Quality Measure Implementation Guide
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Quality Measure Implementation Guide, published by HL7 International / Clinical Quality Information. This guide is not an authorized publication; it is the continuous build for version 1.0.1-cibuild built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/fhir-cqm/ and changes regularly. See the Directory of published versions

Extension: CQM Population Basis

Official URL: http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis Version: 1.0.0
Standards status: Trial-use Active as of 2026-03-03 Maturity Level: 4 Computable Name: CQMPopulationBasis
Other Identifiers: OID:2.16.840.1.113883.4.642.40.61.42.21

The population basis specifies the type of elements in the population. For a subject-based measure, this is boolean (because the subject and the population basis are the same, and the population criteria define yes/no values for each individual in the population). For measures that have a population basis that is different than the subject, this element specifies the type of the population basis. For example, an encounter-based measure has a subject of Patient and a population basis of Encounter, and the population criteria all return lists of Encounters. Note that the subject of a measure can be found in the element subject[x].

Context of Use

Usage info

Usages:

You can also check for usages in the FHIR IG Statistics

Formal Views of Extension Content

Description Differentials, Snapshots, and other representations.

NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
.. Extension C 0..* Extension What type of population
Constraints: popBasis-1
... url 1..1 uri "http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis"
... value[x] 0..1 Value of extension
Binding: FHIRAllTypes (required): The type of elements in the population
.... valueCode code
.... valueDataRequirement DataRequirement

doco Documentation for this format

Terminology Bindings (Differential)

Path Status Usage ValueSet Version Source
Extension.value[x] Base required FHIRAllTypes 📦4.0.1 FHIR Std.

Constraints

Id Grade Path(s) Description Expression
popBasis-1 error Extension If DataRequirement.type is present, it may only contain the elements 'profile' and 'codeFilter'. value.exists() and value.is(DataRequirement) implies ( value.as(DataRequirement).type.exists() and value.as(DataRequirement).limit.empty() and value.as(DataRequirement).sort.empty() and value.as(DataRequirement).dateFilter.empty() and value.as(DataRequirement).subject.empty() and value.as(DataRequirement).mustSupport.empty())
NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
.. Extension C 0..* Extension What type of population
Constraints: popBasis-1
... id 0..1 string Unique id for inter-element referencing
... extension 0..* Extension Additional content defined by implementations
Slice: Unordered, Open by value:url
... url 1..1 uri "http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis"
.... valueCode code
.... valueDataRequirement DataRequirement

doco Documentation for this format

Terminology Bindings

Path Status Usage ValueSet Version Source
Extension.value[x] Base required FHIRAllTypes 📦4.0.1 FHIR Std.

Constraints

Id Grade Path(s) Description Expression
ele-1 error **ALL** elements All FHIR elements must have a @value or children hasValue() or (children().count() > id.count())
ext-1 error **ALL** extensions Must have either extensions or value[x], not both extension.exists() != value.exists()
popBasis-1 error Extension If DataRequirement.type is present, it may only contain the elements 'profile' and 'codeFilter'. value.exists() and value.is(DataRequirement) implies ( value.as(DataRequirement).type.exists() and value.as(DataRequirement).limit.empty() and value.as(DataRequirement).sort.empty() and value.as(DataRequirement).dateFilter.empty() and value.as(DataRequirement).subject.empty() and value.as(DataRequirement).mustSupport.empty())

Summary

Simple Extension with the type code, DataRequirement: The population basis specifies the type of elements in the population. For a subject-based measure, this is boolean (because the subject and the population basis are the same, and the population criteria define yes/no values for each individual in the population). For measures that have a population basis that is different than the subject, this element specifies the type of the population basis. For example, an encounter-based measure has a subject of Patient and a population basis of Encounter, and the population criteria all return lists of Encounters. Note that the subject of a measure can be found in the element subject[x].

Maturity: 4

Differential ViewDifferential View

NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
.. Extension C 0..* Extension What type of population
Constraints: popBasis-1
... url 1..1 uri "http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis"
... value[x] 0..1 Value of extension
Binding: FHIRAllTypes (required): The type of elements in the population
.... valueCode code
.... valueDataRequirement DataRequirement

doco Documentation for this format

Terminology Bindings (Differential)

Path Status Usage ValueSet Version Source
Extension.value[x] Base required FHIRAllTypes 📦4.0.1 FHIR Std.

Constraints

Id Grade Path(s) Description Expression
popBasis-1 error Extension If DataRequirement.type is present, it may only contain the elements 'profile' and 'codeFilter'. value.exists() and value.is(DataRequirement) implies ( value.as(DataRequirement).type.exists() and value.as(DataRequirement).limit.empty() and value.as(DataRequirement).sort.empty() and value.as(DataRequirement).dateFilter.empty() and value.as(DataRequirement).subject.empty() and value.as(DataRequirement).mustSupport.empty())

Snapshot View

NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
.. Extension C 0..* Extension What type of population
Constraints: popBasis-1
... id 0..1 string Unique id for inter-element referencing
... extension 0..* Extension Additional content defined by implementations
Slice: Unordered, Open by value:url
... url 1..1 uri "http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis"
.... valueCode code
.... valueDataRequirement DataRequirement

doco Documentation for this format

Terminology Bindings

Path Status Usage ValueSet Version Source
Extension.value[x] Base required FHIRAllTypes 📦4.0.1 FHIR Std.

Constraints

Id Grade Path(s) Description Expression
ele-1 error **ALL** elements All FHIR elements must have a @value or children hasValue() or (children().count() > id.count())
ext-1 error **ALL** extensions Must have either extensions or value[x], not both extension.exists() != value.exists()
popBasis-1 error Extension If DataRequirement.type is present, it may only contain the elements 'profile' and 'codeFilter'. value.exists() and value.is(DataRequirement) implies ( value.as(DataRequirement).type.exists() and value.as(DataRequirement).limit.empty() and value.as(DataRequirement).sort.empty() and value.as(DataRequirement).dateFilter.empty() and value.as(DataRequirement).subject.empty() and value.as(DataRequirement).mustSupport.empty())

Summary

Simple Extension with the type code, DataRequirement: The population basis specifies the type of elements in the population. For a subject-based measure, this is boolean (because the subject and the population basis are the same, and the population criteria define yes/no values for each individual in the population). For measures that have a population basis that is different than the subject, this element specifies the type of the population basis. For example, an encounter-based measure has a subject of Patient and a population basis of Encounter, and the population criteria all return lists of Encounters. Note that the subject of a measure can be found in the element subject[x].

Maturity: 4

 

Other representations of profile: CSV, Excel, Schematron