N of patients in each category (percentage in parentheses) of the 2010 classification criteria components in patients with RA and other diagnoses
| Symptoms | RA (n=144) | UA (n=98) | Other diagnosis (after week 12, n=26) |
|---|---|---|---|
| Joint involvement | |||
| 1 large joint (%) | 0 (0) | 4 (4.0) | 1 (3.9) |
| 2–10 large joints (%) | 2 (1.3) | 8 (8.1) | 5 (19.3)** |
| 1–3 small joint (%) | 15 (10.5) | 30 (30.3)* | 5 (19.3)*** |
| 4–10 small joints (%) | 23 (16.1) | 23 (23.2) | 3 (11.5) |
| >10 joints (%) | 104 (72.2) | 33 (33.7)** | 12 (63.2)* |
| Serology | |||
| Normal RF or ACPA (%) | 72 (50.0) | 89 (90.8)** | 21 (80.8)* |
| Low positive RF or ACPA (%) | 12 (8.4) | 4 (4.0) | 2 (7.7) |
| High positive RF or ACPA | 60 (41.96) | 5 (5.1)** | 3 (11.5)* |
| Acute Phase reactants | |||
| Abnormal CRP or ESR (%) | 106 (73.6) | 55 (56.1)* | 19 (73.1) |
| Symptom duration | |||
| <6 weeks | 35 (24,5) | 48 (48.5)* | 7 (26.9) |
| Score, mean (IQR) | 7 (6;9) | 4 (3;6)** | 6 (3.25;7)** |
Intergroup difference was estimated with proportion test: 2-sample test for equality of proportions with continuity correction
*p<0.05 compared to patients with RA.
**p<0.001 compared to patients with RA.
***—p<0.001 compared to patients with UA.
ACPA, anti-citrullinated peptide antibodies; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; RA, rheumatoid arthritis; RF, rheumatoid factor; UA, undifferentiated arthritis.