Diagnosing Takayasu Arteritis
The diagnosis of Takayasu arteritis should be made using the 1990 American College of Rheumatology criteria, which requires at least 3 of the following 6 criteria: age of onset <40 years, intermittent claudication, diminished brachial artery pulse, subclavian artery or aortic bruit, systolic blood pressure difference >10 mm Hg between arms, and angiographic evidence of aorta or branch vessel stenosis. 1
Diagnostic Algorithm
Step 1: Clinical Assessment
Identify high-risk demographic features:
- Young adults (typically <40 years of age)
- Female predominance (affects women 10 times more than men)
- Typically presents in third decade of life
Evaluate for key clinical manifestations:
- Constitutional symptoms: weight loss, fatigue, night sweats, anorexia, malaise
- Vascular symptoms: upper extremity claudication, carotid artery pain
- Neurological symptoms: vision loss, lightheadedness, stroke
- Hypertension (especially in Indian-type distribution)
Step 2: Physical Examination
- Perform thorough vascular examination:
- Check for diminished or absent peripheral pulses
- Listen for vascular bruits over subclavian arteries and aorta
- Measure blood pressure in both arms (difference >10 mm Hg is significant)
- Assess for signs of end-organ ischemia
Step 3: Laboratory Testing
Order inflammatory markers:
- Erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP)
Note: These are elevated in approximately 70% of patients in acute phase and 50% in chronic phase 1
Step 4: Imaging Studies
Initial imaging should include thoracic aorta and branch vessel computed tomographic imaging or magnetic resonance imaging 1
Consider appropriate imaging based on suspected vessel involvement:
Step 5: Diagnostic Confirmation
Apply the 1990 American College of Rheumatology criteria:
- Age of onset <40 years
- Intermittent claudication
- Diminished brachial artery pulse
- Subclavian artery or aortic bruit
- Systolic blood pressure difference >10 mm Hg between arms
- Angiographic evidence of aorta or branch vessel stenosis
When 3 of these criteria are present, the sensitivity and specificity for diagnosis are 90.5% and 97.8%, respectively 1
Important Considerations
Disease Distribution Patterns
- Japanese distribution: Primarily affects thoracic aorta and great vessels
- Indian distribution: Primarily affects abdominal aorta and renal arteries 1
Disease Phases
- Acute phase: Characterized by systemic inflammation and constitutional symptoms
- Chronic phase: Characterized by vascular damage and end-organ ischemia 1
Diagnostic Pitfalls to Avoid
- Delayed diagnosis: Many patients experience considerable delay in diagnosis due to lack of specific laboratory tests or biomarkers 4
- Relying solely on inflammatory markers: There may be discrepancies between systemic inflammation and vascular wall inflammation 4
- Inadequate imaging: Using only one imaging modality may miss important findings; consider multiple complementary imaging techniques
- Misinterpreting disease activity: Active disease may be present despite normal inflammatory markers
Management Considerations
- Initial therapy should be corticosteroids at high dose (prednisone 40-60 mg daily) 1
- Disease activity should be monitored through repeated physical examinations and inflammatory markers (ESR or CRP) 1
- Elective revascularization should be delayed until the acute inflammatory state is treated and quiescent 1
Newer Diagnostic Approaches
Recent research has proposed new diagnostic criteria with potentially higher sensitivity and specificity than the ACR criteria. These include age (<40 years), female sex, chest pain/distress, amaurosis, vascular bruits, decreased/absent pulse, and involvement of specific vascular territories 5. However, the ACR criteria remain the most widely validated and accepted standard for diagnosis.