1. Department of Rheumatology and Immunology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100069, P.R. China
2. Department of Rheumatology, First Affiliated Hospital of Baotou Medical College, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, P.R. China
3. Department of Rheumatology and Immunology, Fu Xing Hospital, Capital Medical University, Beijing 100038, P.R. China