The CORRONA Research Foundation (CRF) is an independent, not for profit private foundation. The CRF has access to the deep longitudinal data on patients with rheumatoid arthritis which has been collected by more than 700 rheumatologists in 42 states. These data are derived from approximately 460,000 individual patient visits over a 20+ year span and contain the largest observational database collecting data from both physicians and patients with rheumatic diseases with simultaneous data at the time of clinical encounter.