Comparability of Beckman Coulter Cardiac Troponin I Assays
Caroline G Stanek1, Jose Lima1, Liyun Cao2
1Department of Pathology, The University of Alabama at Birmingham, Birmingham AL, USA.
Insights
Beckman Coulter cardiac troponin I (cTnI) assays show comparable results when used on the same instrument, but differences arise between contemporary and high-sensitivity assays, especially at lower levels. Reporting the specific assay and instrument is recommended for accurate interpretation.
Area of Science:
- Clinical Chemistry
- Biomarker Analysis
- Cardiovascular Diagnostics
Background:
- Cardiac troponin I (cTnI) is a critical biomarker for diagnosing myocardial injury, with changes above the 99th percentile of the upper reference limit (URL) essential for acute myocardial infarction assessment.
- Accurate measurement of cTnI is vital for timely and correct patient management.
Purpose of the Study:
- To evaluate the analytical performance and concordance between the Beckman Coulter contemporary cTnI AccuTnI+3 assay and the high-sensitivity cTnI (hs-cTnI) assay.
- To assess the agreement of hs-cTnI results across different Beckman Coulter instruments (DXI 800 and Access 2).
Main Methods:
- Analyzed 424 patient specimens using the AccuTnI+3 and hs-cTnI assays on the DXI 800 instrument.
- Compared hs-cTnI results from the Access 2 and DXI 800 instruments using 115 patient specimens.
Main Results:
- Between-method comparison on DXI 800 showed good correlation (CC=0.9590) but significant bias (-5.16%) at levels below 20 ng/L.
- Within-method comparison of hs-cTnI on Access 2 and DXI 800 demonstrated high concordance (CC=0.9915) overall.
- hs-cTnI results were more comparable between instruments at levels below 200 ng/L (CC=0.9951).
Conclusions:
- Contemporary AccuTnI+3 and hs-cTnI assays yield comparable results on the DXI 800, particularly above the 99th percentile URL.
- hs-cTnI results are comparable between Access 2 and DXI 800 instruments, especially at concentrations below 200 ng/L.
- Laboratories should report the specific cardiac troponin assay and instrument used to prevent misinterpretation of results.
Objective:
Cardiac troponin I (cTnI) is one of the most sensitive and specific biomarkers of myocardial injury. The rise and/or fall of cardiac troponins above the 99th percentile of the upper reference limit (URL) is required in the assessment of acute myocardial infarction.
Methods:
We analyzed the variation between the Beckman Coulter contemporary cTnI AccuTnI+3 assay and high sensitivity cTnI (hs-cTnI) assay tested on DXI 800 using 424 patient specimens with troponin levels ranging from 0-16754 ng/L. We also analyzed the concordance of the same assay hs-cTnI on different Beckman Coulter instruments Access 2 and DXI 800 using 115 patient specimens with troponin levels ranging from 2-100466 ng/L.
Results:
The between-method comparison of AccuTnI+3 and hs-cTnI on DXI 800 showed a good correlation with the slope of 1.003, correlation coefficient (CC) of 0.9590, and bias of -40.65 (-5.16%). However, comparison of AccuTnI+3 and hs-cTnI in 103 patients with troponin less than 20 ng/L, the 99th percentile of the URL for male, showed the slope of 1.325, CC of 0.7462, and bias of 1.91 (21.53%). The within-method comparison of hs-cTnI on Access 2 and DXI 800 showed the slope was 1.130 with CC of 0.9915, and bias of 840.4 (10.6%). Further examination of the results revealed that hs-cTnI levels were more comparable at levels less than 200 ng/L, with a slope of 1.069, CC of 0.9951, and bias of 2.3 (6.2%).
Conclusion:
These data indicate that contemporary cTnI AccuTnI+3 results above the 99th percentile URL are comparable with hs-cTnI results if both are tested on DXI 800, and hs-cTnI results tested on Access 2 and DXI 800 are comparable at levels less than 200 ng/L. Therefore, to use the Beckman Coulter cTnI assay properly, we suggest the laboratory report cardiac troponins with the assay and instrument names to reduce confusion during results comparison.
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