Association of ultrasound-confirmed axillary artery vasculitis and clinical outcomes in giant cell arteritis

Objectives: The aim of this observational study was to compare clinical outcomes including glucocorticoid treatment and relapses between giant cell arteritis (GCA) patients with (axGCA) and without axillary artery involvement (non-axGCA). Methods: Axillary artery ultrasound was performed in 101 GCA patients at multiple time points. Patients with signs of vasculitis of the axillary arteries at baseline were compared to patients without signs of axillary artery involvement. Cumulative GC doses and relapse rates were calculated as well as survival curves to compare the time until GC discontinuation and occurrence of the first clinical relapse. A linear mixed model was used to assess the effect of a clinical relapse on the intima media thickness (IMT) in axGCA patients. Results: Sixty-seven patients were classified as axGCA, 34 as non-axGCA patients. Compared with non-axGCA, axGCA patients yielded a higher (albeit not significant) median time until GC discontinuation (42 months (95% CI: 33-84) vs 30 months (95% CI: 21-42), p=0.060) and median cumulative GC dose (6801mg (range 1748-34169) vs 5633mg (range: 2553-19967), p=0.051). Time until the first relapse (axGCA: 12 months (95% CI: 8-42) vs non-axGCA: 13.5 months (95% CI: 6-27), p=0522) and relapse rates (2 (range: 0-16) vs 1 (range: 0-13), p=0.67) were similar in both groups. Relapses resulted in an increase of the IMT by 0.18mm (95% CI: 0.07-0.30, p=0.003). Conclusion: Patients with axGCA have a trend towards longer treatment duration and higher GC requirements as compared to non-axGCA patients. A relapse leads to an increase of the IMT by 0.18mm.