Outliers affecting cardiac troponin I measurement: Comparison of a new high sensitivity assay with a contemporary assay on the Abbott ARCHITECT analyser

摘要

Background: False-positive cardiac troponin (Tn) results caused by outliers have been reported on various analytical platforms. We have compared the precision profile and outlier rate of the Abbott Diagnostics contemporary troponin I (TnI) assay with their high sensitivity (hs) TnI assay. Methods: Three studies were conducted over a 10-month period using routine patients' samples. TnI was measured in duplicate using the contemporary TnI assay in Study 1 and Study 2 (n=7011 and 7089) and the hs-TnI assay in Study 3 (n=1522). Critical outliers were defined as duplicate results whose absolute difference exceeded a critical difference (Formula Presented) at a probability level of 0.0005, with one of the results on the opposite side of the decision limit to its partner. Results: The TnI concentration at 10% imprecision (coefficient of variation) for the contemporary TnI assay was 0.034 μg/L (Study 1) and 0.042 μg/L (Study 2), and 0.006 μg/L (6 ng/L) for the hs-TnI assay. The critical outlier rates for the contemporary TnI assay were 0.51% (Study 1) and 0.37% (Study 2) using a cut-off of 0.04 mg/L, and 0% for the hs-TnI assay using gender-specific cut-offs. Conclusion: The significant number of critical outliers detected using the contemporary TnI assay may pose a risk for misclassification of patients. By contrast, no critical outliers were detected using the hs-TnI assay. However, the total outlier rates for both assays were significantly higher than the expected variability of either assay. The cause of these outliers remains unclear.