Macrocomplexes and discordant high-sensitivity cardiac troponin concentrations
Peter A Kavsak1,2, Chantele Roy3, Paul Malinowski3
11 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.
Insights
Analytical comparisons of high-sensitivity cardiac troponin I (hs-cTnI) assays show high correlation between Beckman Coulter and Abbott methods. Significant differences in hs-cTnI results may be caused by macrocomplexes affecting specific assays.
Area of Science:
- Clinical Chemistry
- Cardiovascular Diagnostics
- Assay Interferences
Background:
- Analytical comparisons of high-sensitivity cardiac troponin (hs-cTn) assays are crucial for result validation.
- Interferences and confounders can impact hs-cTn assay interpretation.
- Understanding assay differences ensures reliable clinical decision-making.
Purpose of the Study:
- To compare Beckman Coulter's hs-cTnI assay with Abbott's hs-cTnI assay.
- To evaluate the agreement between these two hs-cTnI methodologies.
- To investigate the cause of significant discrepancies observed between assays.
Main Methods:
- Two hundred plasma samples with existing Abbott hs-cTnI results were retested on both Abbott and Beckman Coulter analyzers.
- Passing-Bablok regression and fold-difference analyses were performed.
- Samples with ≥3-fold differences underwent further testing including Roche hs-cTnT and polyethylene glycol precipitation.
Main Results:
- Beckman and Abbott hs-cTnI concentrations showed high correlation (r=0.95).
- Beckman assay yielded proportionally lower concentrations (slope=0.78).
- Macrocomplexes were identified as the cause of ≥3-fold higher Abbott hs-cTnI results in seven patients, affecting Abbott and Roche assays but not Beckman.
Conclusions:
- High correlation exists between Beckman Coulter and Abbott hs-cTnI assays.
- Significant discrepancies (≥3-fold) between Abbott and Beckman hs-cTnI results can be attributed to macrocomplex interference.
- The Beckman Coulter hs-cTnI assay appears less affected by macrocomplexes compared to the Abbott assay.
Abstract:
Background Analytical comparisons between different high-sensitivity cardiac troponin (hs-cTn) assays are important for reassurance of results performed with different methodologies and to identify potential interferences or confounders to result interpretation. Our objective in the present study was to compare Beckman Coulter's latest hs-cTnI assay to Abbott's hs-cTnI assay and to assess agreement between results. Methods Two hundred ethylenediaminetetraacetic acid plasma samples that had clinically reported hs-cTnI results from the Abbott ARCHITECTi2000 that spanned the analytical range were stored (median = 4 h), re-centrifuged and retested for hs-cTnI on the Abbott ARCHITECTi1000 and Beckman Coulter Access2 analysers. Passing-Bablok regression and fold-differences were evaluated, with differences approximately three-fold between results further subjected to Roche hs-cTnT testing and polyethylene glycol precipitation. Results The Beckman and Abbott hs-cTnI concentrations were correlated ( r = 0.95) with Beckman yielding proportionally lower concentrations (slope = 0.78; 95%CI: 0.74-0.85). There were 12 samples that yielded Abbott hs-TnI concentrations ≥3-fold higher than the Beckman hs-cTnI concentrations; of which nine samples from seven different patients had sufficient quantity for additional testing. All seven patients had macrocomplexes as determined with polyethylene glycol precipitation that affected the Abbott hs-cTnI assay. One patient with Abbott hs-cTnI results >1300 ng/L had polyethylene glycol, heterophile antibodies and creatine kinase-MB testing performed which confirmed that a macrocomplex most likely affected the Abbott and Roche (hs-cTnT = 65 ng/L) assays but not the Beckman (hs-cTnI = 12 ng/L) assay. Conclusion The hs-cTnI concentrations obtained from ethylenediaminetetraacetic acid plasma between the Beckman and Abbott assays are highly correlated, with large differences in concentrations (≥3-fold) between Abbott and Beckman assays possible due to macrocomplexes.
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