Rheumatoid arthritis
Rheumatoid arthritis is a chronic systemic autoimmune disease causing symmetric small-joint polyarthritis of the hands and feet that spares the distal interphalangeal joints, with morning stiffness over an hour. Diagnosis combines the ACR/EULAR classification criteria with rheumatoid factor, anti-CCP antibody, and radiographs. Treat-to-target management anchors on methotrexate, escalating to a biologic or targeted synthetic disease-modifying antirheumatic drug when remission is not reached.
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What this article covers
- Overview
Definition: rheumatoid arthritis (RA) is a chronic systemic autoimmune disease in which loss of tolerance to citrullinated self-proteins drives inflammatory polyarthritis in genetically susceptible people.
- Epidemiology
Prevalence: 0.5% to 1% of the general population.
- Risk factors
Genetic susceptibility: HLA-DRB1 shared epitope alleles bind and present citrullinated peptide antigens; about 100 non-HLA loci also contribute.
- Pathophysiology
Loss of tolerance: PAD converts arginine to citrulline, generating citrullinated peptides that are immunogenic in people with the shared epitope; the resulting autoantibodies can predate clinical arthritis by years.
- Clinical features
Joint distribution: symmetric arthritis of the MCP, PIP, and wrist joints of the hands and metatarsophalangeal (MTP) joints of the feet, sparing the DIP joints; larger joints can also be involved…
- Differential diagnosis
Osteoarthritis: DIP, PIP, and first carpometacarpal predominance with stiffness under 30 minutes and no systemic inflammation, unlike DIP-sparing RA (osteoarthritis).
- Diagnosis
Classify using the 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) criteria: in a patient with at least one joint showing definite synovitis not better explained…
- Management
First-line, start a conventional synthetic DMARD as soon as RA is diagnosed: Methotrexate, the anchor drug: 7.5 to 10 mg PO once weekly, titrated by 2.5 to 5 mg every 2 to 4 weeks to 15 to 25 mg once…
- Complications
Atlantoaxial subluxation: C1-C2 involvement occurs in up to 50% of chronic RA on flexion-extension radiographs; dens erosion can compress the cord or brainstem, so cervical stability must be assessed before intubation.
- Prognosis
Erosive risk concentrates in seropositive disease: persistent polyarthritis with elevated acute-phase reactants and a positive rheumatoid factor or anti-CCP predicts erosion within 1 to 2 years.
- Prevention
Smoking cessation is the single most important modifiable risk-reduction measure, particularly with a family history of RA.
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