Univariate analysis for patients that did develop arthritis and patients that did not
| Variable | Arthritis yes (n=131) | Arthritis no (n=243) | HR (95% CI) | p |
|---|---|---|---|---|
| Age in years, mean (±SD) | 47 (±11) | 49 (±12) | 0.99 (0.98 to 1.00) | 0.20 |
| Female sex, nr (%) | 97 (74) | 188 (77) | 0.95 (0.64 to 1.42) | 0.81 |
| FDR with RA, nr (%) | 38 (29) | 48 (20) | 1.26 (0.86 to 1.85) | 0.23 |
| Current smoker, nr (%) | 46 (35) | 67 (28) | 1.11 (0.77 to 1.60) | 0.57 |
| No alcohol, nr (%) | 58 (44) | 78 (32) | 1.60 (1.11 to 2.29) | 0.01 |
| NSAID use, nr (%)* | 44 (34) | 57 (24) | 1.50 (1.04 to 2.57) | 0.03 |
| Duration of symptoms <12 months, nr (%) | 48 (37) | 72 (30) | 1.47 (1.02 to 2.11) | 0.04 |
| Intermittent symptoms present, nr (%) | 68 (52) | 64 (26) | 2.20 (1.56 to 3.11) | <0.001 |
| Symmetric arthralgia, nr (%) | 102 (78) | 174 (72) | 1.31 (0.87 to 1.98) | 0.20 |
| Arthralgia in upper and lower extremities, nr (%) | 80 (60) | 109 (45) | 1.64 (1.15 to 2.34) | 0.006 |
| Arthralgia in small joints, nr (%)† | 96 (73) | 164 (68) | 1.07 (0.72 to 1.60) | 0.76 |
| VAS pain ≥50, nr (%) | 59 (45) | 69 (28) | 1.87 (1.32 to 2.64) | <0.001 |
| Morning stiffness ≥1 h, nr (%) | 31 (24) | 37 (15) | 1.94 (1.29 to 2.91) | 0.001 |
| Tender joint count, median (IQR) | 0 (0–3) | 0 (0–2) | 1.06 (1.01 to 1.10) | 0.005 |
| Swollen joint(s) reported, nr (%)‡ | 65 (52) | 61 (25) | 2.42 (1.72 to 3.42) | <0.001 |
| CRP positive, nr (%) | 14 (11) | 22 (9) | 1.29 (0.73 to 2.26) | 0.38 |
| Antibody status | <0.001 | |||
| IgM-RF positive, aCCP negative | 12 (9) | 108 (44) | 1 (ref) | |
| aCCP low positive, IgM-RF negative§ | 19 (15) | 46 (19) | 3.22 (1.56 to 6.64) | |
| aCCP high positive, IgM-RF negative¶ | 33 (25) | 45 (18) | 4.73 (2.44 to 9.20) | |
| aCCP and IGM-RF positive | 67 (51) | 44 (18) | 8.87 (4.79 to 16.41) | |
| Shared epitope positive, nr (%) | 83 (63) | 121 (50) | 1.69 (1.17 to 2.42) | 0.005 |
*NSAID use: use of any NSAID in any dosing schedule.
†Small joints: PIPs, MCPs, wrists and MTPs.
‡Presence of a swollen joint as noticed by the patient, but not verified by a rheumatologist.
§aCCP low positive: ≥1× cut-off <3× cut-off.
¶aCCP high positive ≥3× cut-off.
aCCP, anti-cyclic citrullinated peptide; CRP, C reactive protein; FDR, First Degree Relative; IgM-RF, IgM rheumatoid factor; nr, number; MCP, metacarpal phalangeal joint; MTP, metatarso phalangeal joint; NSAID, non-steroid anti-inflammatory drug; PIP, proximal inter phalangeal joint; RA, rheumatoid arthritis; VAS, visual analogue scale.