Snellman E, Aromaa A, Jansén CT, Lauharanta J, Reunanen A, Jyrkinen-Pakkasvirta T, Luoma J, Waal J.
DOI: 10.2340/0001555573388392

The long-term effects of psoriasis heliotherapy were studied in a randomized cross-over trial with a 2-year follow-up. We allocated 95 patients randomly to receive a 4-week heliotherapy course, either at the onset or in the middle of the follow-up period. After a highly significant immediate alleviation of psoriasis about 50% of the patients still had a reduction of psoriasis 6 months later and about 25% one year later. A favourable carry-over treatment effect was still observed during the second follow-up year. Taking advantage of the cross-over design, the effect of heliotherapy was calculated to be statistically significant during the first follow-up year, and the apparent long-term alleviation of psoriasis after the heliotherapy was reflected in a significant period effect. The alleviation of psoriasis was accompanied by a significant decrease in the use of antipsoriatic treatments.