Estimated ultraviolet doses to psoriasis patients during climate therapy

Abstract

Psoriasis is a chronic inflammatory disease affecting about 2-3% of the population. Sun exposure has a positive effect on most lesions, but ultraviolet (UV) radiation also constitutes a carcinogenic potential. Climate therapy is frequently used to treat patients, with the consequence that they may receive high doses of UV. This paper explores UV doses to patients treated in Gran Canaria. Patient UV doses have been estimated for 20 psoriasis patients during a 15-day climate therapy study and compared with the predetermined exposure schedule and doses reported from other studies. Estimates were based on UV measurements and the patients' diaries with information on the time spent in the sun. On the first day of exposure, the patients received on average 5.1 standard erythema doses (SED) estimated to the skin. The average dose for the 15-day study was 166 SED (250 SED for a regular 3-week treatment period). We found no significant correlation between the reduction in psoriasis area severity index scores and UV doses. The UV doses were higher than if they had followed the prescribed exposure schedule and also higher than those reported from other climate therapy studies. It seems beneficial to focus on following the prescribed exposure schedule.