Update on the epidemiology, risk factors, and disease outcomes of rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by joint inflammation, which affects approximately 1% of the population. The benefit of early recognition and treatment has led to an increased interest in the early phases of disease. With the aim of classifying patients earlier in their disease course, new RA classification criteria have been developed. Much attention has been devoted to the identification in the prearthritis phase of arthralgia. The discovery of new risk factors and autoantibodies has led to new theories about the putative mechanisms involved in disease development. Finally, the outcome measures have also evolved, with more emphasis on sustained drug-free remission and patient-reported outcomes. This article reviews the new developments in RA research and discusses the latest insights into epidemiology, risk factors, predisease states, and outcomes.