An archetype is a re-usable, formal definition of domain level information, defined in terms of constraints on an information model. The key feature of the archetype approach to computing is a complete separation of information models (such as object models of software, models of database schemas) from domain models. Thus, archetypes are not part of the software or database of a system. Archetypes can be specialised, and also aggregated, via 'slots', enabling fine-grained re-use. Archetype design principles and technical specifications.
Archetypes have a number of functions:
In health, information, or 'content' that can be modelled using archetypes on things like:
and many others. From the user's point of view, these are the kinds of data which occur in health information systems. Each archetype is a text file, expressed in either ADL syntax or its XML derivative.
(The formal archetype concept was originally described in detail in a paper published online by Thomas Beale, as well as a 2002 OOPSLA paper, providing a more succinct description. These are a bit out of date now, since it doesn't adequately distinguish between archetypes and templates, but still useful background. For modern descriptions, see the specifications).
Archetypes don't define data sets. A data set is defined by a template in openEHR, which is a special kind of archetype that aggregates bits and pieces of other archetypes to form a set of data specific to a particular use, e.g. a screen form or message definition. Data sets almost always contain data points and groups from numerous archetypes.
The above form has been templated from archetypes: each red area contains some specific (usually only a minority of) data elements from one archetype.
Here is a picture that shows a template constructed from elements of archetypes, to define a specific data set, which is then used to generate various useful downstream artefacts.
There are two kinds of archetypes the community needs:
Data import in an openEHR system can now be done as follows:
No. Archetypes are designed to provide systematic interface with terminologies. They are, in themselves, terminology-neutral, because there is no (and probably will never be) single terminology or ontology which describes the whole of medicine in the myriad points of view needed in clinical information systems. ADL is designed instead to have bindings to terminologies, and any given archetype can include bindings to more than one. A binding is the set of mappings from archetype local term and constraint codes to terminology codes and query expressions respectively. See the CKM 'Problem' archetype for an example.
An easy way to think about archetypes and ontologies is based on understanding what they say. Archetypes model information, while ontologies describe (aspects of) reality. For example an archetype for "systemic arterial blood pressure measurement" is a model of what information should be captured for this kind of measurement - usually systolic and diastolic pressure, plus (optionally) patient state (position, exertion level) and instrument or other protocol information. In contrast, an ontology would describe in more or less detail what blood pressure is. This archetype tutorial (PPT) provides a detailed example on slide 12.
If in your philosophical view of the world, "information" is part of "reality" (and this is the strictly correct way to understand the world), then archetypes themselves constitute an ontology, whose subject matter happens to be information. Other "ontologies", as one tends to use the word today, have as their subject matter "reality" (other than information).
See the openEHR Wiki ontology page for more on ontologies and openEHR.
Archetype Definition Language, or ADL, is the formal language for expressing archetypes. It provides a formal, abstract syntax for describing constraints on any domain entity whose data is described by an information model (e.g. expressed in UML/OCL). It is primarily useful when very generic information models are used for representing all data in a system, for example, where the logical concepts Patient, Doctor and Hospital might all be represented using the class Party, Address, and related generic classes. Archetypes are then used to constrain the valid structures of instances of these generic classes to represent the desired domain concepts. In this way future-proof information systems can be built - relatively simple information models and database schemas can be defined, and archetypes supply the specific modelling, completely outside the software.
The 'AOM', or Archetype Object Model, is a sibling specification to ADL, defining the object structures and semantics of a parsed archetype. It is primarily used by tool builders.
The openEHR ADL/AOM 1.4 and 2 specifications.
(For math/logic geeks: ADL syntax is congruent with Michael Kifer's Frame Logic 'queries').
ADL and the AOM are open specifications of openEHR. The 1.4 AOM release was adopted as ISO standard ISO 13606-2.
Yes - the ADL Workbench tool, or 'AWB'. See here for help and download.
The openEHR Clinical Knowledge Manager (CKM) contains the archetypes managed internationally at openEHR.org. Other archetypes may be managed at a national level within your country or some other organisation.
It is important to understand the big picture of archetypes and templates. For archetypes to really work, there does need to be some large scale organisation, in order to allow sharing and quality control. The following is one model of how archetypes should be used "in-the-large":
As can be seen, it is not simply a matter of editing an archetype and putting it into your hospital information system. The wiki page on Development and Governance of Knowledge Artefacts gives more details.
You can download various archetype-authoring tools to build one.
But if you are serious, you are probably a clinical professional, and will want to discuss requirements and ideas first with others, which you can do on the openEHR clinical mailing list, and also with others registered on the openEHR CKM.
The Archetype Object Model provides a standardised object model of archetypes which can be used as the basis of software. Most likely you will want to capitalise on the work already done in various languages. See the openEHR technical mailing list.
Most of the countries, companies, academic institutions and other projects you see here.
CEN TC/251 has adopted the openEHR Archetype Object Model 1.4 and ADL 1.4 as the means of expressing archetypes to be used in conjunction with EHR data sent as CEN EN13606 EHR Extracts; these specifications are snapshotted in the revised EN13606 part 2. Archetypes created directly based on the EN13606 part 1 model fall into the category of legacy archetypes as defined above.
The openEHR ADL 1.5 and AOM 1.5 specifications, currently in late draft, will supersede the 1.4 specifications used by CEN and ISO 13606.