Oral 8-methoxypsoralen photochemotherapy of psoriasis. The European PUVA study: a cooperative study among 18 European centres.

In a multicentre study in eighteen European cities 3175 patients were treated with photochemotherapy (PUVA) for severe psoriasis and data obtained during a period of 39 months were analysed. A response better than marked improvement was obtained in 88.8% of patients; twenty exposures and a total cumulative UVA dose of 96 J/cm2 were required for clearing, the duration of the clearing phase being 5.3 weeks. A comparison of the results of this study with those of a similar multicentre study in the United States on 1300 patients and using a different treatment protocol, revealed that while treatment results and the number of individual treatment sessions were similar the European protocol requires only half the time and less than half the total cumulative UVA dose for clearing of psoriasis. When patients in the European study who received continuous maintenance treatment were compared with patients who received no maintenance treatment the probability that a patient would remain in remission for a period of 80 weeks was the same, irrespective of whether patients received maintenance treatment or not. This study confirms the dramatic efficacy of PUVA in clearing psoriasis and contains two important messages for the reduction of possible long-term hazards of this treatment. Firstly, the total UVA energy requirements for clearing psoriasis strongly depend on the treatment schedule and can be kept low if an individual approach aimed at rapid clearing of psoriasis is used. Secondly, maintenance therapy may not significantly prevent recurrences for prolonged periods of time and may thus not be necessary in most patients.