An older form of light treatment for psoriasis may be better than a newer, safer version, say researchers.
While ultraviolet B light (UVB) has proved to be a convenient and somewhat safe form of treatment for psoriasis patients, it turns out that an older type of light therapy, ultraviolet A (UVA), is more effective in treating the symptoms of psoriasis.
Light therapy is a common treatment for psoriasis. However, UVA requires the use of psoralen, an oral drug, in a treatment called PUVA. Psoralen causes nausea, requires eye protection after treatment and cannot be used in patients who are pregnant or taking other drugs. Additionally, prolonged use of UVA has been shown to increase the risk of some types of skin cancer.
Because of these safety issues, physicians prefer UVB over UVA. However, until now, there has never been a study to determine if they were equally effective.
Researchers from King's College, London studied 93 patients with chronic psoriasis, treating half with PUVA therapy and the other half with UVB therapy. Each patient was treated twice a week and given typical ointments for after treatment skin care.
The patients' skin was analyzed at various points during treatment and scored for the severity of psoriasis.
At the end of the study, 84 percent of the patients undergoing UVA therapy had no signs of their disease by the end of the treatment, while only 65 percent of patients in the UVB group no longer had the disease. Additionally, those patients who were free of their disease required an average of 17 UVA sessions, as opposed to the 28 sessions needed by patients undergoing UVB sessions.
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While UVB still remains a safer treatment, and should be used in those patients who cannot tolerate treatment with UVA, the authors of the study noted that, "PUVA compared with UVB treatment tends to clear psoriasis more reliably, with fewer treatments…and should, therefore, still be used in appropriate patients."
