Imaging is the major determinant in the assessment of disease activity in Takayasu's arteritis

Objective. There are no valid follow-up parameters in the assessment of disease activity in Takayasu's arteritis (TAK). We investigated the impact of vascular imaging in the assessment of disease activity. Methods. Patients TAK who fulfilled the ACR criteria were included. Physician global assessment (PGA), the criteria defined by Kerr et al. and the Indian Takayusu Clinical Activity Score (ITAS2010) were evaluated. Patients were followed up using 3-6 monthly B-mode/Doppler ultrasonography (US) and 6-12 monthly magnetic resonance imaginglangiography (MRI/MRA). Active disease according to vascular imaging (Rad-Active) was defined based on the presence of any of the 3 parameters: (1) new vessel involvement by any imaging technique; (2) an increase in vessel wall thickness on US compared to previous one; (3) the presence of mural contrast enhancement/oedema on MRI/MRA. The agreement of Rad-Active with other disease activity indexes was studied. Furthermore, ITAS-A-Rad index was developed by combining the vascular imaging with ITAS-A. Results. A total of 410 visits in 52 patients were evaluated. The agreement was found to be 76% (kappa: 0.52) between Rad-Active and PGA; 83% (kappa: 057) between Rad-Active and Kerr criteria. Both the agreements of ITAS2010 and acute phase reactants with PGA (69%, kappa:038 and 60%, kappa:022, respectively) and also Kerr's criteria (78%, kappa:0.49 and 42%, kappa:0.05, respectively) were lower compared to those of Rad-Active. Mean ITAS-A-Rad scores were higher in visits with active disease according to PGA and Kerr's criteria. Conclusion. The results of this study suggest that the vascular imaging should be included in the assessment of disease activity in TAK.