Randomized, double-blind, placebo-controlled evaluation of the efficacy of oral psoralen plus ultraviolet A for the treatment of plaque-type psoriasis using the Psoriasis Area Severity Index score (improvement of 75% or greater) at 12 weeks.

BACKGROUND: Psoralen plus ultraviolet A (PUVA) for the treatment of psoriasis has never been evaluated using the Psoriasis Area Severity Index (PASI) in a randomized, double-blind, placebo-controlled trial. The lack of such data limits our capacity to estimate PUVA's efficacy relative to other treatment options that are available today. OBJECTIVES: The purpose of this study was to evaluate the efficacy of PUVA therapy for patients with plaque-type psoriasis. METHODS: This study involved 40 patients with psoriasis; 30 received PUVA and 10 received UVA with placebo. PASI scores were assessed at baseline and every 4 weeks thereafter for 12 weeks. RESULTS: By nonresponder imputation, 60% (18 of 30) in the PUVA group achieved 75% or more improvement in PASI score after 12 weeks of treatment compared with 0% (0 of 10) in the UVA plus placebo group (P < .0001). Using intent to treat with last observation carried forward analysis, 63% (19 of 30) in the PUVA group achieved 75% or more improvement in PASI score compared with 0% (0 of 10) in the UVA plus placebo group (P < .0001). By per protocol analysis, 86% (18 of 21) in the PUVA group as compared with 0% (0 of 7) in the UVA plus placebo group reached 75% or more improvement in PASI score after 12 weeks (P < .0001). LIMITATIONS: The study was relatively small with only 40 patients enrolled and 28 patients who completed the protocol. Further studies that involve head-to-head comparison of PUVA with other treatment modalities are needed. Nonresponder imputation, last observation carried forward with intent to treat, and per protocol analyses each have separate advantages and limitations when determining clinical significance. CONCLUSIONS: This study supports the observation that PUVA is a highly efficacious treatment for chronic plaque psoriasis.