2.1. Study population
We designed a retrospective study recruiting 190 subjects with TA diagnosed according to the criteria of the American College of Rheumatology (ACR).11 All TA patients were screened in Beijing Anzhen Hospital between September 2015 and August 2019. Patients who had other autoimmune diseases were excluded.154 healthy unrelated age- and sex-matched controls without any history of chronic disease were recruited during their physical examinations. Disease activity was assessed in patients with TA based on the National Institutes of Health (NIH) criteria proposed by Kerr et al.12 Clinical classification of TA (I, IIa, IIb, III, IV and V) patients was according to the Numano criteria by catheterography or computed tomography angiography (CTA).13,14 Written informed consent was obtained from all study participants. The study was approved by the Ethical Committee of Beijing Anzhen Hospital, Capital Medical University.