Advanced treatment of temporal phenomena in clinical guidelines

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Advanced treatment of temporal phenomena in
clinical guidelines
Paolo Terenziani1, Luca Anselma2, Alessio
Bottrighi1, Stefania Montani1 1DI, Univ.
Piemonte Orientale A. Avogadro, Via Bellini
25\g, Alessandria, Italy 2DI, Università di
Torino, Corso Svizzera 184, 10149 Torino, Italy
- Introduction
- GLARE (GuideLine Acquisition, Representation
and Execution)
- Temporal constraints and Temporal Reasoning
generalities
- The GLARE approach (data structures, algorithms
and properties)
- Conclusions
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Introduction
Clinical guidelines are a means for specifying
the best clinical procedures and for
standardizing them
Adopting (computer-based) clinical guidelines is
advantageous
Different roles - support - critique - evaluation
- education - ...
Many different computer systems managing clinical
guidelines (e.g., Asgaard, GEM, Gliff, Guide,
PROforma,)
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GLARE(GuideLine Acquisition Representation and
Execution)
- Joint project Dept. Comp. Sci., Univ.
Alessandria (It) P. Terenziani, S.Montani,
A.Bottrighi Dept. Comp. Sci., Univ. Torino (It)
L.Anselma,G.Correndo Az. Osp. S. Giovanni
Battista, Torino (It) G.Molino, M.Torchio
- Domain independent (e.g., bladder cancer,
reflux esophagitis, heart failure) - Phisician-ori
ented User-friendly
Some recent pubblications Terenziani et al.,
AIIMJ 01,07a,07b, AMIA 00,02,03, Medinfo 04,
CGP04a,04b, AIIA 03,05, GIN 04,05, AIME
05a,05b,05c
AMIA06 posters M010 and T120 AMIA06 paper in
session S52
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GLARE Representation Formalism
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Representation FormalismHierarchy of Action Types
Action
Plan
Work action
Query
Conclusion
Decision
Clinical action
Pharmacol. prescription
Diagnostic decision
Therapeutic decision
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Representation Formalismdescription of a
clinical action
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Architecture of the system
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Temporal Constraints in Clinical Guidelines
Temporal constraints are an intrinsic part of
clinical knowledge (e.g., ordering of the
therapeutic actions)
Different kinds of temporal constraints, e.g.,
- duration of actions (min / max) - qualitative
constraints (e.g., before, during) - delays (min
/ max) - periodicity constraints on repeated
actions
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Temporal Constraints in Clinical
Guidelinesrepetitions
TheThe therapy for multiple mieloma is made by
six cycles of 5-day treatment, each one followed
by a delay of 23 days (for a total time of 24
weeks). Within each cycle of 5 days, 2 inner
cycles can be distinguished the melphalan
treatment, to be provided twice a day, for each
of the 5 days, and the prednisone treatment, to
be provided once a day, for each of the 5 days.
These two treatments must be performed in
parallel.
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Managing Temporal Constraint the Problem
Both representation and inference are NEEDED
Temporal Constraints without Temporal Reasoning
(constraint propagation) - are useless - clash
against users intuitions/expectations
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Managing Temporal Constraints the Problem
Implied constraint (temporal reasoning) (1.6) C
ends between 30 and 60 m after the start of A
Correct (consistent) assertion (1.7) C ends
between 30 and 50 m after the start of A
Not correct (inconsistent) assertion (1.8) C
ends more than 70 m. after the start of A
However Temporal Reasoning is NEEDED in order to
support such an intended semantics!
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Managing Temporal Constraints the Problem
DESIDERATA for the Representation formalism
- expressiveness ? capture most temporal
constraints in GL
DESIDERATA for Temporal Reasoning Algorithms
- tractability ? reasonable response time
- correctness ? no wrong inferences
- completeness ? reliable answers
TRADE-OFF!
SPECIALIZED APPROACHES (since 80 in AI
literature)
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Digression Why Completeness is fundamental?
Implied constraint (temporal reasoning) (1.6) C
ends between 30 and 60 m after the start of A
Suppose that temporal reasoning is NOT complete,
so that (1.6) is not inferred
The answer to query (Q1) might be YES (Q1) Is it
possible that C ends more than 70 m. after the
start of A?
Complete Temporal Reasoning is NEEDED in order to
grant correct answers to queries!
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Temporal Constraint Treatment
WHEN Temporal Reasoning is useful in Guidelines?
ACQUISITION
- to check consistency
EXECUTION
- to compare the duration of paths, in
hypothetical reasoning (simulation) facilities
- to check that the time of execution of actions
on patients is consistent with the constraints
in the guideline
- to schedule next actions
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Temporal Representation and Temporal Reasoning
for Clinical Guidelines

• Different kinds of temporal constraints

• No current approach in the AI literature covers
  all of them

• Our proposal an extension of the consensus STP
  approach Dechter et al., 91

• Our goal expressiveness correct, complete and
  tractable inferences

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GLAREs approach (representation)Labeled tree of
STPs (STPs-tree)
Tree of STPs for the multiple mieloma
chemotherapy guideline. The overall therapy (node
N1) is composed by 6 cycles of 5 days plus a
delay of 23 days . In each cycle (node N2), two
therapies are executed in parallel Alkeran (node
N3 Sa and Ea are the starting and ending nodes),
to be repeated twice a day, and Deltacorten (node
N4 Sd and Ed are the starting and ending nodes),
to be repeated once a day. Arcs between any two
nodes X and Y in a STP (say N2) of the STP-tree
are labeled by a pair n,m representing the
minimal and maximal distance between X and Y.
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Consistency checking on STPs-trees
ALGO1 temporal consistency of guidelines Top-down
visit of the nodes in the STPs-tree For each
node in the STPs-tree 1) the consistency of the
constraints used to specify the repetition taken
in isolation is checked 2) the extra temporal
constraints regarding the repetition are mapped
onto STP constraints 3) Floyd-Warshalls
algorithm is applied to the constraints in the
STP plus the extra STP constraints determined
at step 2. Property 1. ALGO1 is correct,
complete, and tractable (it operates in O(N3),
where N is the number of actions in the
guideline).
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Temporal reasoning on guidelines
instantiationsALGORITHM (sketch)
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Temporal reasoning on guidelines instantiations
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CONCLUSIONS
Temporal constraints an essential part of
clinical guidelines
Temporal constraints need a principled
treatment not only representation, but
also correct, complete (and tractable)
inferential mechanisms
Many approaches to time in clinical guidelines in
the literature, but properties of the inferential
mechanisms (if present) quite neglected
GLARE (Guideline Acquisition, Representation and
Execution) a proposal of solution based on an
extension of well-consolidated Artificial
Intelligence techniques