A-336 Comparative Evaluation of Homogeneous Point-of-Care and Central Laboratory Chemiluminescent Immunoassays for High-Sensitivity Cardiac Troponin I
Authors: Ya hui L , Yu J , Cui K , Li Y , Yang Y , Zhu L , Wang M , Hu K , Qian C , Zhou Z 
Published: October 2024

Abstract

Background
Cardiac troponin I (cTnI) is the preferred biomarker for the diagnosis and management of acute myocardial infarction (AMI). Measurement of high-sensitivity cardiac troponin I (hs-cTnI) is useful for the detection of previously missed minor myocardial injuries, the early diagnosis of acute myocardial infarction, the rational diagnosis of high-risk cardiovascular patients, and for clinical therapeutic decision-making and prognostic assessment. Despite the development of both laboratory-based and point-of-care (POC) cTnI assays, discrepancies in testing results between these platforms underscore the need for highly sensitive assays with commutable results across various clinical settings to enhance patient care.

Methods
This study employed biosensor technology to investigate the interaction between troponin I protein and four commercially available anti-troponin I antibodies (G-129-C, 19C7, Ab01, and Ab02), aiming to optimize assay performance. We evaluated the analytical characteristics of two hs-cTnI assays: YHLO iFlash 3000 for central laboratories and Drawray iStar 500 for POC settings. The limit of blank (LoB), limit of detection (LoD), and limit of quantitation (LoQ) were determined for each assay. A cohort of 650 healthy Chinese individuals (304 males and 346 females) was utilized to establish the 99th percentile upper reference limits (URLs). Additionally, a Passing-Bablok analysis was conducted on 227 serum samples to assess the concordance between the two methods.

Results
Kinetic analysis demonstrated that antibody Ab02 exhibited a 20-fold higher affinity compared to 19C7, while Ab01 displayed approximately a 2-fold higher affinity than G-129-C, despite both pairs recognizing the same troponin I epitope. The imprecision levels for iFlash 3000 and iStar 500 hs-cTnI assays were 3.82% and 3.30%, 2.62% and 3.08%, and 1.88% and 1.82% for low, medium, and high-level controls, respectively. The established LoB and LoD for iFlash 3000 and iStar 500 hs-cTnI assays were 0.12 ng/L and 0.22 ng/L, and 0.37 ng/L and 0.44 ng/L, respectively. The correlation between Drawray iStar 500 and YHLO iFlash 3000 assay results was robust (r= 0.9993) across a wide range of troponin I concentrations (0.12 - 39600 ng/L), with measurable concentrations above 50% (83.54%, 87.83%, and 79.77%) for the overall, male, and female cohort. The non-parametric 99th percentile URL of iFlash 3000 hs-cTnI in the study cohort was 9.94 ng/L (90%CI 8.23-13.64 ng/L), with gender-specific variations observed. The coefficient of variation (%CV) at the 99th percentile value was well below 10% for the overall, male, and female cohort (3.42%, 2.82%, and 3.64%).

Conclusions
The findings affirm that both iFlash 3000 and iStar 500 hs-cTnI assays meet the criteria for high sensitivity and exhibit a strong correlation in test results. This correlation suggests their potential for interchangeable use in diverse clinical settings, thereby enhancing patient management. The distinct gender-specific 99th percentile URLs underscore the importance of tailored reference values in clinical assessments. The high precision and low limits of detection and quantitation further validate the reliability of these assays in the early diagnosis and management of AMI patients.