Demographic and clinical characteristics of the different groups of patients
| PsA n=27 | RA n=27 | PsO n=23 | HCs n=19 | |
| Sex distribution (M/F) | 16/11 | 7/20 | 14/9 | 7/12 |
| Age, mean (SD) | 56.8 (10) | 58.3 (11) | 56.6 (9) | 55.7 (10) |
| BMI (SD), kg/m2 | 26.9 (3.3) | 26.3 (3.3) | 25.9 (3.2) | 26.4 (3.6) |
| Employment (n, %) | ||||
| Manual | 6 (22.2) | 4 (14.8) | 6 (26.1) | 4 (21) |
| Intellectual | 11 (40.7) | 12 (44.4) | 9 (39.1) | 8 (42.1) |
| Unemployed | 10 (37) | 11 (40.7) | 8 (34.8) | 7 (36.8) |
| Duration of arthritis symptoms, years (mean (SD)) | 5.6 (4.1) | 6.8 (5.1) | – | – |
| Duration of psoriasis, years (mean (SD)) | 10.3 (10.1) | – | 13.4 (10.7) | – |
| Previous hand dactylitis, n (%) | 14 (51.8) | 0 | – | – |
| Trigger finger, n (%) | 5 (18.5) | 3 (11.1) | 0 | 0 |
| Nail involvement, n (%) | 11 (40.7) | – | 2 (8.7) | – |
| Scalp psoriasis, n (%) | 18 (66.7) | – | 13 (56.5) | – |
| Palmoplantar psoriasis, n (%) | 10 (37) | – | 7 (30.4) | – |
| Swollen joint count ≤1, n (%) | 3 (11.1) | 1 (3.7) | – | – |
| Tender joint count ≤1, n (%) | 4 (14.8) | 4 (14.8) | – | – |
| Increased CRP, n (%) | 1 (3.7) | 1 (3.7) | – | – |
| DAS-28 CRP, mean (SD) | 2.42 (0.48) | 2.48 (0.5) | – | – |
| RA test positive, n (%) | 0 | 20 (74.1) | – | – |
| APCA positive, n (%) | 0 | 19 (70.4) | – | – |
APCA, anticitrullinated peptide antibody; BMI, body mass index; CRP, C reactive protein; DAS-28, disease activity score on 28 joints; HC, healthy control; PsA, psoriatic arthritis; PsO, psoriasis; RA, rheumatoid arthritis.