Clinical features of rheumatoid arthritis

The diagnosis of rheumatoid arthritis (RA) is based on a combination of symptoms, signs, and investigation results. As such, it is mainly based on pattern recognition. Classification criteria are not developed to make accurate diagnoses in individual patients, but for the primary purpose of defining homogeneous disease groups for scientific studies. The RA classification criteria have changed over time. This chapter discusses the process of diagnosing RA, the range of clinical characteristics that contribute to this process, its relationship with evolving classification criteria for the condition, and important differential diagnoses. Current recommendations encourage early recognition of arthritis and RA. Since clinical presentation may differ with disease stage, this chapter will also review how the RA phenotype changes as prearthritis progresses to early undifferentiated arthritis and established RA.