Analytical comparison of three different versions of a high-sensitivity cardiac troponin I assay over 10years

BACKGROUND: Concerns have been raised on the long-term analytical performance of high-sensitivity cardiac troponin (hs-cTn) assays with respect to different reagent formulations, lots and instrumentation. Our goal for the present study was to compare three different versions of an hs-cTnI assay in two different study populations to evaluate if assay re-formulation over 10years has also affected the analytical results. METHODS: Beckman Coulter's CE marked hs-cTnI assay (Access hsTnI, 2017) was tested in 100 lithium heparin plasma samples first tested in 2007 with their prototype hs-cTnI assay and in 100 serum samples tested with their enhanced hs-cTnI assay in 2011 with comparison performed by Passing-Bablok regression. The Beckman Coulter hs-cTnI results from 2017 and 2011 from the serum samples were also compared to the Abbott ARCHITECT i1000 hs-cTnI results (2013) with 3-fold differences used to identify possible outliers. Freeze/thaw stability testing (-20°C) was also performed on normal cTnI (Beckman=4.0ng/L; Abbott=5.3ng/L) and high cTnI concentration (Beckman=77.6ng/L; Abbott=126.1ng/L) lithium heparin plasma pools for both hs-cTnI assays. RESULTS: After 3 freeze-thaws the Beckman hs-cTnI assay yielded minor decreases in concentrations (normal pool -0.7ng/L and high pool -12.6ng/L lower). Regression analyses yielded the following relationship between the Beckman hs-cTnI versions: 2017 hs-cTnI=2.0*(2007 prototype hs-cTnI)-5.1ng/L and 2017 hs-cTnI=1.04∗(2011 enhanced hs-cTnI)-2.5ng/L. Compared to the Abbott 2013 hs-cTnI results, the 2011 Beckman enhanced version had 8 results 3-fold higher, with the 2017 Beckman version yielding 6 results 3-fold lower. CONCLUSIONS: The 2017 Beckman hs-cTnI version (Access hsTnI) is closely aligned with the previous enhanced hs-cTnI assay and appears to have reduced the frequency of aberrantly high results.