Capturing real-life patient care in psoriatic arthritis and its risks: the challenge of analysing registry data

Studies based on registries continue to inform us of many relevant issues in the treatment of arthritic conditions and constitute more than just a supplement of clinical trial data. We can learn about long-term aspects of therapies beyond the scope of most clinical trials and about larger-scale toxicity. The downsides need to be considered in the interpretation of the results and include mainly the biases that are inherent when routine clinical practice is just observed and not steered by a protocol. However, using steered protocols in practice not only would facilitate post hoc analyses of clinical effectiveness, but (as we have learned from research in rheumatoid arthritis) can also improve outcomes of our patients.