An in-house comparative study was performed to demonstrate the equivalence of the Cardiolipin IgM ELISA test system to another commercially available Cardiolipin IgM ELISA test system. Performance was evaluated using 260 specimens as described in Table 1 below. The results of the investigation have been summarized in Table 2 below.
Table 1. Summary of Clinical Specimens
Table 2. Calculation of Relative Sensitivity, Specificity, and Agreement
Relative Sensitivity = 44/47 = 93.6%
95% Confidence Interval* = 86.6 to 100%
Relative Specificity = 163/213 = 76.5%
95% Confidence Interval* = 70.8 to 82.2%
Relative Agreement = 207/ 260 = 79.6%
95% Confidence Interval* = 74.7 to 84.5%
*95% confidence intervals calculated using the exact method. Reproducibility
To evaluate both intra-assay and inter-assay reproducibility, six specimens were tested; eight replicates each, on each of three days. These results were then used to calculate mean unit values, standard deviations, and percent CV. Two of the specimens were strong positives, two were clearly negative, and two were near the assay cut off. The results of the study have been summarized below.
Table 3. Cardiolipin IgM ELISA ; Results of Precision Testing
Day 1: Intra-Assay Reproducibility
Day 2: Intra-Assay Reproducibility
Day 3: Intra-Assay Reproducibility
Intra-Assay Reproducibility; All Days Combined: Cross-Reactivity
To investigate the potential for positive reactions due to cross-reactive antibodies, fourteen specimens which were reactive for various autoantibodies were tested on the anti-Cardiolipin test system. None of the fourteen were positive for antiCardiolipin IgM antibody. The results of this study indicate that the potential for a high degree of cross reactivity with such autoantibodies is not likely.