B-281 Analytical Validation of the Mindray High Sensitivity Cardiac Troponin I Assay

Abstract Background According to recent global guidelines for patients presenting with ischemia, high sensitivity cardiac troponin I and T (hs-cTn) are the preferred biomarkers for the diagnosis and risk assessment of acute myocardial infarction (MI) and myocardial injury. The purpose of our study was to perform an analytical validation study of the Mindray hs-cTnI assay. Methods Analytical studies were designed according to Clinical and Laboratory Standards Institute protocols (CLSI). We used one reagent lot and one CL1200i chemiluminescence Immunoassay Analyzer (Mindray Bio Medical Electronics Co., Shenzhen, China). Following the CLSI EP17 A2 document, the limit of blank (LoB) and limit of detection (LoD) were assessed following analysis of a) Mindray controls without cTnI concentrations added for the LoB and b) 4 lithium heparin (LiHep) fresh samples with low cTnI concentrations, for 3 days for LoB and LoD, with 5 replicates per day (60 replicates per study). For the precision study, according to the CLSI EP15-A3 protocol, we used 12 LiHep fresh samples, measured for 10 days, with 2 runs per day (separated by a minimal time of 2 h) and in replicates of 3 (n = 720). For the 12 samples for the precision study, 7 were chosen with hs-cTnI concentrations close to the manufacturer sex-specific 99th percentile upper reference limits (URL; 31 ng/L for males and 15 ng/L for females). The CLSI EP06 protocol was followed to study linearity, using 9 fresh LiHep samples analyzed the same day in replicates of 7 (n = 63). A blank sample between every sample was used to avoid carryover. Our analytical specification for linearity was an allowable deviation <10%. Analyses were performed with Analyze it for Excel (Method Validation edition, version 6.15). Results Using both parametrical and non-parametrical analyses, LoB was <0.1 ng/L, with a relative light unit (RLU) of 5394. LoD was 0.1 ng/L according to the parametrical analysis. Regarding imprecision, for samples ranging from cTnI concentrations of 1 to 106 ng/L, repeatability had a coefficient of variation (%CV) from 1.15% to 3.83%, and within-laboratory imprecision ranging from 1.69% to 5.03%. Using samples with hs-cTnI concentrations close to the manufacture’s sex-specific upper reference limits (9–36 ng/L), the repeatability and within-laboratory precision was 1.27%–1.61% and 1.92%–2.52%, respectively. The measuring interval for the linearity study ranged from 1.1 to 30 772 ng/L. All analytical parameters met CLSI limits of acceptable performance. No carry over was detected. Conclusion Our analytical observations of the Mindray hs-cTnI assay demonstrate excellent LoB, LoD, imprecision and linearity, that were in alignment of with the manufacturer’s claims and published guidelines for hs-cTnI.