Green CDA has been getting a lot of buzz lately, so I figure it's time for me to add my two bits to the discussion. First of all, this is a research project by HL7 to determine how to simplify CDA. The first part of this project is to explore what [human] processes can be used to enable simple expression concepts described in the CCD implementation guide. It's also an 80% solution that doesn't cover all the complexity supported by CDA or CCD. Getting past the 80% solution to a full solution is the eventual goal, but that IS NOT IN the scope of Green CDA project in HL7.
If "Green" development continues to require human intervention to "Green" other CDA implementation guides, Green CDA will suffer the same problems that other efforts have. Green CDA is one example of a μ-ITS on some of the CCD templates, but there are over 500 templates that have been developed for CDA alone, an only a 10th of these are CCD templates, and not all of those are found in Green CDA. Green will not scale through manual efforts alone, and the complexity of the information will cause incompatibilities across different "Green" efforts. Been there, done that, and have no desire to do it again.
So, the other leg of this research is to examine how the manual processes used to develop Green CDA can be automated through the development of a framework (and governance model) for creating a μ-ITS on an HL7 model that uses templates. Because of the large number of templates involved, we also need a template registry (another HL7 project) to enable access to all of the template development that's been generated over the past 5 years in HL7, IHE, HITSP, Health Story and epSOS, just to name a quick handful.
In The Standards Value Chain, Glenn Marshall does an excellent job of explaining the process of developing and implementing standards, and the related time frames. Green CDA isn't a solution that's just around the corner. Gestation of a new standard isn't sped up by setting unrealistic goals or adding new mothers to help give it birth.
The key concept in CDA after human readable narrative is the clinical statement. This is a sentence in a machine readable language. It turns out that machine readability of this language is not quite as important as human understandibilty for implementors (it took me three years to learn to speak it). Fixing that is going to require invention a new language that works for both audiences. Research and time are required, as well as technology that can simplify the XML and still support the rich information model needed for clinical decision support. After all, if we can exchange the information, but cannot compute with it, we've defeated the purpose of the computable clinical statement altogether.
Healthcare is hard. Making hard problems easy to solve is an even harder problem. Don't expect a miracle this week, this month or even this year. Just give it some time, and it will happen. Continue to watch this space if you want to observe some of the birthing pains.