PARIS – Cranial ultrasound was more sensitive and just as specific as was temporal artery biopsy for the diagnosis of giant cell arteritis, based on the results of a retrospective cohort study reported by Dr. Adam Croft at a press conference held during the annual European Congress of Rheumatology.
Given that ultrasound is noninvasive, associated with fewer risks, and more sensitive than biopsy, "temporal artery biopsy may now be unnecessary (when) clinical suspicion of GCA [giant cell arteritis] is high or quite low," said Dr. Croft of the University of Birmingham, England. "Cranial ultrasound may soon replace temporal artery biopsy in the assessment of patients with a suspected diagnosis of GCA in routine clinical practice."
Giant cell arteritis typically is associated with severe headaches and scalp tenderness on the sides of the forehead that must be distinguished from more benign causes of headache. In GCA, these symptoms result from ocular arterial inflammation and narrowing that respond to high-dose steroid therapy.
The findings were seen in a study of 87 patients who underwent cranial duplex ultrasound for suspected GCA. At 3-month follow-up, 36 patients (41%) had a confirmed clinical diagnosis of giant cell arteritis. Of the 30 patients with a positive cranial ultrasound result, 29 went on to have a confirmed diagnosis. Of the 36 patients with more than three American College of Rheumatology criteria, 21 (58%) had a diagnosis of GCA.
When compared with clinical diagnosis, ultrasound had 81% sensitivity and 98% specificity with a positive likelihood ratio of 41 and a negative likelihood ratio 0.2. The positive predictive value was 97% and the negative predictive value was 88%, he said. In other words, with a positive ultrasound finding, the probability of giant cell arteritis was 41 times higher.
In contrast, when compared with clinical diagnosis, temporal artery biopsy had a sensitivity of 53% and a specificity of 100%. The positive likelihood ratio was 2.3 and the negative likelihood ratio 0.2. The positive predictive value was 100% and the negative predictive value was 47%.
Relying on temporal arterial biopsy results alone leaves "patients at risk of missing out on potentially sight-saving steroid treatment, or of being treated with high-dose steroids unnecessarily," he said. Further, temporal artery biopsy is not without risks. The biopsy can miss the artery and can result is permanent facial nerve damage. A negative biopsy rarely informs practice.
The availability of cranial ultrasound depends on whether one’s practice is located near facilities with the infrastructure and the availability of well-trained rheumatologists and radiologists who can do the scan rapidly, Dr. Croft said in a video interview.
Dr. Croft had no relevant financial disclosures.
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