Univariable logistic regression in the derivation data set with presence of synovitis on joint examination as outcome
| Arthritis (n=271) | No arthritis (n=373) | OR (95% CI) | |
| Male, n (%) | 104 (38) | 86 (23) | 2.1 (1.5 to 2.9) |
| Age, n (%) | |||
| <40 | 49 (18) | 104 (28) | (ref) |
| 40–59.9 | 109 (40) | 172 (46) | 1.3 (0.89 to 2.0) |
| ≥60 | 113 (42) | 97 (26) | 2.5 (1.6 to 3.8) |
| Symptom duration in weeks, n (%) | |||
| <6 | 124 (46) | 103 (28) | 3.8 (2.4 to 5.9) |
| 6–11 | 38 (14) | 62 (17) | 1.9 (1.1 to 3.9) |
| 12–51.9 | 66 (24) | 75 (20) | 2.7 (1.7 to 4.5) |
| ≥52 | 43 (16) | 132 (36) | (ref) |
| Acute onset of symptoms *, n (%) | 122 (45) | 131 (35) | 1.5 (1.1 to 2.1) |
| Symptoms worst in early morning, n (%) | 158 (58) | 214 (57) | 1.1 (0.69 to 1.6) |
| Morning stiffness > 60 min , n (%) | 45 (17) | 40 (11) | 1.7 (1.03 to 2.7) |
| Number of painful joints, n (%) | |||
| 0 | 1 (0) | 10 (3) | (ref) |
| 1–3 | 110 (41) | 82 (22) | 13.2 (1.7 to 105.5) |
| 4–10 | 76 (28) | 123 (33) | 6.1 (0.77 to 49.0) |
| ≥11 | 84 (31) | 158 (42) | 5.2 (0.65 to 41.3) |
| Number of patient-reported swollen joints, n (%) | |||
| 0 | 18 (7) | 71 (19) | (ref) |
| 1–3 | 115 (42) | 119 (32) | 3.7 (2.0 to 6.9) |
| 4–10 | 87 (32) | 115 (31) | 2.9 (1.5 to 5.5) |
| ≥11 | 51 (19) | 68 (18) | 2.9 (1.4 to 5.9) |
| Difficulty with making a fist, n (%) | 156 (58) | 172 (46) | 1.6 (1.1 to 2.4) |
*Patients were asked to define onset of symptoms; either acute onset of symptoms or gradual onset of symptoms, see online supplementary appendix S1.