Large vessel involvement in biopsy-proven giant cell arteritis: incidence, distribution, and predictors.

Objectives: Giant cell arteritis (GCA) is a systemic disease with extensive vascular involvement. The aim of this study was to investigate the cumulative incidence of large vessel involvement (LVI) in GCA, the distribution of vessels involved, and predictors for LVI.Method: Patients with biopsy-proven GCA in a defined area in southern Sweden, diagnosed between 1997 and 2010, were identified through the register of the regional Department of Clinical Pathology. A structured review of all medical records and imaging and histopathology reports was performed. Imaging studies for an age- and sex-matched reference cohort were also reviewed.Results: A total of 164 patients with GCA were investigated, of whom 24 (15%) had LVI. LVI manifestations were detected a median of 3.7 [interquartile range (IQR) 0.7-7.5] years after GCA diagnosis. Aortic involvement was found in 16 patients (10%), mainly aneurysms/ectasias of the thoracic aorta. Two patients had aortic dissections. Fourteen patients had tributary involvement. In the reference population, the cumulative incidence of LVI overall was 10.8% and aortic involvement was found in 5.4%. The presence of giant cells in the biopsy was significantly less frequent among GCA patients with LVI (23% vs. 52%; p=0.01), and a presentation with polymyalgia rheumatica (PMR) was more frequent (44% vs. 20%, p=0.01).Conclusions: The estimated incidence of LVI, detected by imaging in a clinical setting, was higher among patients with GCA than the reference population. The aorta was the most commonly affected vascular territory. The negative association with giant cells may suggest particular mechanisms in this subset of GCA.