The applicable regulations do not specify any particular file type for electronic documents. Therefore, the file type chosen for an export of an eTMF from a CRO for transfer to the sponsor should be according to whatever has been specified in the contractual agreement between both parties. It is strongly recommended that the transfer process is discussed and agreed BEFORE the study commences. This ensures the requirements of the sponsor for archiving can actually be met by the technology being used.
However, there are several factors to take into account when agreeing what file types should be transferred. If the originating system is maintaining documents in their original file type and are being converted to PDF prior to transfer, there are specific regulatory requirements that must be complied with for the migration of documents from one format to another (the EMA TMF guidance specifically refers to this). In addition, regulatory inspectors often wish to open the original document, particularly Excel files as it is easier to search and navigate the content than PDF files. Also bear in mind any non-Office file formats. For example, does the source eTMF include file formats that are dependent upon specific software that might not be available to the sponsor; in this case, conversion to an alternative standard file format might be preferable to ensure ongoing access and readability.