Analytical Performance of the New Sysmex High-Sensitivity Troponin T Assay

Background: We evaluated the Sysmex Highly Integrated Single-Cartridge Luminescence Immunoassay System (HISCL) hs-cTnT assay, and compared its performance to the Roche assay, with derivation of 99th-percentile upper reference limits (99% URLs) for healthy subjects. We assessed the effect of increasing age/decreasing eGFR on the HISCL hs-cTnT. Methods: We verified assay limits of blank/detection, precision and the functional sensitivity. Samples were analyzed on both the Sysmex HISCL and Roche Elecsys analyzers for method comparison. Results: The HISCL assay limit of blank/detection was 1.3/1.9 ng/L, and concentrations corresponding to 20/10% CVs were 1.8/3.3 ng/L. Assay precision of kit controls at 3253 ng/L was 2.2% and at 106 ng/L was 2.5%. Linear regression analysis (n = 2151) showed good agreement (r = 0.95) with the Roche hs-cTnT. Bland-Altman (Roche/HISCL) analysis for samples with hs-cTnT ≤ 52 ng/L showed a mean absolute difference of 3.5 ng/L; for hs-cTnT > 52 ng/L, the mean difference was 2.8%. In a cardio-renal healthy population (n = 1004), the 99% URLs were 14.4/17.0/13.9 ng/L for overall/male/female, respectively; assay CV% was below 10% at these levels. More than 50% of the hs-cTnT in the healthy male and female subjects were measurable above the limit of detection. Hs-cTnT increased with increasing age and decreasing eGFR. Conclusions: In conclusion, the Sysmex HISCL hs-cTnT fulfils the criteria for a high-sensitivity assay, with specific 99th URLs for males and females. Expectedly, the baseline Sysmex hs-cTnT increases with age and decreasing eGFR.