Table 1: Basic demographic and clinical characteristics of psoriatic arthritis (PsA) and psoriasis (PsO) groups.

Variable PsA group () PsO group () Male : female ratio 24 : 22 31 : 11 Age (mean ± SD; years) 54.35 ± 11.87 45.60 ± 15.72 BMI (mean ± SD; kg/m2) 29.38 ± 6.41 28.86 ± 9.80 Current smokers (%) 20 12 Age at diagnosis of PsO (mean ± SD; years) 38.91 ± 14.47 28.84 ± 15.82 Age at diagnosis of PsA (mean ± SD; years) 45.26 ± 13.80 — Disease course severity (mild : moderate to severe)• 0 : 46 6 : 36 Psoriasis guttata (%) 4 20 Arthritis mutilans (%) 2 — Axial arthritis (%) 17 — Distal arthritis (%) 4 — Asymmetrical oligoarthritis (%) 54 — Symmetrical polyarthritis (%) 43 — Therapy      Received MTX therapy (%) 85 57  Received systemic steroid  treatment (%) 13 2  Received 311 nm NB-UVB  therapy (%) 7 38  Received PUVA therapy (%) 2 31  Received biological therapy (%) 13 52

PsO: psoriasis vulgaris, PsA: psoriatic arthritis, BMI: body mass index, MTX: methotrexate, PUVA: psoralen + ultraviolet A, 311 nm NB-UVB: 311-nanometer narrow-band ultraviolet B. Symmetrical arthritis: bilateral arthritis with a frequency of >50%. •Patients previously or currently treated with DMARDs, systemic therapy or full-body phototherapy were regarded as “moderate-to-severe” patients, whereas the others were considered to exhibit a “mild” disease course.