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Clinical adjudication in acute kidney injury studies: findings from the pivotal TIMP-2*IGFBP7 biomarker study.

ABSTRACT: The NEPROCHECK test (Astute Medical, San Diego, CA, USA) combines urinary tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) to identify patients at high risk for acute kidney injury (AKI). In a US Food and Drug Administration registration trial (NCT01573962), AKI was determined by a three-member clinical adjudication committee. The objectives were to examine agreement among adjudicators as well as between adjudicators and consensus criteria for AKI and to determine the relationship of biomarker concentrations and adjudicator agreement.Subjects were classified as AKI 3/3, 2/3, 1/3 or 0/3 according to the proportion of adjudicators classifying the case as AKI. Subjects were classified as Kidney Disease: Improving Global Outcomes (KDIGO) AKI(+) when stage 2 or 3 AKI criteria were met.Concordance between adjudicators and between adjudicators and KDIGO criteria were lower for AKI than non-AKI subjects [78.9 versus 97.3% (P < 0.001) and 91.5 versus 97.9% (P = 0.01)]. Subjects who were AKI 3/3 or 2/3 but KDIGO AKI(-) had higher median [TIMP-2]•[IGFBP7] compared with those who were AKI-1/3 or 0/3 but KDIGO AKI(+) {2.78 [interquartile range (IQR) 2.33-3.56] versus 0.52 [IQR 0.26-1.64]; P = 0.008}. [TIMP-2]•[IGFBP7] levels were highest in patients with AKI 3/3 and lowest in AKI 0/3, whereas AKI 2/3 and 1/3 exhibited intermediate values.In this analysis, urine [TIMP-2]•[IGFBP7] levels correlated to clinically adjudicated AKI better than to KDIGO criteria. Furthermore, in difficult cases where adjudicators overruled KDIGO criteria, the biomarker test discriminated well. This study highlights the importance of clinical adjudication of AKI for biomarker studies and lends further support for the value of urine [TIMP-2]•[IGFBP7].

SUBMITTER: Liu KD

PROVIDER: S-EPMC5039343 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Clinical adjudication in acute kidney injury studies: findings from the pivotal TIMP-2*IGFBP7 biomarker study.

Liu Kathleen D KD Vijayan Anitha A Rosner Mitchell H MH Shi Jing J Chawla Lakhmir S LS Kellum John A JA

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association 20160623 10

<h4>Background</h4>The NEPROCHECK test (Astute Medical, San Diego, CA, USA) combines urinary tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) to identify patients at high risk for acute kidney injury (AKI). In a US Food and Drug Administration registration trial (NCT01573962), AKI was determined by a three-member clinical adjudication committee. The objectives were to examine agreement among adjudicators as well as between adjudicators a ...[more]

PMID: 27342580

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Project description:BackgroundAcute kidney injury (AKI) is frequently observed in serious infections, following nephrotoxic medication, surgery and trauma. Here we tested whether the detection of two recently identified biomarkers for AKI, Tissue Inhibitor of Metalloproteinase-2 (TIMP-2) and Insulin-Like Growth Factor Binding Protein 7 (IGFBP7), depends on the expression of these proteins in cells of the urinary sediment.MethodWe collected urine samples of 33 kidney transplant recipients and 14 non-transplanted patients who all had AKI (stages 1-3 according to KDIGO), and measured [IGFBP7]x[TIMP-2] using the NephroCheck® Astute1 40 ™ meter. Concomitantly, we analyzed IGFBP7 and TIMP-2 mRNA expression by quantitative polymerase chain reaction (qPCR) from urinary sediment of the same patients, and correlated the results with [IGFBP7]x[TIMP-2] (protein), by linear regression analysis. We also determined the association between [IGFBP7]x[TIMP-2] and estimated glomerular filtration rate (eGFR), and between IGFBP7 and TIMP-2 mRNA expression and markers of inflammation. Light microscopy and confocal immunofluorescence served to illustrate changes in the urinary sediment over the time course of renal function improvement.ResultsOf the 47 analyzed AKI patients, 14 presented with ascending urinary tract infection. Serum creatinine (sCr), blood urea nitrogen (BUN) and eGFR in all patients were 3.9±2.28 mg/dL, 47.59±23.1 mg/dL and 22.88±16.0 mL/min/1.73m2, respectively, on average ±standard deviation. [IGFBP7]x[TIMP-2] was 2.33±9.95 (ng/ml)2/1000, and did not associate with IGFBP7 and TIMP-2 gene expression (r = -0.0220, p = 0.4216; respectively r = 0.0972, p = 0.1909). [IGFBP7]x[TIMP-2] did not associate with eGFR; IGFBP7 and TIMP-2 mRNA expression. Improvement of renal function went along with disappearance of casts, decrease in aquaporin1 positive renal epithelial cells and leukocytes from the urinary sediment.ConclusionThe gene expression pattern of IGFBP7 and TIMP-2 from urinary sediment, which contains desquamated renal tubular epithelial cells, did not correlate with [IGFBP7]x[TIMP-2] protein, indicating that IGFBP7 and TIMP-2 measured in the NephroCheck® test originated predominantly from intact but stressed cells of the kidney itself.

Project description:BackgroundThe G1 cell cycle inhibitors tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) have been identified as promising biomarkers for the prediction of adverse outcomes including renal replacement therapy (RRT) and mortality in critically ill adult patients who develop acute kidney injury (AKI). However, the prognostic value of urinary TIMP-2 and IGFBP7 in neonatal and pediatric AKI for adverse outcome has not been investigated yet.MethodsThe product of the urinary concentration of TIMP-2 and IGFBP7 ([TIMP-2]•[IGFBP7]) was assessed by a commercially available immunoassay (NephroCheck™) in a prospective cohort study in 133 subjects aged 0-18 years including 46 patients with established AKI according to pRIFLE criteria, 27 patients without AKI (non-AKI group I) and 60 apparently healthy neonates and children (non-AKI group II). AKI etiologies were: dehydration/hypovolemia (n = 7), hemodynamic instability (n = 7), perinatal asphyxia (n = 9), septic shock (n = 7), typical hemolytic-uremic syndrome (HUS; n = 5), interstitial nephritis (n = 5), vasculitis (n = 4), nephrotoxic injury (n = 1) and renal vein thrombosis (n = 1).ResultsWhen AKI patients were classified into pRIFLE criteria, 6/46 (13%) patients fulfilled the criteria for the category "Risk", 13/46 (28%) for "Injury", 26/46 (57%) for "Failure" and 1/46 (2%) for "Loss". Patients in the "Failure" stage had a median 3.7-fold higher urinary [TIMP-2]•[IGFBP7] compared to non-AKI subjects (P<0.001). When analyzed for AKI etiology, highest [TIMP-2]•[IGFBP7] values were found in patients with septic shock (P<0.001 vs. non-AKI I+II). Receiver operating characteristic (ROC) curve analyses in the AKI group revealed good performance of [TIMP-2]•[IGFBP7] in predicting 30-day (area under the curve (AUC) 0.79; 95% CI, 0.61-0.97) and 3-month mortality (AUC 0.84; 95% CI, 0.67-0.99) and moderate performance in predicting RRT (AUC 0.67; 95% CI, 0.50-0.84).ConclusionsThis study shows that urinary [TIMP-2]•[IGFBP7] has a good diagnostic performance in predicting adverse outcomes in neonatal and pediatric AKI of heterogeneous etiology.

Dataset Information

Clinical adjudication in acute kidney injury studies: findings from the pivotal TIMP-2*IGFBP7 biomarker study.

Publications

Clinical adjudication in acute kidney injury studies: findings from the pivotal TIMP-2*IGFBP7 biomarker study.

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