Comparisons of baseline characteristics between UA-non-RA and UA-RA patients.
| All UA, n = 477 | UA-non-RA, n = 430 | UA-RA, n = 47 | p | |
|---|---|---|---|---|
| Age, yrs, mean (SD) | 46.5 (14.7) | 46.1 (14.6) | 50.6 (15.0) | 0.04 |
| Female, n (%) | 262 (54.9) | 229 (53.3) | 33 (70.2) | 0.03 |
| Duration of joint swelling (days), median (25, 75 percentile) | 29 (10, 61.5) | 28 (9, 62) | 38 (20, 60) | 0.18 |
| BMI, mean (SD) | 25.7 (4.3) | 25.7 (4.3) | 25.8 (4.8) | 0.84 |
| Ever smoker, n (%) | 271 (56.8) | 236 (54.9) | 35 (74.5) | 0.01 |
| RF- and/or ACPA-positive, n (%) | 31 (6.5) | 16 (3.7) | 15 (31.9) | < 0.001 |
| RF- (IgM and IgA) positive, n (%) | 21 (4.4) | 10 (2.3) | 11 (23.4) | < 0.001 |
| ACPA positive, n (%) | 18 (3.8) | 7 (1.6) | 11 (23.4) | < 0.001 |
| ESR mm/h, median (25, 75 percentile) | 18 (9, 36) | 17.5 (9, 35) | 27.5 (12, 48.3) | 0.06 |
| CRP mg/l, median (25, 75 percentile) | 10 (3, 32) | 10 (3, 32) | 11 (3, 32) | 0.45 |
| 68-SJC, median (25, 75 percentile) | 1 (1, 3) | 1 (1, 3) | 3 (2, 5) | < 0.001 |
| 28-TJC, median (25, 75 percentile) | 1 (0, 2) | 1 (0, 2) | 3 (1, 6) | < 0.001 |
| Small joint involvement, n (%) | 216 (45.3) | 183 (42.6) | 33 (70.2) | < 0.001 |
| Swollen shoulder joint, n (%) | 41 (8.6) | 24 (5.6) | 17 (36.2) | < 0.001 |
| Polyarticular arthritis†, n (%) | 54 (11.3) | 38 (8.8) | 16 (34.0) | < 0.001 |
| Oligoarticular arthritis‡, n (%) | 177 (37.1) | 156 (36.3) | 21 (44.7) | 0.26 |
| Monoarticular arthritis, n (%) | 246 (51.6) | 236 (54.9) | 10 (21.3) | < 0.001 |
| Assessor global VAS, mean (SD) | 29.8 (17.1) | 29.1 (16.8) | 36.7 (18) | 0.004 |
| Patient global VAS, mean (SD) | 50.3 (24.7) | 49.6 (24.8) | 56.9 (23.3) | 0.055 |
| HAQ, median (25, 75 percentile) | 0.63 (0.3, 1.1) | 0.63 (0.1, 1.0) | 0.63 (0.5, 1.3) | 0.07 |
| DAS28, mean (SD) | 3.6 (1.1) | 3.5 (1.0) | 4.3 (1.1) | < 0.001 |
| Criteria points, median (25, 75 percentile) | 3 (1, 4) | 2 (1, 3) | 4 (3, 5) | < 0.001 |
↵† > 4 swollen joints.
↵‡ 2 to ≤ 4 swollen joints. UA: undifferentiated arthritis; RA: rheumatoid arthritis; RF: rheumatoid factor; BMI: body mass index; ACPA: anticitrullinated protein antibodies; ESR: erythrocyte sedimentation rate; CRP: C-reactive protein; 68-SJC: 68-joint swollen joint count (standard 66-SJC plus hip joints); 28-TJC: 28-joint tender joint count; VAS: visual analog scale; HAQ: Health Assessment Questionnaire; DAS28: 28-joint Disease Activity Score; UA–non-RA: patients with UA not fulfilling the 2010 ACR/EULAR RA classification criteria during followup; UA-RA: patients with UA fulfilling the 2010 ACR/EULAR RA classification criteria during followup; small joint involvement: metacarpophalangeal joints, proximal interphalangeal joints, second through fifth metatarsophalangeal joints, thumb interphalangeal joints, and wrists; ACR: American College of Rheumatology; EULAR: European League Against Rheumatism.