Baseline characteristics
| Characteristic | No. (total n=244) |
|---|---|
| Age in years, mean ± SD | 47 ± 11 |
| Female sex | 181 (74%) |
| Arthralgia duration in months, median (IQR) | 12 (8–36) |
| Number of reported painful joints, median (IQR) | 2 (0–4) |
| Tender joint count (53 joints), median (IQR) | 0 (0–1) |
| Antibody status | |
| IgM-RF positive, aCCP negative | 81 (33%) |
| aCCP positive, IgM-RF negative | 89 (37%) |
| aCCP and IgM-RF positive | 74 (30%) |
| Antibody levels | |
| IgM-RF (IU/ml), median (IQR)* | 76 (42–123) |
| aCCP (AU/ml), median (IQR)* | 39 (12–145) |
| Shared epitope status | |
| Positive | 128 (52%) |
↵* Patients who were positive only.
aCCP, anti-cyclic citrullinated peptide antibody; AU/ml, arbitrary units/ml; IgM-RF, IgM rheumatoid factor.