Assessing single joints in arthritis clinical trials

Endpoints and outcome measurements to detect changes in joint structure for the assessment of single joints are needed to enable rheumatology clinical trials of therapies targeting preservation of joint structure, especially via locally applied therapies. While the assessment of certain aspects of single joint inflammation and function is accepted in the evaluation of osteoarthritis (OA) using the WOMAC, it tends to be limited to the knee and hip. The advent of therapies that are directed toward a single joint in inflammatory arthritis, including intraarticular cytokine antagonists and gene therapeutics, requires reliable measures to assess change over time in single joints and the clinical meaningfulness of such change. Traditionally, clinical trials for inflammatory arthritis have used composite response indices such as American College of Rheumatology response or improvement in Disease Activity Score as outcomes based on multiple joint clinical measures, acute phase reactants, and functional status. However, it is not known whether these will appropriately detect changes referable to single joint intervention. This Special Interest Group was developed to bring together interested individuals to identify and evaluate outcome measurements for single joints. The knee was the initial focus, as clinical, radiographic, and functional assessments have been well developed for knee OA. A PubMed English language review was conducted before OMERACT 8, evaluating existing clinical instruments in the context of the OMERACT filter. At OMERACT 8, the group developed a research agenda to perform additional validation studies of clinical and functional indices, imaging, synovial histopathology, and soluble biomarkers.