FHIRPath

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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Using Scenario Builder for developing Resources

I had an email this morning from the organizers of the ‘Clinicians On FHIR’ event at the upcoming Working Group Meeting asking if it was possible to use the Scenario Builder to examine a resource type that had been altered after publication (i.e. one that was being worked on for the next release of FHIR – R4). As it turns out, this is quite straightforward to do – albeit with some limitations.

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Adding extensions to a resource

So a colleague of mine asked me this morning if the clinFHIR scenario builder supported modifier extensions.

If you’re not familiar with these, they are extensions that actually change the meaning of the resource to which they are attached. For example, if you wanted to indicate that a patient did not have a particular condition, then you could attach a ‘negation’ extension to the Condition to indicate that you looked for – but did not find – that particular condition. Or, a statement that indicates that a patient is not taking a particular medication.

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A complex scenario…

Bob Milius has kindly allowed me to share an example of a more complex genetics based scenario that he has built (by hand!) – you can download it from here.

To load it into clinFHIR, follow the steps I described in this post and you can then view it as a graph. Here’s an image:

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Import resources into clinFHIR Scenario Builder

Just a short note to let you know that I’ve added the ability to import resources directly into the clinFHIR Scenario Builder (people have asked about this for a while). There are 3 formats currently supported:

• A single Json resource
• A Json bundle
• An XML bundle

(Note that a single XML resource is not yet supported – just place it in a bundle if this is a problem right now)

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