The debate of Green CDA on the wire (both within HL7 and without) is something I've discussed previously.
If you read the HL7 project description for Green CDA, you'll see where it talks about how it is two things:
- A description of a process to produce an XML-based API for creating CDA documents
- The output of executing that process (largely through manual efforts).
The process to date is a manual one, with the intention that there could be tools that support automation of it. This is one of the goals of the ONC sponsorship of the MDHT project, or was at least when they started. But right now, the only published "Green CDA" implementation is the one developed to demonstrate the process in the HL7 Implemenation Guide. I don't know where MDHT is at with respect to creating a "Green CDA" specification, but I suspect it is still a release or two away.
As a process, Green CDA is not well defined enough to enable automation. There will be a lot of discovery about what needs to be done to automate. As an implementation, the sample Green CDA implementation is OK for representing many HITSP C83 constructs, but isn't up to date with the CDA Consolidation guide. I'd hate to see us put more manual effort into creating another manual implementation, because it would really not move the industry forward.
Green CDA takes what HL7 learned from the CCR wars to heart, making the implementation of CDA easier for developers. But these days, I don't think it goes far enough. I have my own idea about what will make it easier for developers. I think we could even combine the "greening" of the models with the development of an HTML5-based CDA implementation that would be even easier for developers to understand and create.
I think the HIT SC either went too far, or not far enough. If we really are going to spend the next 9-12 months designing a format for the next generation of Health IT solutions that could be deployed under Meaningful Use Stage 3, why not take a significant leap forward, instead of remaining with what we have learned thus far. After all, if you are going to introduce "breaking incompatibilities" with current Health IT solutions, why not get something really worthwhile out of it.
I can think of nothing more interesting to work on (even Query Health is a distant second).
P.S. My own guess about the ONC response to the HIT SC Green CDA recommendation, which you can take with a grain of salt, is that the MU Stage 2 rule will NOT recommend Green CDA, but that it WILL reference the CDA Consolidation work. Let's come back to this in 3 months and see if I was right.
P.P.S. Now that CDA Consolidation guide is out in draft form, my next big project is a gap analysis between it, and the HITSP C32/C83/C80 set of documents.