If you are new to HL7, you probably have many questions.
Hopefully this page will point you to an answer.
Frequently Asked Questions
General HL7 FAQ
What is Health Level Seven International (HL7)?
Health Level Seven International is one of several
American National Standards Institute (ANSI) -accredited
Standards Developing Organizations (SDOs) operating in the healthcare arena.
Most SDOs produce standards (sometimes called specifications or protocols) for a
particular healthcare domain such as pharmacy, medical devices, imaging or
insurance (claims processing) transactions. Health Level Seven's domain is
clinical and administrative data.
HL7 provides standards for interoperability that improve care delivery, optimize workflow, reduce ambiguity and enhance knowledge transfer among all of our stakeholders, including healthcare providers, government agencies, the vendor community, fellow SDOs and patients. In all of our processes we exhibit timeliness, scientific rigor and technical expertise without compromising transparency, accountability, practicality, or our willingness to put the needs of our stakeholders first.
Develop coherent, extendible standards that permit structured, encoded health care information of the type required to support patient care, to be exchanged between computer applications while preserving meaning.
Develop a formal methodology to support the creation of HL7 standards from the HL7 Reference Information Model (RIM).
Educate the healthcare industry, policy makers, and the general public concerning the benefits of healthcare information standardization generally and HL7 standards specifically.
Promote the use of HL7 standards world-wide through the creation of HL7 International Affiliate organizations, which participate in developing HL7 standards and which localize HL7 standards as required.
Stimulate, encourage and facilitate domain experts from healthcare industry stakeholder organizations to participate in HL7 to develop healthcare information standards in their area of expertise.
Collaborate with other standards development organizations and national and international sanctioning bodies (e.g. ANSI and ISO), in both the healthcare and information infrastructure domains to promote the use of supportive and compatible standards.
Collaborate with healthcare information technology users to ensure that HL7 standards meet real-world requirements, and that appropriate standards development efforts are initiated by HL7 to meet emergent requirements.
What is HL7's vision and mission?
HL7 provides standards for interoperability that improve care delivery, optimize
workflow, reduce ambiguity and enhance knowledge transfer among all of our stakeholders,
including healthcare providers, government agencies, the vendor community, fellow SDOs and
patients. In all of our processes we exhibit timeliness, scientific rigor and technical
expertise without compromising transparency, accountability, practicality, or our
willingness to put the needs of our stakeholders first.
Hl7's vision is to create the best and most widely used standards in healthcare.
What is a Standard?
A standard is a document, established by consensus that provides rules, guidelines or characteristics for activities or their results. (As defined in ISO/IEC Guide 2:1996)
What is Interoperability?
In this context, interoperability refers to the ability of two or more computer systems to exchange information.
Main Entry: in·ter·op·er·a·bil·i·ty
: ability of a system (as a weapons system) to use the parts or equipment of another system
Source: Merriam-Webster web site
: ability of two or more systems or components to exchange information and to use the information that has been exchanged.
Source: IEEE Standard Computer Dictionary: A Compilation of IEEE Standard Computer Glossaries, IEEE, 1990
"Functional" interoperability is the capability to reliably exchange information without error
"Semantic" interoperability is the ability to interpret, and, therefore, to make effective use of the information so exchanged.
In our context, 'effective use' means that the information can be used in any type of computable algorithm (appropriate) to that information.
All HL7 Meetings are "Open"; anyone can attend. Find the appropriate Work Group from the link below.
Most Work Groups have an electronic mailing list (listserv). Join the appropriate list and listen to the
conversations to decide whether the group is discussing topics that interest you. Joining the list will
also allow you to receive the conference call notifications where you may participate in Work Group calls.
HL7 is a volunteer organization, so you can contribute as much, or as little, as you are able to.
Membership in HL7 is available to everyone interested in the development of a cost-effective approach to system connectivity. Involvement and support from HL7's members is crucial to the ongoing expansion and enhancement of the HL7 standard and the overall success of the organization.
What are the different kinds of Membership? Which is right for me?
HL7 offers three main categories of membership: Individual, Organizational, and Affiliate.
Individual membership is geared toward those with a personal interest in the standard.
Organizational memberships include benefits crucial to those who rely on the standard as part of their business plan—the most critical of these being the right to distribute excerpts of the standard to clients (as part of technical documentation or proposals)—or distribute the standard within your organization.
The method for logging into the website hasn't changed; there is still a Log In link available in the upper right hand corner and at the top of the left navigation menu. Your login and password also remain the same. If you've forgotten then, you can use the Forgot Login link available on the Login screen to have them emailed to you.
I forgot my password, how can I retrieve it?
In the upper right hand corner, click the Log In link. On the resulting page, click the link labeled
"Forgot or don't know your user name or password? Click Here" You will be emailed your username and password.
Why can't I get into my account?
The system may not recognize you as logged in, or your membership may have expired. To confirm that you are logged in,
look in the upper right hand corner of your browser and make sure that your name is listed next to the Log Out link. If
your name is not listed you will need to log in.
It is also possible that your cookies have become corrupt, to correct this log out of the website and log back in again.
If you are unable to log out, you will want to delete your cookies and close your browsers.
If you're sure that you are logged in properly, click Membership then My Membership to confirm that your membership is active.
I think my company has a password that everybody can use, what it is?
Only Benefactors are provided with a generic username and password for their full-time employees. This
login does not have voting privileges. Please contact the key member for your organization who can
provide you with this login. If you do not your organization's key member, please contact HL7
headquarters at HQ@HL7.org or 734-677-7777.
How do I change my password?
Log into HL7.org; click Membership; click My Account and My Membership; Click Change Password in Account Options; Update your password; Click Save Changes.
How do I update my email address?
Log into HL7.org; click Membership; click View My Account and My Membership; Click Update My Profile in Account Options; Update your email address; Click Save Changes.
How do I update my mailing address?
Log into HL7.org; click Membership; click My Account and My Membership; Click Update My Addresses in Account Options; Click the pencil icon next to the address that you want to update; Update your address; Click Save Changes.
How do I check my renewal date and rate?
Log into HL7.org; click Membership; click My Account and My Membership; If you have an active membership your renewal date and renewal rate will appear under My Membership.
How do I update my organizational profile?
Log into HL7.org; click Membership; click My Account and My Membership; Click Update Organization's Contact Info and Update Organization's Profile.
How do I change my membership information?
Log into HL7.org; click Membership; click My Account and My Membership.
How do I change my organization's voting members?
To change the organizational voting members, the key contact person should send an email to
memberInfo@HL7.org indicating the names of the persons to be deleted
and include the new people to be added. The full contact information for the new additions should include
names, title, mailing address, phone/fax and email address. Normal changes take 2-3 business days to be
made to the database and uploaded to the website. Once the changes have been uploaded, the new persons
are sent an email with their login information.
For memberships, when does the year start?
The membership year is annual, beginning with the date the payment for membership is received.
I'm trying to download the standard and can't find it
Many of the standards are available for download from the Standards section of the website,
or can be purchased on CD in the bookstore (discounted rates apply for members). You must be a member
in good standing to access the Member's Only documents on the Standards section of the website. To access
the downloads, log into the HL7 website with your provided login information and click on the Standards link
in the main navigation in the header, then click the standard that you wish to download documents for.
Affiliate members may also access this information by following their affiliate download link to the HL7
website. If you are an affiliate member and need additional help finding this link, please contract your
When I try to (vote, register, etc...) it says I don't have access or that I'm not a member in good standing?
Please review the section entitled "Why can't I get into my account?" above.
If you are still unable to submit, you may not have permissions to access that page or your membership may have expired.
Please contact webmaster@HL7.org.
From the HL7 Development Framework, Section 2.2.1, HL7 Work Effort; An HL7 work effort represents an activity being undertaken by an existing Work Group or Board appointed committee to achieve specific objectives or to produce specific work products.
A Work Group shall consider a work effort to be a project if one or more of the following is true of that work effort:
involves a group outside of HL7 (may require Board approval)
has an objective (statement of what is going to be produced),
will have a finite existence (the end date to be determined by the resources available and the start date), and
if additional funding is required, it will have a budget (including resources and funding sources)
will have at least one participant available to contribute and must have a project leader, if only an interim to get the project started
will have at least two implementers (unless the project is intended to support the HL7 infrastructure)
will have an estimated schedule
Project Management Institute's PMBOK Guide and the publication "The Fast Forward MBA in Project Management" indicate the following:
Typically, a project is a temporary endeavor undertaken to create a unique product or service. All projects have two essential characteristics. (1) Every project has a beginning and an end. (2) Every project produces a unique product. HL7 also recognizes 'Maintenance' projects which usually repeat on an annual basis; these maintenance projects do not need to be re-submitted or have a definite end date.
Temporary means that every project has a definite beginning and a definite end. Temporary does not necessarily mean short in duration, it just means that projects are not ongoing efforts. Furthermore, projects involve something that has not been done before and which is, therefore, unique.
Projects shouldn't be confused with ongoing operations. Ongoing operations have the opposite characteristics of projects in that they have no defined end and they produce similar, often identical, products. Examples of ongoing operations are (a) an insurance company processes thousands of claims every day; (b) a bank teller serves over 100 customers daily, providing a few dozen specific services.
The objective of a project is to attain the objective and close the project. The objective of an ongoing operation is typically to sustain the business.
Define 'task' and 'activity' as related to project management.
Theoretically, 'activity' is the action verb within a 'task'. However, for HL7 projects, 'task' and 'activity' can be considered synonymous terms.
Task/activities should be:
Specific - a single, well defined, discrete activity. The 8/80 is a good guideline -- no task should be smaller than 8 hours or larger than 80 hours.
Achievable - it should be something that can be done as a single deliverable and can be defined as being completed or done such as a document being produced.
Measurable - it should be an activity that can be measured such as a deliverable produced, an elapsed period of time or number of iterations
Do I need to create a Project Scope Statement if my project is not going through the ballot process?
Yes, all projects need to have a Project Scope Statement completed and submitted to the HL7 PMO. A lot of work done by Education, Marketing, Electronic Services, ArB, PIC, etc. does not need to go through the ballot process, however, visibility of that work is necessary. Project Scope Statements are the foundation for communicating project information. They also serve as a tool for Project Facilitators to gather the right information to begin a project as well as track the project's progress.
Do I need to create separate Project Scope Statements for each Implementation Guide or other support documents?
A single PSS can indicate multiple deliverables for the standard being addressed, so, no, a separate PSS does not need to be created for each Implementation Guide or support document for that standard. Simply identify all of the Implementation Guides and documents in the Project Objectives and Deliverables section that are to be produced for the project.
The scope or objective of my project changed. Do I need to create a new PSS?
You may or may not have to as it depends on the change. Oftentimes, the scope or objectives of a project may change during its lifecycle, perhaps, due to regulatory changes or tying back to a different standard.
If the change in scope or objectives is minor, simply update the existing project scope statement, and within Project Insight, indicate the modifications in the appropriate fields. You can also use the 'Misc. Notes' text box for documentation.
If the change in scope or objectives is major, the Project Facilitator should submit a new Project Scope Statement, as many of the original information will not accurately reflect what is being done anymore.
What defines a 'major' or 'significant' change in scope?
Since 'major' and 'significant' are subjective terms, examples may provide better comprehension of a "major" or "significant" change to a project scope statement.
A "major" or "significant change" in project scope is when the impact is that:
The Project End date extends by 6+ months
Additional HL7 funds are required
The Project Intent changes (i.e. the project changes from "Revising a Standard" to "Creating a Standard")
The change in scope will result in an item that qualifies as 'substantive change' as defined in GOM Section 14.08.04.
The Ballot Type changes to a Normative (i.e. the project changes from planning for an Informative ballot to a Normative ballot)
The Realm changes from 'Realm Specific' to 'Universal' (since additional project resources may be necessary to support that change)
The deliverable's backwards compatibility changes from 'Yes' to 'No'
I have submitted my PSS to my Steering Division for approval but have not heard anything from them. What should I do?
First, check the Steering Division's meeting minutes. Look to see if your project was on one of their agendas, and if so, if it was approved or the SD had further questions. Your first point of contact with the SD should be their Project Facilitator. If you can't contact them, contact the Steering Division Representative and Alternate.
If the SD has approved your project, they will submit it to the TSC for approval via the HL7 GForge's
tracker system. To view which approvals your project has gathered, find your project by using the
Searchable Project Database tool, located in the Resources column on the
Do I need to update the PSS if I discover after it's approved that I need to coordinate ballots with other HL7 Work Groups?
Yes, we recommend updating the Ballot Strategy section of the Project Scope
Statement as well as Project Insight. Include the ballot name and release/version
your project is coordinating with.
Contact the HL7 PMO or any member of the HL7 Staff. They'll be able to gather this information for you via their internal staff website.
When withdrawing or reaffirming a standard, does a PSS need to be created and go through the review/approval process?
Yes, for both cases.
In this case 'withdrawing a standard' refers to many things, such as choosing not to extend a standard that has reached its 5 year end-of-life or identifying the need to sunset a standard. By creating a PSS and following the approval process, you give the opportunity to communicate the withdrawal to the HL7 membership and allow them to weigh in on any potential work needed to successfully withdraw the standard.
GOM Section 14.13 has more information on withdrawing a standard.
Reaffirmation of a standard requires a normative ballot.
How do I know the approval status of my project?
Look up your project using the Searchable Project Database,
(located on the www.HL7.org Homepage). The search results will reflect SD and TSC approval statuses either by reflecting the
date the group approved the project or indicated 'Awaiting Approval' if the group has not approved the project.
What approvals are needed if I revise my existing PSS, say the project's scope changes?
The same approval process should be followed whether it's a new project or a scope change to an existing project.
When the scope is changed in a project, an adjusted or new Project Scope Statement will be approved by the primary
WG and the SD, providing the TSC using the same time line and deadlines as submissions for new projects.
Best practice: Use Microsoft Word's 'Track Changes' tool to highlight the changes being made to the Project Scope Statement.
What ballot types are required to go through the project approval process?
All ballot types (Comment Only, Informative, Normative, DSTU) need to go through the project approval process, however, as
identified in the Project Scope Statement, a single project can define ballot plans for multiple types of ballots for the
project, for example, Comment Only >DSTU > Normative or Informative > Normative.
Do I need to go through the project approval process if a standard has expired and will not be reaffirmed?
When a work group has balloted a standard at DSTU, informative, or normative ballot, and decides the standard will be
withdrawn, the withdrawal form is needed for ANSI
notification and must be approved by the Work Group and the TSC.
What is the approval process for HL7 projects that collaborate with ISO or the JIC?
How should a Work Group document the voting results after seeking approval for the PSS?
The ideal way is to post it in meeting minutes, so that they are documented and easily referenced. If that's not possible,
an email to the Listserv will suffice.
How should a Work Group document annual work/maintenance within Project Insight?
A project entry should be opened in Project Insight indicating the annual work and the respective years. This project
should have a Project Status of '3 Year Plan Item'; note that a Project Scope Statement isn't needed for this entry
because it's a 3 Year Plan item and only high level information is necessary. This project can then remain 'as-is',
or modified so it indicates accurate future years.
When the Work Group actually begins the annual work, they should complete a PSS indicating the scope of work involved
and gather the necessary approvals for the PSS. A new project in Project Insight will be created (and will have a
Project Status of 'Active Project'). Once the scope of work has been completed for this project, it will be
Hence, the 3-Year Plan project always remains open; the 'Active Project' PSS will be the project reflecting the
specific annual maintenance being done.
An example of the above situation can be found for Project Service's annual updates to the PSS Template. Project
531 is the 3YP entry indicating the need for the work in 2010, 2011, 2012, 2013 and beyond. Project 581 was
created to identify the specific work that would be done for the 2010 updated template. In January, 2010, project
581 was closed because the new PSS template was released to membership, however project 531 was modified to remove
references to '2010' and remains open to indicate the need for the work each year.
Should a project remain open/active during it's DSTU Test Period?
Yes, it should. This means that the project will continue to show up in the Searchable Project Database and on
Project Insight reports.
Do I need to specify a Reference Information Model (RIM) version in the V3 standard I am developing?
Unless specified, it is assumed that a project incorporates the current version of HL7 infrastructure (RIM,
Datatypes and Vocabulary).
Project Services recommends that your Work Group's modeling facilitator monitor proposed RIM changes that may
impact the standards you are developing for the duration of your project. The modeling facilitator can do this by
subscribing to the firstname.lastname@example.org listerv. For more information on RIM change proposals, contact the
MnM Work Group.
What do I need to do if I want a project document to be publicly available outside of HL7?
It's a rare instance that a project will create and distribute a public document in accordance to the GOM's ruling.
In the instance that a project deliverable does adhere to it, the project team will need to present a proposal to
the Executive Committee to provide funding to create and distribute a document publicly. GOM Section 09.01(d)
indicates that the Executive Committee determines what is publicly available. More information can be found in
Training and Certification
How do I take the certification exam (when, where, study materials, cost)?
Information on certification testing can be found on our website, under Training, Certification.
Links to study guides and sample tests can also be found there. The knowledge required to pass the
test can be obtained by participation in the HL7 Working Group Meetings, by attending HL7 educational
sessions and webinars, fieldwork involving HL7 interfaces or simple self-study of the HL7
specification. To determine what classes are best suited for your needs, first read the document in
the Certification Resources box: “Where are you on the path to certification?” Then see the latest
Working Group meeting or Implementation Workshop brochure and read the tutorial descriptions. Most
individuals new to HL7 take the Intro to V2.x classes, followed by V2 Message Profiles and Conformance
and the V2.x Control Specialist Certification Review, which is the preparatory class for the most current
Vx certification exam. Testing is also currently being offered for the Clinical Document Architecture
(CDA®) and the Version 3 RIM. The test is not All certification testing is offered online.
In addition to HOST testing centers and online proctored testing, you may bring a laptop to test at our
Implementation Workshops (March, July, November) and Working Group Meetings (January, May, September). Register
to take the test from the Certification page on the HL7 website. The member rate is $199 and the non-member
rate is $350. Information on upcoming meetings can be found on our website, under Events.
Is online testing offered?
Certification exams are offered at HOST testing centers, and as online proctored tests from your own computer.
Please see a description of all testing delivery options on the website under Training/Certification.
If I don't pass on the first try, do I have to pay to take it the next time?
Yes, the test fee is charged each time the test is taken.
Is certification really important?
In today's evolving health interoperability field, certification is important and there is definitely a value to having it. This is a point in many contracts and can certainly give you a competitive edge in the job market.
My company does X, and we need to become HL7 compliant, what do we need to do?
You will need to secure a copy of the standard (likely V2), which provides the messages, by domain,
that any system claiming compliance to HL7 should be able to send/receive. HL7 standards are freely available for download, under licensing terms, from the HL7 website Standards tab.
Meetings and Events
When will registration open?
Event registration opens no later than 30 days prior to the event.
I'm new to HL7 and planning on attending an Implementation Workshop or WGM. Which one would be better for me? What classes should I take?
Implementation Workshops are focused on training only. For further information/clarification please contact HL7 headquarters at 734-677-7777.
How do I view my upcoming meeting registrations?
Log into HL7.org; click Membership, and My Membership; If you have registered for any upcoming meetings will appear under My Meeting Registrations.
Registration questions (didn't get an acknowledgement, need a receipt; how do I add a tutorial, cancel a tutorial, change a date, etc.).
Please contact our meeting managers at +1 (734) 677-7777 or email RegInfo@HL7.org.
How do I register another person for an event?
You will need to log out and then log in as that person to register them for an event. If that person does not have a login, you will need to create one for them.
When I go to register for the event, it says I'm not a member, but my organization is a member, how do I get the member price?
There are several reasons this may occur; one may be that your membership has elapsed or that the payment is currently being processed. If you organization has joined in the last 30 days; please check the appropriate box on the registration form. The registration company will verify with our membership department before payment is processed.
Work Group Participation
How do I join a work group?
You may join a work group simply by participating in its conference calls and/or by joining its listserv. For a schedule of conference calls, please go to:
I requested to be subscribed to a listserv, why does it say I'm already subscribed? Or I subscribed to a listserv, why can't I send or receive email?
The listserv has likely already received your request to join the list. If you are still unable to send or receive email from the list however, your request may not have been finalized. The listserv signup process generates a confirmation email which is sent to the requesting email address. Until you click the link within this confirmation email, your subscription will be held. Be sure to check your junk mail folder to fond this confirmation email. If you are unable to find the confirmation email, please send an email to support@HL7.org to have it re-sent.
How do I delete or edit a conference call?
Current co-chairs have access to these features; please go to
once there, click on the call to be removed or edited. The call information will come up; the Editing Options are at the bottom of the page.
What is Version 3?
HL7 V3, like V2.x, is a standard for exchanging messages among information systems that implement healthcare applications. However, V3 strives to improve the V2 process and its outcomes. The original process for defining HL7 messages was established in 1987 and has served us well. The development principles behind HL7 V3 lead to a more robust, fully specified standard.
New capabilities offered in Version 3 include:
Top-down message development emphasizing reuse across multiple contexts and semantic interoperability
Representation of complex relationships
Formalisms for vocabulary support
Support for large scale integration
Solving re-use and interoperability across multiple domain contexts
A uniform set of models
Expanded scope to include community medicine, epidemiology, veterinary medicine, clinical genomics, security, etc.
What is the Reference Information Model (RIM)?
The Reference Information Model (RIM) is the cornerstone of the HL7 Version 3 development process. An object model created as part of the Version 3 methodology, the RIM is a large pictorial representation of the clinical data (domains) and identifies the life cycle of events that a message or groups of related messages will carry. It is a shared model between all the domains and as such is the model from which all domains create their messages. Explicitly representing the connections that exist between the information carried in the fields of HL7 messages, the RIM is essential to our ongoing mission of increasing precision and reducing implementation costs.
How do we use the HL7 RIM for Semantic Interoperability?
What is the Health Level 7 Development Framework (HDF)?
The HDF documents the processes, tools, actors, rules, and artifacts relevant to development of all HL7 standard specifications, not just messaging. This initial version of the HDF methodology specification will address updates to messaging specification, and will be applicable to structured documents and context management.
Eventually, the HDF will encompass all of the HL7 standard specifications, including any new standards resulting from analysis of electronic health record architectures and requirements.
The HL7 Version 2 Messaging Standard — Application Protocol for Electronic Data Exchange in Healthcare Environments — is considered to be the workhorse of data exchange in healthcare and is the most widely implemented standard for healthcare information in the world.
HL7 Version 2.6 represents HL7's latest development efforts to the line of Version 2 Standards that date back to 1989. Version 2.6 represents a major revision to Versions 2.5 and 2.5.1, refining and updating existing messages and adding new messages and domains all based upon proposals submitted and accepted by the HL7 membership.
Global changes from Version 2.5 and 2.5.1 include the following:
the addition of a new segment, UAC – User Authentication Credential, to ALL messages
the replacement of the TS – Timestamp data type with the DTM – Date/Time data type
the replacement of the CE – Coded Element data type with either the CNE – Coded with No Exceptions data type or the CWE – Coded with Exceptions data type
the deprecation of the CNN, NDL, LA1 and LA2 data types
the inclusion of "external" tables referencing a set of coded values defined and published by another standards organization assigned an HL7 number but without designation as an HL7 table (as was previously the practice)
the revision of examples in all chapters to support HIPAA compliance
the inclusion of a new chapter supporting electronic messaging transactions of claims and reimbursement data (which is produced for implementations of HL7 outside of the United States; in the United States, HIPAA law mandates an already in-use set of implementation guides of X12 messages for these purposes)
the inclusion of a new chapter supporting electronic messaging transactions of supply chain management data within healthcare facilities
Version 2.6 was APPROVED AS AN ANSI STANDARD October 12, 2007
Other Initiatives and Standards
What does HL7 have to do with the Electronic Health Record (EHR)?
What does HL7 have to do with Clinical Document Architecture (CDA®)?
The CDA, which was until recently known as the Patient Record Architecture (PRA), provides an exchange model for clinical documents (such as discharge summaries and progress notes)—and brings the healthcare industry closer to the realization of an electronic medical record. The CDA Standard is expected to be published as an ANSI approved standard by the end of the year.
By leveraging the use of XML, the HL7 Reference Information Model (RIM) and coded vocabularies, the CDA makes documents both machine-readable—so they are easily parsed and processed electronically—and human-readable—so they can be easily retrieved and used by the people who need them. CDA documents can be displayed using XML-aware Web browsers or wireless applications such as cell phones.
CDA Release 1 was APPROVED AS AN ANSI STANDARD November 2000.
How does HL7 relate to ONCHIT?
The Office of the National Coordinator for Health Information Technology (ONCHIT) will facilitate the effective use of information technology to improve the quality, efficiency, and safety of health care for all Americans. ONC will collaborate with the public, private, and non-profit sectors to meet the President's goal of the widespread adoption of interoperable electronic health records (EHRs) within ten years. HL7's Standards will assist in achieving interoperability.
CDA is the Clinical Document Architecture, an ANSI-certified standard from Health Level Seven (HL7.org). Release 1.0 was published in November, 2000 and Release 2.0 was published with the HL7 2005 Normative Edition.
CDA specifies the syntax and supplies a framework for specifying the full semantics of a clinical document. It defines a clinical document as having the following six characteristics:
Potential for authentication
A CDA can contain any type of clinical content. Typical CDA documents would be a Discharge Summary, Imaging Report, Admission & Physical, Pathology Report and so on. CDA uses XML, although it allows for a non-XML body (pdf, Word, jpg and so on) for simple implementations.
Who is using it?
CDA is in use world-wide. The most popular use is for inter-enterprise information exchange, such as is envisioned for the US Regional Health Information Organizations (RHIOs). Thus most users are in countries where RHIO-type exchange is well established such as Finland, Greece and Germany and in pilot RHIOs in Canada, Japan, Korea, Mexico, Argentina and elsewhere. CDA is firmly in the plans for many of the nascent US RHIOs and the US Military Health System.
In addition to RHIO usage, CDA is the basis of a good variety of experimental work within academic medical centers and research institutions. Examples of this are the project on CDA note generation with knowledge management and controlled vocabulary at Columbia-Presbyterian in New York, the work on CDA for decision support at Queen Elizabeth II Hospital/Dalhousie University and the Single Source Proof of Concept at Duke Clinical Research Institute.
The largest single producer of CDA documents, however, is the Mayo Clinic, which is producing thousands of CDAs every week and when in full production will reach 50,000 notes/week. Mayo sees CDA as a strategic investment in information that will increase in value over time and which can be reused in multiple applications.
What type of tools are available?
Many vendors have developed CDA-compliant applications for document generation, management and viewing. Since CDA is implemented in XML (Extensible Markup Language, see w3.org), any XML-capable application can work with CDA. So, for example, any web browser, such as MS Internet Explorer or Firefox can parse a CDA document and using an XSL stylesheet, convert it to HTML for display. Similarly, any XML-capable repository can manage CDA.
For document generation, implementers have a variety of choices. Several dictation/transcription vendors offer CDA as an output format. Many EHR vendors can produce CDA, typically as a conversion from a native format. In addition, eForms applications have been developed for CDA using readily-available desktop technology. Some implementations use dynamic forms population from distributed sources to pre-populate CDA with existing data.
The only barrier to CDA generation with existing technology is where insufficient information is available at the source for conversion, but to-date, this has not been a problem from either voice-interface or keyboard-entry applications.
Is it complicated?
CDA introduces the concept of “incremental” semantic interoperability. What this means is that there is a range of complexity allowed within the specification and users must set their own level of compliance. The minimal CDA is a small number of XML-encoded metadata fields (such as provider name, document type, document identifier, and so on) and a body which can be any commonly-used MIME type such as pdf or .doc (Microsoft Word) or even a scanned image file.
While the body of such a document would not be interpretable for applications like decision support, the minimal, standard metadata set and display characteristics mean that such a document could be filed, searched, categorized and retrieved along with more richly-encoded documents. They would all be equally readable at the point of care.
At the high end, CDA documents can be encoded with the full power of the HL7 Reference Information Model (RIM, see below) and controlled vocabulary such as LOINC, SNOMED, ICD, CPT and so on.
What are CDA "levels"?
CDA "levels" are ways of describing the degree of semantic interoperability of a CDA document.
Digression on "Semantic Interoperability": Full semantic interoperability is when a document can drive an arbitrary process, for example, decision support, even if it wasn't designed for that application. So a document with full semantic interoperability can be created for one purpose, like a public health report or for transfer of care, but can be interpreted by other applications with the same degree of confidence that a human would use the information.
So, the concept of "levels" applied to CDA means the degree to which a receiver can expect to drive automated processes. A Level One CDA sets no expectations beyond the standard header metadata and human-readability for the body. A Level Two CDA means that the body is in XML and that the sections and sub-sections are coded. A Level Three CDA contains the same expectations as Levels One and Two, plus it contains some coded information within the sections.
While Levels 1-2-3 provide convenient ways to set rough levels of coding compliance, in practice many gradations and refinements are possible and are in use.
What's the difference between Release 1 & Release 2?
CDA Release 1 (R1) was published in late 2000 and Release 2 (R2) will be published in mid-2005 and will provide an exhaustive list of changes. Most significantly, R2 is updated to the most recent RIM (see below) and adds significant functionality to the CDA body.
The major addition to the CDA body is the clinical statement model which uses RIM structures and controlled vocabulary to permit a much higher level of semantic interoperability. In contrast, R1 was restricted to single coded entries which were not fully expressive.
R1 allowed Levels 1 & 2 (with coded entries); R2 allows Levels 1, 2 and 3 (with clinical statements). While R2 allows greater complexity, it still allows the same low level of encoding as R1 and need not be any more complicated to implement.
How does it relate to the RIM?
XML tags on their own do not have the precision required for clinical system interoperability. For example, does <provider> mean a person or an organization? Is it the person who created the document, signed it or performed some service?
The XML tags in a CDA document are defined by the HL7 Reference Information Model (RIM) which is based on a variant of Unified Modeling Language (UML) and has been developed by literally hundreds of thousands of hours of collaborative work by practitioners, informaticists, vendors and implementers over the past decade. Each release of CDA is based on the version of the RIM current at the time of the ballot. The CDA specification details the relationship of the documents to the model and contains a refined model (RMIM) which takes RIM classes and further constrains them to define the precise parameters of a clinical document.
Is it part of V3?
Yes. CDA is based on the RIM (see above), uses the V3 datatypes and methodology. The core of the CDA R2 body for machine processing (semantic interoperability) is the "clinical statement" model which is used across V3.
Can I see a sample?
Sample documents are published with each ballot and implementation guide. See the "Documents and Presentations" portion of the Structured Documents Work Group web page on HL7.org for links to individual sample documents for both R1 and R2 (from HL7.org, go to Participate -> Work Groups, select Structured Documents and you'll see the link).
Are Implementation Guides available?
The Structured Documents WG, in conjunction with Patient Care WG, has introduced two Implementation Guides that have been balloted in the Spring of 2005 as information documents. These are CDA Care Record Summary, Level 1 and CDA Care Record Summary, Level 2. The most recent drafts are available on the SDWG web page. As of May 2005, they are undergoing revision and will be re-balloted in August.
In addition, many sites have created implementation guides for their own use. See an excellent example from British Columbia, the eMS system in support of transfer of care.
Where did it come from?
CDA grew out of work that originated outside of HL7 in early 1996 when a group of physicians including Tom Lincoln, John Spinosa, Dan Essin, John Mattison and Bob Dolin began to meet to discuss the potential for structured markup in clinical documents. The earliest draft was called the Kona Architecture and was developed in 1997 after the group had joined HL7. Since that time, many people have worked on it and the basic ideas have been refined and developed along with the HL7 Version 3 framework and the RIM. The original group morphed into the HL7 Structured Documents Work Group which is responsible for CDA and other HL7 document types.
How do I get more information?
The best source is the Structured Documents WG web page on HL7.org: from HL7.org, go to Participate -> Work Groups, select Structured Documents. From there, you can download drafts, meeting minutes, documents and presentations and you can also sign up for the SDWG listserv.
How can I get involved?
Anyone can join the Structured Documents listserv and use the information on the Structured Documents web page, and can join Structured Documents listserv, conference calls and meetings. There are no membership requirements for participation and all are welcome.
Real influence on the shape of CDA comes from participation in the ballot process which is available to HL7 members (and to non-members who pay an administrative fee).
To ask additional questions, add to or correct this FAQ, contact the HL7 Director of Technical Services (mailto:webmaster@HL7.org).