National registries of systemic treatment for psoriasis and the European 'Psonet' initiative.

About 11 million people suffer from psoriasis in Europe. This chronic condition may have a dramatic impact on quality of life. About 20% of patients may need systemic treatment to effectively control their disease activity. The introduction of biological agents greatly increased the options of systemic therapies for psoriasis. However, clinical experience with newer systemic therapies is relatively limited, and available data are mostly derived from short-term phase III trials. Except for PUVA and ciclosporin, long-term safety data from formal postmarketing studies are also largely lacking conventional treatment options. Registries provide one mechanism to monitor the long-term safety and effectiveness of treatment in the 'natural environment'. Several European countries have established registries to collect data on systemic psoriasis treatment. Even though different in some aspects of study design and monitoring, the registries share a number of common features: they include all the biological drugs and sometimes all the licensed systemic agents for psoriasis, and they observe the patients for a defined period of time irrespective of the drug given. Combining the results from these registries would increase their power and impact. We are developing an international collaboration called 'Psonet' that will perform a joint analysis of data from 9 individual national psoriasis registries.