Mastering Giant Cell Arteritis Guidelines for SCE Success

Mastering Giant Cell Arteritis Guidelines for SCE Rheumatology Success

Giant Cell Arteritis (GCA), formerly known as temporal arteritis, represents one of the most critical and high-stakes diagnoses in clinical rheumatology and acute medicine. For candidates preparing for the Specialty Certificate Examination (SCE), mastering GCA guidelines is non-negotiable, as missed diagnosis or delayed management can lead to permanent vision loss—a medical emergency.

This guide breaks down the essential diagnostic and management guidelines you need to know to excel in your SCE.

1. Clinical Recognition: The High-Yield Symptoms

GCA is a systemic granulomatous vasculitis primarily affecting medium-to-large arteries, typically occurring in patients over the age of 50. The classic presentation must be immediately recognized:

SCE Tip: Always consider GCA in any patient >50 presenting with new-onset headache and inflammatory markers, especially if associated with PMR symptoms.

2. Diagnostic Pathway: The Urgent Investigations

The diagnostic process for GCA must be executed concurrently with initial treatment due to the high risk of vision loss.

A. Laboratory Markers

1. ESR and CRP: Usually markedly elevated (ESR often >50 mm/hr, CRP often >10 mg/L). However, up to 10% of patients may have normal inflammatory markers (so-called 'occult GCA').

2. Full Blood Count: May show normochromic normocytic anaemia and thrombocytosis.

B. Imaging and Biopsy

1. Temporal Artery Biopsy (TAB): This remains the gold standard. A section of at least 1.5–2.5 cm is required. The key histological finding is granulomatous inflammation with multinucleated giant cells and intimal hyperplasia.

   • Crucial Guideline: Treatment with high-dose steroids should not be delayed while awaiting the biopsy. If GCA is suspected, start steroids immediately. The biopsy remains informative for up to 1-2 weeks after steroid initiation.

2. Vascular Ultrasound (Doppler): Recommended by ACR/EULAR guidelines as a quick, non-invasive investigation. Findings include the characteristic 'halo sign' (a dark hypoechoic wall thickening due to oedema).

   • Note: Ultrasound is often used to guide the biopsy site and can sometimes negate the need for a biopsy if performed by an experienced operator and demonstrating classic findings.

3. Cross-Sectional Imaging (PET/CT/MRA): Useful if large vessel involvement (aortitis) is suspected, particularly in GCA without typical cranial symptoms.

3. Immediate Management: The Steroid Protocol

Management is time-critical. The decision to treat is clinical.

A. Patients Without Visual Symptoms (Standard GCA)

• Oral Prednisolone: Immediate start of high-dose oral corticosteroids (usually 40–60 mg daily).

• Goal: To suppress inflammation quickly and prevent irreversible ischaemia.

B. Patients With Impending or Established Vision Loss (Ophthalmic GCA)

• IV Methylprednisolone: Admit the patient and immediately initiate intravenous (IV) high-dose pulsed steroids (e.g., 500 mg to 1 g daily for 3 days).

• Rationale: IV pulses achieve higher tissue levels faster and are associated with a better chance of salvaging vision in the unaffected eye.

• Following the pulse, switch to high-dose oral prednisolone (e.g., 60 mg daily).

C. Adjunctive Therapy

1. Aspirin: Low-dose aspirin (75 mg daily) is recommended for all patients unless contraindicated, as it reduces the risk of visual loss and stroke.

2. Gastric Protection: PPIs (e.g., Omeprazole) must be prescribed due to high-dose steroid use.

3. Bone Protection: All patients on steroids for more than three months require bone protection (Calcium, Vitamin D, and often a bisphosphonate).

4. Long-Term Management and Monitoring

Steroid treatment is prolonged, typically lasting 1 to 2 years, requiring careful monitoring to prevent relapse and manage side effects.

A. Steroid Tapering

• The dose is gradually reduced based on symptom resolution and normalization of inflammatory markers (ESR/CRP).

• Tapering is slow—often reducing by 10 mg/day every 2–4 weeks initially, becoming much slower below 10 mg (e.g., 1 mg/month).

B. Immunosuppressive Agents (Steroid-Sparing)

For patients with refractory disease, frequent relapses, or those unable to tolerate high steroid doses, steroid-sparing agents are introduced:

• Tocilizumab (TCZ): The IL-6 receptor antagonist is a landmark treatment now widely recommended (NICE/ACR guidelines) for GCA, especially in combination with initial steroids. It has shown superior efficacy in achieving sustained remission compared to steroids alone.

• Methotrexate (MTX): Used occasionally, though evidence of efficacy is weaker than for TCZ.

C. Follow-up and Relapse

Regular monitoring of inflammatory markers is vital. Relapse is typically indicated by:

• Return of GCA symptoms (e.g., headache, jaw claudication).

• Re-elevation of ESR and CRP.

In case of relapse, the steroid dose should be increased to the last effective dose, or higher, depending on the severity of symptoms (IV pulses if vision is threatened).