medwireNews: A fast-track strategy that uses color Doppler ultrasound of the temporal arteries as the first-line investigation for suspected giant cell arteritis (GCA) avoids the need for temporal artery biopsy (TAB) in around two-fifths of cases, according to the results of a prospective, multicenter study.
Of 165 individuals aged a mean of 79 years who were included in the study, 73 (44%) were correctly diagnosed with GCA based on the results of an ultrasound examination and did not require TAB. Moreover, diagnoses remained unchanged when re-evaluated at multiple timepoints over the course of a 2-year follow-up period.
“Our study showed that the use of temporal artery ultrasound may be an efficient way to make the diagnosis of GCA in patients with high clinical suspicion and to reduce imaging costs and the need for biopsy,” report Guillaume Denis (Centre Hospitalier de Rochefort, France) and collaborators in the Annals of Internal Medicine.
GCA is the most prevalent form of vasculitis in people over the age of 50 years and should be treated as a medical emergency because it can lead to blindness, they explain. Corticosteroids are usually given as a pragmatic treatment ahead of a diagnosis being made, which can lead to unnecessary adverse effects in those who do not have the condition.
“This is why a rapid and effective diagnostic strategy is needed,” Denis et al observe. “In our study, the time between the consultation with the specialist and ultrasound was less than 1 day.” Moreover, people who needed a biopsy were given one within 4.5 days.
In 2023, the European Alliance of Rheumatology Associations recommended ultrasound as a first-line investigation for confirming a suspected diagnosis of GCA. The aim of this study was to test a diagnostic strategy aligned with this recommendation that used colour Doppler ultrasound followed by TAB if the results of the ultrasound were negative.
Ultrasound images were designated as being positive or negative based on the presence of a bilateral halo sign, “a homogenous, hypoechoic wall thickening,” located in the superficial temporal arteries, trunk, or branches, explain the researchers.
If people had a negative ultrasound and a negative TAB, they underwent further large-vessel imaging and whether they had GCA or an alternative diagnosis, such as polymyalgia rheumatica, was based on expert opinion.
The study included participants with a high clinical suspicion for GCA, which was defined as being older than 50 years of age with a biological inflammatory syndrome and elevated C-reactive protein (≥6 mg/L) levels.
In addition, participants had to have at least one of the following: specific clinical signs of GCA (abnormal temporal arteries, scalp hyperesthesia, jaw claudication, vision loss, pain in the shoulder girdle or pelvic girdle), general signs (unusual headache, impaired general condition, fever), or evidence of large-vessel vasculitis on computed tomography angiography, magnetic resonance angiography, or positron emission tomography, and no obvious signs of a different diagnosis.
The proportion of patients who had a bilateral temporal halo sign confirmed by ultrasound only among the 136 patients in total who were diagnosed with GCA at 1 month was 54%.
And of the 92 (56%) people who had a negative ultrasound, 64 (70%) had a negative and 28 (30%) a positive TAB result, with 17% of the positive TAB cases confirmed as GCA. A further 21% were diagnosed with GCA based on clinical expertise, additional imaging tests, or both, and an alternative diagnosis was made in 18% of patients.
The researchers acknowledge the small sample size and note that there was no blinding of ultrasound and TAB results when confirming the diagnosis. The study was also limited by the lack of an objective gold-standard comparator and the use of a single diagnostic strategy.
They conclude that their ultrasound-first strategy is efficient for the diagnosis of GCA, but they add that its role in cases of low clinical probability remains to be demonstrated.
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