Measure developers should review the Using CQL with FHIR IG for specific guidance on CQL use. Please note the following exceptions that guidance listed below:

Libraries

For information on libraries, please reference section 2.1 in the Using CQL with FHIR IG.

1. In addition to the conformance statements listed in section 2.1 of the Using CQL with FHIR IG, these two additional conformance statements need to be considered:

Library Versioning

This IG recommends an approach to versioning libraries used in section 2.2 of the Using CQL with FHIR IG.

Library Namespaces

For guidance on library namespaces, refer to section 2.1.3 of the Using CQL with FHIR IG.

Data Model

CQL can be used with any data model. In the context of a Measure, any referenced CQL library must identify the same data model. Additional information can be found in the Using CQL with FHIR IG.

Code Systems

Please reference the Using CQL with FHIR IG Section 2.3.

Value Sets

For information on value sets, reference section 2.4 of the Using CQL with FHIR IG.

Value Set Version

Information on value set versioning can be found in the Using CQL with FHIR IG.

Value Set Expansion

For information on value set expansion, reference the Using CQL with FHIR IG section 2.4.2.

Representation in a Library

The representation of valueset declarations in a Library is discussed in the Measure Conformance Chapter of this IG.

String-based Membership Testing

Please reference section 2.4.4 of the Using CQL with FHIR IG.

Codes

Please reference section 2.5 of the Using CQL with FHIR IG.

Representation in a Library

Please reference section 2.5.1 of the Using CQL with FHIR IG.

The representation of code declarations in a Library is discussed in Measure Conformance Chapter of this IG.

UCUM Best Practices

Please reference section 2.6 of the Using CQL with FHIR IG.

Concepts

Please reference section 2.7 of the Using CQL with FHIR IG

Library-level Identifiers

Please reference section 2.8 of the Using CQL with FHIR IG.

Data Type Names

Please reference section 2.9 of the Using CQL with FHIR IG.

For information on Missing information and how to model that using CQL, please reference section 2.10 of the Using CQL with FHIR IG.

Negation in FHIR

For information on the various uses of negation in FHIR, please review section 2.11 of the Using CQL with FHIR IG.

Attribute Names

All attributes referenced in the CQL follow Conformance Requirement 4.15.

Conformance Requirement 4-15 (Attribute Names):

1. Data model attributes referenced in the CQL:
   a. SHALL NOT Use quoted identifiers
   b. SHALL Use camelCase

Examples of attributes conforming to Conformance Requirement 4.15 are given below. For a full list of valid of attributes, refer to an appropriate data model specification such as QI-Core.

period
authoredOn
result

Aliases and Argument Names

Please reference section 2.13 of the Using CQL with FHIR IG.

Library Resources

Please reference the Using CQL with FHIR IG section 2.14.1.

In addition, please consider the following conformance statement:

Conformance Requirement 4.17 (Library Resources):

1. Content conforming to this implementation guide SHALL use at least the CQLLibrary and CRMIShareableLibrary profile for Library resources. If the library is active and published, conform to CRMIPublishableLibrary.

FHIR Type Mapping

Please refer to section 2.14.2 of the Using CQL with FHIR IG.

Parameters and Data Requirements

Please reference section 2.14.3 of the Using CQL with FHIR IG

RelatedArtifacts

Please reference section 2.14.4 of the Using CQL with FHIR IG.

MIME Type version

Please reference section 2.14.5 of the Using CQL with FHIR IG.

Use of Terminologies

Please reference section 2.15 of the Using CQL with FHIR IG

Time Valued Quantities

Please reference section 2.16 of the Using CQL with FHIR IG.

Translation to ELM

Please reference section 2.17 of the Using CQL with FHIR IG.

Specifying Options

This implementation guide references the cqlOptions extension to support defining the expected translator options used with a given Library, or set of Libraries. When this extension is not used, the recommended options above, including SignatureLevel, SHOULD be used. When this extension is present on a CQLLibrary, it SHALL be used to provide options to the translator when translating CQL for that library. When this extension is present on a CRMIManifestLibrary, it SHALL be used to provide options to the translator unless the options are provided directly by the library.

Conformance Requirement 4.22 (Translator Options):

1. Translator options SHOULD be provided in either a CRMIComputableLibrary or a CRMIManifestLibrary.
2. Translator options specified in a CRMIComputableLibrary take precedence over options defined in a CRMIManifestLibrary.
3. If no translator options are provided, the recommended options above SHOULD be used.
4. If translator options are provided in a Library that is both computable and executable, the options SHALL be consistent with the translator options reported by the ELM content.

ELM Suitability

Please refer to section 2.17.2 of the Using CQL with FHIR IG.