Psoriasis is an autoimmune disease that causes red, raised, scaly patches on the skin. It cannot be cured, but treatments exist to relieve the symptoms. However, according to a new study from researchers in Sweden, these treatments are only effective for 20 per cent of psoriasis patients.

A wide range of treatments is currently available for relieving the symptoms of psoriasis. This chronic condition usually arises in patients with a genetic predisposition and tends to come and go in flare-up episodes. It leads to an accelerated renewal of the skin, causing lesions in the form of red patches with white scales which can be itchy. It can also be a cause of social isolation.

Current treatment options are tailored to the disease's severity and can take the form of pills taken orally, injections or infusions. However, research from Sweden's Umea University and the Swedish Institute for Health Economics has found that these are only effective for one in five patients suffering from moderate to severe psoriasis.

The study, published in The Journal of Dermatological Treatment, is based on PsoReg, the Swedish quality register for systemic treatment of psoriasis. Some 2,646 patients receiving treatment for at least three months were included in the study. The disease's level of severity was assessed by doctors and/or patients, evaluating the impact of the disease on their quality of life.

Over the last decade, the treatment options for psoriasis have advanced and new treatments have become available for moderate to severe forms of the disease, often relying on biologic agents. These can improve the overall look of skin and are generally better tolerated, with fewer side effects.

The researchers found that 18 per cent of patients undergoing systemic treatment continued to experience extensive psoriasis lesions or suffered impairment of their skin-related quality of life. Most of these patients were younger. They were also more often suffering from psoriasis arthritis and were more often smokers.

This result is "concerning," according to the study's authors. They suggest that patients with moderate to severe psoriasis using conventional systemic treatments should consider biologics. Patients already receiving biologics should envisage new therapeutic strategies. The scientists also recommend supporting patients in improving certain lifestyle factors.