The epidemiology of rheumatoid disease: past and present.

The epidemiology of rheumatoid arthritis is poorly defined. We know neither how long rheumatoid arthritis has been a major disease, nor whether its incidence is decreasing. If it is decreasing, is this because of the contraceptive pill or some other variable? We do know that the disease occurs worldwide and that there may be increased prevalence among urban living individuals, compared to their rural counterparts. To some extent the disease 'runs in families', but heritibility is low. Concordance among monozygotic twins is only 32 per cent. Women develop the disease more frequently than men. The prognosis for black males is said to be better than for white females. Whether seronegative 'rheumatoid arthritis' should be considered part of the same disease process is unknown. An agreed definition for rheumatoid arthritis is essential before meaningful genetic and immunogenetic data can be developed. However, it is unclear whether the term rheumatoid arthritis should only be given to those individuals with seropositive erosive disease or whether we should include a self-limiting process of poorly characterized change that is sometimes seen, for example, in the first degree relatives of index cases with disease. The ARA criteria for rheumatoid arthritis are unhelpful since 'possible' and 'probable' rheumatoid arthritis patients almost certainly do not have rheumatoid disease. Moreover, the majority of patients with 'definite' rheumatoid arthritis are seronegative. These subjects may be differentiated from seropositive patients on epidemiological, familial, clinical, immunogenetic, and perhaps radiological grounds. The consensus view is that the DR4 allotype occurs more frequently in severe seropositive disease than in severe seronegative 'rheumatoid arthritis'.(ABSTRACT TRUNCATED AT 250 WORDS)