Rheumatoid arthritis
Formal Definition
A chronic systemic autoimmune inflammatory arthritis characterized by symmetric polyarthritis predominantly affecting small joints of the hands and feet (MCPs, PIPs, MTPs), with morning stiffness lasting >1 hour; associated with seropositivity for rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies, and potential for erosive joint destruction and extra-articular manifestations.
How It's Used on the Ward
"RA" — distinguished from osteoarthritis by its inflammatory nature, symmetry, and small joint predominance.
Example
""35-year-old woman with 6 months of symmetric swelling and morning stiffness in both hands: RF positive, anti-CCP 3x ULN, X-rays showing periarticular osteopenia and early erosions — established RA. Starting methotrexate and folic acid; bridge with low-dose prednisone while MTX takes effect.""
Clinical Context
Diagnostic criteria (2010 ACR/EULAR): joint involvement, serology (RF/anti-CCP), acute phase reactants (CRP/ESR), symptom duration >6 weeks. Morning stiffness >1 hour (inflammatory stiffness), improves with activity — contrasts with osteoarthritis (stiffness after rest, worsens with activity). Extra-articular: interstitial lung disease, rheumatoid nodules, Felty syndrome (RA + neutropenia + splenomegaly), vasculitis. Treat-to-target strategy: DAS28 score guides escalation. DMARDs: MTX first-line; biologics (TNF inhibitors, IL-6 inhibitors, JAK inhibitors) for MTX-inadequate response. Screen for TB and hepatitis before biologics. Perioperative: hold MTX for major surgery (controversy), continue low-dose prednisone.