Table 1.
Characteristics of rheumatoid arthritis (RA) patients and control participantsa
| Participant characteristics | Control (n = 67) | RA (n = 145) | AOSD (n = 6) | OA (n = 31) | SLE (n = 39) |
|---|---|---|---|---|---|
| Mean age, yr (± SEM) | 60.7 ± 2.1 | 56.7 ± 1.2 | 54.3 ± 9.9 | 76.3 ± 1.5b | 38.8 ± 2.1b |
| Sex, n | |||||
| Male | 40 | 24b | 1b | 6b | 6b |
| Female | 27 | 121 | 5 | 25 | 33 |
| Smoking status, n | |||||
| Nonsmoker | 37 | 32 | 1 | 0 | 0 |
| Smoker | 30 | 12 | 0 | 0 | 0 |
| Unknown | 0 | 101 | 5 | 31 | 39 |
| Joint damagec, n | |||||
| I | ND | 42 | ND | ND | ND |
| II | ND | 47 | ND | ND | ND |
| III | ND | 20 | ND | ND | ND |
| IV | ND | 36 | ND | ND | ND |
| Functional classificationd, n | |||||
| I | ND | 24 | ND | ND | ND |
| II | ND | 92 | ND | ND | ND |
| III | ND | 29 | ND | ND | ND |
| IV | ND | 0 | ND | ND | ND |
| Mean DAS28 (CRP) (± SEM) | ND | 4.3 ± 0.1 | ND | ND | ND |
| Mean DAS28 (ESR) (± SEM) | ND | 4.9 ± 0.1 | ND | ND | ND |
| Mean HAQ (± SEM) | ND | 5.8 ± 0.7 | ND | ND | ND |
| Mean WBC (cell count/μL) (± SEM) | ND | 7,307.3 ± 211.0 | 8,950.0 ± 533.1 | 5,134.7 ± 304.8 | ND |
| Mean CRP level, mg/dL (± SEM) | ND | 2.27 ± 0.22 | 2.15 ± 1.14 | 0.08 ± 0.02 | ND |
| Mean ESR, mm/hour (± SEM) | ND | 45.0 ± 2.7 | 40.3 ± 18.6 | ND | ND |
| RF-positived, n (%) | 2/64 (3.1%) | 106/145 (73.1%) | 0/6 (0%) | 2/30 (6.7%) | 2/39 (5.1%) |
| Mean RF, U/mL (± SEM) | 3.7 ± 1.3 | 158.0 ± 20.9 b | 4.8 ± 2.7 | 5.4 ± 1.3b | 3.8 ± 1.0 |
| CCP-positivee, n (%) | 0/59 (0%) | 121/145 (83.4%) | 1/6 (16.7%) | 0/30 (0%) | 3/39 (7.7%) |
| Mean CCP, U/mL (± SEM) | 0.3 ± 0.1 | 261.5 ± 27.2b | 22.5 ± 22.3 | 0.5 ± 0.1b | |
| PSL, n (%) | ND | 89/145 (61.4%) | ND | ND | ND |
| Mean dose, mg/day (± SEM) | ND | 5.91 ± 0.32 | ND | ND | ND |
| MTX, n (%) | ND | 58/145 (40.0%) | ND | ND | ND |
| Mean dose, mg/week (± SEM) | ND | 6.87 ± 0.34 | ND | ND | ND |
| DMARDsf, n (%) | ND | 117/145 (80.7%) | ND | ND | ND |
aRA = rheumatoid arthritis; AOSD = adult-onset Still's disease; OA = osteoarthritis; SLE = systemic lupus erythematosus; DAS28 = 28-joint Disease Activity Score; HAQ = Health Assessment Questionnaire; WBC = white blood cell; CRP = C-reactive protein; ESR = erythrocyte sedimentation rate; RF = rheumatoid factor; CCP = anticyclic citrullinated peptide antibody; PSL = prednisolone; MTX = methotrexate; DMARDs = disease-modifying antirheumatic drugs; bP < 0.05 vs. healthy controls; cSteinbrocker global score (I to IV) [21]; cSteinbrocker functional classification was used, ranging from class I, "complete functional capacity to carry out all usual duties without handicaps," to class IV, "largely or wholly incapacitated with (the person) bedridden or confined to wheelchair" [21]; dcutoff serum concentration of the immunoglobulin M rheumatoid factor (RF) is 20 units/mL; ecutoff serum concentration of the anti-CCP antibody is 4.5 U/mL; fnone of RA patients were treated with tumor necrosis factor α inhibitor at this point.