Recent Developments for Optimal End-Points in Rheumatoid Arthritis Clinical Studies

Clinical studies in patients with rheumatoid arthritis (RA) provide valuable information on the course and outcome of the disease whereas clinical trials provide information on optimal treatment for patients. This paper discusses measurement concepts and most frequently used measures in RA. To optimise the information that can be obtained from clinical studies, uniform measures are essential. Therefore, the international rheumatology community has made an effort to propose uniform end-points for clinical studies in RA. Measurement in RA is traditionally divided into the measurement of `the process' and measurement of `outcome'. Current measures in use include: 1. disease activity measures - global assessments, symptoms (e.g. morning stiffness), health status/ physical function, physical signs (e.g. joint counts) and laboratory assessments; and 2. measures of damage - radiography of affected joints and physical function. Several Outcome Measures in Rheumatology (OMERACT) conferences have resulted in a core set of end-points to be used in RA clinical trials, which are supported by the World Health Organization and International League of Associations for Rheumatology (WHO/ILAR). In addition, the OMERACT conferences focused on minimum important differences for patients and in trials, resulting in recommendations for improvement criteria. Improvement criteria were further developed and validated by both the American College of Rheumatology (ACR) and European League Against Rheumatology (EULAR). The ACR criteria use the WHO/ILAR core set of end-points to define minimum improvement in each of the measures. The EULAR criteria define improvement using the Disease Activity Score.