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

¹ Department of Medical Sciences, Cardiology, and ² Department of Medical Sciences, Clinical Chemistry, Uppsala University, Uppsala, Sweden.
³ Uppsala Clinical Research Centre, Uppsala, Sweden.

^aAddress correspondence to this author at: Department of Clinical Chemistry and Pharmacology, University Hospital, SE-751 85 Uppsala, Sweden. Fax 46-186113703; e-mail per.venge{at}akademiska.se.

Background: Previous studies have shown superior clinical performance of the cardiac troponin I (cTnI) assay from Beckman-Coulter Diagnostics. This assay had a unique combination of monoclonal antibodies with 2 monoclonal antibodies directed against epitopes near the NH₂ terminus of the heart-specific region of troponin I. The approach has been adopted by the new cTnI assay from Abbott Diagnostics. The aim of our study was to investigate whether this approach affects the clinical performance of cTnI assays.

Methods: Cardiac troponin concentrations were measured in a random sample of patients with unstable coronary artery disease included in the GUSTO IV trial (n = 696) by the AccuTnI (Beckman-Coulter Diagnostics), Architect cTnI (Abbott Diagnostics), Immulite 2500 cTnI (Diagnostics Products Corporation), and Elecsys 2010 cTnT (Roche Diagnostics) assays and related to the 1-year mortality. The primary cutoff concentrations were based on the 99th percentile upper reference limits and an imprecision (CV) 10%.

Results: The sensitivities of the AccuTnI and Architect cTnI assays in identifying patients who died within 1 year were equal and were significantly higher (P <0.05) than those of the Immulite 2500 cTnI and the Elecsys cTnT assays. The concordance between the AccuTnI and Architect cTnI assays was 97%, but concordances between the Architect cTnI and the Elecsys cTnT assays were 89%–92% with more at-risk patients (P <0.01 to P <0.001) identified by the Architect cTnI assay.

Conclusions: The Architect cTnI assay has clinical performance similar to that of the AccuTnI, probably as a result of the inclusion of a monoclonal antibody against troponin I epitope 41–49 in the assay.

The following articles in journals at HighWire Press have cited this article:

				J. R Tate, W. Ferguson, R. Bais, K. Kostner, T. Marwick, and A. Carter The determination of the 99th centile level for troponin assays in an Australian reference population Ann Clin Biochem, May 1, 2008; 45(3): 275 - 288. [Abstract] [Full Text] [PDF]

				S. E.F. Melanson, M. J. Tanasijevic, and P. Jarolim Cardiac Troponin Assays: A View From the Clinical Chemistry Laboratory Circulation, October 30, 2007; 116(18): e501 - e504. [Full Text] [PDF]

				P. A. Kavsak, A. M. Newman, V. Lustig, A. R. MacRae, G. E. Palomaki, D. T. Ko, J. V. Tu, and A. S. Jaffe Long-Term Health Outcomes Associated with Detectable Troponin I Concentrations Clin. Chem., February 1, 2007; 53(2): 220 - 227. [Abstract] [Full Text] [PDF]