Ab1299 Limb Arteries Involvement Assessed by FDG/Pet Ct at Diagnosis of Giant Cell Arteritis and Risk of Relapse: An Observational Study

Background: Steroids and anti-IL6 biotherapy are highly effective in obtaining remission in patients with giant cell arteritis (GCA) but the risk of relapses remains high. Objectives: We aimed to identify predictors of relapse in GCA. Methods: All consecutive patients admitted with a new diagnosis of GCA - according to the 2022 ACR/EULAR classification criteria - between January 2011 to December 2021 were eligible for this study. The primary outcome was the GCA relapse rate over the 36-months follow up. Factors associated with the primary outcome and time to first relapse were analyzed. Results: One hundred and eight patients (74 [69-81] years, 64.8% women) with a new diagnosis of GCA were studied. GCA was biopsy-proven in 65 (60.2%) cases. Ninety-eight (90.7%) FDG/PET CT scans performed at diagnosis were available for review. All patients received steroids given for 21.0 [18.0-28.5] months, associated with methotrexate (n=1, 0.9%) or tocilizumab (n=2, 1.9%). During a median follow-up of 27.5 [11.4-35.0] months, relapse occurred in 40 (37%) patients. Multivariable Cox regression model, including age, gender, aortic wall thickness, FDG uptake in arterial wall and IV steroid pulse as covariates, showed that FDG uptake in limb arteries at diagnosis was the only significant factor associated with GCA relapse (HR 3.05 [1.48-6.25], p=0.002). Conclusion: Limb arteries involvement on FDG/PET CT at diagnosis of GCA is associated with the risk of relapse. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.