Influence of prophylactic photochemotherapy on incidence of relapse of psoriasis cleared initially with dithranol.

Forty one patients whose psoriasis cleared with dithranol were given prophylatic photochemotherapy with psoralens and ultraviolet A once a week. With life table analysis the chance of remaining in remission for 16 months was shown to be 42% for these patients, compared with 13% for a group of patients who were not given prophylactic photochemotherapy.