Climate therapy of psoriasis patients at Gran Canaria High UV doses

Psoriasis is a chronic inflammatory disease involving about 2-3% of the European population. Sun exposure has a positive effect on most psoriasis lesions, but ultraviolet (UV) radiation also causes a direct DNA damage in the skin cells and comprises a carcinogenic potential. UV exposure on the skin causes a local as well as a systemic immune suppressive effect, but the relation between sun exposure and these biological effects is not well known. In March 2006 a study was carried out to investigate possible therapeutic outcome mechanisms in 20 psoriasis patients receiving climate therapy at Gran Canaria. This paper presents estimates of their individual skin UV doses based on UV measurements and patients’ diaries with information on 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. During the 15 days study they received 166 SED. There was no significant correlation between the therapeutic improvement and the UV dose. The UV doses were higher than if they had followed the prescribed exposure schedule and also higher than doses found from climate therapy studies at other locations. It seems beneficial to focus on the prescribed exposure schedules.