Quick Overview
Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory arthritis affecting 0.8% of UK adults, with 3:1 female predominance. Causes symmetrical small joint polyarthritis with systemic manifestations and progressive joint destruction if untreated. NICE NG100 emphasizes urgent specialist referral (target ≤3 weeks) and treat-to-target strategy with DMARDs to achieve remission and prevent irreversible damage.
Core Facts & Concepts
Diagnostic Criteria (ACR/EULAR 2010):
- Score ≥6/10 confirms RA (joint involvement, serology, acute-phase reactants, duration)
- Persistent synovitis in ≥1 joint unexplained by other disease
Key Investigations:
- RF positive in 70%, anti-CCP antibody in 70% (more specific, predicts erosive disease)
- Inflammatory markers: ESR/CRP elevated
- X-rays: soft tissue swelling → periarticular osteopenia → joint space narrowing → erosions (diagnostic hallmark)
DAS28 Scoring (Disease Activity Score):
- Assesses 28 joints (tender + swollen counts) + ESR/CRP + global health
- Remission <2.6 | Low activity 2.6-3.2 | Moderate 3.2-5.1 | High >5.1
- Target: DAS28 <2.6 or improvement >1.2 points
Extra-articular Manifestations (25-40%):
- Pulmonary: ILD, pleural effusion, rheumatoid nodules
- Cardiac: pericarditis, accelerated CVD
- Ocular: scleritis, keratoconjunctivitis sicca
- Haematological: anaemia of chronic disease, Felty's syndrome
Problem-Solving Approach
Urgent Referral Criteria (NICE NG100):
- Persistent synovitis (swelling not just pain) in small joints of hands/feet
- Refer within 3 working days if suspected RA
- Squeezed metacarpophalangeal joints (MCP squeeze test) positive if painful
- Morning stiffness >30 minutes (typically 1-2 hours)
Treatment Pathway (Treat-to-Target):
- First-line: Methotrexate (MTX) 15-25mg weekly + folic acid 5mg (6 days/week, not MTX day)
- Combination csDMARDs if inadequate response at 3 months (add hydroxychloroquine/sulfasalazine)
- Biologics (TNF-α inhibitors, rituximab) if 2 csDMARDs fail + DAS28 >5.1
- JAK inhibitors (baricitinib, tofacitinib) as alternative to biologics
Methotrexate Safety (NICE NG100):
- 🚩 FBC, U&E, LFTs at baseline, 2-weekly until stable, then 2-3 monthly
- 🚩 Contraindications: pregnancy (teratogenic), breastfeeding, severe renal/hepatic impairment
- 🚩 Pneumonitis risk: counsel on breathlessness (stop MTX immediately)
- Trimethoprim/co-trimoxazole interaction: severe myelosuppression
Analysis Framework
| Feature | Rheumatoid Arthritis | Osteoarthritis | Psoriatic Arthritis |
|---|---|---|---|
| Pattern | Symmetrical small joints | Asymmetrical large/DIP | Asymmetrical, DIP involvement |
| Morning stiffness | >1 hour | <30 minutes | Variable |
| Serology | RF/anti-CCP positive (70%) | Negative | Negative |
| X-ray | Erosions, periarticular osteopenia | Osteophytes, subchondral sclerosis | Pencil-in-cup, enthesitis |
| Systemic features | Common | Absent | Psoriasis, nail changes |
Red Flags:
- 🚩 Septic arthritis: single hot swollen joint (aspirate urgently)
- 🚩 Atlantoaxial subluxation: cervical myelopathy symptoms
- 🚩 Vasculitis: digital infarcts, purpura, mononeuritis multiplex
Visual Aid
Key Points Summary
✓ Urgent referral ≤3 days for persistent small joint synovitis + morning stiffness >30 min (NICE NG100)
✓ Anti-CCP antibody more specific than RF; predicts erosive disease and guides prognosis
✓ DAS28 target <2.6 (remission); review every 3 months until target achieved, then 6-monthly
✓ Methotrexate 15-25mg weekly is first-line DMARD; requires FBC/U&E/LFTs 2-weekly initially, then 2-3 monthly monitoring
✓ Biologics indicated after failure of 2 csDMARDs AND DAS28 >5.1 on 2 occasions 1 month apart
✓ 🚩 Stop MTX immediately if breathlessness (pneumonitis), oral ulceration, or abnormal bruising/bleeding
✓ Extra-articular: screen for ILD (HRCT), CVD risk, anaemia; atlantoaxial instability risk in longstanding disease
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