Table 1 Characteristics of patients and control individuals
| Patients | Controls | |
|---|---|---|
| Number | 17 | 4 |
| Sex (female/male) | 13/4 | 3/1 |
| Median age (years; range) | 52 (33–78) | 35.5 (34–57) |
| Median disease duration (years; range) | 8 (4–22) | - |
| IgM rheumatoid factor (percentage seropositive) | 82% | - |