Duration of remission period of narrowband ultraviolet B therapy on psoriasis vulgaris

The remission period of psoriasis vulgaris following narrowband ultraviolet B (NB-UVB) light therapy with topical vitamin D(3) application was evaluated retrospectively to investigate the therapeutic efficacy. Fifty-two patients (60 cases) were treated with a 5-day/week protocol of NB-UVB light irradiation plus topical vitamin D ointment application for 1 month and followed up for at least 12 months. We considered re-exacerbation as the time when the patients needed treatment other than topical therapy. The remission period was defined as the duration from the end of treatment until re-exacerbation. Twenty-seven cases (56%) of psoriasis showed a remission period longer than 12 months. The patients with a past history of systemic therapy or phototherapy had a significantly shorter remission period than those without such a history. No statistically significant differences were observed in sex, age, period before treatment, Psoriasis Area and Severity Index score and total irradiation dose. A previous history of systemic therapy or phototherapy may mean that the disease is severe and sufficiently active to form multiple new lesions requiring these treatments. Our results suggest that the 5-day/week NB-UVB light protocol for 4 weeks is an effective and safe treatment for psoriasis vulgaris and can induce long-term remission.