Bath PUVA and psoriasis: is a milder treatment a worse treatment?

The guidelines of the British Photodermatology Group for topical treatment with psoralen and ultraviolet light (PUVA) recommend starting UVA doses between 0.2 and 0.5 J/cm(2), according to the phototype. Our purpose was to evaluate the therapeutic efficacy and tolerability of bath PUVA, with 8-methoxypsoralen (8-MOP), by using lower UVA doses, regardless of phototype.

We compared 2 groups of patients (group 1: n = 10, group 2: n = 20) with chronic plaque-type psoriasis. Group 1 was treated with the usual starting dose and dose progression; group 2 was treated by using a lower first dose, a slower dose progression and reaching a lower maximum dose. The Psoriasis Area and Severity Index (PASI) score was assessed at the initial stages, and every month until the end of the treatment.

In group 1, the median baseline PASI score decreased from 15.2 to 4.5 (p < 0.005, Student's paired t test), while in group 2, it fell from 13.7 to 4.1 (p < 0.005). No statistical difference between the groups is detectable. Severe phototoxic reactions were observed only in 2 patients of group 1. Side effects were not observed in group 2.

Our data indicate that an aggressive bath PUVA treatment is not substantially more effective in clearing chronic plaque-type psoriasis than a milder therapeutic approach.