Scienced by blinding: ultrasound for giant cell arteritis.

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Accurate diagnosis of giant cell arteritis is crucial. Prompt diagnosis can prevent visual loss, but misdiagnosis risks toxicity from unnecessary glucocorticoid treatment. What is the current place of vascular ultrasound in the diagnosis of giant cell arteritis? According to European Alliance of Associations for Rheumatology (EULAR) recommendations, ultrasound is now the first-choice test, 1 Dejaco C Ramiro S Duftner C et al. EULAR recommendations for the use of imaging in large vessel vasculitis in clinical practice. Ann Rheum Dis. 2018; 77: 636-643 Crossref PubMed Scopus (389) Google Scholar whereas the British Society of Rheumatology guideline places ultrasound alongside temporal artery biopsy. 2 Mackie SL Dejaco C Appenzeller S et al. British Society for Rheumatology guideline on diagnosis and treatment of giant cell arteritis. Rheumatology (Oxford). 2020; 59: e1-23 Crossref PubMed Scopus (48) Google Scholar The landmark TABUL study 3 Luqmani R Lee E Singh S et al. The Role of Ultrasound Compared to Biopsy of Temporal Arteries in the Diagnosis and Treatment of Giant Cell Arteritis (TABUL): a diagnostic accuracy and cost-effectiveness study. Health Technol Assess. 2016; 20: 1-238 Crossref PubMed Scopus (209) Google Scholar assessed the role of temporal and axillary artery ultrasound in diagnosis of giant cell arteritis, with the diagnostician masked to the ultrasound result. Diagnosis of giant cell arteritis was made by an experienced clinician and adjudicated by an expert panel, incorporating the temporal artery biopsy result. In TABUL, ultrasound had a sensitivity of 54% and specificity of 81% for a diagnosis of giant cell arteritis, whereas temporal artery biopsy had a sensitivity of 39% and a specificity of 100%, reflecting its disease-defining role. 3 Luqmani R Lee E Singh S et al. The Role of Ultrasound Compared to Biopsy of Temporal Arteries in the Diagnosis and Treatment of Giant Cell Arteritis (TABUL): a diagnostic accuracy and cost-effectiveness study. Health Technol Assess. 2016; 20: 1-238 Crossref PubMed Scopus (209) Google Scholar The low sensitivity of ultrasound in the TABUL study has been attributed to limited sonographer training (requiring ten normal scans and one scan of a so-called hot case) and the limitations of ultrasound machines available during the study period. Subsequent studies have suggested a higher sensitivity for ultrasound for clinical diagnosis, but these studies did not use formal blinding and are therefore potentially biased. 4 Croft AP Thompson N Duddy MJ et al. Cranial ultrasound for the diagnosis of giant cell arteritis. A retrospective cohort study. J R Coll Physicians Edinb. 2015; 45: 268-272 Crossref PubMed Scopus (13) Google Scholar In some centres where temporal artery biopsies are now rarely done, some ultrasound findings are reported to have 100% specificity for giant cell arteritis, 5 Monti S Floris A Ponte C et al. The use of ultrasound to assess giant cell arteritis: review of the current evidence and practical guide for the rheumatologist. Rheumatology (Oxford). 2018; 57: 227-235 Crossref PubMed Google Scholar suggesting that ultrasound might now have become disease-defining in some institutes. Is this shift justified, or is it still premature? Diagnostic accuracy of vascular ultrasound in patients with suspected giant cell arteritis (EUREKA): a prospective, multicentre, non-interventional, cohort studyVascular ultrasound might effectively replace temporal artery biopsy as a first-line diagnostic method in patients suspected of having giant cell arteritis when done by systematically trained ultrasonographers using appropriate equipment and settings. Full-Text PDF