Known Issues & Future Development

This Implementation Guide is part of a public comment release of the PS-CA Specification, intended for review, socialization, and feedback in preparation of PS-CA Version 1.0 for Trial implementation. During development several issues were detected that could not be resolved in time prior to publication; issues with multiple—but no "best"—solutions possible; and issues with conflicting guidance. Some of those issues are listed below. Open issues are those for which no decision has been made, are pending feedback, or, for which there is an outstanding action. Issues are marked as close when a decision has been made, or the issue resolved.

Feedback is requested on both open and closed issues. Instructions for feedback submission can be found at Specification Feedback.

Open Issues

  1. Simplifier fails to display certain extensions

    Simplifier fails to display extensions applied to elements with a choice data type.

    The issue has been raised to the Firely team and is awaiting resolution.

  2. Referenced ValueSets and CodeSystems are not resolvable.

    Some referenced ValueSets are not available at their canonical URL; some (particularly Canada-specific) ValueSets are not on the terminology servers used in IG publication (i.e. tx.fhir.org). Some referenced ValueSets are not currently available as FHIR R4 and may require conversion before use. Primarily, these issues impact validation against Canada Health Infoway-hosted ValueSets during development of derived Implementation Guides. (This doesn't affect deployed systems, since, in that environment, instances will be validated against locally present value sets.) For several of these ValueSets, "stub" resources have been created to stand-in within this Implementation Guide for the unresolvable ValueSets.

    Current guidance is to manually download the referenced value sets from, for example, the Terminology Gateway. Investigation is needed to determine if the problem ValueSets can be made "resolvable" through Infoway, or if they can be added to the standard terminology servers.

  3. Must Support relaxation

    Several elements flagged as Must Support in IPS-UV are not flagged in PS-CA due to feedback received about jurisdictional support. These elements are called out on relevant profile pages in this implementation guide. Feedback is requested about:

    • Whether it was appropriate to relax the Must Support requirement for these specific elements
    • Whether Must Support should be relaxed or added on additional elements
  4. Approach for Sections that IPS Requires (Medication, Allergy, Problem)

    IPS-UV requires a minimum cardinality of 1 on this section to ensure it is always populated with some kind of entry. This constraint has been maintained in the PS-CA. However, an experimental pattern has been developed for systems that wholistically cannot produce content for the profiles in these sections at the time of Version 1.0 of this specification. See discussion on Profiling Conventions and Approach and see Content Not Supported Profiles (PS-CA).

    This pattern is considered a temporary measure to allow for patient summaries to be exchanged in Canada (and internationally) while some systems work to meet the expectations for the full set of patient summary sections.

    Note: Feedback is requested on the support of this pattern from the vendor/solution community to determine feasibility. This approach is likely to evolve as Canada and other national implementations work with the IPS-UV team to identify a pattern for national implementors to account for differing levels of domain prioritization early on in adoption.

  5. Overlapping ValueSet Slicing

    The approach used for slicing of certain Codings and CodeableConcepts may fail validation when a code matches multiple slices. For example, there is overlap between some SNOMED CT GPS concepts and SNOMED CT Canadian Edition concepts, and no way to distinguish which slice the code is supposed to match. A resolution for this issue has not been determined, but it may involve tighter (non-overlapping) definition of the ValueSets defined in this implementation guide.

    Note: In PS-CA version 0.0.4, the above resolution has been applied to certain overlapping ValueSets.

Closed Issues

  1. Extension Slicing

    IPS-UV appears to have issues in how extensions are implemented. For consistency, this pattern was copied into PS-CA for:

    The issue has been raised with IPS and we are awaiting feedback on their direction so as to stay aligned.

    Following discussion with the HL7® IPS team, we have adopted the correction that is expected in the next release of FHIR® IPS.

  2. Simplifier requires packages for dependencies

    Simplifier cannot resolve references to external profiles or extensions that have not been published as a package. This primarily impacts CA Baseline profiles and extensions used within PS-CA.

    Investigation is needed to determine if this is a Simplifier issue, or if a package is needed for CA Baseline.

    A FHIR package for CA baseline has been created which PS-CA declares a formal dependency on.