The prevalence of rheumatoid arthritis in the United Kingdom: new estimates for a new century

Background. It is 40 yr since the last age- and sex-specific estimates of the prevalence of rheumatoid arthritis (RA) for the UK were published. Since then the classification criteria for RA have been revised and there has been evidence of a fall in the incidence of RA, especially in women. Objectives. To estimate the age- and sex-specific point prevalence of RA (defined as fulfilment of a modification of the 1987 ACR classification criteria for RA on the day of assessment). The estimate was made in the primary care setting in Norfolk, UK. Methods. A stratified random sample was drawn from seven age and gender bands. The 7050 individuals selected were mailed a screening questionnaire. Positive responders were invited to attend for a clinical examination. The sample was matched against the names in the Norfolk Arthritis Register (NOAR), a register of incident cases of inflammatory polyarthritis which has been in existence since 1990. Results. The overall response rate was 82%. Sixty-six cases of RA were identified. Extrapolated to the population of the UK, the overall minimum prevalence of RA is 1.16% in women and 0.44% in men. A number of incident cases of RA previously notified to NOAR were not identified as cases in the survey because they had entered into treatment-induced remission. In addition, some cases who failed to attend for examination had significant disability. These prevalence figures are therefore an underestimate. Conclusions. The prevalence of RA in women, but not in men, in the UK may have fallen since the 1950s.