This study is health economic analysis of medicinal treatment options for moderate-to-severe psoriasis vulgaris from the societal perspective. Efficacy data and other clinical outcomes will be derived from an up-to-date meta-analysis of randomized clinical trials (RCTs) for moderate-to-severe psoriasis. Direct and indirect costs will be extracted from various different sources, including summary of product characteristics (SPCs) and the German S3 guideline on psoriasis care, health care utilization data and official statistics.||The study aims to investigate the comparative cost-effectiveness of biologic and conventional systemic treatments currently (as of June 1st, 2012) approved for moderate-to-severe plaque-type psoriasis in Germany. Effectiveness will be measured by means of the pooled (Psoriasis Area and Severity Index) PASI-75 response rates as reported in RCTs Direct cost as well as indirect cost will be considered.