Objective: Takayasu arteritis (TAK) and giant cell arteritis (GCA) are 2 major variants of large vessel vasculitis (LVV). The frequent involvement of large vessels in GCA has raised the possibility that TAK and GCA should be regarded as 1 disease. By detailed phenotyping of a single-center cohort, we aimed to define the differences between TAK and GCA.
Methods: Forty-five patients (23 TAK, 22 GCA) were identified. Baseline characteristics, clinical symptoms, laboratory data, enhanced computed tomography/magnetic resonance imaging, treatments, and clinical courses were retrospectively assessed with descriptive statistics. In addition, latent class analysis of the 45 patients was performed to explore phenotypic differences.
Results: Patients with GCA had more frequent headache (p < 0.01), higher C-reactive protein levels (p = 0.01), and higher erythrocyte sedimentation rates (p = 0.03) than did patients with TAK at diagnosis. With the exception of subdiaphragmatic lesions, the distributions of vessel lesions were not different between TAK and GCA. However, focusing on subclavian and carotid arteries, long tapered-type stenotic lesions were more frequent in GCA than in TAK (p < 0.01). The proportion of patients without relapse was higher in GCA (60%) than in TAK (22%, p = 0.01). Latent class analysis also divided patients with LVV into 2 separate groups consistent with TAK and GCA.
Conclusion: The differences observed in clinical symptoms, inflammatory markers, radiological findings, and clinical courses suggested that TAK and GCA were 2 different diseases. Latent class analysis supported these results. The shape of stenotic lesions in the subclavian and carotid arteries is a useful discriminator between TAK and GCA.
Keywords: GIANT CELL ARTERITIS; IMAGING; LATENT CLASS ANALYSIS; PHENOTYPE; PROGNOSIS; TAKAYASU ARTERITIS.