Table 2.
Correlation between Antiphospholipid Antibody Assays Based on Isotype Class
| Antibody Isotype | Analytes | % Positive Agreement | % Negative Agreement | % Overall Agreement | Kappa (%) 95% (CI) |
|---|---|---|---|---|---|
| IgG | APhL vs aCL | 77 | 98 | 89 | 77 (68-86) |
| APhL vs aB2GPI | 83 | 85 | 85 | 65 (54-76) | |
| aCL vs aB2GPI | 59 | 92 | 77 | 53 (41-65) | |
| IgM | APhL vs aCL | 51 | 97 | 72 | 46 (34-57) |
| APhL vs aB2GPI | 82 | 87 | 86 | 63 (50-75) | |
| aCL vs aB2GPI | 40 | 98 | 67 | 36 (24-49) | |
Concordance was computed based on manufacturers' recommended cut-off values with aCL and aB2GPI assays as reference tests. In the case of aCL vs aB2GPI, aCL was used as the reference test. Percent agreement, kappa and confidence interval (CI) values were generated using the EP evaluator 8.