New versus old: comparison of the 2022 ACR/EULAR versus the 1990 ACR classification criteria for giant cell arteritis in a real-world cohort

This study compares the diagnostic performance of the 1990 American College of Rheumatology (ACR) criteria and the 2022 ACR/European League Against Rheumatism (EULAR) classification criteria for giant cell arteritis (GCA), with focus on the complementary roles of MRI and ultrasound imaging.

A retrospective analysis was conducted on 192 patients presenting with suspected GCA at a tertiary care center between 2017 and 2022. Both classification criteria were applied to all cases, and their sensitivity, specificity, and diagnostic accuracy were compared. The diagnostic contribution of MRI versus ultrasound for bilateral axillary involvement was systematically analyzed.

Among 192 patients, 99 were diagnosed with GCA. The 1990 ACR criteria demonstrated high specificity (0.96, 95%CI: 0.92-1) but limited sensitivity (0.62, 95% CI: 0.52–0.72), primarily failing to classify extracranial large-vessel GCA cases. The 2022 ACR/EULAR criteria showed improved sensitivity (0.97, 95% CI: 0.93-1) and good specificity (0.82, 95% CI: 0.74–0.89). MRI and ultrasound demonstrated comparable performance for bilateral axillary involvement, with each modality exclusively identifying 21 patients who met classification criteria. MRI alone achieved 95% sensitivity (95% CI: 91–99%), while ultrasound alone achieved 94% sensitivity (95% CI: 89–99%). Threshold adjustment from 6 to 7 points improved specificity (0.92, 95% CI: 0.87–0.97) while maintaining high sensitivity.

The 2022 ACR/EULAR criteria outperform the 1990 ACR criteria, particularly for extracranial large-vessel involvement. MRI and ultrasound provide complementary diagnostic contributions with comparable performance, suggesting either modality can effectively support the updated classification criteria.