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®) 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.