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A common idea among some people in health ICT is that an EHR can be constructed as a series of accumulated messages. This idea seems particularly prevalent in government, for the obvious reason that if messages, which already exist, could be aggregated within a central database, nothing more would be needed to create an EHR. However, an inspection of what is needed in an EHR and what messages provide show that this is not the case. The following sections explain why.
Messages usually come from more than one source
In any most non-trivial health information environmentenvironments, messages come from multiple sources - at least typically multiple pathology laboratories. The general case is that each such source uses slightly (or maybe radically) different message structures to transmit the same similar information. Often the software at some sources implement a different version of the same message, while other sources use a different system of messaging altogether.
Clearly using a collection of such disparate as an EHR will not work. At a minimum, format, version and message system conversions would have to be made. Even when the same message structures are used, terminology differences (or lack of coding altogether) will often mean that similar messages cannot be processed in the same way.
Messages are change-based
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