Epidemiology of major and minor relapses in giant cell arteritis according to EULAR definitions: insights from the ARTESER registry.

Objective: To investigate the prevalence, timing, and risk factors at diagnosis associated with relapses in giant cell arteritis (GCA), with a separate analysis of major and minor relapses.

Methods: A retrospective review of patients from the Spanish multicentre GCA registry (ARTESER) was conducted. Relapses were classified using 2018 EULAR definitions.

Results: We included 1,284 patients with at least one year of follow-up. Twenty-six percent experienced relapses, with cumulative rates of 18.1%, 27.9%, 37.6%, and 44.8% at 1, 2, 3, and 4 years, respectively. Multiple relapses were observed in 14.6% of patients during the first year, 10.5% in the second, 9% in the third, and 17.8% in the fourth, reflecting the relapsing-remitting nature of GCA. According to EULAR definitions, major relapses represented 26.7% of all recorded relapses and affected 7.6% of patients.Younger age at diagnosis (HR: 0.976, p= 0.004) and a higher total dose of prednisone at the first relapse (HR: 0.998, p= 0.003) were associated with a reduced risk of overall relapses. Severe ischemic complications (HR: 4.126, p< 0.001) and large-vessel (LV) involvement at diagnosis (HR: 1.992, p= 0.024) significantly increased the risk of major relapses, while younger age (HR: 0.970, p= 0.002) was protective against minor relapses.

Conclusions: Major relapses are not so uncommon, representing a quarter of all relapses. The presence of severe ischemic complications and LV involvement at diagnosis substantially increase their risk.