 Data collection Research coordinators of individual participating hospital will collect the required data on the case report form. However, the data was de-named and special security code was required to access the data. To facilitate the communications between investigators, the case report form was written in Chinese. The primary research institute is responsible for collecting and checking the data of all centers; and will contact the co-investigators in various centers for checking or revising should they had any question. The primary research institute has established an independent study quality control group to implement the disposal plan for all unexpected circumstances that may occur. 