The Antibody Configurations of Cardiac Troponin I Assays May Determine Their Clinical Performance

James, Stefan; Flodin, Mats; Johnston, Nina; Lindahl, Bertil; Venge, Per

doi:10.1373/clinchem.2005.064857

Cited by 65 publications

(53 citation statements)

References 21 publications

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“…Discussion cTn values above the 99th percentile are known to be strong predictors of early adverse events in those with ACS (4,8,(15)(16)(17). This study, in concordance with the prior studies of Venge and colleagues, probed values below the 99th percentile (4,8,9 ).…”

Section: Resultssupporting

confidence: 90%

“…This study, in concordance with the prior studies of Venge and colleagues, probed values below the 99th percentile (4,8,9 ). Using the same assay (AccuTnI), Venge et al (4 ) reported that the 99th percentile for cTnI was Ն0.02 g/L in a young, healthy population.…”

Section: Resultssupporting

confidence: 85%

“…We measured 40 replicates of zero calibrator in 2 reagent lots and used the mean signal plus 2 SD (3 ) to measure the analytical detection limit during the time of analysis to be 0.006 to 0.013 g/L (13 ). Other studies have indicated that the 99th percentile with AccuTnI could be as low as 0.02 to 0.03 g/L (3,4,8,9 ) or as high as 0.10 g/L (5 ). For this study, we used the peak cTnI concentration from each patient to assign patients into the following 4 groups in keeping with the study from Venge et al (4 ): not detectable (Ͻ0.02 g/L), low (normal) but detectable (0.02 to 0.03 g/L), intermediate (99th percentile or above; 0.04 to 0.10 g/L), and high (Ͼ0.10 g/L).…”

Section: Troponin Group Assignmentsmentioning

confidence: 99%

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Long-Term Health Outcomes Associated with Detectable Troponin I Concentrations

et al. 2007

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Background: Recent data suggest that older men with detectable cardiac troponin I (cTnI) concentrations that remain below the 99th percentile concentration cutoff are at increased risk for subsequent cardiovascular events. We designed this study to extend this observation by examining risk prediction in both men and women presenting to an emergency department with chest discomfort. Methods: We obtained data for all-cause mortality and hospital discharges associated with either acute myocardial infarction (AMI) or congestive heart failure (CHF) for up to 8 years after the initial presentation in 448 patients who originally presented in 1996 with acute coronary syndrome (ACS). We performed retrospective analysis for cTnI (AccuTnI™; Beckman Coulter) in frozen plasma samples based on the patients' reported time from onset of symptoms. Peak cTnI concentration was used for risk assessment. Results: Patients with cTnI concentrations >0.02 g/L (i.e., limit of detection), including those whose peak values remained below the 99th percentile (0.04 g/L), were at greater risk for death and AMI/CHF readmissions at 2, 5, and 8 years of follow-up compared with those with peak cTnI <0.02 g/L. All results were statistically significant (P <0.05) except for death within 2 years among patients with normal but detectable cTnI (0.02 to 0.03 g/L), relative to the group with values <0.02 g/L. Kaplan-Meier analyses indicated that both

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Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 85%

Section: Troponin Group Assignmentsmentioning

confidence: 99%

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Long-Term Health Outcomes Associated with Detectable Troponin I Concentrations

et al. 2007

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“…Several research groups used one of these assays to determine the levels of HNL/NGAL in urine and drew the conclusion that HNL/NGAL is a biomarker of AKI (12,13,16 -18). Our previous results indicated that the antibody configuration had an effect on the clinical performance of the assay (19,25). We also reported, for the first time, the existence of several molecular forms of HNL/NGAL in urine obtained from patients after cardiac surgery and that the presence of dimeric and monomeric forms and their ratios changed after operation (19).…”

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confidence: 79%

The Origin of Multiple Molecular Forms in Urine of HNL/NGAL

Cai

Rubin

Wang

et al. 2010

Clinical Journal of the American Society of Nephrology

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254

213

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Results: The major molecular form of HNL/NGAL secreted by neutrophils is dimeric, whereas the major form secreted by HK-2 cells is monomeric. This was reflected by a predominance of the monomeric form in urine from patients with AKI and the dimeric form in patients with UTIs. The epitope specificities of the antibody used in the ELISAs had a profound effect on assay performance and paralleled differences of the antibodies to identify the different forms of urine HNL/NGAL.Conclusions: The monomeric form is the predominant form secreted by tubular epithelial cells, and the dimeric form is the predominant form secreted by neutrophils. The development of molecular form-specific assays for HNL/NGAL may be a means to identify the origin of HNL/NGAL in urine and construct more specific tools for the diagnosis of AKI.

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“…The classification outlined above is seemingly robust and easy to communicate but is weakened by its lack of consideration of the actual clinical performance characteristics of assays. In previous reports, we have shown that cTnI assays of similar analytical sensitivities had very different clinical performance for outcome prediction depending on the antibody configurations of the assays and possible autoantibody interferences (5)(6)(7). To reemphasize this point, we have reevaluated the VIDAS cTnI assay and compared the clinical performance of this assay in a head-to-head comparison with 2 current laboratory assays, the Access AccuTnI and Architect cTnI assays, and with 2 pointof-care tests (POCTs), the i-Stat and Stratus CS cTnI assays.…”

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confidence: 99%

Cardiac Troponin Assay Classification by Both Clinical and Analytical Performance Characteristics: A Study on Outcome Prediction

Lindahl

2013

Clinical Chemistry

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BACKGROUND Cardiac troponin assays have been classified according to whether they measure the 99th percentile concentration of a healthy reference population with imprecision (expressed as CV) of ≤10%, between 10% and 20%, or >20%. Assays in these categories have been deemed “guideline acceptable,” “clinically usable,” or “not acceptable,” respectively. We compared four widely used “clinically usable” cardiac troponin I (cTnI) assays with an assay designated “not acceptable” for accuracy in predicting the clinical outcome of death. METHODS Blood was collected from 259 men and 249 women, mean (SD) age 68.8 (17.8) and 70.2 (17.8) years, respectively, admitted to the emergency department for suspected myocardial infarction. We measured cTnI by the Access, Architect, i-Stat, Stratus CS, and VIDAS assays. Deaths in this population were recorded over a 31-month period. RESULTS We found VIDAS cTnI assay measurement CVs of 10% and 20% at concentrations of 0.04 and 0.02 μg/L, respectively. Comparing at the 10% CV cutoff concentration, VIDAS cTnI was less sensitive than the Access and Architect assays (P < 0.001) but more sensitive than i-Stat (P < 0.001) and Stratus CS (P < 0.001) in identifying patients with poor outcomes. At the 20% CV cutoff, the VIDAS assay was equivalent to the other assays in identifying patients with poor outcomes. CONCLUSIONS For outcome prediction, the VIDAS cTnI assay was clinically equivalent or superior to other cTnI assays judged to be acceptable from a pure analytical standpoint. Thus, comparison of cardiac troponin assays should consider not only analytical performance, but also clinical performance characteristics.

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The Antibody Configurations of Cardiac Troponin I Assays May Determine Their Clinical Performance

Cited by 65 publications

References 21 publications

Long-Term Health Outcomes Associated with Detectable Troponin I Concentrations

Long-Term Health Outcomes Associated with Detectable Troponin I Concentrations

The Origin of Multiple Molecular Forms in Urine of HNL/NGAL

Cardiac Troponin Assay Classification by Both Clinical and Analytical Performance Characteristics: A Study on Outcome Prediction

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