=Paper=
{{Paper
|id=Vol-2042/paper40
|storemode=property
|title=Developing a Semantic Web-based Framework for Executing the Clinical Quality Language Using FHIR
|pdfUrl=https://ceur-ws.org/Vol-2042/paper40.pdf
|volume=Vol-2042
|authors=Guoqian Jiang,Eric Prud’Hommeaux,Harold Solbrig
|dblpUrl=https://dblp.org/rec/conf/swat4ls/JiangPS17
}}
==Developing a Semantic Web-based Framework for Executing the Clinical Quality Language Using FHIR==
https://ceur-ws.org/Vol-2042/paper40.pdf
Developing A Semantic Web-based Framework for
Executing the Clinical Quality Language Using FHIR
Guoqian Jiang1, Eric Prud’Hommeaux2, Guohui Xiao3, and Harold R. Solbrig1
1
Mayo Clinic, Rochester, MN, 55905, USA
2
W3C/MIT, Cambridge, MA 02142, USA
3
Free University of Bozen-Bolzano, Bolzano, 39100, Italy
jiang.guoqian@mayo.edu
Abstract. The Clinical Quality Language (CQL) is a HL7 specification, aiming
to provide a human-readable language to define clinical quality measures and
decision support rules while it makes logic expressions independent of any spe-
cific data model (e.g., Quality Data Model, HL7 Fast Healthcare Interoperabil-
ity Resources – FHIR). FHIR adopts RDF as its third representa-
tion/interchange format in addition to XML and JSON, and uses the Shape Ex-
pressions (ShEx) schema to standardize and validate the FHIR RDF graphs. In
this presentation, we propose a Semantic Web-based framework that enables
the execution of CQL using the FHIR RDF technologies. The framework com-
prises the following four modules: 1) a CQL-to-SPARQL transformation mod-
ule; 2) a value set service module; 3) a FHIR RDF transformation module; and
4) a ShEx-based data validation module. We implemented a prototype to
demonstrate the utility of the framework and discussed the challenges and on-
going tasks.
Keywords: Clinical Quality Language, FHIR, RDF.
1 Introduction
Future advances in translational and precision medicine research will be increasingly
dependent on the creation of patient cohorts encompassing both highly detailed phe-
notypic and molecular data. The growth of electronic health records (EHRs) has been
recognized as a viable and efficient model for enabling translational and precision
medicine research1. The distinct advantages of EHRs include cost efficiency, large
amounts of available clinical data, and the ability to analyze data over time, however,
the data are highly complex, inaccurate and frequently missing. The healthcare infor-
matics community faces huge methodological and computational challenges in repur-
posing EHRs for translational and precision medicine research, with respect to stand-
ards-based data normalization, effective data integration and accurate phenotyping.
2
The Clinical Quality Language (CQL)2, 3 is a HL7 specification providing a human-
readable language to define clinical quality measures and decision support rules. As
the creation of EHR-driven phenotype algorithms shares many common requirements
with the definition of clinical quality measures/clinical decision support rules, there
are emerging interests in the clinical research informatics communities to explore the
CQL as a tool for the standard representation and execution of phenotype algorithms
(i.e., structured selection criteria designed to produce research-quality phenotypes)
driven by EHRs. Notably, the phenotype execution and modeling architecture (PhE-
MA)4 consortium has been looking into the standard representation and execution of
phenotype algorithms using CQL and related standards5.
HL7 Fast Healthcare Interoperability Resources (FHIR)6 is an emerging next-
generation standards framework for the exchange of electronic healthcare data. FHIR
adopted the Resource Description Framework (RDF) as its third representa-
tion/interchange format in addition to XML and JSON, and uses the Shape Expres-
sions (ShEx) schema to standardize the structure of FHIR RDF graphs7. The HL7
ITS/W3C RDF Task Force has made initial decisions how the FHIR RDF graphs look
like, and our team at Mayo Clinic reviewed the existing FHIR RDF decision docu-
ments and created a minimal set of elements, defined the FHIR ShEx transformation
rules for the elements. We implemented the FHIR ShEx transformation tools and
evaluated the utility of the FHIR ShEx schemas leveraging the ShEx validation tools
developed in the W3C ShEx community7. This enables promising opportunities for
the clinical research informatics communities to leverage existing semantic tools de-
veloped in the Semantic Web communities for standards-based data integration and
phenotype algorithm definition. The objective of this study is to propose a Semantic
Web-based framework for executing the CQL using FHIR to enable a next-generation
EHR-driven phenotyping infrastructure.
2 System Architecture
Fig. 1 shows a Semantic Web-based framework of executing the CQL over the FHIR
data using RDF technologies. The framework is comprised of the following four
modules: 1) a CQL-to-SPARQL transformation module; 2) a value set service mod-
ule; 3) a FHIR RDF transformation module; and 4) a ShEx-based data validation
module.
The CQL-to-SPARQL transformation module. CQL is designed to cover three
levels of representations. In the conceptual level, CQL is defined for authors to pro-
duce libraries containing human-readable yet precise logic. In the logic level, the
Expression Logic Model (ELM) is used for machine-friendly rendering of the CQL
logic. In the physical level, different implementation environments will be leveraged
to execute the ELM, in which the translation from ELM to target environment lan-
guage is needed. In this module, as our target environment language is the SPARQL
query language, a CQL-to-SPARQL transformation tool is needed for the CQL exe-
cution. The representation in ELM can provide the CQL parsing supports for type
verification, type inference and operator resolution, and process higher-level con-
structs like temporal patterns. There is a complete implementation of the CQL-to-
3
ELM Translator3, the API of which is utilized for parsing and processing CQL. The
Jena SPARQL API8 is used for building target SPARQL queries.
Fig. 1. The system architecture for executing CQL using the FHIR RDF technologies.
The value set service module. Value set is one of key CQL constructs, specifying
that logic within the CQL library may reference the specified value set by the given
name. For instance, the statement [valueset "Antibiotic Medications":
'2.16.840.1.113883.3.464.1003.196.12.1001' ] means the value set of antibiotic medi-
cations can by referenced by its name and resolved by its OID through external value
set services. By default, the Value Set Authority Center (VSAC)9 value set services
are recommended. In this module, a tool is developed to invoke the external VSAC
services and retrieve the coded values and associated metadata required for the
SPARQL query construction.
The FHIR RDF transformation module. As mentioned above, the FHIR RDF has
become part of the official FHIR STU3 release and a FHIR RDF transformation tool
has been incorporated into the FHIR building toolkit. Our team at Mayo Clinic is
actively developing tools that help the FHIR RDF transformation from either XML or
JSON formats. In addition, large volumes of clinical data are stored in the relational
databases and the tools (e.g., Ontop14) that support the execution of SPARQL queries
over relational databases can be leveraged to transform the relational data into the
FHIR-based RDF representation.
The ShEx-based data validation module. ShEx is a constraint language for formally
describing RDF structures and can serve the same role with RDF as that of XML
schema to XML. Validating an RDF node against a shape tests the adjacent nodes
against the constraints in the shape. As mentioned above, FHIR ShEx schemas have
become part of the official FHIR release. The FHIR ShEx transformation and valida-
tion tools will be leveraged and extended to support the data validation needs in exe-
cuting the CQL.
4
3 Prototype Implementation
We are actively implementing each module of the framework for executing the CQL-
based phenotype algorithms using the FHIR RDF technology. We have first examined
available FHIR-based CQL examples and identified a number of patterns for building
the SPARQL queries. Fig. 2 shows such a SPARQL pattern. The VSAC value set
services were invoked to retrieve the codes for two value sets “Acute Pharyngitis” and
“Acute Tonsillitis”, in which 17 and 19 codes (from the code systems SNOMED CT
and ICD-10-CM) were retrieved respectively. A Java-based program was developed
for transforming identified patterns from CQL to SPARQL while invoking the VSAC
value set services to retrieve coded values in a value set.
For the FHIR RDF transformation tools, we have implemented a stand-alone tool to
convert FHIR resources in the JSON format to their equivalent in the FHIR RDF
format10. We are also developing a FHIR-based data access framework to enable ex-
posing the clinical data stored in the OHDSI CDM-based data repositories in the
FHIR RDF format through leveraging an ontology of the FHIR metadata vocabulary
and an open-source Ontology-based Data Access (OBDA) system Ontop11,14, in
which an OHDSI virtual machine12 is used to provide sample clinical research data
for the testing purpose. A test query generated from Fig. 2 was run successfully
against the FHIR-Ontop-OHDSI platform and 1640 patients were identified. The
results were verified accurate using the OHDSI cohort identification tool.
Fig. 2. An example pattern identified for building a SPARQL query.
5
4 Discussion and Conclusion
In this study, we proposed a framework for executing CQL-based phenotype algo-
rithms using FHIR RDF technologies and demonstrated the feasibility of using CQL
and FHIR in support of EHR-driven phenotype algorithm creation and execution. It
turns out that temporal patterns (e.g., ages, intervals) are commonly used in CQL, and
existing SPARQL functions may need to be extended to capture and execute such
patterns effectively. While CQL uses the basic expression definition capabilities de-
fined by FHIRPath13 for its core expression terms, we noticed that there are some
discrepancies between FHIRPath expressions and FHIR RDF decisions, which needs
to be harmonized through a community-based collaboration in the future.
Acknowledgement: This study is supported in part by NIH grants U01 HG009450,
U01 CA180940, and R01 GM105688.
References
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2. HL7 Cross-Paradigm Specification: Clinical Quality Language, Release 1, 2017.
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