2018 EULAR Guidelines Validated: Use of Imaging and Pretest Probability in Giant Cell Arteritis Diagnosis

The use of a clinical pretest probability (PTP) score and a color duplex ultrasound (CDUS) can accurately diagnose giant cell arteritis (GCA) based on the European Alliance of Associations for Rheumatology (EULAR) recommendations for the use of imaging to diagnose GCA, according to a study results published in RMD Open.

Temporal artery biopsy (TAB) has traditionally been the gold standard for diagnosing GCA. However, evidence has emerged that CDUS is more sensitive, less invasive, faster, and less expensive than TAB for GCA diagnosis.

The 2018 EULAR guidelines for the management of large-vessel vasculitis (LVV) state that a GCA diagnosis can be made in patients with high clinical suspicion of GCA and a positive imaging test, without additional testing (biopsy or other imaging), though there is no standard tool to determine high or low clinical suspicion.

Researchers of the current study sought to validate the EULAR recommendations using the Southend PTP score (SPTPS) to measure clinical suspicion of GCA.

Patients who were referred to a fast-track clinic between 2016 and 2020 were included in the study. The STPTS scores for each patient were calculated and categorized as low- (<9), intermediate- (9-12), or high- (>12) risk.

Patients underwent CDUS of the temporal arteries, including their common trunks and parietal and frontal branches. In some cases, the axillary, subclavian, and carotid arteries were also examined.

Diagnosis was confirmed after at least 9 months of follow-up, based on clinical presentation, CDUS or other imaging, or TAB.

A receiver operating characteristic (ROC) curve and the accuracy of STPTS in predicting GCA were calculated.

Among 297 patients, 97 (32.7%) were diagnosed with GCA. The area under the ROC curve was 0.787.

The percentage of patients in the low-, medium-, and high-risk categories who had GCA was 9.5% (n=10/105), 32% (n=40/125), and 70.2% (n=47/67), respectively. Researchers observed 1 false-negative result in the low-risk group and 1 false-positive result in the high-risk group. Overall, 98% of GCA patients were correctly classified.

Limitations of the study included the retrospective study design and a subjective assignment of the value of each component of the SPTPS.

The researchers concluded, “Combining the results of a PTP score, such as SPTPS, and the CDUS allows for an accurate diagnosis of GCA, as established by the EULAR group, with less than 2% misclassification of diagnosis.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

Fernández-Fernández E, Monjo I, Peiteado D, Balsa A. Validity of the EULAR recommendations on the use of ultrasound in the diagnosis of giant cell arteritis. RMD Open. Published online April 5, 2022. doi:10.1136/ rmdopen-2021-002120