Table 1.
Baseline demographic and disease characteristics
| Total (n = 1355) | Change in ACPA titer level (maximum/minimum) | P value | |||
|---|---|---|---|---|---|
| < 3 (n = 763) | 3.1–5 (n = 297) | > 5 (n = 295) | |||
| Age, years, mean (SD) | 60.0 (13.8) | 59.7 (14.5) | 59.6 (13.3) | 61.0 (12.2) | 0.35 |
| Female, n (%) | 963 (71.1) | 610 (80.0) | 248 (83.5) | 241 (81.7) | 0.39 |
| BMI, mean (SD) | 21.7 (3.7) | 21.7 (3.9) | 21.7 (3.3) | 21.7 (3.5) | 0.99 |
| Smoker (ever), n (%) | 246 (18.2) | 146 (19.1) | 47 (15.8) | 53 (18.0) | 0.45 |
| Disease duration, months, mean (SD) | 1.8 (5.4) | 1.8 (6.0) | 1.8 (5.0) | 1.6 (4.0) | 0.85 |
| Observational period (months), mean (SD) | 4.6 (2.4) | 45.7 (28.7) | 65.5 (22.6) | 68.7 (22.9) | < 0.001 |
| Number of ACPA measurements, mean (SD) | 5.3 (2.6) | 4.6 (2.4) | 6.1 (2.3) | 6.5 (2.5) | < 0.001 |
| RF (%) | 88.1 | 86.7 | 89.9 | 89.9 | 0.37 |
| RF, IU/ml, mean (SD) | 150.4 (242.5) | 155.1 (260.4) | 148.4 (238.8) | 140.6 (196.0) | 0.77 |
| ACPA (max), U/ml, mean (SD) | 392.8 (579.7) | 290.9 (365.0) | 435.5 (499.5) | 613.3 (934.6) | < 0.001 |
| ACPA (min), U/ml, mean (SD) | 137.8 (204.9) | 170.1 (246.2) | 112.6 (123.7) | 71.9 (112.1) | < 0.001 |
| ESR, mm/h, mean (SD) | 31.8 (26.4) | 29.7 (25.6) | 33.0 (26.1) | 35.7 (28.2) | < 0.05 |
| CRP, mg/L, mean (SD) | 12.4 (24.1) | 10.5 (19.6) | 11.3 (19.1) | 18.3 (35.2) | < 0.001 |
| CDAI, mean (SD) | 11.7 (9.4) | 11.2 (9.3) | 11.8 (9.1) | 12.9 (9.8) | 0.06 |
| SDAI, mean (SD) | 13.2 (10.9) | 12.5 (10.5) | 13.1 (10.3) | 14.9 (12.3) | 0.05 |
| DAS28 (ESR), mean (SD) | 3.7 (1.4) | 3.6 (1.4) | 3.8 (1.4) | 4.0 (1.4) | < 0.01 |
| Tender joints, mean (SD) | 2.4 (3.3) | 2.3 (3.4) | 2.4 (3.0) | 2.6 (3.3) | 0.1 |
| Swollen joints, mean (SD) | 2.5 (3.2) | 2.5 (3.3) | 2.4 (3.1) | 2.7 (3.3) | 0.23 |
| MTX, n (%) | 55 (4.1) | 27 (2.0) | 15 (5.1) | 13 (4.4) | 0.51 |
| MTX, mg, mean (SD) | 7.1 (2.8) | 7.2 (2.5) | 6.7 (3.3) | 7.4 (3.2) | 0.78 |
| MTX (3 months) n (%) | 859 (63.4) | 477 (62.5) | 201 (67.7) | 181 (61.4) | 0.21 |
| MTX (3 months), mg, mean (SD) | 8.2 (3.1) | 8.1 (3.0) | 8.1 (2.9) | 8.3 (3.4) | 0.72 |
| Prednisolone, n (%) | 30 (2.2) | 16 (2.1) | 7 (2.4) | 7 (2.4) | 0.95 |
| Prednisolone, mg, mean (SD) | 6.8 (8.6) | 6.4 (8.7) | 3.2 (2.3) | 11.4 (11.3) | 0.21 |
| Prednisolone (3 months), n (%) | 418 (30.8) | 213 (27.9) | 99 (33.3) | 106 (35.9) | < 0.05 |
| Prednisolone (3 months), mg, mean (SD) | 6.7 (11.5) | 5.9 (8.7) | 7.1 (14.1) | 8.0 (13.5) | 0.27 |
| bDMARDs or tsDMARDs, n (%) | 30 (2.2) | 11 (1.4) | 10 (3.4) | 9 (3.1) | 0.09 |
| bDMARDs or tsDMARDs (3 months), n (%) | 395 (29.2) | 200 (26.2) | 96 (32.3) | 99 (33.6) | < 0.05 |
One-way analysis of variance for continuous variables; Kruskal–Wallis test for CDAI, SDAI and DAS28-ESR; Fisher’s exact test for categorical variables among the three groups
bDMARD biological disease-modifying anti-rheumatic drug, BMI body mass index, CDAI clinical disease activity index, CRP C-reactive protein, DAS28 Disease Activity Score 28-joint count, ESR erythrocyte sedimentation rate, MTX methotrexate, RF rheumatoid factor, SD standard deviation, SDAI simplified disease activity index, tsDMARD targeted synthetic disease-modifying anti-rheumatic drug