The Norfolk Arthritis Register ( NOAR ) D .

The Norfolk Arthritis Register (NOAR) has been re c ruiting and fo l l ow i n g patients with early inflammatory poly-arthritis (IP) since 1989. Approximately thre e-q u a rt e rs of the patients fo l-lowed satisfy classification criteria for rheumatoid arthritis (RA) by 5 years from symptom onset. This paper sum-m a rises the publ i c ations wh i ch have been based on the NOAR cohort with respect to the incidence and prevalence of IP and RA, genetic and environmental risk factors for the development of IP, outcome following the development of IP and predictors of outcome. It also discusses methodological issues in examining the treatment effect in observational cohorts and the costs to the healthcare system of patients with early IP. Introduction The Norfolk Arthritis Register (NOAR) was established during 1989. By the beginning of 1990, all the general practitioners (GPs) in what was then the Norwich Health Authority had been visited and asked to participate. A team of metrologists (research nurses and a re s e a rch occupational therapist) had been re c ruited and trained to take a standardised history and examine joints for tenderness, swelling and deformity in a reproducible way. From 1 January 1990, the GPs and local rheumatolo-gists referred to NOAR all adults (age ≥ 16) who they saw with two or more