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FHIR® & CQL - A Primer

(#2 in a series of 4 blogs that preview Track 3 of the 2021 Digital Quality Summit sessions.) 

In this second session, Anne-Marie Smith (NCQA) and Linda Michaelsen (Optum, representing the HL7 DaVinci project) take a deeper dive into the digital Breast Cancer Screening Measure to explain the two most important standards/technologies underlying digital quality measures: FHIR and CQL. Both are HL7 defined and maintained. 

Let’s start by looking at FHIR, which is pronounced “fire” and stands for “Fast Healthcare Interoperability Resource(s).” FHIR defines the content (data format) in discrete portions—“Resources”—which allows exchange of only the data needed. FHIR also makes use of modern transports like RESTful API technologies, which are widely used and adopted in web-based technologies across many industries. 

FHIR is a third-generation interface standard defined by HL7 (the second generation includes concepts and documents such as CDA, CCD, CCDA). It is also justified at having “Fast” in its name: It is fast in a programmatic/operational sense (APIs are essentially real-time interfaces) and adoption by the programming community is almost effortless because it leverages widely used technologies and concepts, including XML and JSON. 

CQL stands for “Clinical Quality Language.” CQL is used to write measure logic and define other important aspects of a quality measure. It is easy to read and understand because it leverages other concepts like data models (e.g., FHIR), common helper libraries and value sets, which provide a powerful standards-based foundation for CQL, allowing its syntax to “hide” much of its
complexity and letting the measure developer focus on the measure-specific aspects. 

What is FHIR-CQL? In this context, “FHIR” refers to the data model that CQL uses. Until now, there was QDM—another widely used data model—but the industry is clearly moving toward FHIR-CQL, which has significant advantages. 

After FHIR and CQL are thoroughly explored in Session 3, we’ll be ready to explore the dQM roadmap and digital measure operations in Session 4. More in the upcoming blog! 

Additional Resources: 

Overview - FHIR v4.0.1 ( 

Understanding FHIR-CQL ( 

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