Stream: cda to fhir
Topic: comparisons
Jeffrey A. Ford (Jul 06 2018 at 15:15):
I am a complete beginner to all things HL7 and I have been tasked with comparing the FHIR and CDA standards. FHIR is described as a "flexible" application due to the RESTful interface and CDA is static with its read-only structure. While both provide XML document production of patient information exchange and both can interact with external code systems, why would you talk a tried and true CDA user into changing to FHIR? or would you? Your thoughts are most welcomed. Thanks.
Lloyd McKenzie (Jul 06 2018 at 16:03):
CDA isn't read-only per se. CDA documents can be created and, in some cases, updated. However you're correct that they're typically more static than a RESTful interface. It's important to note that FHIR isn't just a RESTful interface - with FHIR you can do messaging, documents and other types of exchange as well as REST. So there isn't anything that CDA can do that FHIR can't do from an architecture perspective. (But there are lots of things FHIR can do that CDA can't do.)
If the comparison is documents vs. REST, Documents give you tight control over human readability with a specific table of contents to navigate the data and strict expectations around rendering. It's also a robust mechanism for persistence where there's an expectation that systems will store all of the data unchanged. It does require more negotiation around interoperability because there's a need to decide what the table of contents should look like and what data should be in the document vs. handled as external references. REST gives you lighter-weight interoperability with minimal negotiation. It also gives you query capabilities, better ability to drive and control workflow, etc.
From a syntax and tooling perspective, FHIR is easier for implementers to work with. It's easier to read, easier to write code for, etc. However, CDA has been around for longer, and in some places, has much deeper market penetration. In a few places, it's mandated by regulation.
There's work underway to support conversion between FHIR and CCDA (which is a lot of what this stream is about)
Jeffrey A. Ford (Jul 06 2018 at 16:58):
Great! Thanks for the isightful answer. Especially with the mandated via regulation in certain areas. I continue to get my head around where the CDA meets a better use case than FHIR in excanging healthcare attachments/documents. not necessarily messaging per se.
Lloyd McKenzie (Jul 06 2018 at 18:17):
There shouldn't be a situation where CDA meets the use-case better than FHIR because FHIR documents can do everything CDA can do (while being easier to read/implement). The primary reason to go with CDA rather than FHIR would be the support within the implementer community and/or the regulatory requirements. If all of your partners know how to consume CDA and don't know how to consume FHIR, you're going to want to spit out CDA. (Though some implementers might choose to create CDA internally and then convert for external consumption.)
Jeffrey A. Ford (Jul 07 2018 at 14:25):
Great information. Thanks for clearing that up for me!
Last updated: Apr 12 2022 at 19:14 UTC
