Large vessel vasculitis is a risk factor for relapse only in giant cell arteritis patients without polymyalgia rheumatica.

Objectives: To evaluate differences in presentation and outcome of GCA patients with and without large vessel vasculitis (LVV) and according to the extent and severity of LVV.

Methods: Consecutive patients diagnosed with GCA between 2003 and 2020 who have had FDG PET imaging at diagnosis ≤3 days after initiation of glucocorticoids (GC) and followed for ≥12 months at the University Hospitals Leuven (Belgium) were included retrospectively. PET scans were visually scored (0-3) in seven vascular areas and a total vascular score (TVS) was calculated. LVV was defined as FDG uptake ≥2 in any large vessel.

Results: We included 238 GCA patients, of which 169 (71%) had LVV. LVV patients were younger (69 vs 74 years, P < 0.001) and more frequently female (72% vs 49%, P = 0.001). In patients without PMR symptoms, the presence of LVV was associated with relapse (aOR 3.05 [95% CI 1.32-7.43], P = 0.011) and with a lower probability of stopping GC (aHR 0.59 [95% CI 0.37-0.94], P = 0.025). However, in those with PMR symptoms, there was no difference in relapse risk (aOR 1.20 [95% CI 0.53-2.66], P = 0.657) and in the probability of stopping GC (aHR 1.25 [95% CI 0.75-2.09], P = 0.394) between patients with and without LVV. A higher TVS was associated with an increased risk of relapse (aOR 1.09 [95% CI 1.04-1.15], P = 0.001) in patients without PMR symptoms, but not in those with PMR symptoms (aOR 1.01 [95% CI 0.96-1.07], P = 0.693).

Conclusion: LVV is a risk factor for relapse in GCA patients without PMR symptoms with a higher relapse risk in those with higher TVS.