A common ground theory
of medical decision-making
1: The CREDO stack
John Fox
Department of Engineering Science
University of Oxford and OpenClinical
Thanks to …
Clinicians
Psychologists, Informatics/CS/AI
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Alyssa Alabassi
John Bury
Robert Dunlop
John Emery
Marc Gutenstein
Andrzej Glowinski
Mike O’Neil
Vicky Monaghan
Vivek Patkar
Jean-Louis Renaud-Salis
Robert Walton
Matt Williams
Guy Wood-Gush
Andrew Coulson
Ioannis Chronakis
Subrata Das
David Glasspool
Omar Khan
Paul Krause
Simon Parsons
Mor Peleg
Ali Rahmanzadeh
Matt South
Rory Steele
Paul Taylor
Richard Thomson
Summary
• Medicine is a rich and challenging domain for decision
science and decision engineering
• It raises major challenges and curiously neglected
questions at many levels
– theory, technology, applications and more …
• The common ground theory aims to provide a general
framework in which to
– Promote discussion across disciplines
– Clarify research questions and
– Develop practical solutions
• The CREDO stack is a particular instance, but there are
many others
The borders of the common ground
• “Prescriptive” (axiomatic, rational) theories
– Lindley “there is only one correct way to take a decision”
– EUT, Multicriteria DT, game theory, … and many ad hoc variants
• “Descriptive” (empirical, explanatory) theories
– Cognitive (Nobel Laureates - Herbert Simon, Daniel Kahneman)
– Neuroscience (neuroanatomy, neuropsychology, “hot cognition”)
– Ecological (e.g. Gary Klein “naturalistic” theories)
• “Practical” (engineering, design) theories
– Decisions are often framed and made with respect to standard practice
– Decision systems may need to engage with accepted practice
Medical motivation:
Quality and safety of patient care
• UK National health service
– Vincent data on medical error in Acute Hospitals
• >10% acute hospital admissions in NHS lead to avoidable medical
error
• US Institute of Medicine
– IOM: “To err is human”; “Crossing the quality chasm”
– McGlynn: Quality of Health Care Delivered to Adults in the
USA
Quality of Health in the USA
McGlynn NEJM 2003
The CREDO stack
Diversity of medical decisions
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Screening for and classification of hazards;
Risk stratification and management;
Selection of tests and investigations;
Diagnosing the cause(s) of clinical complaints;
Selecting treatments and other interventions;
Prescribing drugs (routes, dosages, polypharmacy etc.);
Referring patient to a colleague
Deciding whether a decision is needed;
Initiating, adjusting and stopping treatments;
Deciding whether earlier decisions are correct or not; if
not why not; adjust; reverse, reframe, retake;
Diversity of medical decisions
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Screening for and classification of hazards;
Risk stratification and management;
Selection of tests and investigations;
Diagnosing the cause(s) of clinical complaints;
Selecting treatments and other interventions;
Prescribing drugs (routes, dosages, polypharmacy etc.);
Referring patient to a colleague
Deciding whether a decision is needed;
Initiating, adjusting and stopping treatments;
Deciding whether earlier decisions are correct or not; if
not why not; adjust; reverse, reframe, retake;
MDM is reason based
Refer to specialist colleague if …
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7.
There is a possible life threatening condition
I don’t know what to do or lack sufficient knowledge
The NICE clinical guideline says I should
Patient is eligible for a research trial
Difficult patient, and I can’t resolve issue by myself
Patient has asked to be referred
Colleague or mentor has suggested I should …
MDM is dynamic
• Decision-makers must deal with changing and
often unpredictable circumstances
• Decisions are not just choices, they are points in an
evolving narrative (patient and professional)
• Common ground theory should address the whole
cycle of decision-making:
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When is a decision needed? what is the goal of the decision?
What knowledge and strategies are relevant?
When is it appropriate and safe to commit?
When is it necessary to revisit and revise commitments as the
situation evolves?
Example: cancer care
Example: cancer care
Example: decisions in context
The CREDO stack
A common ground theory
Goals
Beliefs
Actions
Options
Commitments
Plans
From decision science to decision engineering: the CREDO stack
ResearchGate 2014
Example: risk assessment
Assess
risk
Goals
Worried,
well
Beliefs
Moderate
risk
Actions
Genetic, statistical &
other lines of reasoning
Options
Population or
moderate or
high risk
Commitments
Plans
Example: test selection
Investigate
for possible
cancer
tr
Pain,
nodule
Goals
Beliefs
Order
Mammogram &
ultrasound Actions
Mammogram,
ultrasound
Options
Ultrasound
Mammogram
CT etc.
Age, symptoms,
…
Family history
Commitments
Plans
Reasons and decisions
Argument construction
Knowledge U Data
LA
(Claim, Reason, Qualifier)
{(Claim, Reason, Qualifier)}
Agg (Claim, Modality)
Argument aggregation
Fox et al ECAI, 1992; UAI 1994; Fox and Das, 2000
Krause et al Computational Intelligence 1995
Uncertainty and arguments
• Quantitative
[0,1]
[-1,+1]
{1,2,3,…n}
degree of belief (e.g. probability, possibility)
bipolar measures (e.g. belief functions)
ad hoc weighting of arguments
• Qualitative
+
{+,-}
{++,--, +, -}
“supporting” arguments
“supporting” and “opposing” arguments
… plus “confirming” and “excluding”
• Modal
Linguistic (perhaps, possible, probable, plausible …)
Formalising the common ground theory
The CREDO stack
The knowledge ladder
Agents
Expert systems, Personal care agents
Plans
Care pathways, workflows
Decisions
Rules
Descriptions
Concepts
Symbols
Reasons (arguments, evidence, preferences)
Alerts, reminders, interpretations
Medical facts, Clinical notes
Class hierarchies, semantic networks
Diseases, Symptoms, Findings, Drugs
Terminologies, coding systems
The CREDO stack
PROforma: Reification into “tasks”
Enquiries
Goals
Actions
Beliefs
Plan
Decision
Candidates
Actions
Commitments
Plans
Fox et al, MIE 1996;
Fox and Das, AI in hazardous applications, MIT Press, 2000
Decision engineering
The CREDO stack
Applications
Care pathways in cardiology
UPMC (USA), NHS (NZ) , NHS
UK
Diagnosis and treatment in endocrine conditions (thyroid,
diabetes)
AACE (USA)
Decision support for general practitioners
BPAC (NZ)
Triage for common conditions
NHS Choices (UK)
Supporting the breast MDT- Royal Free Hospital
BASO 2008, ASCO 2009, BMJ
Open, 2012
Triple assessment of suspected breast cancer
Brit J Cancer 2006
Chemotherapy for children with acute lymphoblastic leukaemia
Brit J Haematology 2005
Planning care for women at risk of breast/ovarian cancer
Methods of Information in Medicine
2004
GP referrals for common cancers
MEDINFO 2003
Genotype of HIV+ patients interpretation and selection of antiretrovirals (InferMed, Hoffman la Roche)
AIDS 2002
Genetic risk assessment
BMJ 1999, 2000
Support for mammographic screening
Medical Imaging 1999
Prescribing in general practice
BMJ 1997
The CREDO stack
Decision support: human interaction
Summary
• Medicine is a challenging domain for
– Understanding human error and expertise
– Developing decision theory, empirical science and
engineering methods
• It raises many important questions and some
strangely neglected ones
– This will require contributions from many disciplines but
there is a high level of fragmentation in decision science
• The “domino” is a first draft of a common ground
theory, to promote interdisciplinary discussion
• The CREDO stack validates the theory to a first
approximation demonstrates its practical value