A comparison of twice-weekly MPD-PUVA and three times-weekly skin typing-PUVA regimens for the treatment of psoriasis.

The most frequent PUVA treatment regimen in current use is three times weekly, using skin typing to estimate the starting dose. Recently, it was suggested that twice-weekly treatment, using the minimal phototoxic dose (MPD) to calculate suberythemal starting doses of UVA, achieved similar clearance rates with fewer treatments and a lower cumulative UVA dose. We have carried out a trial on 83 patients, comparing twice-weekly MPD-PUVA with three times-weekly skin typing-PUVA, in order to test this hypothesis. Although clearance rates were comparable between the two regimens, there was no overall significant difference in the number of treatments or in the cumulative UVA doses at clearance. However, for patients with skin types I and II the cumulative UVA dose was significantly higher using the twice-weekly MPD regimen (70.0 J/cm2 vs. 55.8 J/cm2; P < 0.05). Our results do not confirm that there is a reduction in cumulative UVA dosage with twice-weekly MPD-PUVA.