The Evaluation of Cardiac Troponin I Assays Measured Radiometer AQT90 Flex and ReLIA Analyzers and Determination of Heterophilic Antibody Positivity Rate

Measurement of cardiac troponin I (cTnI) is important for the diagnosis of myocardial infarction and for risk stratification. The aim of this study was to compare the diagnostic performance of AQT90 Flex cTnI and ReLIA cTnI assays as based Vidas Ultra cTnI results, and also determine rate of the heterophilic antibody (HAs) positivity. A total of 246 cTnI and HAs assays were performed from the blood and serum samples. The diagnostic cut-off value for cTnI assays was accepted as 0.01 μg/L, 0.023 ng/mL and 0.15 ng/mL for Vidas Ultra, AQT90Flex and ReLIA analyzers, respectively. Sensitivity, specificity, predictive value of positive and negative test, false positive and negative rate and efficiency were calculated. The sensitivity, negative predictive value, false positivity rate and accuracy of cTnI assay performed on AQT90 Flex analyzer were higher than cTnI assay performed on ReLIA analyzer. However, cTnI assay performed on ReLIA analyzer have higher specificity and false negativity rate as compared to cTnI test performed on AQT90 Flex analyzer. The agreement of cTnI results were calculated using of kappa analysis. The analysis revealed a substantial agreement between cTnI assays performed on Vidas Ultra and AQT90 Flex analyzer (p<0.001, κ=0.618), and fair agreement between cTnI assays performed on Vidas Ultra and ReLIA analyzer (p<0.001, κ=0.373).The positivity rate of HAs was found as 4.87%. The results of the study showed that AQT90Flex cTnI assay has higher sensitivity and accuracy, lower specificity and false negativity rate as compared to ReLIA cTnI assay. However, fairly lower heterophilic antibody positivity rate is found