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A Migration to an openEHR-Based
Clinical Application
Hajar KASHFI
1
, Olof TORGERSSON
Department of Computer Science and Engineering,
Chalmers University of Technology and University of Gothenburg, Sweden
Abstract. MedView is a suit of clinical applications for recording, retrieving and
visualizing patient records, which has been developed and in use for more than ten
years. By the introduction of the openEHR architecture, the MedView project
started an investigation to migrate from its locally developed framework to
openEHR. Issues related to this process, have been discussed in this paper.
Keywords. openEHR, medical application, two-level modelling, archetype
1. Introduction
MedView
2
focuses on understanding and implementing the chain “formalize-collect-
view-analyse-learn” in oral medicine, in other words, using computing technology to
handle clinical information such that clinicians more systematically can learn from
gathered data [1]. Several tools have been developed for formalization, acquisition,
visualization and analysis and sharing of data. As of January 2009, the main database at
the clinic of oral medicine in Gothenburg contains data and digital images from well
over 20,000 examinations making it a unique collection of information in its area.
MedView is based on its own locally developed framework. In a time when data
sharing is becoming increasingly important, this limits the possibilities for its
development and expansion. By the introduction of the openEHR architecture, the
MedView project started an investigation to migrate from its framework to openEHR.
Motivations, and issues related to this process, have been discussed in this paper.
2. Comparing MedView and openEHR Approaches
openEHR is an EHR development framework that facilitates the level four of
interoperability [2]. In a two-level modelling approach, which has been used in
openEHR, a system is built from a general model that describes the basics of the
system, and provides stable implementation for the parts that do not change often [3].
This stable basic system is then complemented with specialized artefacts that are
created from tools or models provided by the basic system.
1
Corresponding Author: Department of Computer Science and Engineering, Chalmers University of
Technology, SE-412 96 Gothenburg, Sweden; E-mail: hajar.kashfi@chalmers.se.
2
http://medview.se/.
Medical Informatics in a United and Healthy Europe
K.-P. Adlassnig et al. (Eds.)
IOS Press, 2009
© 2009 European Federation for Medical Informatics. All rights reserved.
doi:10.3233/978-1-60750-044-5-152
152
In openEHR two-level modelling, the first level is the reference model (RM) [2]
that describes all basic data structures, overall organization of the EHR, etc. The second
level is made up of archetypes, which enables the creation of meaningful domain-
models of clinical knowledge from the reference model building blocks. Archetypes
specify valid EHR entries, their sequence, and structure. The division of systems into
two levels provides for a clear division between the technical and medical parts of the
system, and makes it possible to develop the clinical part independently of the system
implementation. openEHR-based system architecture consists of four different layers:
x The Persistence layer includes EHR, an instance of RM, and is the kernel for
openEHR-based system.
x The Knowledge layer includes archetypes and templates, which at run time,
will be used for data validation and presentation.
x The Service layer includes services required for creating, storing and
retrieving EHR. Moreover, services for connecting to terminologies and
online archetype repositories are in this layer.
x The Application layer includes application specific services that access EHR
in the persistence layer through the service layer.
Figure 1. Migration from MedView to openEHR: An architectural perspective
While the reference model of openEHR is rather elaborate including, for instance,
details about time and versioning, MedView uses a very simple model. Clinical records
are described as being made up of a number of examinations that are connected through a
patient identifier. Each examination then consists of a number of sections defining
different clinical concepts like “Biopsy” in terms of sets of term/value pairs (see Figure
2). The second level in MedView is made up of the actual definitions of clinical content
that is very similar to openEHR conceptually. Clinical content should be defined by
clinicians and the medical concepts can change without requiring any modifications to
software. MedView architecture consists of these layers (see Figure 1):
x The Data Layer includes medical records and related images.
x The Knowledge Layer consists of templates
3
, terms, and values.
x The Mediator Layer mediates between lower layers, and the application layer.
3
To prevent any confusion between MedView templates and openEHR templates, MedView templates are
written in Italics.
H. Kashfi and O. Torgersson / A Migration to an openEHR-Based Clinical Application 153
x The Application Layer includes application specific services, which can access
medical records through the knowledge and mediator layers.
Motivations for Migration to an openEHR-Based Architecture
In openEHR, archetypes are re-usable maximal models of clinical concepts like blood-
pressure examination. An existing archetype can be re-defined or extended through
sub-classing. A template can combine several archetypes but also allows modifications
like excluding parts of an archetype.
Figure 2. A MedView examination form, generated based on a template
In MedView, a simpler model is used where clinicians define templates by
combining agreed upon basic units called terms. For instance, “The type of local
anaesthetic” is represented by the term “Anest-type”. When a new notion needs to be
introduced, a new term is defined that can then be used in future templates. Figure 2
shows an instance examination entry form generated from a template.
A clear limitation in MedView is that it is impossible to combine several templates
to form larger units. In openEHR, the idea of maximal data sets, redefining and
extending existing archetypes and combining several archetypes to templates facilitates
sharing of clinical data. Further, the quality of data in MedView is not sufficiently high
since validation of data is basic. For instance, for the term “Anest-type” two possible
values specified in the template are “Citanest-octapressin” and “Xylocian-adrenalin”
though clinician at the time of data entry can enter a different value or even leave it
empty. That results in data inconsistency, and makes sharing even harder. By using
archetypes in openEHR, one can put detailed constraints on data. Data is validated
based on corresponding archetypes and the storage of invalid data is not possible.
H. Kashfi and O. Torgersson / A Migration to an openEHR-Based Clinical Application154
Finally, MedView combines demographic and clinical information in examinations,
which decreases privacy. Hence, we started investigating migration from the current
framework to openEHR, which overcomes all deficiencies in MedView.
3. Method and Results of Migration to openEHR-Based MedView
A migration to an openEHR-based MedView consists of several processes (see Figure 1):
x Creating archetypes and templates.
x Translating MedView records to EHRs in openEHR and creating a persistence
layer. For this purpose, the most convenient option, XML, is used. Up to now,
more than 20,000 clinical examinations have been recorded. Each examination
is stored in a text file including term/value pairs. In this translation, a mapping
from current terms to nodes in archetypes is required. This has to be created,
at least partly, by hand, but the actual translation will be done automatically.
x Developing a service layer to connect applications to the kernel. Java is used
for developing required services.
x Extending existing Java-based applications to support openEHR.
4. Discussion and Conclusion
Since MedView is specifically aimed at providing clinicians with useful tools for several
tasks, a switch to openEHR must not lead to severe negative effects on any of these tasks.
For each application, changes required to make them openEHR-enabled should be
investigated.
x Knowledge Management: MedView provides tools that are used for creating
local terminologies and managing forms for data entry. In moving to
openEHR, one could either use the existing openEHR archetype and template
editors, or create new ones better adapted to MedView. Because of lack of
time, the second option is not a solution for now. However, due to the high
complexity of existing openEHR tools, developing more usable editors will
probably be considered for the future.
x Data Collection: MedRecords automatically generates data entry forms based
on XML templates (see Figure 1). In an openEHR MedView, this application
should generate GUIs based on archetypes and templates, a non-trivial task.
Further, the GUIs must not only be functional, but also have high usability.
x Clinical Viewing: MedView makes a clear separation between entering and
viewing clinical data. The tool MedSummary, aimed at clinical viewing, uses
natural language generation to create a summary of one or more examination
records and associated images. The style and contents of the text can be
defined by the clinicians themselves, using a special editor. In moving to
openEHR, there are no hard technical problems related to using the same kind
of presentation. All that is required is knowledge about what kind of data is
available, and some software glue retrieving archetype-based data.
x Analytical Viewing: In MedView, visual exploration of stored clinical data is
possible using mVisualizer [4]. A move to openEHR will require some re-
thinking when it comes to visualization tools. This is because mVisualizer
H. Kashfi and O. Torgersson / A Migration to an openEHR-Based Clinical Application 155
assumes that the basic unit to visualize is sets of term/value pairs. Further
investigations will be needed to find a suitable visualization model.
x Personal Viewing: In MedView suit, mPhoto helps clinicians to search and
browse through images together with their corresponding examination data. A
move to openEHR would not mean anything for mPhoto in principle, but a
new search mechanism has to be implemented.
4.1. Problems Encountered in Using openEHR
During our efforts to migrate to openEHR we have encountered some problems:
x Complexity of the specifications: The current stable release of the openEHR
specifications is 885 pages. If some relevant specifications are included, the
total is 1,016 pages. Additionally, there are UML-diagrams and
documentation of code. Getting a grip on this is not an easy task.
x Complexity of archetypes: The archetype model is very powerful and allows
expressing complicated clinical concepts. It also takes some time to learn and
we have not found much documentation aimed at helping clinicians develop
archetypes. Further, the existing archetype editors cannot really be said to help
inexperienced archetype developers beyond hiding the actual syntax.
x Lack of implementation: In our preferred language, Java, the openEHR
implementation lacks important parts like templates, persistence, and services.
4.2. Conclusion
Our investigation proved that, a migration from traditional MedView to openEHR-
based MedView is possible in principle. Moreover, in developing the knowledge layer
and persistence layer because of current style of modelling in MedView this migration
is straightforward. Nevertheless, more effort is required for the other two layers;
especially for the service layer as a result of lack of implementation. Further, for
visualization applications a visualization model based on openEHR should be found.
Acknowledgements. We would like to thank openEHR community, technical and Java mailing
list members for their helpful discussions and supports. The work was funded by the Swedish
Governmental Agency for Innovation Systems (VINNOVA), grant 2006-02792.
References
[1] Jontell, M., Mattsson, U., Torgersson, O. (2005) MedView: An instrument for clinical research and
education in oral medicine. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and
Endodontology 99(1):55–63.
[2] Beale, T., Heard, S. (2007) openEHR Architecture Overview.
http://www.openehr.org/svn/specification/TAGS/Release-1.0.1/publishing/architecture/overview.pdf.
[3] Beale, T. (2002) Archetypes: Constraint-based domain models for future-proof information systems. In
Baclawski, K., Kilov, H. (Eds.) Eleventh OOPSLA Workshop on Behavioral Semantics: Serving the
Customer, Northeastern University, Boston, 16–32,
http://www.openehr.org/publications/archetypes/archetypes_beale_oopsla_2002.pdf.
[4] Erichson, N., Torgersson, O. (2005) mVisualizer: Easily accessible data exploration for clinicians.
Studies in Health Technology and Informatics 116:725–730.
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