Performance characteristics of ACPA assays at the cut-off defined by the manufacturer. 95% CIs are presented between brackets
| Thermo Fisher ACPA | Roche ACPA | Svar ACPA | IDS ACPA | Orgentec ACPA | Abbott ACPA | Euroimmun ACPA | BioRad ACPA | Siemens ACPA | |
| Unit | U/mL | U/mL | U/mL | AU/mL | U/mL | U/mL | RU/mL | U/ml | U/mL |
| Measuring range | 0.4–340 | 7–500 | 1.6–3200 | 1.2–320 | 1–1000 | 0.5–195.6 | 1–200 | 0.5–300 | 0.54–200 |
| Manufacturer’s cut-off | 10 | 17 | 25 | 5 | 20 | 5 | 5 | 3 | 5 |
| Sensitivity | 63.1 (58.1 to 67.8) | 62.6 (57.6 to 67.3) | 61.3 (56.3 to 66.1) | 62.6 (57.6 to 67.3) | 57.8 (52.8 to 62.7) | 62.1 (57.1 to 66.8) | 64.6 (59.7 to 69.3) | 60.8 (55.5 to 65.8) | 63.5 (58.3 to 68.5) |
| Specificity | 97.6 (96.5 to 98.4) | 96.7 (95.5 to 97.7) | 97.4 (96.3 to 98.3) | 96.4 (95.5 to 97.7) | 97.8 (96.7 to 98.6) | 97.7 (96.6 to 98.5) | 94.9 (93.4 to 96.1) | 96.8 (95.5 to 97.8) | 97.3 (96.1 to 98.2) |
| LR+ | 26.3 (17.7 to 38.3) | 19.2 (13.7 to 26.8) | 23.5 (16.2 to 34.1) | 19.2 (13.7 to 26.8) | 25.8 (17.2 to 38.7) | 26.6 (17.0 to 39.5) | 12.6 (9.6 to 16.5) | 18.9 (13.3 to 26.9) | 23.4 (16.0 to 34.4) |
| LR− | 0.4 (0.3 to 0.4) | 0.4 (0.3 to 0.4) | 0.4 (0.4 to 0.4) | 0.4 (0.3 to 0.4) | 0.4 (0.4 to 0.5) | 0.4 (0.3 to 0.4) | 0.4 (0.3 to 0.4) | 0.4 (0.4 to 0.5) | 0.4 (0.4 to 0.5) |
ACPA, anti-citrullinated protein/peptide antibody; LR−, negative likelihood ratio (1−sensitivity/specificity); LR+, positive likelihood ratio (sensitivity/1−specificity).