Disease characteristics compared across serology status
| Variable | Seronegative RA (n=36) | Seropositive RA (n=198) | p Value |
|---|---|---|---|
| Age, years | 55.8 (15.4) | 50.7 (13.3) | 0.04 |
| Female, n (%) | 21 (58.3) | 124 (62.6) | 0.63 |
| Disease duration, months | 4.8 [2.5–11.7] | 5.9 [2.9–9.9] | 0.89 |
| Positive for ACPA, n (%) | NA | 187 (94.4) | |
| Positive for RF IgM | NA | 154 (77.8) | |
| Positive for RF IgA | NA | 110 (55.6) | |
| DAS* | 3.9 (1.2) | 3.4 (1.2) | 0.03 |
| 44 SJC | 17 [11–25] | 8 [4–13] | <0.001 |
| CRP, mg/L | 7.3 [3.0–27.0] | 7.0 [3.0–18.0] | 0.48 |
| ESR, mm/h | 14.0 [10.0–29.0] | 20.5 [12.0–33.0] | 0.21 |
| Ritchie Articular Index | 7.5 [3.5–14.0] | 7.0 [4.0–13.0] | 0.73 |
| Physician global VAS 0–100 mm | 49.1 (21.1) | 38.9 (20.2) | 0.006 |
| Patient global VAS 0–100 mm | 50.0 (26.6) | 49.6 (23.9) | 0.92 |
| Total US joint score† | 55 [31–82] | 25 [15–40] | <0.001 |
| US PD joint score | 16 [7–27] | 7 [3–14] | <0.001 |
| US GS joint score | 37 [23–58] | 18.5 [10–27] | <0.001 |
| Joints with US synovitis | 16 [9–20] | 6 [3–10] | <0.001 |
| Total US tendon score | 3 [0–7] | 0 [0–3] | <0.001 |
| US PD tendon score | 1 [0–4] | 0 [0–2] | 0.008 |
| US GS tendon score | 2 [0–3] | 0 [0–2] | <0.001 |
| Total van der Heijde-modified Sharp score | 5.5 [2.0–13.0] | 4.0 [1.5–8.0] | 0.20 |
| Joint space narrowing | 1.5 [0.0–6.0] | 1.0 [0.0–3.0] | 0.06 |
| Erosion score | 3.0 [1.0–6.5] | 3.0 [1.0–4.5] | 0.43 |
| EQ-5D | 0.66 [0.11–0.76] | 0.66 [0.23–0.73] | 0.84 |
| Pain VAS 0–100 mm | 45.5 (26.3) | 48.1 (23.5) | 0.55 |
| Fatigue VAS 0–100 mm | 41.5 (29.8) | 40.0 (28.4) | 0.78 |
| RAID score | 4.7 (2.3) | 4.4 (2.1) | 0.53 |
| PROMIS HAQ | 36.3 [13.8–58.8] | 29.5 [17.5–48.8] | 0.78 |
| SF-36 PCS | 32.5 (7.9) | 36.6 (9.7) | 0.37 |
| SF-36 MCS | 48.6 (11.9) | 49.3 (10.3) | 0.75 |
Bold indicates p-values less than 0.05.
Values are median [25th–75th centiles] or mean (SD), unless otherwise indicated.
*Original disease activity score based on ESR, patient global, 44 SJC and Ritchie Articular Index.
†Ultrasonography (US) semiquantitative scoring system with ranges 0–3 for grey scale (GS) and power Doppler (PD) in 36 joints and 4 tendons. (Total US joint score, range: 0–216. Total US tendon score, range: 0–24.)
ACPA, anticitrullinated peptide antibody; CRP, C reactive protein; DAS, disease activity score; EQ-5D, EuroQol-5 Dimensions (UK weighted); ESR, erythrocyte sedimentation rate; MCS, Mental Components Summary; PCS, Physical Components Summary; PROMIS HAQ, Patient-Reported Outcome Measurement Information System Health Assessment Questionnaire; RA, rheumatoid arthritis; RAID, Rheumatoid Arthritis Impact of Disease (range from 0 to 10, with higher scores indicating greater impact of disease); RF, rheumatoid factor; SF-36, 36-item Short Form Health Survey; SJC, swollen joint count; VAS, Visual Analogue Scale.