Baseline patient demographics and disease characteristics by RF and anti-CCP serostatus
| Characteristic | RF positive (n=412) | RF negative (n=165) | p Value positive vs negative | Anti-CCP positive (n=364) | Anti-CCP negative (n=188) | p Value positive vs negative | RF and anti-CCP double positive (n=308) | RF and anti-CCP double negative (n=127) | p Value double positive vs double negative |
|---|---|---|---|---|---|---|---|---|---|
| Age, years | 59.1 (12.7) | 61.1 (12.8) | 0.099 | 59.8 (12.4) | 59.7 (13.3) | 0.829 | 59.2 (12.6) | 60.8 (13.1) | 0.270 |
| BMI, kg/m2 | 26.6 (5.3) | 27.7 (5.6) | 0.016 | 26.8 (5.6) | 27.5 (5.3) | 0.057 | 26.3 (5.3) | 27.3 (5.3) | 0.042 |
| RA duration, years | 7.8 (8.5) | 5.5 (7.2) | <0.001 | 7.7 (8.5) | 5.4 (6.1) | 0.005 | 7.9 (8.7) | 5.2 (5.9) | 0.002 |
| CRP, mg/L | 18.6 (28.1) | 12.1 (21.1) | <0.001 | 17.2 (25.7) | 14.5 (23.4) | 0.002 | 17.7 (26.5) | 11.9 (21.5) | <0.001 |
| ESR, mm/hour | 35.7 (24.3) | 26.9 (21.6) | <0.001 | 34.8 (23.6) | 28.3 (22.1) | 0.001 | 35.3 (24.0) | 25.9 (21.7) | <0.001 |
| DAS28 (CRP) (derived) | 4.8 (1.0) | 4.8 (1.1) | 0.978 | 4.7 (1.0) | 4.9 (1.1) | 0.113 | 4.7 (1.0) | 4.8 (1.1) | 0.475 |
| CDAI | 26.20 (12.82) | 28.22 (14.73) | 0.240 | 27.43 (13.45) | 28.10 (14.27) | 0.818 | 27.45 (13.49) | 30.10 (15.47) | 0.351 |
| HAQ-DI | 1.4 (0.7) | 1.4 (0.7) | 0.463 | 1.4 (0.7) | 1.4 (0.7) | 0.880 | 1.4 (0.7) | 1.4 (0.6) | 0.874 |
| Radiographic erosion, % | 62.8 | 46.5 | 0.001 | 61.4 | 50.3 | 0.019 | 62.5 | 47.5 | 0.006 |
| Concurrent non-biological DMARDs, % | 0.183 | ||||||||
| MTX only | 68.9 | 59.9 | 69.4 | 62.1 | 70.5 | 61.9 | |||
| MTX+other non-biological DMARDs | 11.7 | 17.5 | 0.117 | 11.3 | 15.0 | 0.267 | 9.4 | 15.2 | 0.183 |
| Other non-biological DMARDs | 19.4 | 22.6 | 19.3 | 22.9 | 20.1 | 22.9 | |||
| Concurrent corticosteroid, % | 71.8 | 62.4 | 0.029 | 73.1 | 59.6 | 0.001 | 72.1 | 59.8 | 0.017 |
| Mean dose, mg/day | 7.55 (7.10) | 8.00 (8.15) | 0.895 | 7.31 (4.26) | 8.23 (8.13) | 0.708 | 7.32 (4.31) | 8.57 (9.35) | 0.786 |
| Tobacco use, % | 17.7 | 9.1 | 0.01 | 15.9 | 12.8 | 0.377 | 16.2 | 9.4 | 0.071 |
| Comorbidities, % | |||||||||
| Metabolism/nutrition disorders | 26.2 | 35.2 | 0.042 | 29.1 | 33.5 | 0.330 | 27.6 | 36.2 | 0.085 |
| Nervous system disorders | 1.2 | 4.8 | 0.013 | 3.0 | 2.7 | 1.0 | 1.6 | 3.1 | 0.294 |
Data are mean (SD) unless otherwise specified.
Numbers in bold indicate differences of statistical significance.
BMI, body mass index; CCP, cyclic citrullinated peptide; CDAI, Clinical Disease Activity Index; CRP, C reactive protein; DAS28, Disease Activity Score in 28 joints; DMARD, disease-modifying antirheumatic drug; ESR, erythrocyte sedimentation rate; HAQ-DI, Health Assessment Questionnaire-Disability Index; MTX, methotrexate; RA, rheumatoid arthritis; RF, rheumatoid factor.