theoretical framework for building expert systems in
psychiatry, and for future research.
We believe medical expert system development
in general faces a number of challenges in relation to
the domains of conceptual modelling,
implementation, and social and organisational
aspects. The main problems of the previous
approaches(e.g. INTERNIS-1/ CADUCEUS
(Wolfram, 1995); (Miller, 1984); CADIAG-1 and
CADIAG-2 (Adlassnig and Kolarzs, 1986);
Parsimonious Covering Theory (Reggia and Peng,
1987); A Process Model of Diagnostic Reasoning
(Stausberg and Person, 1999) to development of
medical expert systems include: failure to develop
conceptual models that capture the depth of the
domain; difficulties in developing a sufficiently
large knowledgebase; and failure to take into
consideration the social and organisational issues
related to operational aspects of the implemented
system. The authors have discussed these aspects in
a separate paper (including the limitations of the
previous approaches), and have proposed a
development framework in order to overcome these
challenges (Fernando et al., 2011). The very first
step towards developing a successful medical expert
system is developing a conceptual model that
captures the depth and the complexity of clinical
reasoning in specialised medical domains. This
paper and the previous one attempt to achieve this
first step, specifically in the field of psychiatry.
2 KNOWLEDGEBASE MODEL
The key to successful clinical inference is the
structure of the knowledgebase. Whilst there are
approaches in which the knowledgebase is
independent from the inference process (e.g.
CLASSIKA (Gappa et al., 1993), PROTÉGÉ (Tu et
al., 1995), such approaches are deemed unsuitable
for a highly specialised knowledge domain such as
psychiatry, in which the inference mechanism is
dependent on the knowledgebase structure from the
clinician’s perspective.
The knowledgebase encompasses three domains:
diagnostic knowledge; etiological knowledge; and
the treatment knowledge, which may be organized
as a hierarchy as described in Figure-1. The
diagnostic domain of the knowledgebase consists of
layers representing respectively individual
symptoms, and clinical phenomena, in which
symptoms combine to form unique clinical
phenomena. The etiological domain of the
knowledgebase consists of layers representing
respectively model concepts, and explanatory
models, which can be derived from a number of
etiological theories in psychiatry including ego-
psychology (Freud 1923); self-psychology (Kohut,
2009); object-relations theory (Ogden, 1983);
attachment theory (Bowlby, 1969); cognitive
schema therapy model (Young et al., 2003); and
Interpersonal Therapy Model (Weissman et al.,
2000). Each explanatory model consists of a unique
combination of model concepts. Each clinical
phenomenon is related to one or more model
concepts, thus bridging the diagnostic domain and
the etiological domain of the knowledgebase. The
treatment domain consists of layers representing
respectively treatment components, and individual
treatments. Each treatment comprises a unique
combination of treatment components. Figure-2
explains the knowledgebase model using an
example, in which the two symptoms “low self-
confidence” and “oversensitivity to criticism” along
with several other symptoms form the clinical
phenomenon “Low self-esteem”. Next, this clinical
phenomenon is related to the model concept,
“Cognitive schema of defective self” in the
etiological knowledge domain. One explanatory
model is shown in the next layer of the etiological
knowledgebase, and it is made up of three model
concepts: “Predisposing events”, “Cognitive schema
of defective self” and “Precipitating events”. This
explanatory model is related to the treatment
component “Cognitive Re-structuring” in the
treatment knowledge domain, which happens to be a
part of the treatment “Cognitive Behaviour
Therapy”. The clinical basis of this structure of the
knowledgebase is not within the scope of this paper
and is covered elsewhere (Fernando et al., 2011).
Clinical phenomena are made up of a
constellation of symptoms, and arguably play a more
critical role in clinical reasoning in psychiatry
compared to other branches of medicine. They are
directly related to phenomenological concepts in
psychiatry, and can be considered as core clinical
features or recurrent themes in clinical scenarios.
Diagnostic inference based on clinical phenomena is
considered to have more reliability and validity
compared to that based on symptoms, since each
clinical phenomenon is a unique constellation of a
number of clinical symptoms.
The main components of the diagnostic
knowledgebase and their relations are defined as
follows.
={
,
,…,
} is the set of all symptoms.
ℎ={
,
,…,
} is the set of all clinical
phenomena.
HEALTHINF 2012 - International Conference on Health Informatics
330