Rheumatoid Arthritis

Ref: Davidson's Principles & Practice of Medicine

Rheumatoid Arthritis

A common inflammatory arthritis characterized by synovitis, exacerbations (flares), and remissions.

📊 High Yield Epidemiology:
• Sex Ratio: Female : Male = 3:1
• Genetic: HLA-DRβ1 (Shared epitope) & HLA-B.
• Env. Trigger: Smoking 🚬 (Associated with more severe disease & reduced treatment response).
• Prevalence: 0.8-1.0% (Europe/S.Asia). Highest in Pima Indians (5%).

1. Pathogenesis

T & B Cells Infiltrate Synovium
⬇
Macrophages Activated (TNF-α, IL-1, IL-6)
⬇
Synovial Fibroblasts Proliferate ⮕ PANNUS Formation
(Releases ADAMTS-5 & Metalloproteinases)
⬇
Osteoclast Activation (RANKL) ⮕ Bone Erosion

2. Clinical Features

  • Pattern: Symmetrical, small joints (MCP, PIP, MTP), Wrist.
  • Morning Stiffness: Severe, lasts >1 hour.
  • Onset: Insidious (common), Acute (elderly), or Palindromic.
🖐 Deformities (Late Stage):
  • Swan Neck: PIP hyperextension + DIP flexion.
  • Boutonnière: PIP flexion + DIP hyperextension.
  • Z-deformity: of the thumb.
  • Feet: Cock-up toes, Valgus hindfoot, loss of arch.
  • Rupture: 4th/5th extensor tendons (due to ulnar subluxation).

3. Extra-Articular Features

Occurs in Seropositive (RF/ACPA+) patients.

Eyes: Sjögren's (Dry eye), Scleritis (Painful/Red).
Lungs: Pulmonary fibrosis, Pleural effusions, Nodules.
Heart: Pericarditis, increased atherosclerosis risk.
Skin: Rheumatoid Nodules (extensor surfaces).
Neurological Complications:
  • Carpal Tunnel: Median nerve compression.
  • Tarsal Tunnel: Posterior tibial nerve (burning sole/toes).
  • Atlanto-axial Subluxation: Cervical spine instability.
🚨 Emergency: Cord Compression
Atlanto-axial subluxation can be fatal.
Suspect if: Occipital headache or "electric shock" in arms.
Action: Urgent Neurosurgical Referral.
Rare Syndromes:
  • Felty Syndrome: RA + Splenomegaly + Neutropenia.
  • Amyloidosis: Presents with nephrotic syndrome.

4. Diagnosis & Investigations

  • Serology: Anti-CCP (ACPA) - 98% Specific. RF (Rheumatoid Factor) - Less specific (70% +ve).
  • Acute Phase: ESR & CRP (Raised).
  • Criteria (Score ≥6/10): Based on Joint count, Serology, Duration, Acute phase reactants.

5. Detailed Management

Goal: Suppress inflammation, prevent erosions, maintain function (Monitor via DAS28 Score).

Step 1: First Diagnosis (Induction)

Start cDMARDs promptly. Use corticosteroids as a "bridge".

Drug Dose & Regimen Duration
Prednisolone
(Corticosteroid)		 • Start: 30 mg daily (PO)
• Taper: Reduce by 5 mg every 2 weeks. 		~12 Weeks (Withdrawal)
Methotrexate (MTX)
(Anchor Drug)		 • Start: 15 mg Weekly (PO)
• Escalate: Up to max 25 mg Weekly based on response.
• Plus: Folic Acid 5mg Weekly (to reduce toxicity). 		Long-term maintenance

Step 2: Escalation (If response inadequate)

If monotherapy fails or toxicity occurs, switch to Triple Therapy.

Triple Therapy Combination:
  1. Methotrexate (MTX)
  2. Sulfasalazine (SSZ)
  3. Hydroxychloroquine (HCQ)

*Note: Can also switch oral MTX to Subcutaneous MTX for better efficacy.

Step 3: Resistant Disease

If disease activity remains high despite cDMARDs:

  • Biologics: Anti-TNF-α (e.g., Infliximab, Etanercept, Adalimumab).
  • tsDMARDs: JAK inhibitors (e.g., Tofacitinib).

*Biologics work better when co-prescribed with MTX.

🏥 Managing Flares:
  • Local Joint Injection (Depot Steroid).
  • IM Depot Steroid (Deep gluteal).
  • Short course oral Prednisolone.
🤰 Pregnancy & Lactation Protocol
• Contraindicated: Methotrexate (Stop 3 months prior), Leflunomide (Stop 24 months prior!), Cyclophosphamide.
• Safe to use: Sulfasalazine, Hydroxychloroquine, Prednisolone (for flares), Anti-TNF-α (generally safe).
• Analgesia: Paracetamol is choice. NSAIDs okay until 20 weeks.

~ Study hard!

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