Prevention Status Extension

Canonical	../StructureDefinition/nexus-emr-prevention-status-extension
Status	draft (experimental) · 1.26.0
Base	Extension (constraint)
Context	Observation (element)
Source	FSH · JSON

The Nexus EMR Preventions product status for a screening or other prevention Observation.

FSH

The authored source of truth: extensions/PreventionStatusExtension.fsh (edit on GitHub). One FSH file may define several related artifacts.

// PreventionStatusExtension.fsh
// Carries the Nexus EMR Preventions product status (Completed | Completed Externally | Refused)
// on screening/other prevention Observations, where FHIR's required Observation.status binding
// cannot distinguish completed-externally from completed, nor represent refusal-as-declined.
// Context is Observation ONLY — Immunization represents all three product statuses natively
// (status + primarySource/reportOrigin/statusReason), so it carries no extension.
// Scoping rationale: PSD-465 / FHIR-23 / Preventions SDD Decision 2.

Extension: PreventionStatusExtension
Id: nexus-emr-prevention-status-extension
Title: "Prevention Status Extension"
Description: """
The Nexus EMR Preventions product status for a screening or other prevention `Observation`.

`Observation.status` has a required binding and cannot carry the product's three-value set:
**Completed** and **Completed Externally** both derive to `final`, which PRD 02.04 requires tracked
distinctly, and **Refused** derives to `cancelled`, which misstates patient-declined intent.

This extension preserves the product value verbatim; the native status remains the best-effort
interop derivation (completed → final, completed-externally → final, refused → cancelled).

**Precedence:** a native `status` of `entered-in-error` -- the retraction path -- overrides this
extension unconditionally. Readers use the extension when present and derive from native elements
when absent, since pipeline-sourced resources will not carry it.

`Immunization` is intentionally out of context: all three product statuses round-trip from its
native elements.
"""
* ^url = "../StructureDefinition/nexus-emr-prevention-status-extension"
* ^status = #draft
* ^experimental = true
* ^date = "2026-07-28"
* ^publisher = "WELLSTAR Technologies Corp."
* ^contact.name = "Nexus EMR FHIR Implementation Guide"
* ^contact.telecom.system = #url
* ^contact.telecom.value = ".."
* ^jurisdiction = urn:iso:std:iso:3166#CA "Canada"
* ^context[0].type = #element
* ^context[0].expression = "Observation"
* . ^short = "Nexus Preventions product status (completed | completed-externally | refused)"
* . ^definition = """
The product-level prevention status as chosen by the user in the Nexus EMR Preventions module. Values:

- `completed` = performed/administered at this clinic
- `completed-externally` = performed outside this clinic (functionally equivalent to completed for most reporting; tracked distinctly per PRD 02.04)
- `refused` = the patient declined — a decided, concluded state (not "pending"; the Preventions module records no not-yet-happened events, per the 2026-07-28 governance ruling)

Used in combination with (not instead of) FHIR `Observation.status`. Native `entered-in-error` overrides this extension.
"""
* extension 0..0
* url 1..1
* value[x] 1..1 MS
* value[x] only code
* valueCode from NexusEmrPreventionStatusVS (required)
* valueCode ^short = "Nexus prevention status code (one of the 3 codes in NexusEmrPreventionStatusCS)"

// ValueSet for the 3 Nexus prevention status codes
ValueSet: NexusEmrPreventionStatusVS
Id: nexus-emr-prevention-status-vs
Title: "Prevention Status Value Set"
Description: "The 3 Nexus EMR Preventions product status codes (Pending was cut from phase-1 scope, 2026-07-28)."
* ^status = #draft
* ^experimental = true
* ^url = "../ValueSet/nexus-emr-prevention-status-vs"
* include codes from system NexusEmrPreventionStatusCS

CodeSystem: NexusEmrPreventionStatusCS
Id: nexus-emr-prevention-status-cs
Title: "Prevention Status Code System"
Description: "Nexus EMR Preventions product status codes (PRD: Preventions Phase 1, §02.04, as amended by the 2026-07-28 scope decision removing Pending)."
* ^url = "../CodeSystem/nexus-emr-prevention-status-cs"
* ^status = #draft
* ^experimental = true
* ^caseSensitive = true
* ^content = #complete
* #completed "Completed" "The prevention was performed/administered at this clinic. Native derivation: Observation.status = final."
* #completed-externally "Completed Externally" "The prevention was performed outside this clinic (external/remote provider). Functionally equivalent to completed for most reporting; tracked distinctly for in-depth reporting and automations. Native derivation: Observation.status = final. Analogous to Immunization.primarySource = false / reportOrigin (the Observation equivalent of a non-primary source); the external performer or source MAY additionally be carried via Observation.performer or a Provenance."
* #refused "Refused" "The patient declined the prevention — a decided, concluded state. Native derivation: Observation.status = cancelled (best-effort; this extension is the source of truth for refusal-as-declined)."