[Therapeutic effectiveness of psoralen-UV-A bath therapy in psoriasis].

INTRODUCTION The use of psoralen baths with long-wave UV radiation, known as PUVA bath therapy, is useful in the treatment of psoriasis. The therapy is not associated with systemic adverse effects and the dose of UV-A radiation administered is lower. The objectives of this study aimed to identify the variables that influence the effectiveness of PUVA bath therapy and the duration of remission, as well as to determine factors that predict relapse. It also aimed to assess the effectiveness of a protocol using the minimal phototoxic dose and to compare two concentrations of 8-methoxypsoralen. PATIENTS AND METHODS Two hundred nine patients with moderate-severe plaque psoriasis attended between 1994 and 2000 were included in the study. The characteristics and therapeutic outcomes of the sample were recorded. Survival curves were plotted for the disease-free interval after a good response to treatment. A proportional hazard model was used to assess the factors that influence the duration of remission. RESULTS Therapeutic outcomes were better in patients with greater photosensitivity (p = 0.03). Application of the minimal phototoxic dose protocol was not associated with greater phototoxicity during treatment. The median duration of remission was 7 months. Those patients who had previously undergone oral PUVA therapy and those who did not achieve a substantial reduction in the psoriasis area and severity index (PASI) score were at greater risk of relapse. CONCLUSIONS A lower final PASI extended the lesion-free period.