| Cases (n = 98) | Controls (n = 163) | |
| Females: n (%) | 55 (56.1) | 77 (45.6) |
| Age at interview-years: median (IQR) | 54 (43–62) | 46 (35–59) |
| Age at onset of arthritis-years: median (IQR) | 50 (36–58) | N/A |
| Duration of arthritis-years: median (IQR) | 4 (3–5) | N/A |
| Age at onset of psoriasis-years: median (IQR) | 29 (17–47) | 19.5 (12–34) |
| Ever seen a dermatologist: n (%) | 64 (64.9) | 161 (98.8) |
| Ever hospitalised for psoriasis: n (%) | 19 (19.4) | 53 (32.5) |
| Ever systemic* therapy for psoriasis: n (%) | 10 (13.6) | 63 (43.8) |
| SAPASI when worst: median (IQR) | 2.6 (0.6–8.2) | 9.9 (2.3–23.2) |
*Excludes methotrexate or sulphasalazine.