Distribution of the components of the 2010 ACR/EULAR score set among misclassified patients (percentage in parentheses)
| Misclassified | ||
|---|---|---|
| Category | False positive n=44 | False negative n=22 |
| Joint involvement | ||
| 1 large joint (%) | 0 (0) | 0 (0) |
| 2–10 large joints (%) | 0 (0) | 2 (9.1) |
| 1–3 small joint (%) | 1 (2.3) | 7 (31.8) |
| 4–10 small joints (%) | 3 (6.8) | 10 (45.5) |
| >10 joints (%) | 40 (90.9) | 3 (13.6) |
| Serology | ||
| Normal RF or ACPA (%) | 35 (79.6) | 18 (81.8) |
| Low positive RF or ACPA (%) | 1 (2.3) | 1 (4.6) |
| High positive RF or ACPA | 8 (18.2) | 3 (13.6) |
| Acute-phase reactants | ||
| Normal CRP or ESR (%) | 14 (31.8) | 9 (40.9) |
| Abnormal CRP or ESR (%) | 30 (68.2) | 13 (59.1) |
| Symptoms duration | ||
| <6 weeks | 14 (31.8) | 10 (45.5) |
| ≥6 weeks | 30 (68.2) | 12 (54.6) |
| Score, median (IQR) | 7 (6;7) | 5 (5;5.75) |
ACPA, anti-citrullinated peptide antibodies; CRP, C-reactive protein; ESR-erythrocyte sedimentation rate; RF, rheumatoid factor.