Analytical and clinical performance evaluation of a new high-sensitivity cardiac troponin I assay

Objectives: To validate the analytical performance and diagnostic accuracy for non-ST-segment elevation myocardial infarction (NSTEMI) with a new high-sensitivity cardiac troponin I (hs-cTnI) assay on the automated light-initiated chemiluminescent assay (LiCA (R)) platform. Methods: Comprehensive analytical validations were performed, and the 99th percentile upper reference limit (URL) from apparently healthy individuals were established. We evaluated the diagnostic performance of the assay for NSTEMI. Results: The limit of quantitation (LoQ) were 1.9 ng/L (20% CV) and 5.1 ng/L (10% CV). The sex-specific 99th percentile URLs were 17.6 ng/L (4.2% CV) for men (age 20-79y) and 14.2 ng/L (4.9% CV) for women (age 19-89y) in serum, 14.4 ng/L (4.9% CV) for men (age 19-88y) and 12.9 ng/L (5.2% CV) for women (age 19-87y) in plasma, respectively. Detection rates in healthy individuals were from 98.7 to 99.1%. The correlation coefficient and median bias between LiCA and Architect were 0.985 and 0.1% (-2.0-2.9%) in full analytical range of serum specimens. In lower range (<100 ng/L), LiCA had an overall positive bias 6.7% (-1.6-13.3%), R=0.949. At the specific medical decision levels (15.2, 26.2 and 64.0 ng/L), assay difference was estimated to be <10%. No significant differences on AUC, sensitivity and specificity, NPV and PPV were found between LiCA and Architect for the diagnosis of NSTEMI. Conclusions: LiCA hs-cTnI is a precise, highly sensitive and specific assay that meets the requirement of a 3rd generation (level 4) high-sensitivity method. The diagnostic accuracy of LiCA assay for NSTEMI is comparable to the established Architect hs-cTnI assay.