Psoriatic skin lesions of patients with psoriatic arthritis who receive standard treatment with golimumab (50 mg or 100 mg s.c. once a month depending on total body weight whether below or above 100 kg, respectively) are exposed to UVB-311nm phototherapy on a randomized body half (left or right; head exempt) 3 x per week for six weeks and/or until complete response (defined as reduction in PASI to \< 3). A patient qualifies if A) golimumab was started within a week or B) after 3 months of golimumab treatment the PASI reduction is smaller than 90%. PASI score, patient visual analogue score (VAS) for therapeutic response, and patient VAS for severity of skin lesions is assessed weekly; and at follow-up visits at month 3, 6, and 12. The primary hypothesis is that phototherapy increases the PASI reduction on the exposed body site by more than 20%. Paired Wilcoxon testing for differences in PASI and patient VAS scores is done; Fisher exact test is applied to determine differences in complete remission, PASI reduction \> 90%, \> 75% and/or 50% between body sites.
