Cardiac troponin I measurement with the ACCESS immunoassay system: analytical and clinical performance characteristics.
We evaluated the ACCESS cardiac troponin I (cTnI) immunoassay as a marker for myocardial infarction (MI). Total imprecision was 6.0% to 13.5%, the minimum detectable concentration was 0.007 microg/L, and the limit of quantitation was 0.046 microg/L. Comparison of cTnI measurement between the ACCESS and Stratus systems (n = 114) showed a proportional difference: ACCESS cTnI = 0.0996 Stratus cTnI + 0.049 microg/L (r = 0.811). Fifty-nine of 61 ambulatory patients without cardiac symptoms had no detectable cTnI (95% range, 0.00 to 0.025 microg/L). The optimum cutoff for discriminating MI (n = 289, 45 with MI) was 0.15 microg/L by receiver operator characteristic curve analysis; at this cutoff, the ACCESS cTnI assay showed a sensitivity of 88.9% (95% CI, 79.7-98.1%) and specificity of 91.8% (95% CI, 88.4-95.2%). The ACCESS cTnI assay results showed 89.4% and 93.0% concordance with the MB isoenzyme of creatine kinase (CK-MB) mass and Stratus cTnI results, respectively, for classification of patients with suspected MI. The ACCESS cTnI assay appears to show sensitivity and specificity comparable with those of both CK-MB mass and Stratus cTnI assays for the diagnosis of MI in patients presenting within 12 h of onset of symptoms.
Christenson
R H
RH
Department of Pathology, University of Maryland School of Medicine, Baltimore 21201, USA. rchriste@umabnet.ab.umd.edu
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McCormack
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Keffer
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D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis; D004796:Clinical Enzyme Tests; D003402:Creatine Kinase / Q000097:blood; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007527:Isoenzymes; D007676:Kidney Failure, Chronic / Q000097:blood; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000737:chemistry / Q000293:injuries; D009135:Muscular Diseases / Q000378:metabolism; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D019210:Troponin I / Q000032:analysis* / Q000097:blood
D015415:Biomarkers; D007527:Isoenzymes; D019210:Troponin I; D003402:Creatine Kinase