a common ground theory of medical decision-making 2: the knowledge ladder john fox department of...
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A common ground theory of medical decision-making
2: The knowledge ladder
John Fox Department of Engineering Science
University of Oxford and OpenClinical
Knowledge based systems and theories of knowledge
• Expert systems– “a piece of software which uses databases of expert knowledge to
offer advice or make decisions in such areas as medical diagnosis”
• Knowledge based systems– “A KBS is a computer program that reasons and uses knowledge
to solve complex problems”
• Knowledge representation– “use of symbols … in a conceptual model of the world; symbols
are arranged in order to form semantic constructions and express relations between concepts”
Knowledge engineering
• Representation and formalisation of knowledge– Domain specific and general knowledge– Theory and semantics of concepts and ontologies
• Knowledge acquisition– Elicitation of knowledge from human experts – Semi-automatic methods (e.g. machine learning)
• Symbolic processing techniques– Computational architectures for knowledge processing– Practical tools for creating and maintaining knowledge
bases
PROforma: A knowledge representation language for decision engineering
• A general notation for modelling clinical processes
• Grounded in a logical theory of decisions, plans and knowledge
• Applications are composed out of a minimal set of generalised task models
Fox et al, Proc. MIE 1996;Fox and Das, MIT Press, 2000
Sutton and Fox JAMIA, 2003
Formalising and sharing knowledge
Source content
Trials, systematic reviews, guidelines,
evidence
Point of care
e.g. Routine care, clinical research, patient services
Machine executablemodels of practice
PROforma+
Open access, open source repository
Repertoire
The medical knowledge ladder
Concepts
Terms
Descriptions
Rules
Decisions
Plans
Agents
WHO International classification of diseases
Terms
Primary healthcare
Information Support
Otherhealthcare
related classifications
3-character core
• Diagnoses• Symptoms• Abnormal Lab findings• Injuries and poisonings• External causes of morbidity and
mortality• Factors influencing health status
Speciality codes
• oncology• dentistry• dermatology• psychology• neurology• obstetrics & gynaecology• rheumatology &
orthopaedics• general medical practice
International Nomenclature
of Diseases
SNOMED Systematized NOmenclature of MEDicine
• A general purpose, comprehensive medical terminology
• Computer-readable standard• Representing and indexing “virtually all of the
events found in the medical record”• SNOMED CT (Clinical Terms) is being widely
promoted as a global language (English)
Concepts
Terms
Concepts
• Formalisms for organising and formalising the meaning of concepts in a domain
• Domain concepts linked together in a network using relations characteristic of the domain
• Class hierarchies – Inheritance of attributes over classes
Ontologies and descriptions
• Capture common understanding of the meaning of information – Between people, computers, both
• Enable sound techniques for reasoning, decision-making, planning, learning … by computers
• Introduce standards across medical specialties • Enable trustworthy use and reuse of domain
knowledge
Concepts
Terms
Ontologies and descriptions(compare semantic networks, dependency graphs, BNs)
Descriptions
Cancer
Breast cancer
IS_A
Chemotherapy
Radiotherapy
Treatments
IS_A
IS_A
Symptoms
Lump
Weight loss
IS_A
IS_A
causes
caused_by
Patient1 Patient2
instanceinstance
Concepts
Terms
Descriptions
Rules
Rule-based decision support
if last_creatinine is not present thenalert_text := "No recent creatinine available.
Consider ordering creatinine before giving IV
contrast.";conclude true;
elseif last_creatinine > 1.5 thenalert_text := ”This patient has an elevated
creatinine.Giving IV contrast may worsen renal
function." ;conclude true;
else conclude false;endif;
Reasoning over ontologies
if Subclass is a kind of Class andProperty is a property of Class
then Property is a property of SubClass
If Disease is a cause of Symptom andPatient has Symptom
then possible diagnosis of Symptom in Patient is Disease
Description logics
• Descriptions of medical facts and clinical data stated in propositional sentences in some L
• First order predicate calculus is a commonly used and versatile/powerful tool for reasoning over ontologies and descriptions
• Known to be computationally intractable in worst case – do not need all the power of FOPC; – adopt simpler axioms with more favourable
computational properties– http://en.wikipedia.org/wiki/Description_Logics
PROforma “task” ontology
Concepts
Terms
Descriptions
Terms to descriptions
Concepts
Terms
Descriptions
Rules
Rules in PROforma
Concepts
Terms
Descriptions
Rules
Decisions
PROforma decision engineering
Concepts
Terms
Descriptions
Rules
Decisions
PROforma decision model
Concepts
Terms
Descriptions
Rules
Decisions
Plans
Decisions in context: workflows, care plans and pathways
Kinds of decision-making and expertise
Concepts
Terms
Descriptions
Rules
Decisions
Plans
Agents
https://en.wikipedia.org/wiki/Expert_system
Conclusions
• Understanding medical expertise requires general models for reasoning, decision-making, planning etc (of course)
• … but a key (the largest?) component of medical expertise is what the expert knows
• AI and knowledge representation research have shown that knowledge is semantically complex but systematically structured
• Theories of knowledge and techniques of knowledge engineering open up exciting possibilities for formalising and sharing medical expertise and exploring new techniques for improving decision-making and the quality and safety of common medical practice
Conversations are two way…
• OpenClinical.net is based on a kind of publishing model (compare Wikipedia)
• Question to behavioural scientists - how can we engage the stakeholders to use it?– Professionals– Patients– Providers
• “The problem is in the implementation” … incentives, bonuses, payoffs, …?