Baseline characteristics of patients, overall and according to ACPA and RF status
| Total (N=970) | ACPA/RF status | |||||
| ACPAneg/RFneg (N=262) | ACPApos/RFneg (N=60) | ACPAneg/RFpos (N=117) | ACPApos/RFpos (n=531) | P values | ||
| Sociodemographic characteristics | ||||||
| Female, n (%) | 752 (77.5) | 205 (78.2) | 46 (76.7) | 88 (75.2) | 413 (77.8) | 0.92 |
| Age, mean (SD) | 55.8 (13.4) | 57.3 (13.7) | 55.9 (12.1) | 57.6 (11.9) | 54.6 (13.7) | 0.02 |
| Post-secondary education, n (%) Missing, n (%) | 576 (59.4) 44 (4.5) | 165 (63.0) 17 (6.5%) | 38 (63.3) 2 (3.3) | 64 (54.7) 5 (4.3) | 309 (58.2) 20 (3.8) | 0.18 |
| Smoking status, n (%) | ||||||
| Never | 433 (44.6) | 125 (47.7) | 26 (43.3) | 46 (39.3) | 236 (44.4) | 0.27 |
| Past | 348 (35.9) | 87 (33.2) | 27 (45.0) | 47 (40.2) | 187 (35.2) | |
| Current | 148 (15.3) | 34 (13.0) | 5 (8.3) | 19 (16.2) | 90 (16.9) | |
| Missing | 41 (4.2) | 16 (6.1) | 2 (3.3) | 5 (4.3) | 18 (3.4) | |
| Rural residential area, n (%) | 173 (17.8) | 50 (19.1) | 11 (18.3) | 17 (14.5) | 95 (17.9) | 0.76 |
| Disease characteristics | ||||||
| RA duration since diagnosis, mean (SD) | 5.1 (8.0) | 4.8 (7.6) | 6.6 (8.9) | 3.8 (6.6) | 5.4 (8.4) | 0.11 |
| Early RA (duration ≤1 year since diagnosis), n (%) | 481 (49.6) | 134 (51.1) | 25 (41.7) | 61 (52.1) | 261 (49.2) | 0.55 |
| DAS28-ESR (0–9.4), mean (SD) Missing, n (%) | 4.2 (1.6) 51 (5.3) | 4.3 (1.6) 13 (5.0) | 3.8 (1.5) 4 (6.7) | 4.1 (1.5) 5 (4.3) | 4.3 (1.6) 29 (5.5) | 0.10 |
| TCJ-28 (0–28), mean (SD) | 6.2 (6.3) | 7.1 (6.8) | 4.7 (5.2) | 5.9 (6.0) | 5.9 (6.2) | 0.02 |
| SJC-28 (0–28), mean (SD) | 5.3 (4.7) | 5.7 (4.8) | 4.5 (4.3) | 4.8 (4.8) | 5.3 (4.7) | 0.16 |
| PtGA (0–10), mean (SD) Missing, n (%) | 4.8 (2.8) 28 (2.9) | 5.1 (2.8) 8 (3.1) | 4.3 (2.8) 0 | 4.7 (2.6) 5 (4.3) | 4.7 (2.8) 15 (2.8) | 0.08 |
| PhGA (0–10), mean (SD) Missing, n (%) | 4.3 (2.5) 102 (10.5) | 4.4 (2.5) 29 (11.1) | 3.8 (2.0) 2 (3.3) | 3.9 (2.4) 17 (14.5) | 4.4 (2.6) 54 (10.2) | 0.18 |
| CDAI (0–76), mean (SD) | 20.5 (13.6) | 22.3 (14.0) | 17.2 (11.6) | 19.5 (13.0) | 20.2 (13.7) | 0.03 |
| SDAI (0.1–86), mean (SD) Missing, n (%) | 22.0 (14.1) 92 (9.5) | 23.6 (14.6) 18 (6.9) | 18.2 (11.6) 8 (13.3) | 20.5 (13.5) 8 (6.8) | 21.9 (14.1) 58 (10.9) | 0.04 |
| HAQ-DI (0–3), mean (SD) Missing, n (%) | 1.1 (0.8) 43 (4.4) | 1.2 (0.8) 16 (6.1) | 0.9 (0.7) 2 (3.3) | 1.3 (0.7) 5 (4.3) | 1.0 (0.7) 20 (3.8) | 0.002 |
| HAQ-PI (0–10), mean (SD) Missing, n (%) | 1.4 (0.8) 43 (4.4) | 1.5 (0.9) 16 (6.1) | 1.4 (0.8) 2 (3.3) | 1.6 (0.8) 5 (4.3) | 1.3 (0.8) 20 (3.8) | 0.002 |
| Number of comorbidities, mean (SD) Missing, n (%) | 3.4 (2.5) 41 (4.2) | 3.7 (2.4) 16 (6.1) | 3.7 (2.5) 2 (3.3) | 3.8 (2.4) 5 (4.3) | 3.2 (2.5) 18 (3.4) | 0.02 |
| Treatment characteristics | ||||||
| Prior use of bDMARDs, n (%) Missing, n (%) | 238 (24.5) 13 (1.3) | 57 (21.8) 2 (0.8) | 20 (33.3) 0 | 31 (26.5) 1 (0.9) | 130 (24.5) 5 (0.9) | 0.33 |
| Prior use of csDMARDs, n (%) Missing, n (%) | 748 (77.1) 7 (0.7) | 205 (78.2) 2 (0.8) | 48 (80.0) 0 | 95 (81.2) 1 (0.9) | 400 (75.3) 4 (0.8) | 0.47 |
| Current use of bDMARDs, n (%) | 196 (20.2) | 55 (21.0) | 14 (23.3) | 30 (25.6) | 97 (18.3) | 0.28 |
| Current use of csDMARDs, n (%) | 849 (87.5) | 229 (87.4) | 51 (85.0) | 101 (86.3) | 468 (88.1) | 0.88 |
| Current use of MTX, n (%) | 689 (71.0) | 171 (65.3) | 40 (66.7) | 88 (75.2) | 390 (73.5) | 0.06 |
| Current MTX dose, mg/week, mean (SD) | 18.9 (5.7) | 19.6 (5.2) | 19.1 (5.8) | 18.0 (5.7) | 18.8 (6.0) | 0.21 |
| Current use of oral steroids | 169 (19.2) | 46 (17.6) | 8 (13.3) | 13 (11.1) | 102 (19.2) | 0.16 |
| Current steroid dose, mg/day, mean (SD) | 11.1 (8.7) | 10.0 (7.1) | 12.7 (15.2) | 10.6 (8.4) | 11.5 (8.9) | 0.73 |
| Steroid dose at last visit, mg/day, mean (SD) | 6.4 (10.2) | 5.5 (7.2) | 7.1 (10.9) | 5.4 (7.5) | 6.9 (11.8) | 0.69 |
Bold values indicate statistically significant.
ACPA, anticitrullinated protein antibody; bDMARDs, biologic disease-modifying antirheumatic drugs; CDAI, Clinical Disease Activity Index; csDMARDs, conventional synthetic DMARDs; DAS28-ESR, 28-joint Disease Activity Score-erythrocyte sedimentation rate; HAQ-DI, Health Assessment Questionnaire Disability Index; HAQ-PI, Health Assessment Questionnaire Pain Index; MTX, methotrexate; PhGA, physician global assessment; PtGA, patient global assessment; RA, rheumatoid arthritis; RF, rheumatoid factor; SDAI, Simplified Disease Activity Index; SJC-28, 28-joint swollen count; TCJ-28, 28-joint tender count.