Distribution of arterial lesions in Takayasu's arteritis and giant cell arteritis

Abstract

Objectives: To compare patterns of arteriographic lesions of the aorta and primary branches in patients with Takayasu's arteritis (TAK) and giant cell arteritis (GCA).

Methods: Patients were selected from two North American cohorts of TAK and GCA. The frequency of arteriographic lesions was calculated for 15 large arteries. Cluster analysis was used to derive patterns of arterial disease in TAK versus GCA and in patients categorised by age at disease onset. Using latent class analysis, computer derived classification models based upon patterns of arterial disease were compared with traditional classification.

Results: Arteriographic lesions were identified in 145 patients with TAK and 62 patients with GCA. Cluster analysis demonstrated that arterial involvement was contiguous in the aorta and usually symmetric in paired branch vessels for TAK and GCA. There was significantly more left carotid (p=0.03) and mesenteric (p=0.02) artery disease in TAK and more left and right axillary (p<0.01) artery disease in GCA. Subclavian disease clustered asymmetrically in TAK and in patients ≤55 years at disease onset and clustered symmetrically in GCA and patients >55 years at disease onset. Computer derived classification models distinguished TAK from GCA in two subgroups, defining 26% and 18% of the study sample; however, 56% of patients were classified into a subgroup that did not strongly differentiate between TAK and GCA.

Conclusions: Strong similarities and subtle differences in the distribution of arterial disease were observed between TAK and GCA. These findings suggest that TAK and GCA may exist on a spectrum within the same disease.

Figure 1

Cluster patterns in Takayasu’s arteritis and giant cell arteritis. Arrows denote the split point between clusters containing the right and left subclavian arteries. Tree dendograms in this figure were derived using ϕ correlation coefficients.

Figure 2

Cluster patterns stratified by age at disease onset. Patterns of arterial disease for patients in the <40 and the 40–55 year age groups at the time of disease onset resembled TAK, and arterial patterns for patients in the >55 year age group resembled giant cell arteritis. Cluster patterns in this figure were derived using principal component analysis.

Figure 3

Latent class membership stratified by age at disease onset. Membership in latent class 1 was associated with an increased likelihood for Takayasu’s arteritis. Membership in latent class 2 was associated with an increased likelihood for giant cell arteritis and was more frequent in subjects >60 years at disease onset. Membership in latent class 3 was not associated with an increased likelihood for either Takayasu’s arteritis or giant cell arteritis and comprised the majority of patients with large vessel vasculitis across all age strata.