Description of patients and controls.
| ExRA* | RA Controls | Healthy Controls | |
|---|---|---|---|
| N | 34 | 67 | 81 |
| Male/female | 13/21 | 29/38 | 25/56 |
| Age, yrs, mean (SD) | 64.6 (12.1) | 63.9 (11.4) | 49.4 (10.8) |
| Disease duration, yrs, mean (SD) | 12.1 (11.6) | 11.5 (9.7) | n/a |
| RF-positive | 30/31 (97%) | 45/65 (69%) | n/d |
| Anti-CCP-positive | 25/31 (81%) | 38/66 (58%) | n/d |
| Rheumatoid nodules** | 15/32 (47%) | 12/67 (18%) | n/a |
| HAQ, mean (SD) | 1.32 (0.88) | 0.72 (0.74) | n/d |
| Swollen joints, mean (SD) | 7.1 (5.8) | 2.9 (3.4) | n/d |
| Ritchie’s index, mean (SD) | 10.5 (8.4) | 8.0 (7.4) | n/d |
| Current DMARD, n (%) | 17 (50) | 52 (72) | 0 |
| Current corticosteroids, n (%) | 12 (35) | 18 (27) | 0 |
| CRP, mg/L, median (IQR) | 21.5 (9.0–52.5) | 6.9 (2.2–14.0) | n/d |
| COMP-C3b, AU, median (IQR) | 1.98 (1.49–2.65) | 2.55 (2.02–3.29) | 0.59 (0.49–0.81) |
| COMP, U/l, median (IQR) | 8.85 (4.90–11.68) | 8.80 (6.25–10.50) | 7.02 (5.79–8.65) |
| sTCC, AU/ml, median (IQR) | 3.00 (1.67–7.50) | 2.40 (0.75–3.41) | 0.01 (0–0.09) |
↵* One or more of the following: major cutaneous vasculitis (n = 11; leg ulcers or purpura, verified by biopsy or dermatologist; nailfold lesions alone do not qualify), pericarditis (n = 9; symptomatic and verified by echocardiography), pleuritis (n = 8, symptomatic and verified by radiograph), Felty syndrome (n = 5; persistent neutropenia and splenomegaly), neuropathy (n = 4; symptomatic mononeuropathy/polyneuropathy, verified by electroneurography/electromyography).
↵** Current, or previous, based on medical records. COMP: cartilage oligomeric matrix protein; RA: rheumatoid arthritis; ExRA: extraarticular RA; AU: arbitrary units; CRP: C-reactive protein; HAQ: Health Assessment Questionnaire; n/a: not applicable; n/d: not determined; RF: rheumatoid factor; anti-CCP: antibodies against cyclic citrullinated peptide; DMARD: disease-modifying antirheumatic drug; sTCC: soluble terminal complement complex; IQR: interquartile range.