Comparison of Performance between the Elecsys 4th and 5th Generation STAT Cardiac Troponin T Immunoassays

Abstract

Objective: To evaluate the analytical and clinical performance of the 5^th GEN cTnT assay by comparing it with the 4^th GEN assay.

Methods: Imprecision, analytical measurement range (AMR), reference interval, and quantitative comparison were studied. Qualitative comparisons of the two assays for randomly selected patients with the cTnT test orders and patients with elevated N-terminal proB-type natriuretic peptide (NT-proBNP), decreased estimated glomerular filtration rate (eGFR), and increased procalcitonin were performed.

Results: Within-run and between-run CVs of the 5^th GEN assay were 0.6-2.3% and 3.1-5.0% with AMR of 8-10,000 ng/L and reference interval of <19 ng/L. Regression analysis of the two assays showed linear relationship: y (5^th GEN)=0.899x (4^th GEN)+26, r=0.9993 with a positive bias of the 5^th GEN assay in samples with cTnT <150 ng/L and a negative bias in samples with cTnT >500 ng/L compare to the 4^th GEN assay. Agreement was 88.1% (95% CI: 80.4 to 93.1%) between the two methods according to the 99^th percentile threshold. In patients with elevated NT-proBNP, decreased eGFR, and increased procalcitonin, agreements were 79.4%, 92.7%, and 100%.

Conclusion: The 5^th GEN cTnT assay demonstrates excellent precision and acceptable AMR. Compared to the 4^th GEN assay, the 5^th GEN assay shows a negative bias for samples with cTnT >500 ng/L but a positive bias for samples with cTnT <150 ng/L and identifies more patients with elevated cTnT.

Keywords: cardiac troponin T; heart failure; high-sensitivity assay; kidney failure; myocardial infarction; sepsis.