Early inflammatory polyarthritis: results from the norfolk arthritis register with a review of the literature. I. Risk factors for the development of inflammatory polyarthritis and rheumatoid arthritis.

Soon after people develop a chronic disease such as rheumatoid factor (RF)] are features of chronic or severe disease, and may not appear until months or rheumatoid arthritis (RA), they ask their physicians two searching questions: the first is ‘Why me? ’ and the years after disease onset. second is ‘What will happen to me now? ’ In 1989 the ARC Epidemiology Unit set up the Norfolk Arthritis The Norfolk Arthritis Register Register (NOAR) with the aim of providing answers to these two questions. This paper is the first in a series of The Norfolk Arthritis Register (NOAR) is a populationbased register which aims to recruit all patients who two reviews which focus on the work of NOAR, a register of a primary care-based inception cohort of potentially have RA by using deliberately broad inclusion criteria. Details of the register have been published patients with inflammatory polyarthritis (IP). The present paper examines genetic and environmental risk elsewhere [2]. General practitioners (GPs) working in the former Norwich Health Authority, which covers a factors for the development of IP and of its subset, RA. The second paper summarizes the natural history and population of almost 0.5 million, predominantly (99%) of European Caucasoid origin, notify NOAR of adults predictors of prognosis [87]. In both papers the NOAR data are presented in the context of a detailed review of (age 16 yr or older) who have swelling of at least two peripheral joints which has persisted for a minimum of the literature which summarizes current knowledge in this challenging area. 4 weeks. A parallel notification system operates from the local hospitals. Patients who do not satisfy the 1987 American College of Rheumatology (ACR) criteria for Background RA are later excluded if they are referred to hospital and are given a diagnosis other than RA, psoriatic The cause and prognosis of any disease are best studied by identifying incident cases from the general populaarthritis, viral arthritis or undifferentiated IP. tion. The study of prevalent cases makes it difficult to distinguish factors which lead to the development of Assessment of patients referred to NOAR disease from those which influence disease outcome. Hospital-based studies may be subject to selection bias. Within 2 weeks of notification, patients are visited at home by a research nurse, who takes a history using a A major problem in studying rheumatoid arthritis (RA) lies in the definition of the disease. The earlier in the structured questionnaire and examines the following joints for tenderness, soft-tissue swelling and deformity: course we try to identify patients, the harder it is to distinguish different forms of inflammatory polyarthritis distal interphalangeal joints, proximal interphalangeal joints (PIP), metacarpophalangeal joints (MCP), wrists, (IP). Many of the criteria currently used to classify RA [1] [e.g. radiological erosions, rheumatoid nodules and elbows, shoulders, knees, ankles and metatarsophalangeal joints (MTP). Patients are asked to provide a blood sample, which is frozen as serum and EDTA-antiSubmitted 26 August 1999; revised version accepted 3 March 2000. coagulated specimens. Patients are assessed annually for Correspondence to: D. Symmons, ARC Epidemiology Unit, a minimum of 5 yr. At each visit patients are asked to University of Manchester Medical School, Oxford Road, Manchester M13 9PT, UK. complete the Stanford Health Assessment Questionnaire