- GROUP I ("high need") patients: adult patients with moderate to severe plaque psoriasis who are either not controlled by, or are intolerant to or have contraindications to at least two currently available systemic therapies (e.g. photochemotherapy, cyclosporine, methotrexate, oral retinoids, fumaric acid esters, efalizumab, etanercept). GROUP II ("low need") patients: adult patients with moderate to severe plaque psoriasis who have undergone pre-treatment with no more than one currently available systemic therapy (e.g. photochemotherapy, cyclosporine, methotrexate, oral retinoids, fumaric acid esters, efalizumab, etanercept). A patient showing contraindications towards two systemic treatments, who has never been pretreated with a systemic therapy will be assigned to GROUP II ("low need").