Additional effect of excimer light therapy in patients with psoriasis under other therapies

Excimer light is an effective therapy for psoriasis resulting in faster clearance and a longer remission. We studied its additional effect in patients with psoriasis under other therapies. Subjects were composed of 261 patients with psoriasis, all of which were treated with topical application of steroid and vitamin D mixed ointment. Other therapies were composed of apremilast and biologics. PASI 100 rate were evaluated until 12 months after the start of its therapy. PASI 100 rate was elevated from 13 patients (5.0%) to 34 patients (13.0%, P < 0.01). Twenty-one of 63 patients (33.3%, P < 0.01) not reaching PASI 100 reached it after excimer light therapy. The addition of excimer light therapy in each treatment showed no significant difference compared with that before addition. Irradiation amount in patients with guselkumab (822 ± 259 mJ) was significantly smaller that with excimer only (1370 + 731 mJ) and that with IL-17 (1747 ± 749 mJ). In addition, irradiation amount in patients reached PASI-100 in Guselkumab (717 ± 75 mJ) which was significantly smaller that in the excimer only group (1530 ± 450 mJ). Additional effect of excimer light therapy in psoriasis, especially in patients with guselkumab, was speculated.