Urinary metabolomics to develop predictors for pediatric acute kidney injury.

BACKGROUND: Acute kidney injury (AKI) is characterized by an abrupt decline in glomerular filtration rate (GFR). We sought to identify separate early urinary metabolomic signatures at AKI onset (with-AKI) and prior to onset of functional impairment (pre-AKI). METHODS: Pre-AKI (n=15), AKI (n=22), and respective controls (n=30) from two prospective PICU cohort studies provided urine samples which were analyzed by GC-MS and DI-MS mass spectrometry (193 metabolites). The cohort (n=58) was 8.7±6.4 years old and 66% male. AKI patients had longer PICU stays, higher PRISM scores, vasopressors requirement, and respiratory diagnosis and less commonly had trauma or post-operative diagnosis. Urine was collected within 2-3 days after admission and daily until day 5 or 14. RESULTS: The metabolite classifiers for pre-AKI samples (1.5±1.1 days prior to AKI onset) had a cross-validated area under receiver operator curve (AUC)=0.93 (95%CI 0.85-1.0); with-AKI samples had an AUC=0.94 (95%CI 0.87-1.0). A parsimonious pre-AKI classifier with 13 metabolites was similarly robust (AUC=0.96, 95%CI 0.89-1.0). Both classifiers were similar and showed modest correlation of high-ranking metabolites (tau=0.47, p<0.001). CONCLUSIONS: This exploratory study demonstrates the potential of a urine metabolite classifier to detect AKI-risk in pediatric populations earlier than the current standard of diagnosis with the need for external validation. A higher resolution version of the Graphical abstract is available as Supplementary information with inner reference to ESM for GA.

24-hour ambulatory blood pressure monitoring 9 years after pediatric cardiac surgery: a pilot and feasibility study.

BACKGROUND: Children undergoing cardiac surgery are at risk of high blood pressure (BP), a risk factor for cardiovascular and kidney disease. Twenty-four-hour ambulatory BP monitoring (ABPM) is a reference standard hypertension (HTN) test. Little data exist on ABPM abnormalities in children several years post cardiac surgery. This study aimed to (a) determine ABPM feasibility; (b) describe and compare ABPM measures and abnormalities (percent load, masked HTN [MH]; non-dipping, mean systolic/diastolic BP > 95th percentile; pre-HTN (ABPM); white-coat HTN [WCH]) to casual BP; and (c) compare BP in patients with and without acute kidney injury (AKI). METHODS: Prospective, follow-up pilot study of children (0-18 years) who underwent cardiac surgery from 2007 to 2009 at Montreal Children's Hospital. We recorded if participants had post-operative AKI and assessed the following outcomes at 9-year follow-up: casual BP classified by three single-visit measures (normal; elevated BP [eBPSingleVisit]; HTNSingleVisit); ABPM. Bivariable analyses were used to compare characteristics between groups. RESULTS: Twenty-three patients (median [interquartile range], 8.6 [8.0, 9.0] years post cardiac surgery) were included; 16 (70%) male. Six participants (26%) had eBPSingleVisit or higher. On ABPM, 11 (48%) had ≥ 1 abnormality: 9 (39%) had non-dipping; 3 (13%) had pre-HTN; 3 (13%) had WCH; none had HTN or MH. There were no differences in ABPM according to AKI status. CONCLUSION: Our pilot study determined that ABPM was feasible in children years after cardiac surgery and frequently identified ABPM abnormalities. Future research in larger populations is needed to define specific risk factors for HTN in children after cardiac surgery.

Serum Creatinine Monitoring After Acute Kidney Injury in the PICU.

OBJECTIVES: It is unknown whether children with acute kidney injury during PICU admission have kidney function monitored after discharge. Objectives: 1) describe postdischarge serum creatinine monitoring after PICU acute kidney injury and 2) determine factors associated with postdischarge serum creatinine monitoring. DESIGN: Secondary analysis of longitudinal cohort study data. SETTING: Two PICUs in Montreal and Edmonton, Canada. PATIENTS: Children (0-18 yr old) surviving PICU admission greater than or equal to 2 days from 2005 to 2011. Exclusions: postcardiac surgery and prior kidney disease. Exposure: acute kidney injury by Kidney Disease: Improving Global Outcomes serum creatinine definition. INTERVENTIONS: None. MEASUREMENTS: Primary outcome: postdischarge serum creatinine measured by 90 days, 1 year, and 5-7 years. SECONDARY OUTCOMES: Healthcare events and nephrology follow-up. ANALYSIS: Proportions with outcomes; logistic regression to evaluate factors associated with the primary outcome. Kaplan-Meier analysis of time to serum creatinine measurement and healthcare events. MAIN RESULTS: Of n = 277, 69 (25%) had acute kidney injury; 29/69 (42%), 34/69 (49%), and 51/69 (74%) had serum creatinine measured by 90 days, 1 year, and 5-7 year postdischarge, respectively. Acute kidney injury survivors were more likely to have serum creatinine measured versus nonacute kidney injury survivors at all time points (p ≤ 0.01). Factors associated with 90-day serum creatinine measurement were inpatient nephrology consultation (unadjusted odds ratio [95% CI], 14.9 [1.7-127.0]), stage 2-3 acute kidney injury (adjusted odds ratio, 3.4 [1.1-10.2]), and oncologic admission diagnosis (adjusted odds ratio, 10.0 [1.1-93.5]). A higher proportion of acute kidney injury versus nonacute kidney injury survivors were readmitted by 90 days (25 [36%] vs 44 [21%]; p = 0.01) and 1 year (33 [38%] vs 70 [34%]; p = 0.04). Of 24 acute kidney injury survivors diagnosed with chronic kidney disease or hypertension at 5-7 year follow-up, 16 (67%) had serum creatinine measurement and three (13%) had nephrology follow-up postdischarge. CONCLUSIONS: Half of PICU acute kidney injury survivors have serum creatinine measured within 1-year postdischarge and follow-up is suboptimal for children developing long-term kidney sequelae. Knowledge translation strategies should emphasize the importance of serum creatinine monitoring after childhood acute kidney injury.

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.

Perspectives of Pediatric Nephrologists, Intensivists and Nurses Regarding AKI Management and Expected Outcomes.

Background: Acute kidney injury (AKI) in critically ill children is associated with increased risk for short- and long-term adverse outcomes. Currently, there is no systematic follow-up for children who develop AKI in intensive care unit (ICU). Objective: This study aimed to assess variation regarding management, perceived importance, and follow-up of AKI in the ICU setting within and between healthcare professional (HCP) groups. Design: Anonymous, cross-sectional, web-based surveys were administered nationally to Canadian pediatric nephrologists, pediatric intensive care unit (PICU) physicians, and PICU nurses, via professional listservs. Setting: All Canadian pediatric nephrologists, PICU physicians, and nurses treating children in the ICU were eligible for the survey. Patients: N/A. Measurements: Surveys included multiple choice and Likert scale questions on current practice related to AKI management and long-term follow-up, including institutional and personal practice approaches, and perceived importance of AKI severity with different outcomes. Methods: Descriptive statistics were performed. Categorical responses were compared using Chi-square or Fisher's exact tests; Likert scale results were compared using Mann-Whitney and Kruskal-Wallis tests. Results: Surveys were completed by 34/64 (53%) pediatric nephrologists, 46/113 (41%) PICU physicians, and 82 PICU nurses (response rate unknown). Over 65% of providers reported hemodialysis to be prescribed by nephrology; a mix of nephrology, ICU, or a shared nephrology-ICU model was reported responsible for peritoneal dialysis and continuous renal replacement therapy (CRRT). Severe hyperkalemia was the most important renal replacement therapy (RRT) indication for both nephrologists and PICU physicians (Likert scale from 0 [not important] to 10 [most important]; median = 10, 10, respectively). Nephrologists reported a lower threshold of AKI for increased mortality risk; 38% believed stage 2 AKI was the minimum compared to 17% of PICU physicians and 14% of nurses. Nephrologists were more likely than PICU physicians and nurses to recommend long-term follow-up for patients who develop any AKI during ICU stay (Likert scale from 0 [none] to 10 [all patients]; mean=6.0, 3.8, 3.7, respectively) (P < .05). Limitations: Responses from all eligible HCPs in the country could not obtained. There may be differences in opinions between HCPs that completed the survey compared to those that did not. Additionally, the cross-sectional design of our study may not adequately reflect changes in guidelines and knowledge since survey completion, although no specific guidelines have been released in Canada since survey dissemination. Conclusions: Canadian HCP groups have variable perspectives on pediatric AKI management and follow-up. Understanding practice patterns and perspectives will help optimize pediatric AKI follow-up guideline implementation.

Contexte: L'insuffisance rénale aiguë (IRA) chez les enfants gravement malades est associée à un risque accru d'issues défavorables à court et à long terme. En ce moment, il n'existe aucun suivi systématique pour les enfants qui développent une IRA pendant un séjour à l'unité des soins intensifs (USI). Objectif: Cette étude visait à évaluer les variations dans la prise en charge de l'IRA, de son importance perçue et de son suivi, tant au sein des groupes de professionnels de la santé (PS) qu'entre les différents groupes de PS. Conception: Des sondages transversaux à remplir de façon anonyme en ligne ont été menés à l'échelle nationale auprès de néphrologues pédiatriques canadiens, de médecins des unités de soins intensifs pédiatriques (USIP) et de membres du personnel infirmier des USIP ayant été répertoriés à partir de listes professionnelles. Cadre: Tous les néphrologues pédiatriques canadiens, médecins et membres du personnel infirmier qui traitent des enfants en USI étaient admissibles à répondre au sondage. Patients: S/O. Mesures: Les sondages comportaient des questions à choix multiples et des questions de type échelle de Likert qui portaient sur les pratiques actuelles de la gestion et de suivi à long terme de l'IRA, notamment sur les approches institutionnelles et personnelles de pratique et sur l'importance perçue de la gravité de l'IRA avec différents résultats. Méthodologie: Des statistiques descriptives ont été réalisées. Les réponses catégorielles ont été comparées à l'aide du chi-carré ou de tests exacts de probabilité de Fisher; les résultats des échelles de Likert ont été comparés à l'aide de tests de Mann-Whitney et de Kruskal-Wallis. Résultats: Les sondages ont été complétés par 53 % des néphrologues pédiatriques (34/64), 41 % des médecins d'USIP (46/113) et par 82 membres du personnel infirmier d'USIP (taux de réponse inconnu). Plus de 65 % des prestataires de soins ont déclaré que l'hémodialyse était prescrite par le service de néphrologie, alors que la dialyze péritonéale et la thérapie de remplacement rénal continu (TRRC) étaient confiées à la fois à la néphrologie, à l'USI ou à un modèle partagé néphrologie-USI. L'hyperkaliémie grave était l'indication la plus importante de la TRR pour les néphrologues et les médecins en USIP (échelle de Likert de 0 [pas important] à 10 [le plus important]; médiane = 10, 10, respectivement). Les néphrologues ont signalé un seuil inférieur d'IRA pour l'augmentation du risque de mortalité; 38 % d'entre eux estimaient que l'IRA de stade 2 était le seuil minimum, contre 17 % des médecins en USI et 14 % du personnel infirmier. Les néphrologues étaient plus susceptibles que les médecins et le personnel infirmier des USIP de recommander un suivi à long terme pour les patients qui développent une IRA pendant leur séjour en USI (échelle Likert de 0 [aucun] à 10 [tous les patients]; moyennes respectives = 6,0; 3,8 et 3,7 [p < 0,05]). Limites: Il n'a pas été possible d'obtenir les réponses de tous les PS admissibles au pays. Des différences d'opinions sont possibles entre les PS qui ont répondu au sondage et ceux qui ne l'ont pas fait. De plus, la conception transversale de notre étude pourrait ne pas refléter adéquatement les changements apportés aux lignes directrices et aux connaissances depuis la fin de cette enquête, bien qu'aucune ligne directrice particulière n'ait été publiée au Canada depuis la diffusion du sondage. Conclusion: Les divers groupes de professionnels de la santé canadiens ont des points de vue différents en ce qui concerne la prise en charge et le suivi de l'IRA chez les enfants. La compréhension des modèles de pratique et des perspectives permettra d'optimiser la mise en œuvre de directives de suivi de l'IRA pédiatrique.

Urine Neutrophil Gelatinase-Associated Lipocalin and Kidney Injury Molecule-1 to Detect Pediatric Cisplatin-Associated Acute Kidney Injury.

Background: Few studies have described associations between the AKI biomarkers urinary neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) with AKI in cisplatin-treated children. We aimed to describe excretion patterns of urine NGAL and KIM-1 and associations with AKI in children receiving cisplatin. Methods: Participants (n=159) were enrolled between 2013 and 2017 in a prospective cohort study conducted in 12 Canadian pediatric hospitals. Participants were evaluated at early cisplatin infusions (at first or second cisplatin cycle) and late cisplatin infusions (last or second-to-last cycle). Urine NGAL and KIM-1 were measured (1) pre-cisplatin infusion, (2) post-infusion (morning after), and (3) at hospital discharge at early and late cisplatin infusions. Primary outcome: AKI defined by serum creatinine rise within 10 days post-cisplatin, on the basis of Kidney Disease Improving Global Outcomes guidelines criteria (stage 1 or higher). Results: Of 159 children, 156 (median [interquartile range (IQR)] age: 5.8 [2.4-12.0] years; 78 [50%] female) had biomarker data available at early cisplatin infusions and 127 had data at late infusions. Forty six of the 156 (29%) and 22 of the 127 (17%) children developed AKI within 10 days of cisplatin administration after early and late infusions, respectively. Urine NGAL and KIM-1 concentrations were significantly higher in patients with versus without AKI (near hospital discharge of late cisplatin infusion, median [IQR] NGAL levels were 76.1 [10.0-232.7] versus 14.9 [5.4-29.7] ng/mg creatinine; KIM-1 levels were 4415 [2083-9077] versus 1049 [358-3326] pg/mg creatinine; P<0.01). These markers modestly discriminated for AKI (area under receiver operating characteristic curve [AUC-ROC] range: NGAL, 0.56-0.72; KIM-1, 0.48-0.75). Biomarker concentrations were higher and better discriminated for AKI at late cisplatin infusions (AUC-ROC range, 0.54-0.75) versus early infusions (AUC-ROC range, 0.48-0.65). Conclusions: Urine NGAL and KIM-1 were modest at discriminating for cisplatin-associated AKI. Further research is needed to determine clinical utility and applicability of these markers and associations with late kidney outcomes.

KIdney aNd blooD prESsure ouTcomes in Childhood Cancer Survivors: Description of Clinical Research Protocol of the KINDEST-CCS Study.

Background: Approximately 30% of childhood cancer survivors (CCSs) will develop chronic kidney disease (CKD) or hypertension 15 to 20 years after treatment ends. The incidence of CKD and hypertension in the 5-year window after cancer therapy is unknown. Moreover, extent of monitoring of CCS with CKD and associated complications in current practice is underexplored. To inform the development of new and existing care guidelines for CCS, the epidemiology and monitoring of CKD and hypertension in the early period following cancer therapy warrants further investigation. Objective: To describe the design and methods of the KIdney aNd blooD prESsure ouTcomes in Childhood Cancer Survivors study, which aims to evaluate the burden of late kidney and blood pressure outcomes in the first ~10 years after cancer therapy, the extent of appropriate screening and complications monitoring for CKD and hypertension, and whether patient, disease/treatment, or system factors are associated with these outcomes. Design: Two distinct, but related studies; a prospective cohort study and a retrospective cohort study. Setting: Five Ontario pediatric oncology centers. Patients: The prospective study will involve 500 CCS at high risk for these late effects due to cancer therapy, and the retrospective study involves 5,000 CCS ≤ 18 years old treated for cancer between January 2008 and December 2020. Measurements: Chronic kidney disease is defined as Estimated glomerular filtration rate <90 mL/min/1.73 m2 or albumin-to-creatinine ratio ≥ 3mg/mmol. Hypertension is defined by 2017 American Academy of Pediatrics guidelines. Methods: Prospective study: we aim to investigate CKD and hypertension prevalence and the extent to which they persist at 3- and 5-year follow-up in CCS after cancer therapy. We will collect detailed biologic and clinical data, calculate CKD and hypertension prevalence, and progression at 3- and 5-years post-therapy. Retrospective study: we aim to investigate CKD and hypertension monitoring using administrative and health record data. We will also investigate the validity of CKD and hypertension administrative definitions in this population and the incidence of CKD and hypertension in the first ~10 years post-cancer therapy. We will investigate whether patient-, disease/treatment-, or system-specific factors modify these associations in both studies. Limitations: Results from the prospective study may not be generalizable to non-high-risk CCS. The retrospective study is susceptible to surveillance bias. Conclusions: Our team and knowledge translation plan is engaging patient partners, researchers, knowledge users, and policy group representatives. Our work will address international priorities to improve CCS health, provide the evidence of new disease burden and practice gaps to improve CCS guidelines, implement and test revised guidelines, plan trials to reduce CKD and hypertension, and improve long-term CCS health.

Tubular injury and cell-cycle arrest biomarkers to predict acute kidney injury in noncritically ill children receiving aminoglycosides.

Aim: NGAL, IL-18, KIM-1 as well as urinary TIMP2 and IGFBP7 and their mathematical product (TIMP2*IGFBP7) were evaluated for detecting pediatric aminoglycoside acute kidney injury (AG-AKI). Methods: In a prospective study, noncritically ill children received aminoglycosides (AG) ≥3 days. The area under the curve (AUC) for biomarkers to detect AKI was calculated by a) days before AKI onset; b) treatment days. Results: There were 113 AG episodes (68% febrile neutropenia). The AKI group had a higher proportion with febrile neutropenia. The AKI group had significantly lower NGAL 3 days before AKI, as patients with febrile neutropenia had a lower NGAL during AG treatment (p < 0.05). NGAL, IL-18 and TIMP2*IGFBP7 had AUC ≥0.73 at 3, 2 and 2 days before AKI onset. Conclusion: NGAL, IL-18 and TIMP2*IGFBP7 were modest early biomarkers of AG-AKI. Febrile neutropenia was associated with lower NGAL.

Acute Kidney Injury and Risk of CKD and Hypertension after Pediatric Cardiac Surgery.

BACKGROUND AND OBJECTIVES: The association of AKI after pediatric cardiac surgery with long-term CKD and hypertension development is unclear. The study objectives were to determine whether AKI after pediatric cardiac surgery is associated with incident CKD and hypertension. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This was a prospective cohort study of children of 1 month to 18 years old who were undergoing cardiac surgery at two tertiary care centers (Canada, United States). Participants were recruited before cardiac surgery and were followed during hospitalization and at 3, 12, 24, 36, and 48 months after discharge. Exposures were postoperative AKI, based on the Kidney Disease Improving Global Outcomes (KDIGO) definition, and age <2 years old at surgery. Outcomes and measures were CKD (low eGFR or albuminuria for age) and hypertension (per the 2017 American Academy of Pediatrics guidelines) at follow-up, with the composite outcome of CKD or hypertension. RESULTS: Among 124 participants, 57 (46%) developed AKI. AKI versus non-AKI participants had a median (interquartile range) age of 8 (4.8-40.8) versus 46 (6.0-158.4) months, respectively, and higher preoperative eGFR. From the 3- to 48-month follow-up, the cohort prevalence of CKD was high (17%-20%); hypertension prevalence was also high (22%-30%). AKI was not significantly associated with the development of CKD throughout follow-up. AKI was associated with hypertension development at 12 months after discharge (adjusted relative risk, 2.16; 95% confidence interval, 1.18 to 3.95), but not at subsequent visits. Children aged <2 years old at surgery had a significantly higher prevalence of hypertension during follow-up than older children (40% versus 21% at 3-month follow-up; 32% versus 13% at 48-month follow-up). CONCLUSIONS: CKD and hypertension burden in the 4 years after pediatric cardiac surgery is high. Young age at surgery, but not AKI, is associated with their development.