We have just published a whitepaper on the use of Office Open XML in Health at the address below:

Using Office Open XML Formats to Support Electronic Health Records Portability and Health Industry Standards

Abstract: Empowering patients and consumers to exchange Electronic Health Records securely is a big debate in the health industry across the globe. Learn how to use Office Open XML Formats and custom XML formats to exchange data securely. This particular scenario shows the use of Health Level Seven (HL7) Clinical Document Architecture (CDA) to represent the Electronic Health Record in an industry standard format. It also shows how to include the data in a secured document, based on Office Open XML Formats, for portability across multiple care providers.

The paper comes with sample code that is very easy to install and test with minimal requirements on the machine to help illustrate the concept outlined in the whitepaper.

I also want to point out an entry on Oliver Bell's blog about a similar topic.