Healthcare data standards 101: HL7, FHIR and more

June 16, 2022

If you spend any time reading about healthcare data, you’ve probably come across the acronyms HL7 and FHIR. If you’ve ever wondered what exactly HL7 is or what FHIR stands for, then you’ve come to the right place. Here is our primer on these terms and others to help you decode healthcare data blog posts, white papers, product spec sheets and more.

What are healthcare data standards?

First, let’s talk about what healthcare data standards are. When computers, the internet and, more specifically, electronic health records (EHRs) first became widely used, there were no standards in place for how data was entered, stored or used. But without standards, healthcare providers can’t share patient data in a format that can be easily used or understood by another provider or system. Having systems that talk to one another is the gold standard of interoperability, and consistent application of healthcare data standards is the starting place for interoperability.

Since  standards weren’t in place when healthcare data started, they have evolved over time to attempt to address this issue. Now, there are numerous healthcare data standards, in the U.S. and globally, that cover the terminologies used, how data is formatted and how data is stored and transferred. HL7 and FHIR are two of the standard systems used specifically for transferring data.  

What is HL7?

Health Level Seven (HL7) is one of the largest standards development organizations (SDOs) in healthcare. It is an international organization accredited by the American National Standards Institute (ANSI). It was founded in 1987 and is dedicated to developing a comprehensive framework and standards for data exchange, integration and sharing, as well as retrieval of electronic health information. 

What is HL7v2?

HL7 version 2 is a healthcare messaging standard developed by HL7. It is a set of rules defining how healthcare data can be sent from one system to another. In HL7v2, a message comprises segments, which contain individual pieces of information called fields. The fields in each segment are in a specific order and format. There are different message types for different use cases; for example, variations of “ADT” messages send demographic updates, and “QBP” messages request immunization history. 

What is C-CDA?

Consolidated Clinical Document Architecture (C-CDA) is another set of standards created by HL7 for the structure and content of electronic documents. It is the primary framework used in the U.S. for electronic medical documents. C-CDA consists of many different document templates that can be used depending on the circumstance, including elements for both structured and unstructured data. For example, there are templates for referral notes and diagnostic imaging reports.  

What is FHIR?

In 2014, HL7 created the Fast Healthcare Interoperability Resources (FHIR) standard for transmitting healthcare data electronically. The FHIR framework has two basic components: resources and APIs.

Resources are basic modular components of data that define the data elements and relationships. There are resources for things like patient demographics, medications, family history and claims all over the healthcare environment. These resources can be bundled for specific use cases. FHIR also has a common set of application programming interface (APIs) standards. Applications can use the APIs to interact directly with the data instead of a document-based exchange. FHIR uses RESTful (Representational State Transfer) interfaces, a method of exchanging information that has all the information needed to service the request. It is what the internet uses and what allows healthcare to take advantage of technology that is already developed and well understood by developers. 

FHIR makes it easier for developers to use healthcare data, and it can be used in mobile phone apps and cloud communications in addition to EHR-based sharing. 

Are there other healthcare data standards?

Yes! HL7v2 and FHIR are the tip of the iceberg. FHIR is extremely important because it is how third parties (outside of EHRs and providers) can use healthcare data. But here are some of the other common standards you’ll encounter in healthcare:

  • X12: These standards support business-to-business transactions in healthcare, insurance, supply chain and other industries
  • USCDI (United States Core Data for Interoperability): A standardized set of health data that all healthcare systems and APIs must support
  • Direct: A technical standard widely used by EHR systems for the secure exchange of personal health information. It uses Health Information Service Providers (HISPs), which use encryption and digital signing, for security when sending and receiving health data
  • DICOM (Digital Imaging and Communications in Medicine): An international standard and file format for medical images, such as CT scans, MRIs and printer images
  • SCRIPT: An industry standard for prescriptions
  • CDISC (Clinical Data Interchange Standards Consortium): A standards-developing organization for clinical trial data

On top of these storage and transportation standards is a host of naming and terminology standards:

  • ICD-10-CM: Developed by the WHO for diseases and diagnoses
  • CPT (Current Procedure Terminology): Developed by the AMA for medical procedures and services, specifically used in billing
  • HCPCS (Healthcare Common Procedure Coding System): An extended version of the CPT
  • LOINC (Logical Observation Identifiers Names and Codes): Used for laboratory tests and clinical observations
  • NPI (National Provider Identifier): Each healthcare provider in the U.S. has a unique NPI
  • SNOMED CT (Systematized Nomenclature of Medicine Clinical Terms): Codes for clinical information, including symptoms, procedures, diagnoses, family history and more
  • NDC (National Drug Code): Coding system for pharmacy products that includes manufacturer and package codes, which means drugs in different size packages will have different NDCs
  • RxNorm: A catalog of all clinical drugs and drug delivery devices based on active ingredients, strength and dose form, making it more useful for interoperability

HL7, FHIR and other healthcare data standards are improving the future of care

While not without problems and challenges, healthcare data standards provide the building blocks that the industry needs for improving care. They are the first step toward interoperability, not only between provider EHRs, but also between innovative applications, payers, the government and patients. Usable, understandable, accessible data can improve the patient experience and unlock insights that will lead to better healthcare for everyone.