Baseline characteristics of ACPA and RF subgroups. Values are n (%) unless otherwise specified. Bonferroni correction for multiple comparisons performed. P value significant if < 0.0167.
| Characteristics | Seropositive | ||||||
|---|---|---|---|---|---|---|---|
| ACPA+RF–, n = 105 | n | ACPA–RF+, n = 144 | n | ACPA+RF+, n = 376 | n | p | |
| Age, yrs, mean (SD) | 47 (14)* | 104 | 55 (13) | 144 | 51 (13) | 376 | < 0.0001 |
| Males | 26 (25) | 105 | 30 (21) | 144 | 89 (24) | 376 | 0.9873 |
| Symptom duration, days, mean (SD) | 196 (95) | 105 | 176 (98) | 144 | 202 (108) | 376 | 0.0606 |
| Ever smoker | 55 (52.9) | 104 | 80 (55.6) | 144 | 234 (62.2) | 376 | 0.0523 |
| SJC28, mean (SD) | 6.5 (6.3) | 104 | 7.1 (5.9) | 138 | 6.2 (5.3) | 369 | 0.3105 |
| TJC28, mean (SD) | 8.1 (6.4) | 104 | 6.3 (6.2) | 138 | 7.1 (5.9) | 369 | 0.0776 |
| ESR, mean (SD) | 21.8 (19.2) | 101 | 27.7 (24.1) | 137 | 28.6 (22.7) | 359 | 0.0271 |
| CRP, mg/l, mean (SD) | 12.3 (17.9) | 102 | 13.3 (16.3) | 139 | 13.8 (17.2) | 360 | 0.7485 |
| Erosions | 22 (24.2) | 91 | 28 (22.8) | 123 | 74 (24.4) | 303 | 0.8777 |
| DAS28, mean (SD) | 4.6 (1.5) | 97 | 4.7 (1.4) | 131 | 4.8 (1.5) | 347 | 0.5715 |
| HAQ, mean (SD) | 0.48 (0.63) | 99 | 0.61 (0.63) | 138 | 0.62 (0.64) | 368 | 0.1488 |
| 1987 ACR RA criteria | 51 (50)‡ | 103 | 81 (58)‡‡ | 139 | 300 (81) | 369 | < 0.0001 |
| 2010 ACR/EULAR RA criteria | 77 (73)‡ | 105 | 120 (83) | 144 | 338 (90) | 376 | < 0.0001 |
| DMARD | 76 (77)‡ | 99 | 125 (89) | 140 | 333 (91) | 368 | 0.0005 |
| Biologics | 2 (2) | 99 | 5 (3.8) | 140 | 11 (3) | 368 | 0.7466 |
| Corticosteroids | 44 (44) | 99 | 86 (61) | 140 | 180 (49) | 368 | 0.8824 |
↵* p < 0.0167 for ACPA+RF– versus ACPA–RF+.
↵‡ p < 0.0167 for ACPA+RF– versus ACPA+RF+.
↵‡‡ p < 0.0167 for ACPA–RF+ versus ACPA+RF+. ACPA: anticitrullinated protein antibodies; RF: rheumatoid factor; SJC28: swollen joint count of 28 joints; TJC28: tender joint count of 28 joints; ESR: erythrocyte sedimentation rate; CRP: C-reactive protein; DAS28: 28-joint Disease Activity Score; HAQ: Health Assessment Questionnaire; ACR: American College of Rheumatology; RA: rheumatoid arthritis; EULAR: European League Against Rheumatism; DMARD: disease-modifying antirheumatic drug.