Evaluation of anti-citrullinated peptide antibody using different procedures, and rheumatoid factor by enzyme immunoassay in patients with rheumatoid arthritis and a control population
| CCP2, commercial kit | (Cfc6-cf0) Home made EIA | AKA (IFI) | RF (EIA) | CCP2 negative RF positive | CCP2 positive RF negative | CCP2 or RF positive | |
|---|---|---|---|---|---|---|---|
| Values are n (%) unless specified. | |||||||
| AKA, anti-keratin antibodies; CCP, cyclic citrullinated peptide; EIA, enzyme immunoassay; RA, rheumatoid arthritis; RF, rheumatoid factor; SLE, systemic lupus erythematosus; SS, Sjogren’s syndrome; y, year. | |||||||
| RA (n = 140) | 90 (64.3) | 67 (47.9) | 68 (48.6) | 84 (60.0) | 15 (10.7) | 12 (8.6) | 105 (75.0) |
| RA >2 y (n = 75) | 58 (77.3) | 45 (60.0) | 46 (61.3) | 50 (66.7) | 4 (5.3) | 7 (9.3) | 62 (82.7) |
| <2 y (n = 65) | 32 (49.2) | 22 (33.8) | 22 (33.8) | 34 (52.3) | 10 (15.4) | 5 (7.7) | 35 (53.8) |
| <6 months (n = 21) | 10 (47.6) | 4 (19.0) | 2 (9.5) | 12 (57.1) | 1 (4.8) | 1 (4.8) | 13 (61.9) |
| SS (n = 47) | 2 (4) | 1 (2) | 5 (10) | 22 (47) | – | – | – |
| SLE (n = 51) | 0 (–) | 2 (4) | 3 (6) | 16 (31) | – | – | – |
| Healthy subjects (n = 33) | 0 (–) | 0 (–) | 0 (–) | 3 (10) | – | – | – |
| Specificity (%) | 96.4 | 97.1 | 93 | 69 | – | – | – |