Background/Purpose: To determine if disease extent on ultrasound (US) of temporal and axillary arteries predicts a relapsing course of giant cell arteritis (GCA).

Methods: We conducted a single-centre retrospective study in which consecutive patients diagnosed with GCA between January 2019 (beginning of GCA fast-track US evaluations in the department) and May 2021 records were reviewed. Using Cox proportional hazards regression, we evaluated if disease extent, defined as the number of vessels showing non-compressible halo – ‘halo count’ – on baseline US scan performed as part of the diagnostic work-up is able to predict the risk of relapse in GCA.

Results: A total of 72 patients with a clinical diagnosis of GCA in which an US scan was performed in the diagnostic work-up were included. Thirty-seven (51.4%) experienced a relapse of GCA (median follow-up of 20.9 months; median time-to-first relapse of 6.3 months), ultimately needing treatment escalation. In a multivariable Cox regression model (n=72; -2 log likelihood = 275.63; chi-square = 8.03; df = 3; P = 0.045), halo count was found to be a significant predictor of time-to-relapse in GCA (HR = 1.19; CI 95% 1.04, 1.35; P = 0.012) after adjustment for patient sex and presence of ischaemic symptoms.

Conclusion: GCA disease extent as defined by US halo count at the time of diagnosis may predict relapsing disease and may help clinicians stratify care for these patients. Larger prospective studies are needed to confirm our findings.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/giant-cell-arteritis-relapse-risk-could-the-extent-of-vessel-involvement-on-temporal-and-axillary-arteries-ultrasound-be-a-prognostic-marker/