1. Department of Neurology and Multiple Sclerosis Research Center Third Affiliated Hospital Sun Yat‐sen University GuangzhouChina
2. Department of Neurology Fifth Affiliated Hospital Sun Yat‐sen University Zhuhai China
3. Department of Biostatistics, Epidemiology and Informatics University of Pennsylvania Philadelphia PA USA
4. Department of Neurology Second People's Hospital of Foshan Foshan China