I’ve known about FHIRPath for some time, though I must admit I haven’t paid a lot of attention to it.

Put briefly, FHIRPath is a specification that describes how to identify (and potentially extract) data from a resource using a path based syntax. From the spec:

Of particular importance is the ability to easily and precisely express conditions of basic logic, such as those found in requirements constraints (e.g. Patients must have a name), decision support (e.g. if the patient has diabetes and has not had a recent comprehensive foot exam), cohort definitions (e.g. All male patients aged 60-75), protocol descriptions (e.g. if the specimen has tested positive for the presence of sodium), and numerous other environments.

with these features:

  • Graph-traversal: FHIRPath is a graph-traversal language; authors can clearly and concisely express graph traversal on hierarchical information models (e.g. HL7 V3, FHIR, vMR, CIMI, and QDM).
  • Fluent: FHIRPath has a syntax based on the Fluent Interface pattern
  • Collection-centric: FHIRPath deals with all values as collections, allowing it to easily deal with information models with repeating elements.
  • Platform-independent: FHIRPath is a conceptual and logical specification that can be implemented in any platform.
  • Model-independent: FHIRPath deals with data as an abstract model, allowing it to be used with any information model.

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Implementation Guide viewer

Just a short post to describe some updates to the Implementation Guide viewer (which I’ve renamed from ‘profile viewer’ as it was described in this post.) Thanks to some comments in the FHIR chat from my friend John Moehrke I’ve done some work on the ‘Graph visualizer’ component of the viewer.

The idea is to make it easier to understand the contents of an Implementation Guide, and the relationships between them. Currently limited to Profiles, Extensions & ValueSets – but no reason why it couldn’t be extended (or won’t be 🙂 ).

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‘Extending’ a ValueSet in a profile

In the last post we talked about ValueSets and CodeSystems – and in particular how the ValueSet can be thought of as the set of possible values from one or more CodeSystems for a particular element in a given context.

As you know, the spec provides ValueSets and bindings for all coded elements, and a common need when profiling is likely to be to ‘extend’ the set of possible values – take the contents already in the ValueSet and add others. What’s the best pattern to do that?

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‘Default’ namespaces in HL7 v2

So I had an interesting question this week about coded values when importing data from HL7 v2 messages into a data store, and then subsequently exporting them in FHIR interfaces.

The specific question was what should the ‘default’ namespace be when the namespace is not specified in the v2 message?

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EU Data Protection

Great post from Rene Spronk on the European Union GDPR (General Data Protection Regulation) standards in the context of healthcare interoperability…

clinFHIR profile viewer

Over the years I’ve made a number of attempts to build a profile viewer – to a mixed amount of success. The issue is becoming more urgent though, as profiles (as part of Implementation Guides) start to become published, and vendors such as Orion Health need to think about how we are to support them.

The issue is even more important for vendors in the international space, as our solutions are going to have to support different profiles in different countries, and we cannot assume that the profiles will be in alignment even for the same concept.

We’re not going to solve that issue right now (though it does highlight that the developers of profiles need to be aware of it and ideally working to avoid it as much as possible), but the ability to view profiles from different jurisdictions and analyse them in a common way is going to be important. Read more of this post

Changing a ValueSet in a profile

I learned something today.

Actually, most days I do learn something (and occasionally remember it later on) but this one is worth recording here.

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