Rheumatoid Arthritis

Rheumatoid arthritis is a chronic, systemic autoimmune disease that produces symmetric inflammation of the synovial joints, classically the small joints of the hands and feet, and can lead to erosive joint damage, deformity, and extra-articular and cardiovascular complications. It is the prototypical inflammatory arthropathy and the model for the modern treat-to-target approach in rheumatology.

Definition

Rheumatoid arthritis is a chronic systemic autoimmune disorder characterised by persistent symmetric inflammatory synovitis, frequently with circulating rheumatoid factor and anti-citrullinated protein antibodies, that can cause progressive cartilage and bone erosion.

Scope

This topic covers the immunopathology, clinical features, autoantibody serology, and classification of rheumatoid arthritis, and the principles of disease-activity monitoring that frame its management. It is a clinical-entity reference entry describing how the disease is understood and classified, not a source of individualised diagnostic or therapeutic advice.

Core questions

• How do autoantibodies and synovial inflammation produce joint destruction in rheumatoid arthritis?
• What distinguishes seropositive from seronegative rheumatoid arthritis?
• How is disease activity measured and used to guide a treat-to-target strategy?

Key concepts

• Symmetric inflammatory polyarthritis
• Rheumatoid factor and anti-citrullinated protein antibodies (ACPA)
• Synovial pannus and bone erosion
• 2010 ACR/EULAR classification criteria
• Disease-activity scores (DAS28, CDAI, SDAI)
• Extra-articular manifestations
• Cardiovascular comorbidity

Mechanisms

Rheumatoid arthritis arises from a breakdown of immune tolerance in genetically susceptible individuals, often years before symptoms, marked by the appearance of anti-citrullinated protein antibodies and rheumatoid factor. The inflamed synovium becomes infiltrated by T cells, B cells, and macrophages and proliferates into a destructive pannus; pro-inflammatory cytokines such as TNF, IL-6, and IL-1 amplify inflammation and activate osteoclasts, leading to the cartilage loss and bone erosion that characterise progressive disease. This cytokine-driven mechanism underlies the rationale for targeted biologic therapies.

Clinical relevance

Rheumatoid arthritis is recognised through symmetric small-joint synovitis, prolonged morning stiffness, supportive serology (rheumatoid factor, ACPA), and raised inflammatory markers, and is classified using the 2010 ACR/EULAR criteria. Because early sustained control of inflammation is associated with reduced structural damage, prompt referral and objective disease-activity assessment are emphasised at a population level. This entry is descriptive and does not constitute individual clinical advice.

Epidemiology

Rheumatoid arthritis affects roughly 0.5-1% of adults worldwide, with a two-to-three-fold female predominance and typical onset between the fourth and sixth decades. Smoking and specific HLA-DRB1 'shared epitope' alleles are established risk factors, and patients carry an elevated cardiovascular risk attributable in part to chronic systemic inflammation.

Evidence & guidelines

The 2010 ACR/EULAR classification criteria standardised how rheumatoid arthritis is identified for study and practice, and EULAR and ACR management recommendations set out an evidence-based, treat-to-target framework using conventional synthetic, biologic, and targeted synthetic DMARDs. These documents summarise population-level evidence and recommendations rather than prescribing for individuals.

History

Rheumatoid arthritis was delineated as a distinct entity in the nineteenth and early twentieth centuries and separated from other arthritides by its serology after the discovery of rheumatoid factor in the 1940s. The identification of anti-citrullinated protein antibodies and the shared-epitope hypothesis clarified its autoimmune basis, while the arrival of methotrexate as an anchor drug and of TNF and other cytokine inhibitors transformed prognosis and inspired the treat-to-target paradigm.

Debates

When should biologic therapy be introduced relative to conventional DMARDs?

Recommendations generally favour starting with conventional synthetic DMARDs such as methotrexate and escalating to biologic or targeted synthetic agents if treatment targets are not met, but the optimal timing and sequencing of escalation remain debated at the level of guideline evidence.

Key figures

• Iain McInnes
• Georg Schett
• Josef Smolen
• Lars Klareskog
• Daniel Aletaha

Seminal works

• mcinnes-2011
• klareskog-2009
• aletaha-2010
• smolen-2016-ra

Frequently asked questions

What does it mean for rheumatoid arthritis to be 'seropositive'?

Seropositive disease means rheumatoid factor and/or anti-citrullinated protein antibodies are detectable; these patients tend to have a more erosive course, but seronegative rheumatoid arthritis also occurs and is diagnosed clinically with supportive criteria.

Why is rheumatoid arthritis considered a systemic disease?

Beyond the joints it can involve the lungs, eyes, blood vessels, and other organs, and chronic inflammation contributes to an increased cardiovascular risk, so it is regarded as systemic rather than purely articular.