MyHR: CDA or PDF?

Nov 22, 2018

Quoting from the story Sue Dunlevy wrote about John Halamka after his visit to Australia for Wild Health this week (paywalled):

The My Health record is a noble idea but the standard they chose is from 1995, it uses PDFs, it’s not computable, it is just digitised paper,” he told News Corp Australia

Technically, the MyHR is a document repository where the repository uses a modified variant of XDS (for the ‘personally controlled’ bit) and the documents are all CDA documents. A small number of the CDA documents are simply wrappers around PDF documents (<5%) but the rest are full CDA documents with variable amounts of coded data embedded in them (some quite comprehensive indeed).

In spite of the fact that it’s a repository of CDA documents, most of the commentary in the media describes them as PDF documents, and John’s comments reflect that - based on what people told him while he was here. 

So if the repository is full of CDA documents, why all the commentary about PDF? Actually, the answer is pretty simple: 

  • Consumers (patients) cannot get the CDA documents; all they can get is a print out of the presented part of the CDA document - that is, in effect, PDF (and probably is literally PDF, if they print to PDF)

Aside: I’m not sure why it would be such a problem for consumers to get their own data, but this is a long standing prohibition 

  • Clinicians can download the CDA documents directly to their systems, and the systems are able to extract the data from the CDA documents. But mostly, this doesn’t happen (for a variety of reasons), and all the clinician gets is a presented view of the CDA document, just like if it was PDF

  • The purpose of the system was to collate data, but the lack of solid data and clinical agreements have made that very hard to do, and the collation views that are offered are less useful than first intended - so they’re not very high profile. More generally, the system doesn’t support integrated data based work flows - it mostly behaves like a repository of PDF documents

  • Finally, the public (and journalists, and politicians) have an inherent understanding of PDF (all of us read them, and many of us produce them), and use imprecise language with regard to standards . “PDF-like” quickly transits to just simply “PDF”. This even happens in the general healthcare IT community

I’ve given up trying to dispute the language - programmers and analysts working directly with the system know better, but since the system mostly functions like a repository of PDF documents, I think there’s bigger things to focus on. 

But if you like precision in your language… the MyHR is a CDA based system, not a PDF based system.