Comparison of phototherapy two times and four times a week with low doses of narrow-band ultraviolet B in Asian patients with psoriasis

Background/Aims: The optimum narrow-band (TL-01) ultraviolet (UV) B weekly treatment frequency for psoriasis has yet to be defined, especially in Asian patients with TL-01. Our purpose was to compare 2x weekly and 4x weekly therapy with narrow-hand UVB at low doses for psoriasis vulgaris. Methods: Sixty-nine patients with moderately severe psoriasis were recruited and allocated to the 2x weekly or 4x weekly treatment group. The patients were treated with a new protocol using low doses of narrow-band UVB with varied exposure increments. Outcomes were evaluated by means of Psoriasis Area and Severity Index (PASI) scores, time (weeks), cumulative UVB dose and number of treatments to clearance. Results: No significant difference was found between the two regimens in the PASI score at the end of treatment, in the proportion of patients whose skin cleared during treatment and in the time to clearance (8 weeks). Those who completed treatment achieved clearance after a median of 16 exposures with 2x weekly treatment compared with 32 exposures with 4x weekly treatment (P=0.0304), and 12.5 minimal erythema dose multiples (MEDs) compared with 39.7 MEDs (P=0.0470). Acute side effects of the treatment were similar for the two groups (P=0.8462). Conclusion: For skin phototype III-V populations, a greater long-term risk is expected, connected with the higher cumulative UVB dose and number of exposures required in the 4x weekly group. Therefore, 4x weekly phototherapy mill no longer be used for psoriasis.