Analytical evaluation of an automated immunoassay for cardiac troponin I: The Vidas Troponin I assay

Cardiac troponin I (cTnI) is a sensitive and specific biochemical marker of myocardial damage. We assessed the analytical performance of the Vidas Troponin I assay (Biomerieux). Controls and serum pools were used to determine the precision, analytical sensitivity and linearity; 97.5 and 99.5 percentiles concentrations were determined from the reference population. Fifty corresponding samples of serum and plasma (lithiumheparin) were tested and the results compared. The in vitro stability of serum and plasma samples was assessed at 20 C, 4 C and 20 C, respectively. Samples of serum were used to assess the agreement between the Vidas Troponin I method and the revised Dimension RxL cTnI method (DadeBehring). The total imprecision (CVs) was 13.15.2% for concentrations ranging between 0.25 and 19.8 g/l cTnI. The lower detection limit was <0.1 g/l. The upper reference limit (97.5 and 99.5 percentiles) was 0.11 g/l and 0.12 g/l, respectively (CV >10%). The assay was linear up to 21 g/l. The concentrations in lithiumheparin plasma were higher compared to those of the matched serum samples. The study of the agreement between the Vidas and Dimension RxL cTnI assays showed a total concordance of 96% with a bias value of 0.042. The Vidas Troponin I test is a fast, precise and sensitive method for the determination of cTnI.