Data variables have been added for internal quality and integrity checks. If any component of the required mandatory data elements are missing, or any of the validation roles of logic aren't meet, the data will be automatically rejected. In order to audit the accuracy of in-hospital data, the investigators randomly select 10-20% of each participating sites' in-hospital data, and require the coordinators to scan the coordinating medical record, and transferred to NCC using encryption flash drive. 2 physicians from NCC abstract all medical record data independently, and compare the data between NCC data abstraction and coordinators' database. The accuracy report of each sites are fed back to each participating site yearly. The on-site auditing are conducted once a year for each site. The main aim of on-site auditing is to ensure the consecutiveness of data registry. The investigators randomly select a period of time to check original record of surgery, and abstract data regarding patient ID and in-hospital outcomes. Any mismatch of auditing data with submitting data will be reported to NCC and participating sites.