Unambiguous trial identification

Clinical trials usually involve participants from more than one institution, and often more than one country. As each country will have its own requirements for clinical trials research conducted within its borders it is possible that single trials could be included on more than one registry, and hence appear on more than one registry database. A further complication is that the data appearing on each registry database about a single trial may differ: for example, the trial title or the countries of recruitment may have been entered differently, or one record may be more up to date than another.