Rheumatoid Arthritis

1. Clinical Overview

Summary

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterised by symmetrical inflammatory polyarthritis, primarily affecting the small joints of the hands and feet. It represents the most common inflammatory arthritis worldwide, with a prevalence of approximately 0.5-1% in developed countries. [1,2] The hallmark pathological feature is persistent synovial inflammation leading to progressive cartilage and bone destruction, resulting in joint deformity and functional disability if left untreated.

The disease has a 3:1 female predominance and typically presents in the fourth to sixth decades of life. [3] RA is fundamentally an autoimmune condition driven by loss of tolerance to citrullinated self-proteins, with characteristic autoantibodies including rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies. [4]

Early recognition and treatment within the "window of opportunity" (first 3 months of symptoms) is critical, as prompt initiation of disease-modifying antirheumatic drugs (DMARDs) can significantly alter disease trajectory, prevent irreversible joint damage, and improve long-term outcomes. [5,6] The modern treat-to-target strategy, aiming for clinical remission or low disease activity, has transformed prognosis for many patients.

Key Clinical Facts

• Definition: Chronic symmetric inflammatory polyarthritis with systemic manifestations
• Prevalence: 0.5-1% in developed countries; 0.75% in UK population [1,2]
• Sex Ratio: Female:Male = 3:1 [3]
• Peak Onset: 40-60 years of age
• Pathognomonic Features: Symmetrical small joint synovitis + positive RF/anti-CCP antibodies
• Gold Standard Diagnosis: Clinical criteria (2010 ACR/EULAR) + serology + imaging
• First-line Treatment: Methotrexate 15-25mg weekly [7]
• Prognosis: Good with early aggressive treatment; progressive disability if untreated [6]

Clinical Pearls

Window of Opportunity Pearl: The first 3 months represent a critical therapeutic window. Early DMARD initiation during this period leads to better long-term outcomes, higher remission rates, and reduced radiographic progression. [5,6]

Anti-CCP Pearl: Anti-CCP antibodies are more specific (95%) than RF (85%) for RA and predict erosive disease. Positive anti-CCP with negative RF still suggests RA. [4,8]

Extra-articular Pearl: Remember the major extra-articular manifestations: Lungs (ILD in 10-20%), Heart (pericarditis, IHD risk), Eyes (scleritis, episcleritis), Vasculitis (1-5%), and Felty syndrome (RA + splenomegaly + neutropenia). [9]

Morning Stiffness Pearl: Morning stiffness lasting > 60 minutes is a cardinal feature distinguishing inflammatory arthritis (RA) from mechanical conditions (osteoarthritis, which typically has less than 30 minutes of stiffness). [1]

Treat-to-Target Pearl: Assess disease activity every 3 months using DAS28 score. If target (remission or low disease activity) not achieved, escalate therapy within 3 months. [7]

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2. Epidemiology

Global Distribution and Prevalence

Rheumatoid arthritis affects approximately 0.5-1% of the adult population worldwide, with significant geographic variation. [1,2] The highest prevalence is observed in:

• North America: 0.5-1%
• Northern Europe: 0.8-1.1%
• Southern Europe: 0.3-0.7%
• Developing countries: Generally lower (0.1-0.5%)

The United Kingdom has a prevalence of approximately 0.75%, translating to over 400,000 affected individuals. [2]

Incidence Rates

Annual incidence rates vary by region:

• Overall: 20-50 cases per 100,000 population per year [1]
• Women: 30-70 per 100,000
• Men: 15-30 per 100,000
• Peak incidence age: 40-60 years in women, 50-70 years in men [3]

Demographics

Risk Factors

Major Risk Factors for RA Development:

Protective Factors:

• Breastfeeding (RR 0.5-0.7)
• Moderate alcohol consumption (controversial; may reduce risk by 20-30%)
• Oral contraceptive use (weak protective effect)

Temporal Trends

Recent epidemiological studies suggest:

• Incidence: Possible slight decline in some Western countries over past 30 years [1]
• Severity: Decrease in severe erosive disease (likely due to earlier, more aggressive treatment)
• Mortality gap: RA patients still have 1.5-2x higher mortality than general population, primarily from cardiovascular disease [15]

Ethnic Variations

• Native Americans: Highest prevalence (5-6% in some tribes, e.g., Pima Indians)
• Caucasians: Intermediate prevalence (0.5-1%)
• Africans/Afro-Caribbeans: Lower prevalence (0.2-0.5%)
• Asians: Variable (0.2-0.4% in China/Japan; higher in urban vs rural populations)

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3. Aetiology and Pathophysiology

Aetiology

RA is a multifactorial disease resulting from complex interactions between genetic susceptibility and environmental triggers in a permissive immunological environment.

Primary Causes:

1. Autoimmune dysregulation: Loss of tolerance to citrullinated self-antigens
2. Genetic predisposition: HLA-DRB1 shared epitope and non-HLA genes (PTPN22, STAT4, TRAF1-C5)
3. Environmental triggers: Smoking, infections, microbiome alterations

Key Genetic Associations:

Molecular Pathophysiology

The pathogenesis of RA can be conceptualized in three distinct phases:

Phase 1: Initiation (Pre-clinical Phase)

This phase occurs months to years before clinical arthritis develops.

Key Events:

1. Protein Citrullination

   • Post-translational modification of arginine residues to citrulline
   • Catalyzed by peptidylarginine deiminase (PAD) enzymes (particularly PAD2 and PAD4)
   • Triggered by environmental factors (smoking, infection, mucosal inflammation)
   • Sites: Lungs, gingiva, gut mucosa

2. Breaking of Immune Tolerance

   • Citrullinated proteins presented on HLA-DR4 (shared epitope) to T cells
   • Loss of central and peripheral tolerance mechanisms
   • Generation of anti-CCP antibodies (can be detected 5-10 years before symptoms) [4]

3. Autoantibody Production

   • Anti-CCP antibodies (67% sensitive, 95% specific for RA) [8]
   • Rheumatoid factor (RF) - IgM antibody against Fc portion of IgG (70% sensitive, 85% specific) [8]
   • Anti-carbamylated protein (anti-CarP) antibodies
   • Multiple antibody fine specificities (epitope spreading)

Phase 2: Immune Amplification (Early Synovitis)

This phase marks the onset of clinical arthritis.

Cellular Events:

1. T-Cell Activation

   • CD4+ T helper cells recognize citrullinated antigens
   • Th1 response: IFN-γ production, macrophage activation
   • Th17 response: IL-17, IL-21, IL-22 production (critical for chronicity) [16]

2. B-Cell and Plasma Cell Activation

   • Autoantibody production (RF, anti-CCP)
   • Formation of ectopic germinal centers in synovium
   • B cells act as antigen-presenting cells

3. Macrophage Activation

   • M1 pro-inflammatory phenotype dominates
   • Key source of inflammatory cytokines

4. Cytokine Storm

   • TNF-α: Central cytokine; drives inflammation, angiogenesis, osteoclast activation
   • IL-1: Synergizes with TNF-α; drives cartilage degradation
   • IL-6: Acute phase response, B-cell differentiation, Th17 development
   • IL-17: Neutrophil recruitment, osteoclastogenesis
   • GM-CSF: Myeloid cell activation and survival

5. Synovial Inflammation

   • Synovial lining hyperplasia (normally 1-2 cells thick → 10-15 cells)
   • Inflammatory cell infiltrate: T cells, B cells, plasma cells, macrophages
   • Neoangiogenesis (VEGF-driven)
   • Formation of pannus (invasive granulation tissue)

Phase 3: Joint Destruction (Chronic Established RA)

Without effective treatment, chronic inflammation leads to irreversible damage.

Destructive Mechanisms:

1. Pannus Formation

   • Aggressive synovial tissue invades cartilage and bone at joint margins
   • Fibroblast-like synoviocytes (FLS) acquire aggressive phenotype
   • FLS produce matrix metalloproteinases (MMPs)

2. Cartilage Degradation

   • MMPs (MMP-1, MMP-3, MMP-13): Degrade collagen type II
   • Aggrecanases (ADAMTS-4, ADAMTS-5): Degrade proteoglycans
   • Direct contact between pannus and cartilage
   • Chondrocyte apoptosis

3. Bone Erosion

   • Osteoclast activation: Driven by RANKL (receptor activator of NF-κB ligand)
   • RANKL produced by activated T cells and synovial fibroblasts
   • TNF-α and IL-17 upregulate RANKL expression
   • Focal bone erosions at pannus-bone interface
   • Periarticular osteopenia (systemic bone loss)

4. Subchondral bone marrow edema

   • Detected on MRI before erosions visible on X-ray
   • Predicts sites of future erosions
   • Osteitis with inflammatory infiltrate

Key Therapeutic Targets:

Environmental Triggers

Smoking:

• Strongest environmental risk factor for RA development [12]
• Particularly for anti-CCP positive RA
• Gene-environment interaction: HLA-DR4 + smoking → RR 20-40 for RA
• Mechanism: Induces citrullination in bronchial epithelium via PAD enzyme activation

Infectious Agents (Proposed):

• Porphyromonas gingivalis: Produces PAD enzyme; strong association with periodontitis and RA [14]
• Proteus mirabilis: Molecular mimicry hypothesis (shared epitopes with HLA-DR4)
• Epstein-Barr virus (EBV): Found in RA synovium; controversial role

Microbiome:

• Alterations in gut microbiome composition (dysbiosis) in RA patients
• Prevotella copri enrichment in new-onset RA
• Mucosal immunity and citrullination at gut mucosa may trigger disease

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4. Clinical Presentation

Typical Presentation

The classical presentation of RA is a middle-aged woman (40-60 years) presenting with:

• Insidious onset of symmetrical small joint pain and swelling over weeks to months
• Predominantly affecting metacarpophalangeal (MCP), proximal interphalangeal (PIP), and metatarsophalangeal (MTP) joints
• Prolonged morning stiffness (> 60 minutes, often 2-3 hours)
• Improvement with activity, worsening with rest
• Constitutional symptoms: Fatigue, low-grade fever, weight loss

Early RA Features (Within 3 Months)

Recognition of early RA is critical as treatment within this "window of opportunity" improves outcomes. [5,6]

Early Clinical Features:

• Symmetrical polyarthritis (≥3 joint areas)
• Hand involvement (MCP, PIP, wrists)
• Morning stiffness > 30 minutes
• "Squeezability test" positive (pain on squeezing across MCPs or MTPs)
• May be RF/anti-CCP negative initially (seronegative early RA)

Red Flags Requiring Urgent Rheumatology Referral:

• Small joint synovitis (MCP, PIP, MTP)
• Involvement of ≥3 joints
• Symptoms > 6 weeks
• Positive squeeze test
• Family history of RA or other autoimmune disease

Joint Distribution Patterns

Joints typically SPARED:

• Distal interphalangeal (DIP) joints
• Thoracolumbar spine
• Sacroiliac joints (differentiates from spondyloarthropathies)

Morning Stiffness Characteristics

• Duration: Typically > 60 minutes; often 2-4 hours in active disease
• Pattern: Worst on waking; improves with movement
• "Gelling": Stiffness after periods of inactivity
• Assessment: Useful disease activity marker; improves with effective treatment

Examination Findings

Hands:

• Synovitis: Boggy swelling at MCP/PIP joints; warm, tender
• Ulnar deviation at MCPs (late)
• Swan neck deformity: PIP hyperextension + DIP flexion (rupture of volar plate)
• Boutonnière deformity: PIP flexion + DIP hyperextension (rupture of central slip)
• Z-thumb: Hyperextension of IP joint + flexion of MCP
• Palmar subluxation of MCPs
• Wrist involvement: Swelling, radial deviation, loss of extension
• Carpal tunnel syndrome (25% of RA patients)
• Muscle wasting: Intrinsic hand muscles (thenar, hypothenar, interossei)

Feet:

• MTP subluxation ("dislocation of toes upward")
• Broadening of forefoot
• Hallux valgus
• Hammer toes
• Plantar callosities

General Examination Findings:

• Low-grade fever (in active disease)
• Cachexia (advanced disease)
• Pallor (anaemia of chronic disease)
• Lymphadenopathy (generalized, reactive)

Extra-articular Manifestations

Extra-articular disease occurs in 30-40% of RA patients and is associated with more severe disease, seropositivity (especially high-titre RF and anti-CCP), and increased mortality. [9]

1. Rheumatoid Nodules (20-30%)

Characteristics:

• Firm, non-tender subcutaneous nodules
• Locations: Extensor surfaces (elbows, forearms), pressure points, Achilles tendon
• Size: 2mm to several centimeters
• Histology: Central necrosis + palisading macrophages + fibrous capsule
• Association: Seropositive RA, severe disease, methotrexate therapy (paradoxically can accelerate nodulosis)

Clinical Significance:

• Generally benign but can ulcerate or become infected
• Internal nodules rare but serious (lungs, heart valves, vocal cords)

2. Pulmonary Manifestations (10-20%)

Interstitial Lung Disease (ILD):

• Most common serious pulmonary complication (10-20% clinical; up to 60% subclinical on HRCT) [9]
• Patterns: Usual interstitial pneumonia (UIP) most common; NSIP also seen
• Risk factors: Male sex, smoking, older age, RF/anti-CCP positive, HLA-DRB1
• Presentation: Progressive dyspnoea, dry cough, bibasal crackles
• Investigation: HRCT chest (ground glass, honeycombing), PFTs (restrictive pattern, reduced DLCO)
• Management: Avoid methotrexate if significant ILD; consider rituximab, mycophenolate, or nintedanib
• Prognosis: Variable; UIP pattern has worse prognosis (median survival 3-5 years)

Other Pulmonary Features:

• Pleural disease: Pleural effusion (exudative, low glucose, low pH, high LDH)
• Pulmonary nodules: Rheumatoid nodules in lung parenchyma
• Caplan syndrome: RA + pneumoconiosis + lung nodules (coal workers, silicosis)
• Bronchiectasis: Increased frequency in RA
• Pulmonary hypertension: Rare; poor prognosis

3. Cardiovascular Manifestations

Increased Cardiovascular Risk:

• RA patients have 1.5-2x higher risk of myocardial infarction and stroke [15]
• Chronic inflammation accelerates atherosclerosis
• Traditional risk factors often underestimate true CV risk in RA
• Management: Aggressive CV risk factor modification; consider RA as CV risk multiplier

Direct Cardiac Involvement:

• Pericarditis: Most common (30% autopsy series; 5% clinically apparent)
  • "Presentation: Chest pain, pericardial friction rub, ECG changes"
  • Constrictive pericarditis rare but serious
• Myocarditis: Rare; can cause heart failure
• Valvular disease: Rare; rheumatoid nodules on valves
• Conduction abnormalities: AV block, bundle branch block

4. Ocular Manifestations (1-5%)

5. Haematological Manifestations

Anaemia (30-60%):

• Anaemia of chronic disease: Most common; normocytic, normochromic; low serum iron, low TIBC, high/normal ferritin
• Iron deficiency: From NSAIDs/GI blood loss
• Folate deficiency: From methotrexate
• Severity correlates with disease activity

Felty Syndrome (less than 1%):

• Triad: RA + splenomegaly + neutropenia (less than 1.5 x 10⁹/L)
• Typically severe, seropositive RA with extra-articular features
• Complications: Recurrent infections (skin, respiratory), leg ulcers
• Management: DMARDs (methotrexate); rituximab; G-CSF; splenectomy if severe

Thrombocytosis:

• Common in active RA (reactive thrombocytosis)
• Correlates with disease activity

6. Rheumatoid Vasculitis (1-5%)

Features:

• Now rare (improved RA treatment)
• Typically occurs in long-standing, seropositive RA with erosive disease
• Male > female
• Often presents after joint disease "burns out"

Clinical Manifestations:

• Cutaneous: Nail fold infarcts, digital gangrene, palpable purpura, leg ulcers
• Peripheral neuropathy: Mononeuritis multiplex, distal sensory neuropathy
• Visceral: Bowel ischaemia, myocardial infarction, stroke (rare but serious)

Investigation:

• Raised inflammatory markers
• Biopsy: Leukocytoclastic vasculitis, necrotizing vasculitis
• ANCA usually negative (unlike other systemic vasculitides)

Management:

• High-dose corticosteroids (prednisolone 1mg/kg)
• Cyclophosphamide or rituximab
• Plasma exchange in severe cases
• Poor prognosis (5-year mortality 30-50%)

7. Neurological Manifestations

Cervical Spine (40% of RA patients):

• Atlanto-axial subluxation (C1-C2): Most common and dangerous
  • Anterior subluxation (90%), vertical subluxation, rotatory subluxation
  • "Risk factors: Long-standing RA, seropositive, erosive disease, steroid use"
  • "Presentation: Neck pain, occipital headache; myelopathy (late - weakness, hyperreflexia, sensory level, bladder/bowel dysfunction)"
  • "Investigation: Flexion-extension cervical spine X-rays; MRI if myelopathy suspected"
  • "Anterior atlanto-dental interval (AADI): > 3mm abnormal (measured on lateral X-ray)"
  • "Management: Soft collar; surgical fusion if AADI > 9mm or myelopathy present"
  • "Preoperative screening: All RA patients require cervical spine imaging before intubation for surgery"

Peripheral Neuropathy:

• Carpal tunnel syndrome: Most common (25%); due to wrist synovitis
• Peripheral sensory neuropathy: Mild, distal, "glove and stocking"
• Mononeuritis multiplex: Suggests vasculitis

8. Renal Manifestations

Direct renal involvement from RA is rare (less than 5%).

Causes of Renal Impairment in RA:

• Amyloidosis (AA type): From chronic inflammation; nephrotic syndrome; biopsy shows Congo red positive deposits; now rare with modern RA treatment
• Drug-induced: NSAIDs (interstitial nephritis, acute tubular necrosis), ciclosporin (nephrotoxicity), gold (membranous nephropathy)
• Vasculitis: Rare; glomerulonephritis

9. Other Extra-articular Manifestations

Sjögren's Syndrome (Secondary): 10-15% of RA patients

• Dry eyes (keratoconjunctivitis sicca) + dry mouth (xerostomia)
• Anti-Ro (SSA) and anti-La (SSB) antibodies

Osteoporosis:

• Increased fracture risk (2-3x higher than general population)
• Mechanisms: Inflammation-driven bone loss, glucocorticoid use, reduced mobility
• Screening: DEXA scan recommended
• Management: Bisphosphonates, calcium/vitamin D supplementation

Metabolic Syndrome:

• Increased prevalence in RA
• Lipid paradox: Active RA associated with low cholesterol; treatment raises cholesterol but reduces CV events

Clinical Phenotypes

Seronegative RA (20-30%):

• RF and anti-CCP negative
• Generally milder disease (though exceptions exist)
• Less erosive
• Fewer extra-articular manifestations
• Diagnostic challenge (can mimic other conditions)

Seropositive RA (70-80%):

• RF and/or anti-CCP positive
• More aggressive disease
• Higher risk of erosions and extra-articular disease

Elderly-Onset RA (> 60 years):

• More equal sex distribution
• Larger joint involvement more common
• Higher acute phase response
• Distinction from polymyalgia rheumatica can be challenging

Palindromic Rheumatism:

• Recurrent episodes of monoarthritis/oligoarthritis
• Each episode lasts 1-3 days
• Complete resolution between attacks
• 30-50% progress to persistent RA

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5. Differential Diagnosis

The differential diagnosis of RA is broad, particularly in early disease when presentation may be atypical.

Key Differentials with Distinguishing Features

Approach to Distinguishing RA from Mimics

Clinical Clues Favouring RA:

• Symmetry: Symmetrical involvement of small joints (hands, feet)
• Joint pattern: MCP, PIP, wrist, MTP involvement; DIP sparing
• Duration: Symptoms > 6 weeks
• Morning stiffness: > 60 minutes
• Progression: Persistent, progressive (not episodic)

Investigations to Differentiate:

1. Serology: RF, anti-CCP, ANA, ENA, HLA-B27
2. Inflammatory markers: ESR, CRP
3. Imaging: X-rays (erosions in RA), ultrasound (synovitis, power Doppler signal)
4. Synovial fluid analysis: If monoarthritis (exclude septic arthritis, crystals)

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6. Investigations

Diagnostic Approach

The diagnosis of RA is clinical but supported by laboratory and imaging findings. No single test is diagnostic.

Serological Tests

Rheumatoid Factor (RF)

Characteristics:

• IgM antibody directed against Fc portion of IgG
• Sensitivity: 60-70% in early RA; up to 80% in established RA [8]
• Specificity: 80-85% [8]
• Important: Can be positive in healthy elderly (5-10%), chronic infections (hepatitis C, endocarditis), other autoimmune diseases (Sjögren's, SLE)

Interpretation:

• High titres (> 3x upper limit normal) more specific for RA
• Negative RF does NOT exclude RA (20-30% are seronegative)
• Positive RF predicts more severe, erosive disease

Anti-Cyclic Citrullinated Peptide (Anti-CCP) Antibodies

Characteristics:

• Antibodies against citrullinated proteins
• Sensitivity: 67% in early RA; 75-80% in established RA [4,8]
• Specificity: 95-98% - highly specific for RA [4,8]
• More specific than RF

Clinical Significance:

• Can be detected years before symptom onset (5-10 years) [4]
• Predicts erosive disease and worse prognosis
• Positive anti-CCP + negative RF still suggests RA
• Titre correlates with disease severity
• Useful for diagnosis in seronegative (RF-negative) patients

Recommendation:

• Both RF and anti-CCP should be checked in suspected RA
• If both negative, repeat in 3-6 months (may seroconvert)

Inflammatory Markers

Important:

• Normal inflammatory markers do NOT exclude RA (10-20% have normal ESR/CRP)
• Useful for monitoring disease activity and treatment response

Haematology

Full Blood Count:

• Anaemia: Normocytic, normochromic (anaemia of chronic disease); severity correlates with disease activity
• Thrombocytosis: Reactive; correlates with disease activity
• Neutropenia: Suggests Felty syndrome (if splenomegaly present)

Imaging

Plain Radiography (X-rays)

Indications:

• Baseline assessment in all RA patients (hands and feet)
• Follow-up to assess progression (annual or biannual in early disease)

Classic Radiographic Features of RA:

Early Changes (First 6-12 Months):

1. Periarticular soft tissue swelling
2. Juxta-articular osteopenia (earliest bony change)
3. Uniform joint space narrowing (cartilage loss)

Established Disease: 4. Marginal erosions (at joint margins where pannus invades bone)

• Hands: MCP, PIP, wrists (ulnar styloid, carpal bones)
• Feet: MTP joints (especially 5th MTP)

5. Subluxation and deformity
   • Ulnar deviation at MCPs
   • Swan neck and boutonnière deformities
   • MTP subluxation

Advanced Disease: 6. Ankylosis (joint fusion) - rare, mainly wrists and carpus 7. Secondary osteoarthritis

Interpretation Pearls:

• Erosions are irreversible - emphasizes importance of early treatment
• Bilateral symmetry is characteristic
• DIP joints spared (unlike osteoarthritis or psoriatic arthritis)

Scoring Systems:

• Sharp/van der Heijde score: Quantifies erosions and joint space narrowing; used in clinical trials

Ultrasound (US)

Advantages:

• More sensitive than clinical examination for detecting synovitis
• Can detect erosions earlier than X-ray
• Power Doppler signal indicates active inflammation (hyperaemia)
• No radiation
• Can guide aspirations/injections

Findings in RA:

• Synovial hypertrophy (grey scale)
• Increased vascularity (power Doppler signal)
• Joint effusions
• Erosions (seen earlier than on X-ray)
• Tenosynovitis

Clinical Use:

• Diagnostic uncertainty (is synovitis present?)
• Assessment of disease activity
• Monitoring subclinical synovitis
• Increasingly used in routine practice

Magnetic Resonance Imaging (MRI)

Advantages:

• Most sensitive imaging modality for early RA
• Detects synovitis, tenosynovitis, erosions, and bone marrow oedema
• Bone marrow oedema (osteitis) predicts sites of future erosions [17]
• Can visualize changes months to years before X-ray changes

Findings in RA:

• Synovitis (enhanced with gadolinium)
• Bone marrow oedema (high T2 signal)
• Early erosions
• Tenosynovitis
• Cartilage damage

Clinical Use:

• Early RA when diagnosis uncertain
• Assessing disease activity in difficult cases
• Research settings
• Not routinely required for diagnosis

RAMRIS Score (RA MRI Scoring System):

• Standardized scoring for synovitis, bone marrow oedema, and erosions
• Used in clinical trials

Synovial Fluid Analysis

Indications:

• Monoarthritis or oligoarthritis (to exclude septic arthritis, crystal arthropathy)
• Not routinely required in typical polyarticular RA

Findings in RA:

• Appearance: Turbid, yellow
• White cell count: 5,000-50,000/mm³ (inflammatory range; lower than septic arthritis)
• Neutrophil predominance (> 70%)
• Glucose: Reduced (but not as low as septic arthritis)
• Protein: Elevated
• Culture: Negative (unless superimposed infection)
• Crystals: Absent

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7. Classification and Scoring Systems

2010 ACR/EULAR Classification Criteria for RA

The 2010 criteria replaced the 1987 ACR criteria, with emphasis on early disease detection to facilitate prompt treatment.

Target Population:

• Patients with at least 1 joint with definite clinical synovitis
• Synovitis not better explained by another disease

Scoring System (Score ≥6 out of 10 = Definite RA):

Definitions:

• Small joints: MCPs, PIPs, 2nd-5th MTPs, thumb IPs, wrists
• Large joints: Shoulders, elbows, hips, knees, ankles
• ULN: Upper limit of normal for the laboratory test

Interpretation:

• Score ≥6 → Definite RA (sensitivity 85%, specificity 82% for RA diagnosis)
• These are classification criteria (for research/trials), not diagnostic criteria
• Clinical judgment remains paramount

Disease Activity Scoring

DAS28 (Disease Activity Score in 28 Joints)

The DAS28 is the most widely used composite disease activity measure. [7]

Components:

1. Tender joint count (TJC): 28 joints assessed
2. Swollen joint count (SJC): 28 joints assessed
3. ESR (mm/hr) or CRP (mg/L)
4. Patient global assessment (PGA): Visual analogue scale (VAS) 0-100mm

28 Joints:

• Shoulders (2), elbows (2), wrists (2), MCPs (10), PIPs (10), knees (2)

Calculation:

• DAS28-ESR = 0.56√(TJC28) + 0.28√(SJC28) + 0.70ln(ESR) + 0.014(PGA)
• DAS28-CRP: Alternative formula using CRP

Interpretation:

Clinical Use:

• Assess disease activity at every visit (minimum every 3 months)
• Guide treatment decisions (treat-to-target approach)
• Monitor treatment response
• EULAR Response Criteria: Based on change in DAS28 and current level

Limitations:

• Does not include feet (other than through patient global score)
• Heavily weighted towards patient-reported symptoms
• Can be affected by fibromyalgia/chronic pain

Alternative Disease Activity Measures:

CDAI (Clinical Disease Activity Index):

• TJC28 + SJC28 + PGA (0-10 scale) + physician global assessment (0-10 scale)
• Advantage: No need for laboratory test; can be calculated in clinic immediately

SDAI (Simplified Disease Activity Index):

• TJC28 + SJC28 + PGA (0-10 scale) + physician global assessment (0-10 scale) + CRP (mg/dL)
• Similar to CDAI but includes CRP

ACR Response Criteria (ACR20/50/70):

• Used mainly in clinical trials
• ACR20: 20% improvement in tender/swollen joint counts + 20% improvement in ≥3 of 5 other measures

Radiographic Progression Scoring

Sharp/van der Heijde Score:

• Quantifies erosions (scale 0-5 per joint) and joint space narrowing (scale 0-4 per joint)
• Assessed in hands and feet
• Total score 0-448
• Used primarily in clinical trials to assess structural damage progression

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8. Management

The goals of RA management are:

1. Achieve remission or low disease activity (treat-to-target)
2. Prevent joint damage and preserve function
3. Minimize treatment toxicity
4. Improve quality of life

The modern approach emphasizes early aggressive treatment and tight control with regular monitoring and escalation.

General Principles

Treat-to-Target Strategy:

• Set target: Remission (DAS28 less than 2.6) or low disease activity if remission not achievable
• Assess disease activity every 3 months
• If target not met, escalate therapy within 3 months
• Continue monitoring even after target achieved [7]

Window of Opportunity:

• Treat within 3 months of symptom onset improves long-term outcomes [5,6]
• Early DMARD therapy prevents erosions and improves remission rates

Acute Flare Management

Symptom Relief (Bridge Therapy):

1. NSAIDs:

   • For pain and inflammation
   • Always prescribe with PPI (RA patients at high GI risk)
   • Examples: Naproxen 500mg BD, Ibuprofen 400mg TDS
   • Cautions: Renal impairment, cardiovascular disease, elderly, GI bleeding risk
   • Avoid in severe heart failure

2. Corticosteroids:

   • Rapid symptom relief while awaiting DMARD effect (DMARDs take 6-12 weeks)

   Options:

   • Oral: Prednisolone 10-15mg daily, taper over 6-8 weeks
   • Intramuscular: Methylprednisolone 120mg IM (lasts 2-4 weeks)
   • Intra-articular: For individual problematic joints; triamcinolone 10-40mg depending on joint size

   Principles:

   • Use lowest dose for shortest duration
   • NOT a substitute for DMARDs
   • Long-term steroids (> 7.5mg prednisolone daily) increase infection, cardiovascular, and osteoporosis risk

3. Analgesia:

   • Paracetamol 1g QDS
   • Avoid opiates long-term (dependence risk, minimal efficacy)

Disease-Modifying Antirheumatic Drugs (DMARDs)

Conventional Synthetic DMARDs (csDMARDs)

1. Methotrexate (MTX) - FIRST-LINE

Dosing:

• Start 15mg once weekly (oral or subcutaneous)
• Escalate by 5mg every 2-4 weeks to target dose 15-25mg weekly
• Maximum 25mg weekly
• Subcutaneous route if oral ineffective or GI side effects

Co-prescription (ESSENTIAL):

• Folic acid 5mg once weekly (on different day to MTX) - reduces side effects [7]

Mechanism:

• Inhibits dihydrofolate reductase → impairs purine synthesis → anti-proliferative and anti-inflammatory effects

Monitoring:

Contraindications:

• Pregnancy and breastfeeding (teratogenic)
• Severe renal impairment (eGFR less than 30 ml/min)
• Severe hepatic impairment
• Active infection
• Immunodeficiency
• Significant pulmonary disease (relative - risk of pneumonitis)

Side Effects:

• Common: Nausea (20%), mouth ulcers, diarrhoea, fatigue (day after MTX dose)
• Haematological: Myelosuppression (monitor FBC) - macrocytosis common and benign; leucopenia/thrombocytopenia require dose reduction
• Hepatotoxicity: Elevated transaminases (10-15%); rarely cirrhosis with long-term use
• Pulmonary: Pneumonitis (1-2%) - presents with dry cough, dyspnoea, fever; discontinue MTX immediately; consider steroids
• Infections: Modestly increased risk

Patient Counselling:

• Take ONCE WEEKLY (not daily - fatal errors have occurred)
• Take folic acid on different day
• Avoid alcohol (increased hepatotoxicity)
• STOP methotrexate if vomiting/diarrhoea (risk of severe myelosuppression from dehydration)
• Effective contraception required (men and women) - stop 3 months before conception
• Report: mouth ulcers, dyspnoea, rash, fever

Efficacy:

• ACR20 response: 60-65% at 6 months
• Time to effect: 6-12 weeks
• Anchor drug - most other DMARDs/biologics used in combination with MTX

2. Sulfasalazine

Dosing:

• Start 500mg daily; increase weekly by 500mg to target 2-3g daily (in divided doses)

Mechanism:

• Unclear; possibly inhibits NF-κB activation

Monitoring:

• FBC, LFTs, U&Es: Baseline, every 2 weeks for 3 months, then every 3 months

Side Effects:

• GI upset (nausea, diarrhoea) - common; dose-related
• Rash, headache
• Myelosuppression (less than MTX)
• Hepatotoxicity
• Oligospermia (reversible)
• Orange discoloration of urine and contact lenses

Efficacy:

• Slightly less effective than MTX monotherapy
• Often used in triple therapy (MTX + SSZ + HCQ)

Pregnancy:

• Safe in pregnancy and breastfeeding (unlike MTX)

3. Hydroxychloroquine (HCQ)

Dosing:

• 200-400mg daily (based on ideal body weight: ≤6.5mg/kg/day to reduce retinal toxicity risk)

Mechanism:

• Interferes with antigen presentation; anti-inflammatory

Monitoring:

• Ophthalmology review: Baseline, then annual after 5 years of treatment (retinal toxicity)
• FBC, LFTs, U&Es: Less intensive monitoring than MTX

Side Effects:

• Generally well tolerated
• GI upset (nausea)
• Skin rash, photosensitivity
• Retinopathy (rare if dose ≤6.5mg/kg/day; usually after > 5 years)
• ECG changes (prolonged QT)

Efficacy:

• Weakest of the csDMARDs
• Often used in mild RA or combination therapy

Pregnancy:

• Safe in pregnancy and breastfeeding

4. Leflunomide

Dosing:

• 10-20mg once daily (no loading dose recommended)

Mechanism:

• Inhibits de novo pyrimidine synthesis

Monitoring:

• FBC, LFTs, BP: Baseline, every 2 weeks for 6 months, then every 2 months

Side Effects:

• Diarrhoea (20%)
• Hypertension (monitor BP)
• Hepatotoxicity
• Myelosuppression
• Alopecia
• Peripheral neuropathy (rare)

Contraindications:

• Pregnancy (teratogenic; long half-life - cholestyramine washout required before conception)
• Severe hepatic impairment
• Severe renal impairment

Efficacy:

• Similar efficacy to MTX
• Alternative if MTX not tolerated

Triple Therapy (MTX + Sulfasalazine + Hydroxychloroquine)

Indications:

• Inadequate response to MTX monotherapy
• Alternative to adding biologic DMARD

Evidence:

• Superior to MTX monotherapy [18]
• Comparable efficacy to MTX + anti-TNF in some studies

Approach:

• Optimize MTX first
• Add sulfasalazine → add hydroxychloroquine (sequential addition)

Biologic DMARDs (bDMARDs)

Biologics are indicated when:

1. Inadequate response to ≥2 csDMARDs (including MTX at adequate dose)
2. High disease activity (DAS28 > 5.1) despite csDMARD therapy
3. Poor prognostic factors (high RF/anti-CCP, early erosions)

General Principles:

• Usually given in combination with MTX (improves efficacy, reduces immunogenicity)
• Requires specialist initiation (rheumatology)
• Screening before starting:
  • Tuberculosis (CXR, IGRA/tuberculin skin test)
  • Hepatitis B and C serology
  • HIV (if risk factors)
  • Vaccinations up to date (live vaccines contraindicated once on biologic)

TNF Inhibitors (Anti-TNF)

Agents:

Mechanism:

• Neutralize TNF-α (key pro-inflammatory cytokine)
• Adalimumab, infliximab, golimumab: Monoclonal antibodies
• Etanercept: Soluble TNF receptor fusion protein
• Certolizumab: PEGylated Fab fragment

Efficacy:

• ACR20 response: 60-70% at 6 months (with MTX)
• Radiographic progression reduced by 50-80%
• Work faster than csDMARDs (response within 2-4 weeks)

Side Effects:

• Infections: 2x increased risk overall; serious infections 1.5-2x increased
  • "Opportunistic infections: TB reactivation (screen and treat latent TB), invasive fungal infections"
  • Respiratory tract infections most common
• Malignancy: Possible small increased risk of lymphoma (controversial)
• Infusion/injection reactions: Especially infliximab
• Demyelination: Avoid in multiple sclerosis or family history
• Heart failure: Contraindicated in moderate-severe heart failure (NYHA III-IV)
• Drug-induced lupus: Rare

Monitoring:

• No routine blood monitoring required (unlike csDMARDs)
• Assess for infection symptoms at each visit
• Monitor disease activity (DAS28) every 3 months

Switching Anti-TNF Agents:

• If primary failure (no response by 3-6 months) → switch to different mechanism
• If secondary failure (loss of response) → can try different anti-TNF or switch mechanism

IL-6 Inhibitors

Agents:

• Tocilizumab: IV 8mg/kg monthly or SC 162mg weekly
• Sarilumab: SC 200mg every 2 weeks

Mechanism:

• Monoclonal antibodies against IL-6 receptor (IL-6R)
• IL-6 drives inflammation, acute phase response, and Th17 differentiation

Efficacy:

• Similar to anti-TNF agents
• Can be used as monotherapy (without MTX) with good efficacy - useful if MTX not tolerated

Side Effects:

• Infections: Similar to anti-TNF
• Neutropenia: Monitor FBC; dose-dependent
• Thrombocytopenia: Monitor
• Hyperlipidaemia: Cholesterol rises (but CV risk may still decrease); monitor lipids
• Hepatotoxicity: Monitor LFTs
• GI perforation: Rare; avoid if diverticular disease

Monitoring:

• FBC, LFTs, lipids: Baseline, 4 weeks, 8 weeks, then every 3 months

B-Cell Depletion

Agent:

• Rituximab: IV 1000mg at day 0 and day 14 (repeated courses every 6-12 months based on response)

Mechanism:

• Chimeric monoclonal antibody against CD20 (B-cell surface marker)
• Depletes B cells (but spares plasma cells)
• Reduces RF production, autoantibody formation, antigen presentation

Indications:

• Inadequate response to anti-TNF (often second-line biologic)
• Seropositive RA (RF/anti-CCP positive) - better response

Efficacy:

• ACR20 response: 50-60%
• Effect lasts 6-12 months per course

Side Effects:

• Infusion reactions: Pre-medicate with methylprednisolone, antihistamine, paracetamol
• Infections: Increased risk (B-cell depletion)
• Hypogammaglobulinaemia: Monitor immunoglobulins; increased risk with repeated courses
• Progressive multifocal leukoencephalopathy (PML): Extremely rare in RA (more common in SLE)

Monitoring:

• Immunoglobulins before each course
• Hepatitis B serology (risk of reactivation)

T-Cell Co-stimulation Blockade

Agent:

• Abatacept: IV 500-1000mg (weight-based) monthly or SC 125mg weekly

Mechanism:

• Fusion protein of CTLA-4 and IgG Fc
• Blocks CD28-CD80/86 interaction (co-stimulatory signal for T-cell activation)
• Prevents full T-cell activation

Efficacy:

• ACR20 response: 60-70%
• Similar to anti-TNF

Side Effects:

• Generally well tolerated
• Infections (similar to other biologics)
• Infusion reactions (mild)
• COPD exacerbations (caution in COPD patients)

Advantages:

• Can be used in patients with history of malignancy (less concern than anti-TNF)
• Effective in seronegative RA (unlike rituximab)

Targeted Synthetic DMARDs (tsDMARDs) - JAK Inhibitors

Agents:

Mechanism:

• Small molecule inhibitors of Janus kinase (JAK) enzymes
• JAKs transduce signals from multiple cytokine receptors (IL-6, IL-12, IL-23, IFN, etc.)
• Oral agents (unlike biologics which are injectable)

Indications:

• Inadequate response to ≥1 csDMARD
• Alternative to biologic DMARDs

Efficacy:

• ACR20 response: 60-70%
• Can be used as monotherapy or with MTX

Side Effects:

• Infections: Herpes zoster reactivation (2-4x increased); serious infections
• Thrombosis: Small increased risk of VTE, especially in elderly or those with CV risk factors
• Malignancy: Possible increased risk (ongoing monitoring)
• Cytopenias: Lymphopenia, anaemia, neutropenia (dose-dependent)
• Hyperlipidaemia: Monitor lipids
• GI perforation: Rare

Monitoring:

• FBC, LFTs, lipids: Baseline, 4 weeks, 12 weeks, then every 3 months
• Creatinine, creatine kinase

Contraindications:

• Active serious infection
• Absolute lymphocyte count less than 0.5 x 10⁹/L
• Haemoglobin less than 8 g/dL
• Absolute neutrophil count less than 1 x 10⁹/L

Regulatory Considerations:

• MHRA (UK) and FDA warnings regarding increased cardiovascular events and malignancy in patients ≥65 years or with CV risk factors
• Consider alternative DMARDs in high-risk patients

Treatment Algorithm

Step 1: Newly Diagnosed RA

• Start Methotrexate 15mg weekly + folic acid 5mg weekly + short-term prednisolone taper (or IM methylprednisolone)
• Escalate MTX to 25mg weekly over 8-12 weeks
• Assess at 3 months (DAS28)

Step 2: Inadequate Response to MTX Monotherapy

• Add Sulfasalazine + Hydroxychloroquine (triple therapy)
• OR
• Add biologic DMARD (anti-TNF, tocilizumab, abatacept) or JAK inhibitor
• Choice depends on: patient factors, comorbidities, cost, local formulary

Step 3: Inadequate Response to First Biologic

• Switch to different biologic (different class preferred)
• E.g., Anti-TNF → Tocilizumab or Rituximab or Abatacept

Step 4: Multiple Biologic Failures

• Sequential trials of different biologics/JAK inhibitors
• Consider combination csDMARDs if not already tried
• Specialist rheumatology input

Surgical Management

Indications:

• Joint replacement: End-stage arthritis (hip, knee, shoulder) with severe pain and functional impairment
• Synovectomy: Persistent synovitis in single joint despite medical therapy (temporary benefit)
• Tendon repair: Ruptured tendons (especially extensor tendons in hand)
• Carpal tunnel decompression: Median nerve compression from wrist synovitis
• Cervical spine fusion: C1-C2 subluxation with neurological involvement or AADI > 9mm

Preoperative Considerations:

• Cervical spine imaging (flexion-extension X-rays) before intubation - risk of atlanto-axial subluxation
• Medication management:
  • Continue MTX perioperatively (new evidence suggests safe and improves outcomes)
  • "Biologics: Hold 1 dosing interval before surgery; restart when wound healing complete"
  • "JAK inhibitors: Hold 3 days before surgery; restart when wound healing complete"
  • "Prednisolone: May need stress dose steroids if on long-term steroids"

Special Populations

Pregnancy and RA

Pre-conception Counselling:

• STOP teratogenic drugs ≥3 months before conception:
  • Methotrexate (men and women)
  • Leflunomide (cholestyramine washout required)
• STOP biologics and JAK inhibitors before conception (timing varies by agent)

Disease Activity in Pregnancy:

• ~50% of women experience improvement or remission during pregnancy
• ~90% flare postpartum (within 3 months)

Safe Medications in Pregnancy:

• Sulfasalazine (with folic acid 5mg daily)
• Hydroxychloroquine
• Prednisolone (crosses placenta minimally; safe)
• Azathioprine (if severe disease)
• Certolizumab pegol (only anti-TNF that doesn't cross placenta significantly; can be used throughout pregnancy)

Contraindicated in Pregnancy:

• Methotrexate
• Leflunomide
• JAK inhibitors
• Most biologics (except certolizumab with caution)

Breastfeeding:

• Sulfasalazine, hydroxychloroquine, prednisolone: Safe
• Methotrexate: Contraindicated
• Biologics: Limited data; generally avoid

Elderly-Onset RA (> 60 Years)

Characteristics:

• More equal sex distribution
• Larger joints affected more commonly
• Higher acute phase response
• May mimic polymyalgia rheumatica

Management Considerations:

• Higher infection risk with immunosuppression
• Comorbidities (renal impairment, cardiovascular disease) affect drug choices
• Lower doses of JAK inhibitors (baricitinib 2mg)
• Fracture risk (DEXA scan, bisphosphonates)

Renal Impairment

Drug Dosing Adjustments:

• Methotrexate: Reduce dose if eGFR 30-60; contraindicated if eGFR less than 30
• Leflunomide: Caution if severe renal impairment
• Sulfasalazine: Caution if severe renal impairment
• NSAIDs: Avoid (nephrotoxic)
• Biologics: Most require no dose adjustment; monitor closely

Interstitial Lung Disease (ILD)

Implications:

• Avoid methotrexate (risk of pneumonitis)
• Consider rituximab, mycophenolate, or abatacept
• Tocilizumab may worsen ILD
• Monitor respiratory function

Monitoring and Follow-Up

Frequency:

• First 3 months on csDMARDs: FBC, U&Es, LFTs every 2 weeks
• Stable on csDMARDs: FBC, U&Es, LFTs every 3 months
• Disease activity assessment (DAS28): Every 3 months minimum

Long-term Monitoring:

• Cardiovascular risk: Annual CV risk assessment; aggressive risk factor modification
• Bone health: DEXA scan if on long-term steroids or risk factors
• Infection screening: Before starting biologics; annual influenza and pneumococcal vaccination
• Malignancy: Skin surveillance if on JAK inhibitors or history of malignancy

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9. Complications

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10. Prognosis

Natural History Without Treatment

Historically, untreated RA led to:

• Progressive joint destruction and deformity
• Severe functional disability (50% unable to work within 10 years)
• Reduced life expectancy (10-15 years shorter than general population)
• High rates of extra-articular complications

Outcomes with Modern Treatment

The prognosis of RA has dramatically improved with early aggressive DMARD therapy and treat-to-target approaches. [6]

Remission Rates:

• With early treatment (less than 3 months): 40-60% achieve remission
• With delayed treatment (> 12 months): 20-30% achieve remission

Functional Outcomes:

• Early treatment: 70-80% maintain good function at 10 years
• Delayed treatment: 40-50% maintain good function at 10 years

Radiographic Progression:

• DMARDs reduce erosion rate by 50-70%
• Biologics reduce erosion rate by 70-90%
• Early treatment (less than 3 months) prevents erosions in majority

Prognostic Factors

Poor Prognosis Indicators:

• Serology: High-titre RF and/or anti-CCP positive
• Early erosions: Erosions on X-ray at presentation
• High disease activity: DAS28 > 5.1
• High acute phase response: ESR > 30, CRP > 20
• Functional impairment: HAQ score > 1.5
• Smoking: Continued smoking
• Extra-articular disease: Nodules, vasculitis, ILD
• Genetic: HLA-DR4 shared epitope (particularly homozygotes)
• Demographics: Young onset, female sex

Good Prognosis Indicators:

• Seronegative (RF and anti-CCP negative)
• No erosions at baseline
• Low disease activity at baseline
• Early treatment initiation
• Good response to initial DMARD

Mortality

RA is associated with reduced life expectancy of 5-10 years compared to general population. [15]

Main Causes of Death:

1. Cardiovascular disease (40%): MI, stroke, heart failure
2. Infections (20%): Respiratory infections most common
3. Respiratory disease (15%): ILD, COPD
4. Malignancy (10%): Lymphoma (2-3x increased risk)
5. Renal disease (5%)

Standardized Mortality Ratio (SMR): 1.5-2.0 (i.e., 1.5-2x higher than general population)

Trends:

• Mortality gap has narrowed with modern treatment (biologics, tight control)
• Cardiovascular mortality still elevated despite RA treatment improvements

Quality of Life

Impact on Quality of Life:

• Pain and stiffness affect daily activities
• Fatigue is major symptom (80% of patients)
• Psychological impact: Depression (15-20%), anxiety
• Work disability: 30-40% stop working within 5 years if poorly controlled

Improvement with Treatment:

• Tight disease control significantly improves QoL
• Remission associated with near-normal QoL in many patients

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11. Prevention and Screening

Primary Prevention

Risk Reduction Strategies:

• Smoking cessation: Strongest modifiable risk factor
• Periodontal health: Treat periodontitis
• Healthy weight: Avoid obesity
• Diet: Mediterranean diet may reduce risk (limited evidence)

No Established Screening Program:

• RF/anti-CCP screening in asymptomatic individuals not recommended
• Exception: First-degree relatives with symptoms should be referred early

Secondary Prevention (Early Diagnosis)

Importance:

• Treat within "window of opportunity" (first 3 months)
• Early referral guidelines:
  • Small joint synovitis
  • Involvement of ≥3 joints
  • Morning stiffness > 30 minutes
  • Positive squeeze test (MCPs/MTPs)
  • Symptoms > 6 weeks

Primary Care Red Flags:

• Unexplained joint swelling
• Family history of RA + new joint symptoms
• Symmetrical small joint involvement

Tertiary Prevention (Prevent Complications)

Cardiovascular Disease Prevention:

• Annual CV risk assessment (use RA as 1.5x multiplier)
• Statin if 10-year risk > 10%
• Blood pressure control
• Diabetes screening and management
• Smoking cessation

Infection Prevention:

• Vaccinations:
  • Annual influenza vaccine
  • Pneumococcal vaccine (PPV23 and PCV13)
  • Shingles vaccine (if age ≥50 and not on biologics; use non-live vaccine)
  • COVID-19 vaccination
  • NO live vaccines on biologics or high-dose immunosuppression
• Tuberculosis screening before starting biologics

Osteoporosis Prevention:

• DEXA scan at diagnosis if:
  • Long-term steroids anticipated (≥3 months)
  • Postmenopausal women
  • Men > 50 years with risk factors
• Bisphosphonates if on long-term prednisolone ≥7.5mg daily
• Calcium and vitamin D supplementation

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12. Key Guidelines

EULAR Recommendations for Management of RA (2022 Update)

Overarching Principles:

1. Treatment decisions should be based on shared decision-making between patient and rheumatologist
2. Rheumatologists are the primary care providers for RA
3. RA has significant individual and societal costs which should be considered

Key Recommendations: [7]

1. Treatment should aim for sustained remission or low disease activity in every patient
2. Methotrexate should be part of the first treatment strategy
3. In DMARD-naïve patients, start MTX (+ short-term glucocorticoids) rapidly after diagnosis
4. If target not reached with first csDMARD strategy, consider adding or switching to another csDMARD, or adding a biologic or JAK inhibitor
5. Biologics and JAK inhibitors should be combined with a csDMARD (preferably MTX)
6. In patients refractory to MTX and/or other csDMARD strategies, any biologic or JAK inhibitor may be used
7. If treatment target is sustained, DMARDs can be tapered (but not stopped completely)

ACR Guidelines for RA Management (2021)

Pharmacologic Treatment Recommendations:

• DMARD-naïve, moderate-high disease activity: MTX monotherapy conditionally recommended over other csDMARD monotherapy
• Inadequate response to MTX: Addition of biologic or JAK inhibitor conditionally recommended over triple therapy
• Biologic choice: No strong preference among biologic classes for most patients

NICE Guideline NG100 (2018)

Diagnosis and Referral:

• Refer adults with suspected RA to rheumatology urgently (within 3 working days) if small joint involvement, ≥3 joints affected, or symptoms > 3 months

Treatment:

• Start DMARDs (ideally MTX + at least 1 other DMARD + short-term glucocorticoids) within 3 months of persistent symptoms
• Measure disease activity monthly until DAS28 less than 2.6 for 6 months
• Offer biologics if DAS28 > 5.1 despite treatment with ≥2 csDMARDs (including MTX)

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13. Exam-Focused Content

Common MRCP Questions

Question 1: "What are the extra-articular manifestations of RA?"

Model Answer:

"Rheumatoid arthritis has multiple extra-articular manifestations affecting approximately 30-40% of patients, particularly those who are seropositive with severe disease.

Pulmonary: Interstitial lung disease occurs in 10-20% and is the most serious pulmonary complication, presenting with progressive dyspnoea and bibasal crackles. Pleural disease with effusions, pulmonary nodules, and Caplan syndrome in coal workers are also seen.

Cardiovascular: RA patients have 1.5-2 times higher cardiovascular risk. Direct cardiac involvement includes pericarditis, which is the most common cardiac manifestation, plus rare myocarditis and valvular disease.

Ocular: Keratoconjunctivitis sicca from secondary Sjögren's syndrome is most common. Scleritis is serious and vision-threatening, requiring urgent ophthalmology referral and systemic immunosuppression.

Haematological: Anaemia of chronic disease is common. Felty syndrome is the triad of RA, splenomegaly, and neutropenia, predisposing to infections.

Rheumatoid nodules: Occur in 20-30%, typically on extensor surfaces and pressure points in seropositive disease.

Vasculitis: Now rare but serious, presenting with nail fold infarcts, digital gangrene, mononeuritis multiplex, or visceral involvement.

Cervical spine: Atlanto-axial subluxation occurs in 10-30% and can cause cervical myelopathy. All RA patients require cervical spine imaging before intubation for surgery."

Question 2: "How would you investigate suspected rheumatoid arthritis?"

Model Answer:

"I would approach the investigation of suspected rheumatoid arthritis systematically using a combination of serological tests, inflammatory markers, and imaging.

Serology: I would check rheumatoid factor and anti-CCP antibodies. Anti-CCP is more specific at 95% compared to RF at 85%, though both have similar sensitivity around 70%. Anti-CCP predicts erosive disease and can be positive years before symptoms develop. Positive anti-CCP with negative RF still suggests RA.

Inflammatory markers: I would measure ESR and CRP to assess disease activity, though these can be normal in 10-20% of RA patients. These markers are useful for monitoring treatment response.

Haematology: Full blood count may show anaemia of chronic disease, which correlates with disease activity, and reactive thrombocytosis.

Imaging: Initial X-rays of hands and feet establish baseline and may show early features of periarticular osteopenia, soft tissue swelling, or marginal erosions. Ultrasound with power Doppler is more sensitive for detecting synovitis and can identify erosions earlier than X-ray. MRI is the most sensitive imaging modality and can detect bone marrow oedema, which predicts sites of future erosions.

Synovial fluid analysis: If monoarthritis is present, joint aspiration is essential to exclude septic arthritis or crystal arthropathy. In RA, the fluid shows inflammatory features with 5,000-50,000 white cells, neutrophil predominance, and no organisms or crystals.

The 2010 ACR/EULAR classification criteria integrate these findings, requiring a score of at least 6 out of 10 based on joint involvement, serology, acute phase reactants, and symptom duration."

Question 3: "What is your approach to DMARD therapy in rheumatoid arthritis?"

Model Answer:

"My approach follows the treat-to-target strategy outlined in EULAR guidelines, aiming for remission or low disease activity.

Initial Treatment: I would start methotrexate 15mg once weekly as first-line therapy, co-prescribing folic acid 5mg once weekly on a different day. I would escalate MTX to 15-25mg weekly over 8-12 weeks to reach an adequate dose. I would add short-term prednisolone 10-15mg daily or intramuscular methylprednisolone as bridge therapy while awaiting DMARD effect, which takes 6-12 weeks.

Monitoring: In the first 3 months, I would check FBC, U&Es, and LFTs every 2 weeks to detect myelosuppression or hepatotoxicity. Once stable, I would monitor every 3 months.

Assess Response: At 3 months, I would assess disease activity using DAS28 score. If the target of remission (DAS28 less than 2.6) or low disease activity is not achieved, I would escalate therapy within 3 months.

Second-Line: If inadequate response to MTX monotherapy, I have two options: add sulfasalazine and hydroxychloroquine for triple therapy, or add a biologic DMARD or JAK inhibitor. Choice depends on disease severity, prognostic factors such as high RF/anti-CCP or early erosions, and patient factors.

Biologics: These require DAS28 > 5.1 despite trial of at least 2 csDMARDs including MTX. I would screen for tuberculosis, hepatitis B and C, and ensure vaccinations are up to date before starting. Anti-TNF agents like adalimumab or etanercept are common first-line biologics, used in combination with MTX.

Pregnancy: I would counsel patients of childbearing age that methotrexate and leflunomide are teratogenic and must be stopped 3 months before conception. Sulfasalazine, hydroxychloroquine, and certolizumab are safe alternatives."

Question 4: "What are the indications for biologic therapy in RA?"

Model Answer:

"Biologic DMARDs are indicated in rheumatoid arthritis when there is inadequate response to conventional synthetic DMARDs.

Criteria: According to NICE and BSR guidelines, biologics are indicated when:

1. Disease activity remains high with DAS28 > 5.1 on at least two occasions one month apart
2. Despite adequate trials of at least 2 conventional DMARDs including methotrexate at 25mg weekly (unless contraindicated)
3. Each DMARD should be trialed for at least 3 months at adequate dose

Poor Prognostic Factors: Biologics may be considered earlier if poor prognostic factors are present, including high-titre RF or anti-CCP antibodies, early erosions on imaging, or extra-articular disease.

Contraindications: I would screen for absolute contraindications including active serious infection, active malignancy, severe heart failure (NYHA class III-IV for anti-TNF agents), demyelinating disease, or pregnancy.

Pre-treatment Screening: Before starting biologics, I would perform tuberculosis screening with chest X-ray and IGRA or tuberculin skin test, hepatitis B and C serology, HIV testing if risk factors, and ensure pneumococcal and influenza vaccinations are current. Live vaccines are contraindicated once on biologic therapy.

Choice of Biologic: First-line biologic options include anti-TNF agents (adalimumab, etanercept), IL-6 inhibitors (tocilizumab, sarilumab), T-cell co-stimulation blockade (abatacept), or JAK inhibitors (baricitinib, tofacitinib). Choice depends on patient factors such as comorbidities - for example, tocilizumab can be used as monotherapy if MTX is not tolerated, while abatacept may be preferred if history of malignancy.

Monitoring: After starting biologics, I would assess response at 3 and 6 months using DAS28. If inadequate response by 6 months, I would switch to a different biologic class."

Viva Model Answers

Opening Statement:

"Rheumatoid arthritis is a chronic systemic autoimmune disease characterised by symmetrical inflammatory polyarthritis, primarily affecting the small joints of the hands and feet. It has a prevalence of approximately 0.5-1% with a 3:1 female predominance, typically presenting in the fourth to sixth decades of life."

Key Facts to Mention:

• Pathophysiology: Loss of tolerance to citrullinated proteins, anti-CCP antibody production, synovial inflammation, pannus formation, and progressive joint destruction via RANKL-mediated osteoclast activation
• Window of Opportunity: Treatment within first 3 months improves long-term outcomes and prevents erosions
• Diagnosis: 2010 ACR/EULAR criteria based on joint involvement, serology (RF and anti-CCP), acute phase reactants, and symptom duration
• First-line Treatment: Methotrexate 15-25mg weekly with folic acid; short-term steroids as bridge therapy
• Treat-to-Target: Aim for remission (DAS28 less than 2.6); assess every 3 months; escalate if target not met
• Extra-articular: ILD (10-20%), cardiovascular disease (1.5-2x risk), atlanto-axial subluxation (10-30%), rheumatoid nodules (20-30%), vasculitis (1-5%), Felty syndrome (less than 1%)
• Monitoring: FBC, U&Es, LFTs every 2 weeks initially on MTX, then every 3 months; watch for myelosuppression and hepatotoxicity

Evidence to Quote:

• "EULAR 2022 guidelines recommend MTX as first-line with treat-to-target strategy" [7]
• "Anti-CCP has 95% specificity for RA and predicts erosive disease" [4,8]
• "Early treatment within 3 months improves remission rates from 20-30% to 40-60%" [5,6]

Common Mistakes to Avoid

❌ Missing the window of opportunity: Delaying DMARD therapy beyond 3 months significantly worsens long-term outcomes

❌ Not checking both RF AND anti-CCP: Anti-CCP is more specific and can be positive when RF is negative; check both

❌ Starting biologics before optimizing MTX dose: Must trial MTX at adequate dose (15-25mg) for at least 3 months before adding biologic

❌ Forgetting folic acid with methotrexate: Always co-prescribe folic acid 5mg weekly (on different day) to reduce side effects

❌ Missing extra-articular manifestations: Systematically assess for ILD, cardiovascular disease, ocular involvement, atlanto-axial subluxation

❌ Not screening for TB before biologics: Mandatory screening (CXR + IGRA/tuberculin test) to prevent TB reactivation

❌ Inadequate monitoring: FBC, U&Es, LFTs every 2 weeks for first 3 months on MTX is essential to detect toxicity early

❌ Telling patients to take MTX daily instead of weekly: Fatal errors have occurred; emphasize ONCE WEEKLY dosing

❌ Not advising contraception on MTX: Methotrexate is highly teratogenic; must stop 3 months before conception

❌ Forgetting cervical spine assessment before surgery: All RA patients need cervical spine imaging before intubation due to atlanto-axial subluxation risk

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14. References

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20. Singh JA, Cameron C, Noorbaloochi S, et al. Risk of serious infection in biological treatment of patients with rheumatoid arthritis: a systematic review and meta-analysis. Lancet. 2015;386(9990):258-265. PMID: 25975452

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Last Reviewed: 2026-01-05 | MedVellum Editorial Team | Evidence Level: High