Background/Purpose: Giant cell arteritis (GCA) is a systemic disease with extensive vascular involvement. The mechanisms underlying the diversity of GCA phenotypes are incompletely understood. The purpose of this study was to investigate predictors of large vessel involvement (LVI) in a population based cohort of patients with GCA.

Methods: Patients with biopsy-proven GCA were identified using a regional pathology register. Patients with positive temporal artery biopsies (TAB) performed between 1997 and 2010 who were diagnosed with GCA in two defined areas of the region were included. A structured review of histopathology reports and case records through July 2016 of all the identified patients was performed. Reports of all relevant radiological and clinico-physiological studies were reviewed, and cases with LVI were identified according to a pre-specified protocol. LVI was defined as aneurysm, ectasia or stenosis of the aorta or its main branches. Patients were censored at the date of first LVI, death, migration from the area or July 29, 2016. Event free survival was estimated using the Kaplan-Meier method. Potential predictors of LVI were also examined using Cox regression models.

Results: A total of 274 patients with biopsy-proven GCA (77 % women) were included. The mean age at GCA onset was 75.7 years (standard deviation (SD) 8.1). Fifty-one patients (19 %) had documented LVI during the follow-up. The median time from diagnosis of GCA to detection of LVI was 4.5 years (interquartile range 0.6-7.4). There were 32 patients with aortic involvement (63% of those with LVI; 12 % of all GCA cases). LVI occurred to a similar extent in women and men (75^th percentile of LVI-free survival 12.9 and 13.1 years, respectively; p=0.96). Survival free of LVI was significantly longer in patients with giant cells present in the TAB (75^th percentile 13.7 vs 6.7 years; p=0.014). There was a trend towards reduced risk of LVI with increasing age at GCA diagnosis (hazard ratio (HR) 0.81 per SD; 95 % confidence interval 0.61-1.08). Other histopathology features, visual symptoms, platelet count, CRP, ESR or symptoms of polymyalgia rheumatica had no significant impact on the risk of LVI. In age-adjusted analysis, the presence of giant cells in the TAB was associated with a reduced risk of LVI (HR 0.48; 95 % CI 0.27-0.86).

Conclusion:

Clinical features of GCA had no major impact on the risk of LVI. However, the negative association with giant cells in the biopsy suggests that patients with LVI constitute a subset of GCA with particular disease mechanisms.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-presence-of-giant-cells-in-the-temporal-artery-biopsy-is-associated-with-reduced-risk-of-future-large-vessel-involvement-in-patients-with-biopsy-proven-giant-cell-arteritis/