The descriptive epidemiology of rheumatoid arthritis

This chapter describes the incidence, prevalence, and mortality of rheumatoid arthritis (RA) in adult populations around the world. Studies can only be compared if they have used the same case definition. The characteristics of the 1987 American College of Rheumatology (ACR) and the 2010 ACR/European League against Rheumatism (EULAR) classification criteria sets are discussed. In recent times several epidemiological studies have been set in large healthcare databases and have used physician diagnosis together with disease-modifying antirheumatic drugs (DMARD) prescription as the case definition. Most incidence and prevalence data on RA come from North America and Europe. Considerable insight into the relative frequency of RA has come from modelling studies in the Global Burden of Disease project 2010. The occurrence of RA is highest in the Pima and some other Native American groups; and lowest in low- and middle-income countries of Africa, South and East Asia, and the Middle East. The mortality of RA is increased relative to the general population. The mortality is falling with time, but in parallel with falls in the general population.