This is the current version of the PS-CA Implementation Guide. Other releases of the PS-CA Implementation Guide may be found at Guides.

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 rendering of base cardinalities on elements with profiled data types

    On profiles viewed directly through Simplifier pages (instead of through this guide) the renderer will artificially render differences that are carried over from the data type but not present in differential.

    One example of this is the visualization of a 0..1 cardinality for reaction.manifestation which has a base cardinality of 1..1.

    Implementers are strongly encouraged to review the profiles within the IGuide pages and to check the JSON/XML structureDefinition if there is a question of a change in cardinality from the profiles.

  2. Simplifier rendering of bindings on medicationReference

    Bindings from the parent element in MedicationStatement.medication(x) and MedicationRequest.medication(x) are being rendered on top of medicationReference slices to show the SCT example value set that the Base FHIR standard applies to the medication element. These slices notably should not have any binding as they are a reference.

  3. Validation Tooling - Expanding Value Sets / Intersectional Value Sets

    There are two tooling issues leading to IPS value sets not being expanded and validated against by current FHIR tools:

    1. The is a current limitation in Simplifier validation tooling to perform expansion and filter capabilities that are necessary for the validator to determine if a slice is met on loaded examples.
    2. More broadly, there is a known issue with the FHIR Validator Tooling/FHIR terminology server that the validator uses (tx.fhir.org) not supporting value sets that combine multiple value sets and/or apply filters as part of the sequence for defining the value set (an approach IPS uses for many of its value sets).
      • After this fix is applied, Implementers will be able to validate the examples including IPS value sets against the FHIR Validator GUI - IG Package is loaded and can be validated against by selecting "Options" and then choosing "https://packages.simplifier.net/ca.infoway.io.psca" from the dropdown of Implementation Guides.

  4. 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.

    Note: The IPS Free Set Value Sets canonical urls have been included in this release but for a short period of time will be unresolvable until they are published at their canonical url.

  5. 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

  6. 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.

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.

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

  3. Simplifier rendering of certain extensions

    Simplifier fails to display extensions applied to elements with a choice data type. The following issues have been raised to the Firely team and are awaiting resolution.

  4. Overlapping ValueSet Slicing with IPS Terminology

    This specification surfaces the SNOMED CT IPS Free Set value sets that have been identified by IPS for the purposes of providing implementers with early insights into the terminologies that are being promoted for international exchange use cases. In some cases, where there has been a SNOMED CT CA value set identified as the Proposed Pan-Canadian Value Set, there is a conflict in coverage of concepts between the two slices. This occurs with the ProblemsSnomedCtIpsFreeSet, AllergyIntoleranceIPSFreeSet, and the AllergyReactionIPSFreeSet value sets.

    The current modeling of the published IPS Free Set value sets creates challenges in the ability for validators to differentiate between the slices (even when value set exclusions are defined). In order to ensure proper validation against Canadian terminology in this release, any IPS Free Set slices that are in conflict with a SCTCA slice have been removed.

    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 IPS Free Set concepts and SNOMED CT Canadian Edition concepts, and no way to distinguish which slice the code is supposed to match.

    Note: The above resolution has been applied to noted overlapping IPS Free Set ValueSets in PS-CA versions 0.3.0 and later.