-acquired AKI in hospitalized children in China. The judicious use of ibuprofen and close monitoring of kidney function in children are needed.

Association of Non-Steroidal Anti-Inflammatory Drugs with Kidney Health in Ambulatory Older Adults

BACKGROUND/OBJECTIVES

Non-steroidal anti-inflammatory drugs (NSAIDs) can cause kidney injury, especially in older adults. However, previously reported associations between NSAID use and kidney health outcomes are inconsistent and limited by reliance on serum creatinine-based GFR estimates. This analysis investigated the association of NSAID use with kidney damage in older adults using multiple kidney health measures.

DESIGN

Cross-sectional and longitudinal analyses.

SETTING

Multicenter, community-based cohort.

PARTICIPANTS

Two thousand nine hundred and ninty nine older adults in the Health ABC Study. A subcohort (n = 500) was randomly selected for additional biomarker measurements.

EXPOSURE

Prescription and over-the-counter NSAID use ascertained by self-report.

MEASUREMENTS

Baseline estimated glomerular filtration rate (eGFR) by cystatin C (cysC), urine albumin-to-creatinine ratio (ACR), kidney injury molecule-1 (KIM-1), and interleukin-18 (IL-18) were measured in 2,999 participants; alpha-1 microglobulin (α1m), neutrophil gelatinase-associated lipocalin (NGAL), propeptide type III procollagen (PIIINP), and uromodulin (UMOD) were measured in 500 participants. GFR was estimated three times over 10 years and expressed as percent change per year.

RESULTS

Participants had a mean age of 74 years, 51% were female, and 41% African-American. No eGFR differences were detected between NSAID users (n = 655) and non-users (n = 2,344) at baseline (72 ml/min/1.73 m² in both groups). Compared to non-users, NSAID users had lower adjusted odds of having ACR greater than 30 mg/g (0.67; 95% confidence interval (CI) = 0.51-0.89) and lower mean urine IL-18 concentration at baseline (-11%; 95% CI = -4% to -18%), but similar mean KIM-1 (5%; 95% CI = -5% to 14%). No significant differences in baseline concentrations of the remaining urine biomarkers were detected. NSAID users and non-users did not differ significantly in the rate of eGFR decline (-2.2% vs -2.3% per year).

CONCLUSION

Self-reported NSAID use was not associated with kidney dysfunction or injury based on multiple measures, raising the possibility of NSAID use without kidney harm in ambulatory older adults. More research is needed to define safe patterns of NSAID consumption.

A novel strategy for identifying early acute kidney injury in pediatric hematopoietic stem cell transplantation

Acute kidney injury (AKI) is a common complication in pediatric hematopoietic stem cell transplantation (HSCT). Serum creatinine is an imprecise biomarker of AKI. We hypothesized that combining creatinine with serum cystatin C (cysC) and urinary neutrophil gelatinase-associated lipocalin (NGAL) more effectively characterizes AKI during the first 28 days of HSCT and better identifies patients at risk of adverse outcomes than creatinine alone. We prospectively assessed the type and severity of AKI in 80 consecutive allogeneic HSCT patients using weekly creatinine, cysC, and NGAL. We combined the biomarkers to define 7 Composite Types of AKI, including All Positive AKI (simultaneously detected creatinine, cysC, and NGAL AKI). Outcomes included renal replacement therapy and transplant-related mortality. In all, 75% of patients had AKI by at least one measure; 33% developed >1 type of AKI. Mild AKI often preceded Severe AKI. Patients with creatinine or NGAL AKI that were Severe or Repeated tended to have worse outcomes. The five patients with All Positive AKI had the highest rates of morbidity and mortality. AKI evaluation with creatinine, cysC, and NGAL provides a comprehensive profile of early AKI and narrowly identifies patients at highest risk of adverse outcomes, providing opportunities for early, impactful intervention.

Cardiopulmonary Bypass and AKI: AKI Is Bad, So Let's Get Beyond the Diagnosis

It is now well-established that AKI is a serious and common complication following cardiopulmonary bypass (CPB) in both children and adults, adverse outcomes may occur in the short term as well as long term, with higher incidence of chronic kidney disease, increased healthcare utilization and higher frequency of cardiovascular events in patients who develop post-CPB AKI. Despite the advances in our understanding of the pathogenesis of the disease and the improvement in diagnostic tools, our therapeutic options have remained suboptimal. There are multiple challenges in designing a clinical therapeutic AKI trial, including a multi-factorial etiology, difficulties with accurate diagnosis of AKI, achievement of adequate study power, and determination of appropriate outcomes. We are often left with "supportive" care. Studies have shown some benefit to AKI bundles, but adherence to bundle guidelines may be suboptimal. Current best practices should include maintenance of adequate renal perfusion pressure and avoidance of fluid overload, with consideration of early renal replacement therapy. Finally, multi-center trials of AKI therapies are crucial to finding treatment for this devastating complication of CPB.

Subclinical AKI: ready for primetime in clinical practice?

There has been considerable progress over the last decade in the standardization of the acute kidney injury (AKI) definition with the publication of the RIFLE, AKIN, KDIGO and ERBP classification criteria. However, these classification criteria still rely on imperfect parameters such as serum creatinine and urinary output. The use of timed urine collections, kinetic eGFR (estimated glomerular filtration rate), real time measurement of GFR and direct measures of tubular damage can theoretically aid in a more timely diagnosis of AKI and improve patients' outcome. There has been an extensive search for new biomarkers indicative of structural tubular damage but it remains controversial whether these new markers should be included in the current classification criteria. The use of these markers has also led to the creation of a new concept called subclinical AKI, a condition where there is an increase in biomarkers but without clinical AKI, defined as an increase in serum creatinine and/or a decrease in urinary output. In this review we provide a framework on how to critical appraise biomarker research and on how to position the concept of subclinical AKI. The evaluation of biomarker performance and the usefulness of the concept 'subclinical AKI' requires careful consideration of the context these biomarkers are used in (clinical versus research setting) and the goal we want to achieve (risk assessment versus prediction versus early diagnosis versus prognostication). It remains currently unknown whether an increase in biomarkers levels without functional repercussion is clinically relevant and whether including biomarkers in classification criteria will improve patients' outcome.

Subclinical acute kidney injury is associated with adverse outcomes in critically ill neonates and children

Background

Research on acute kidney injury (AKI) has focused on identifying early biomarkers. However, whether AKI could be diagnosed in the absence of the classic signs of clinical AKI and whether the condition of subclinical AKI, identified by damage or functional biomarkers in the absence of oliguria or increased serum creatinine (sCr) levels, is clinically significant remains to be elucidated in critically ill children. The aims of the study were to investigate the associations between urinary cystatin C (uCysC) levels and AKI and mortality and to determine whether uCysC-positive subclinical AKI is associated with adverse outcomes in critically ill neonates and children.

Methods

In this prospective cohort study, uCysC levels were serially measured during the first week after intensive care unit (ICU) admission in a heterogeneous group of patients (n = 510) presenting to a tertiary neonatal and pediatric ICU. The diagnosis of neonatal AKI that developed during the first week after admission was based on neonatal KDIGO criteria or sCr >1.5 mg/dL, and pediatric AKI was based on Kidney Disease: Improving Global Outcomes (KDIGO) criteria. The term “uCysC(−)” or “uCysC(+)”, indicating the absence or presence of tubular injury, was defined by the optimal peak uCysC cutoff value for predicting ICU mortality.

Results

The initial and peak uCysC levels were significantly associated with AKI and mortality, and had an area under the receiver operating characteristic curve of 0.76 and 0.81, respectively, for predicting mortality. At the optimal cutoff value of 1260 ng/mg uCr, the peak uCysC displayed sensitivity of 79.2% and specificity of 72.3% for predicting mortality. Among all patients, 130 (25.5%) developed uCysC(+)/AKI(−) status during the first week after admission. The adjusted odds ratio for patients with uCysC(+)/AKI(−) status in association with an increased risk of mortality compared with that for patients with uCysC(−)/AKI(−) was 9.34 (P < 0.001). Patients with uCysC(+)/AKI(−) spent 2.8 times as long in the ICU as those with uCysC(−)/AKI(−) (P < 0.001).

Conclusions

Both initial and peak uCysC levels are associated with AKI and mortality and are independently predictive of mortality in critically ill neonates and children. Subclinical AKI may occur without detectable loss of kidney function, and uCysC-positive subclinical AKI is associated with worse clinical outcomes in this population.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2193-8) contains supplementary material, which is available to authorized users.