Retention of the Electronic Medical Record (EMR) needs to be differentiated from data migration. The latter is one method of retaining data. For a paper-based record, retention means keeping it for a desired period of time in its original structure. By ensuring that the structure is intact, the original content is also preserved.
Retaining the EMR poses peculiar problems. First of all, the structure and content of the EMR need to be more clearly defined if it is to be retained. Even though many software providers name their applications as EMR, they are actually providing a system to facilitate clinicians to perform clinical care activities i.e. an application more appropriately named the Clinical Information System (CIS). The CIS contains a lot more data that what constitutes the EMR. No software developers in their right mind would develop systems just for the recording of events or incidents.
There are 3 purposes for which data need to be retained:

1. Business continuity
2. Continuity of care
3. Preservation of a historical record

The continuity of care problem that emerges when a changeover to new system occurs is similar to the situation that exists when a patient is referred to another institution (using a different system) where the care provider provides sufficient information to his/her counterpart to enable continuity of care. Such information consists of  a letter and a summary of all events, findings and results for all visits made in the referring facility. For most instances in an electronic system, it is adequate to provide a summary of historical data regarding all events, findings and results for all visits made rather than carrying over the entire data contained in the CIS or Medical Record. The summary is actually a report created by extracting historical data from the database. It is quite possible to extract the entire data making up the Medical Record but for continuity of care this is quite unnecessary.
Data migration is essential only in instances where the critical points in the clinical care process, i.e. the clarification of diagnosis and firming up of the treatment plan, has not been sorted out. In cases where the definite diagnosis has been made and the treatment plan has been decided on, a case summary would be sufficient to enable the subsequent care provider to gain an insight on what had transpired earlier.
On the other hand, preservation of Medical Record for a certain duration is required by law. It would be simple if it is already created for each patient at each visit. Unfortunately, very few if any HIS have a built in facility to extract and present the EMR at the end of a visit. Most CIS (or even the so called ‘Electronic Medical Record System’) do not have this capability. Most institutions or software developers think that in order to preserve the Medical Record, the entire CIS need to be retained. I am advocating here that the EMR being a record need only be preserved in the form of a readable document created from a report extracted from the CIS. So, efforts should be made to define the data elements that make up the EMR, standardize its structure (sequence and arrangement) and develop the means of constructing it.
Read more about this subject in my article