This proposal represents a competitive renewal of the Boston University Multidisciplinary Clinical Research Center grant which was established in 2001 and built on a strong foundation of outstanding epidemiology and clinical research. The strong record of accomplishment in patient oriented medical research at Boston University has been not only maintained in the last four years but expanded. What we propose creates new directions and areas of research for this already productive group of investigators who work together closely, and it promises to produce further major insights into rheumatic disease causation and treatment. Led by Director, Dr. David Felson and Associate Director, Dr. Saralynn Allaire, this group of full-time MCRC investigators who work together in shared office space will meet weekly in Methodology Core group meetings to discuss and review both projects proposed here and other funded and non-funded clinical research. This Core will provide support for the proposed projects: "Bracing in Patellofemoral Osteoarthritis: A Clinical Trial", David J. Hunter, PI, "Risk Factors for Gout Attacks: A Case-crossover Study", Yuqing Zhang, PI, "Interplay of Thrombosis and Inflammation in Vasculitis", Peter Merkel, PI. An administrative unit will provide oversight to ensure that these projects are successfully accomplished and that core resources for support of these and other projects are allocated efficiently.