Multi-site participation of this registry project will be rolled out in stages, and will be offered to centres with appropriate expertise. Pilot countries included Australia, Korea, Taiwan, Singapore, Malaysia, Japan, Thailand and Turkey and sites will be selected based on their potential research (interest, resources, and expected patient volume). Additional sites may be added in the future from countries in Asia Pacific, Middle East and Latin America. Japan has an independent national ITP registry run by the government, however voluntary participation of interested Japanese investigators in this database will be welcomed, therefore allowing comparison of data between Japanese and non-Japanese patients.