Clinical and demographic data of the study participants
| negRA (n=49) | PsA (n=73) | P value | |
| Female:Male | 39:10 | 29:44 | <0.0001 (χ2) |
| Age (minimum–maximum in years) | 64.2 (32–83) | 56.2 (30–78) | 0.003 |
| Disease duration (minimum–maximum in years) | 11.6 (1–41) | 9.0 (0–24) | 0.042 |
| DAS28-CRP (minimum-maximum) | 2.6 (0–6.2) | 2.3 (0.96–4.09) | 0.093 |
| % active (DAS28 >3.2) | 30.6% | 28.8% | |
| % remission (DAS28 <2.6) | 55.1% | 57.5% | |
| CRP (±SD) (mg/L) | 5.7±7.4 | 6.7±13.8 | 0.642 |
| Rheumatoid factor positive | None | None | |
| Anti-CCP positive | None | None | |
| MTX (±SD) (mg)* | 13.2±4.8 | 14.1±3.2 | 0.368 |
| % from total patients | 44.9% | 50.7% | 0.531 (χ2 ) |
| Glucocorticoid (±SD) (mg) | 6.2±5.0 | 5.6±3.5 | 0.651 |
| % from total patients | 38.8% | 34.2% | 0.610 (χ2 ) |
| Leflunomide (±SD) (mg) | 15.8±4.7 | 13.6±4.5 | 0.266 |
| % from total | 24.5% | 15.1% | 0.192 (χ2 ) |
| On immunotherapy | 13 | 35 | 0.018 (χ2) |
| Anti-TNF | 15.1% | 27.8% | |
| Anti-IL-6R | 3.8% | 0% | |
| Anti-CTLA-4 | 1.9% | 0% | |
| Anti-IL-12/IL-23 | 0% | 6.3% | |
| JAK-blockade | 5.7% | 0% |
p-values above 0.05 are indicated in italic.
*The average dosage of each medication (MTX, glucocorticoid and leflunomide) was calculated only for the patients taking that medication. The p-values bove 0.05 are indicated in italic.
anti-CCP, anticyclic citrullinated peptide antibodies; CRP, C reactive protein; CTLA, cytotoxic T-lymphocyte-associated protein 4 inhibitor; DAS28, disease activity score; IL, interleukin; JAK, janus kinase inhibitor; MTX, methotrexate; nd, not determined; TNF, anti-tumor necrosis alpha.