Rheumatoid Arthritis

RA Basics - Joint Under Siege

• Chronic, systemic autoimmune inflammatory disorder causing symmetrical, erosive polyarthritis.
• Epidemiology: ~1% global (India ~0.75%); F:M 3:1; peak onset 30-50 yrs.
• Risk Factors:
  • Genetic: HLA-DR4 (Shared Epitope), PTPN22.
  • Environmental: Smoking (major!), infections (P. gingivalis, EBV).
• Pathogenesis:
  • T/B cell dysregulation → autoantibodies (RF, ACPA).
  • Key cytokines (TNF-α, IL-1, IL-6) drive synovitis, pannus formation, leading to cartilage & bone erosions.

⭐ Smoking is the most significant modifiable environmental risk factor for developing RA, especially seropositive RA (ACPA+).

RA Signs - The Body's Complaint

• Articular (Joints):
  • Symmetrical polyarthritis (MCP, PIP, MTP, wrists). Spares DIPs.
  • Morning stiffness > 1 hour, eases with activity.
  • Pain, swelling, tenderness.
  • Late deformities: Swan neck, Boutonnière, ulnar deviation.
  • Atlantoaxial subluxation (C1-C2).
• Extra-articular Manifestations:
  • Systemic: Fever, fatigue, weight loss.
  • Rheumatoid nodules (extensor surfaces).
  • Pulmonary: Pleurisy, nodules, ILD. Caplan syndrome (RA + pneumoconiosis).
  • Cardiac: Pericarditis, ↑CV risk.
  • Ocular: Scleritis, episcleritis, Sjogren's.
  • Heme: Anemia of chronic disease.
  • 📌 Felty's Syndrome: RA + Splenomegaly + Neutropenia.
  • Vasculitis (nail-fold infarcts).
  • Neuro: Carpal tunnel syndrome.

⭐ Felty's syndrome (RA, splenomegaly, neutropenia) is a classic triad associated with severe, long-standing RA and increased risk of infections.

RA Detective - Cracking the Case

• 2010 ACR/EULAR Criteria: Score ≥ 6/10 for diagnosis.
  • Key domains:
    • Joints: Number & size (small > large).
    • Serology: RF, Anti-CCP (ACPA) levels.
    • Acute Phase Reactants: ESR, CRP.
    • Symptom Duration: ≥ 6 weeks.
• Key Investigations:
  • Serology:
    • Rheumatoid Factor (RF): Positive in ~70-80%; not specific.
    • Anti-CCP (ACPA): Highly specific (~95%); often positive early.

      ⭐ Anti-CCP antibodies are more specific for RA than RF and may predict more severe, erosive disease.

  • Inflammatory Markers: ↑ ESR, ↑ CRP (correlate with disease activity).
  • Imaging:
    • X-rays (Hands & Feet): Periarticular osteopenia, joint space narrowing, marginal erosions (characteristic but late).
    • Ultrasound/MRI: Detect synovitis, early erosions.
  • Synovial Fluid Analysis: Inflammatory (WBC 2,000-50,000/µL, >50% PMNs, sterile, poor mucin clot).

RA Battle Plan - Taming the Flame

Goal: Remission or Low Disease Activity (LDA). Employ Treat-to-Target (T2T) strategy. Monitor disease activity (DAS28, CDAI) every 1-3 months.

• Non-Pharmacological:

  • Patient education, physiotherapy, occupational therapy.
  • Lifestyle: Smoking cessation, weight management, joint protection.

• Pharmacological:

  • Bridge Therapy: Glucocorticoids (low-dose, short-term, e.g., Prednisolone ≤10 mg/day), NSAIDs for symptom relief.
  • csDMARDs (Conventional Synthetic):
    • Methotrexate (MTX): Anchor drug. Start within 3 months of diagnosis. Dose: 7.5-25 mg/week. Folic acid supplementation (1-5 mg/day or 5 mg/week 24-48h post-MTX).
    • Alternatives/Adjuncts: Leflunomide (LEF), Sulfasalazine (SSZ), Hydroxychloroquine (HCQ - mild RA/combo).
  • bDMARDs (Biologic): If csDMARDs fail (inadequate response after 3-6 months of optimal therapy).
    • TNF-α inhibitors: Etanercept, Infliximab, Adalimumab.
    • Others: Rituximab (anti-CD20), Tocilizumab (anti-IL6R), Abatacept (CTLA4-Ig).
    • ⚠️ Screen for latent TB, HBV, HCV before initiating.
  • tsDMARDs (Targeted Synthetic - JAK inhibitors): Tofacitinib, Baricitinib, Upadacitinib. Oral. For csDMARD/bDMARD failure/intolerance.

⭐ Methotrexate (MTX) is the cornerstone DMARD; initiation within 3 months of RA diagnosis is crucial for better prognosis.

High‑Yield Points - ⚡ Biggest Takeaways

• Symmetrical polyarthritis of small joints (MCP, PIP) with morning stiffness > 1 hour.
• Key serology: Rheumatoid Factor (RF) and highly specific Anti-CCP antibodies.
• Common extra-articular features: rheumatoid nodules, interstitial lung disease, vasculitis.
• X-ray shows juxta-articular osteoporosis, erosions, and joint space narrowing.
• Early DMARD (e.g., Methotrexate) therapy is crucial to prevent joint damage.
• Felty's syndrome: RA triad of arthritis, splenomegaly, and neutropenia.
• Caplan syndrome: RA with pneumoconiosis and intrapulmonary nodules.