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

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

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.

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%.

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.