BackgroundImmune and vascular ageing are proposed risk factors for giant cell arteritis (GCA). Data on the impact of age at diagnosis of GCA on the clinical presentation and course of the disease are scarce.MethodsPatients with GCA followed at referral centres within the Italian Society of Rheumatology Vasculitis Study Group were enrolled up to November 2021. Patients were grouped according to age at diagnosis: ≤64, 65–79 and ≥80 years old.ResultsThe study included 1004 patients, mean age 72.1±8.4, female 70.82%. Median follow-up duration was 49 (IQR 23–91) months. Patients in the oldest group (≥80 years) had significantly more cranial symptoms, ischaemic complications and risk for blindness compared with the groups 65–79 and ≤64 years (blindness: 36.98% vs 18.21% vs 6.19%; p<0.0001). Large-vessel-GCA was more frequent in the youngest group (65% of patients). Relapses occurred in 47% of patients. Age did not influence the time to first relapse, nor the number of relapses. Older age was negatively associated with the number of adjunctive immunosuppressants. Patients >65 years old had 2–3 fold increased risk for aortic aneurysm/dissection up to 60 months follow-up. Serious infections, but not other treatment-related complications (hypertension, diabetes, osteoporotic fractures), were significantly associated with older age. Mortality occurred in 5.8% of the population with age >65, cranial and systemic symptoms as independent risk factors.ConclusionsThe highest risk of ischaemic complications, aneurysm development, serious infections and the possible undertreatment make of GCA a very challenging disease in the oldest patients.