Macrocomplexes and discordant high-sensitivity cardiac troponin concentrations

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.