What are the diagnostic criteria for giant cell (temporal) arteritis?

From the Guidelines

Diagnosing giant cell arteritis (GCA) requires a combination of clinical evaluation, laboratory tests, and imaging studies, with a focus on symptoms like new-onset headache, scalp tenderness, jaw claudication, visual disturbances, and constitutional symptoms, as well as elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels, and imaging findings of vessel wall inflammation and stenosis on temporal artery biopsy, color duplex ultrasonography, magnetic resonance imaging, or positron emission tomography 1. The diagnosis should begin with a thorough history and physical examination, focusing on symptoms like new-onset headache, scalp tenderness, jaw claudication, visual disturbances, and constitutional symptoms such as fever, weight loss, and fatigue.

• Key symptoms include:
  • New-onset headache
  • Scalp tenderness
  • Jaw claudication
  • Visual disturbances
  • Constitutional symptoms such as fever, weight loss, and fatigue Laboratory tests are essential, particularly ESR and CRP, which are typically elevated in GCA, as noted in a systematic review and meta-analysis of the diagnostic accuracy of symptoms, physical signs, and laboratory tests for GCA 1.
• Key laboratory tests include:
  • Erythrocyte sedimentation rate (ESR)
  • C-reactive protein (CRP)
  • Complete blood count to show normocytic anemia The gold standard for diagnosis is a temporal artery biopsy, which should be performed promptly but should not delay treatment if GCA is strongly suspected, as emphasized in the 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of giant cell arteritis and Takayasu arteritis 1.
• Key diagnostic criteria include:
  • Temporal artery biopsy with inflammatory infiltrates and multinucleated giant cells
  • Imaging findings of vessel wall inflammation and stenosis on color duplex ultrasonography, magnetic resonance imaging, or positron emission tomography Imaging studies like color duplex ultrasonography, magnetic resonance imaging, or positron emission tomography can be helpful, especially when biopsy results are negative but clinical suspicion remains high, as noted in the 2021 guideline for the prevention of stroke in patients with stroke and transient ischemic attack 1. Early diagnosis is crucial as prompt treatment with high-dose corticosteroids (typically prednisolone 40-60 mg daily) can prevent serious complications like permanent vision loss, and treatment should be initiated urgently, with high-dose steroids started quickly within the first 24 hours after symptoms onset 1.

From the Research

Diagnostic Criteria for Giant Cell Arteritis

The diagnostic criteria for giant cell arteritis (GCA) involve a combination of clinical, laboratory, and imaging findings.

• The gold standard for diagnosis is temporal artery biopsy (TABx), which shows transmural inflammation, but a negative biopsy does not rule out the disease 2.
• The American College of Rheumatology criteria for the classification of GCA include an erythrocyte sedimentation rate (ESR) of 50 mm/h or more, but GCA may occur with normal ESR in a percentage of about 4 to 15% 3.
• Clinical suspicion must be confirmed with a positive biopsy, and color duplex ultrasonography is a noninvasive method for supporting a diagnosis of GCA with high sensitivity and specificity 3, 4.
• Vascular ultrasound might effectively replace temporal artery biopsy as a first-line diagnostic method in patients suspected of having GCA when done by systematically trained ultrasonographers using appropriate equipment and settings 4.
• Noninvasive imaging techniques, such as temporal artery ultrasound and positron emission tomography/computed tomography (PET/CT), are increasingly used in the absence of temporal artery biopsy to confirm diagnostic suspicions of GCA 5.

Laboratory and Imaging Findings

• Laboratory evidence of an acute-phase reaction, such as elevated ESR and C-reactive protein (CRP) levels, is common in GCA, but some patients may have normal ESR and CRP levels 3, 5.
• Imaging modalities, such as color duplex ultrasonography and PET/CT, may aid in the diagnosis of GCA and have estimated sensitivities and specificities of 78% and 79% for temporal artery ultrasound, and 71% and 91% for PET/CT, respectively 4, 5.
• The signs and symptoms of GCA can be classified into four subsets: cranial arteritis, extracranial arteritis, systemic symptoms, and polymyalgia rheumatica, and patients may develop any combination of these manifestations 6.

Clinical Diagnosis

• The diagnosis of GCA is clinical and is not discarded by a negative TABx, and patients with classic clinical manifestations of temporal arteritis but with a negative TABx should be treated aggressively 2.
• The final diagnosis should be based on all clinical, laboratory, imaging, and histological findings, and meeting classification criteria is not equivalent to making the diagnosis in individual patients 6.