Table 1.
Baseline demographic and clinical characteristics by diagnosis group*
| Variables | Overall (N=126) | RA (N=81) | UA (N=45) | p Value |
|---|---|---|---|---|
| Female, n (%) | 88 (70%) | 61 (75%) | 27 (60%) | 0.07 |
| Age (years), median (IQR) | 51 (40–58) | 51 (39–57) | 51 (43–59) | 0.457 |
| Disease duration (months), median (IQR)† | 4 (2–7.5) | 4 (2–8) | 3 (2–6) | 0.28 |
| IgM-RF positive, n (%) | 56 (44%) | 49 (60%) | 7 (16%) | <0.001 |
| Anti-CCP positive, n (%) | 51 (40%) | 49 (60%) | 2 (4%) | <0.001 |
| IgM-RF and anti-CCP positive, n (%) | 43 (34%) | 41 (51%) | 2 (4%) | <0.001 |
| IgM-RF and anti-CCP negative, n (%) | 62 (49%) | 24 (30%) | 38 (84%) | <0.001 |
| ESR (mm/h), median (IQR)† | 20 (9–35) | 25 (11–37) | 12 (5–25) | 0.003 |
| CRP (mg/L), median (IQR)‡ | 6.2 (3–22.7) | 8 (3.7–28.3) | 3 (1.9–12.5) | 0.003 |
| TJC68, median (IQR) | 7.5 (2–17) | 14 (5–23) | 2 (1–4) | <0.001 |
| SJC66, median (IQR) | 5 (1–9) | 7 (4–12) | 2 (1–3) | <0.001 |
| DAS28, median (IQR)§ | 4.5 (3.1–5.7) | 5.1 (4.3–6.1) | 3.3 (2.7–3.9) | <0.001 |
| MBDA score, median (IQR) | 42 (32–59) | 46 (34–61) | 35 (18–44) | 0.001 |
| HAQ score, median (IQR)¶ | 1.1 (0.5–1.6) | 1.3 (0.8–1.8) | 0.6 (0.3–1.3) | 0.001 |
*Parameters were summarised as number (n (%)) or median (IQR) as appropriate. p Values were calculated using the χ2 test for categorical variables and Wilcoxon's rank-sum test for continuous variables.
†Values missing for 1 patient with RA and 1 patient with UA.
‡Values missing for 1 patient with RA.
§Values missing for 2 patients with RA and 1 patient with UA.
¶Values missing for 4 patients with RA.
Anti-CCP, anticyclic citrullinated peptide; CRP, C reactive protein; DAS28, disease activity score based on 28 joints (based on ESR); ESR, erythrocyte sedimentation rate; HAQ, Health Assessment Questionnaire; IgM-RF, immunoglobulin M rheumatoid factor; MBDA, multi-biomarker disease activity; RA, rheumatoid arthritis; SJC66, swollen joint count based on 66 joints; TJC68, tender joint count based on 68 joints; UA, unclassified arthritis.