Ambiguity and Ambiguity and Vagueness in Clinical Vagueness in Clinical Practice GuidelinesPractice Guidelines

Shlomi Codish, MDShlomi Codish, MDRichard Shiffman, MD, MCISRichard Shiffman, MD, MCIS

Yale Center for Medical Yale Center for Medical InformaticsInformatics

OverviewOverview

Definitions and backgroundDefinitions and background Classification modelClassification model Implications for authoring and Implications for authoring and

implementationimplementation

Linguistic definitionsLinguistic definitions

Vague: lacking clear borders, Vague: lacking clear borders, having borderline cases having borderline cases ““Dan is tall.”Dan is tall.”

Ambiguous: capable of being Ambiguous: capable of being understood in two or more understood in two or more possible senses or wayspossible senses or ways““I will meet you at the bank.”I will meet you at the bank.”

IntroductionIntroduction

Focus: human users of CPGsFocus: human users of CPGs Clinicians – reduced adherence or accuracyClinicians – reduced adherence or accuracy

Grol (1998), Shekelle (2000)Grol (1998), Shekelle (2000)

ImplementersImplementers

Ambiguity is often used to describe Ambiguity is often used to describe vaguenessvagueness ““disambiguation” has been used for the disambiguation” has been used for the

resolution of both ambiguity and vaguenessresolution of both ambiguity and vagueness

Research on vague Research on vague termsterms

Kong et al. NEJM 1986 Kong et al. NEJM 1986 ““qualitative expressions of probability”qualitative expressions of probability” Large variability in interpretationLarge variability in interpretation Comparable ranking as in previous Comparable ranking as in previous

study for 7 terms despite variable study for 7 terms despite variable interpretation :interpretation : certain > probable > likely > not certain > probable > likely > not

unreasonable >unreasonable >possible > unlikely > neverpossible > unlikely > never

Other factors affecting Other factors affecting interpretationinterpretation

Mapes (1979) – importance of contextMapes (1979) – importance of context Compare interpretation of Compare interpretation of rarerare in: in:

“…“…in the case of this beta blocker drug side effects are in the case of this beta blocker drug side effects are rarerare””

“…“…in the case of this antihistaminic drug side effects are in the case of this antihistaminic drug side effects are rarerare””

Kahneman and Tversky – importance of framingKahneman and Tversky – importance of framing Decision making affected by framingDecision making affected by framing

Options presented in terms of Options presented in terms of lives savedlives saved or or lives lostlives lost

ambiguity ≠ uncertaintyambiguity ≠ uncertainty

NJ judge to rule on nude beachNJ judge to rule on nude beach

Stolen painting found by treeStolen painting found by tree

Prostitutes appeal to governorProstitutes appeal to governor

OverviewOverview

IntroductionIntroduction Classification model for ambiguity Classification model for ambiguity

and vaguenessand vagueness Implications for authoring and Implications for authoring and

implementationimplementation

Development Development methodologymethodology

MEDLINE and Web of Science MEDLINE and Web of Science databasesdatabases

Review of the linguistics literatureReview of the linguistics literature Lists of terms and categoriesLists of terms and categories Validation with random collection of Validation with random collection of

100 CPG100 CPG

Model AxesModel Axes

Axis I: Ambiguity or vagueness?Axis I: Ambiguity or vagueness? Sub classification of ambiguitySub classification of ambiguity Sub classification of vaguenessSub classification of vagueness

Axis II: RationaleAxis II: Rationale Deliberate or inadvertentDeliberate or inadvertent Causes of deliberate vaguenessCauses of deliberate vagueness

Axis III: ImplementersAxis III: Implementers Logical component affectedLogical component affected If <condition> then <action> because If <condition> then <action> because

<explanation><explanation>

Axis 1 - AmbiguityAxis 1 - Ambiguity

Syntactic ambiguity: Syntactic ambiguity: structure or syntaxstructure or syntax ……mother with untreated disease mother with untreated disease oror disease that has disease that has

been treated for 2 or more weeks been treated for 2 or more weeks andand is who is judged is who is judged

to be noncontagious at the time of delivery…to be noncontagious at the time of delivery…

Semantic ambiguity: “classic” ambiguity Semantic ambiguity: “classic” ambiguity

Pragmatic ambiguity: reader and writer have Pragmatic ambiguity: reader and writer have

different interpretationsdifferent interpretations Example: Example: Disclosure of adolescent HIV status Disclosure of adolescent HIV status should should

legally requirelegally require the consent of the adolescent. the consent of the adolescent.

(()

)

Pragmatic ambiguityPragmatic ambiguity

3

cm

4 cm

x

3. Find x.

Here it is

Ocular Trauma – by Wade Clarke © 2005

Axis 1 - VaguenessAxis 1 - Vagueness Underspecification is a form of vagueness Underspecification is a form of vagueness

that occurs when terms are used with that occurs when terms are used with insufficient details for interpretation.insufficient details for interpretation. moderate, severe, elderly, adultmoderate, severe, elderly, adult ……should be treated should be treated promptlypromptly and and aggressivelyaggressively..

Ordinal scales of underspecified wordsOrdinal scales of underspecified words

Temporal scale:

Probabilistic scale:

Quantitative scale:

Never

Always

Impossible

None

Certain

All

rare sometimes

common

unlikely possible

probable

few some many

Axis I - VaguenessAxis I - Vagueness

Strength qualifiers (a.k.a. hedges)Strength qualifiers (a.k.a. hedges) It is It is generally recommendedgenerally recommended that the that the

antibiotic beads be removed 2 weeks…antibiotic beads be removed 2 weeks… It is prudent to…It is prudent to…

Passive voicePassive voice Memory complaints should be evaluated and Memory complaints should be evaluated and

the individual followed to assess progressionthe individual followed to assess progression

Axis II - rationaleAxis II - rationale

Only the authors know the rationale Only the authors know the rationale Inadvertent ambiguity or vagueness Inadvertent ambiguity or vagueness

is a failure of authoring and editingis a failure of authoring and editing It might also result from a failure to It might also result from a failure to

recognize the problems ambiguity recognize the problems ambiguity and vagueness create:and vagueness create: “…“…please appreciate that we will not please appreciate that we will not

necessarily have full agreement on the necessarily have full agreement on the fine points of wording as each of us has fine points of wording as each of us has his or her own writing style…” his or her own writing style…”

Axis II – deliberate Axis II – deliberate vaguenessvagueness

Insufficient scientific evidenceInsufficient scientific evidence Lack of consensus among authorsLack of consensus among authors Other considerationsOther considerations

LegalLegal EconomicEconomic EthicalEthical ReligiousReligious

Axis III – logical Axis III – logical componentcomponent

The logical part affected by The logical part affected by vagueness impacts vagueness impacts implementation:implementation: <condition> affects <condition> affects decidabilitydecidability <action> impacts <action> impacts executabilityexecutability <explanation> does not seriously <explanation> does not seriously

impact implementabilityimpact implementability

Axis I

VaguenessAmbiguity

Semantic

Pragmatic

Syntactic

Strength qualifiers

Underspecification

Passive voice

Probabilistic QuantitativeTemporal Non-ordinalunderspecification

Axis II

Deliberate Inadvertent

Ethical/Religious

Legal

Insufficient Scientific background

Economic

Axis III

Action (executability)

Explanation

Condition(decidability)

Ambiguity or vagueness in CPG recommendation

OverviewOverview

IntroductionIntroduction Classification modelClassification model Implications for authoring and Implications for authoring and

implementationimplementation

Remedies – axis 1Remedies – axis 1

Numerical values (or ranges) for Numerical values (or ranges) for termsterms

Ranking words relative to one Ranking words relative to one anotheranother

Lists of ‘good’ and ‘bad’ termsLists of ‘good’ and ‘bad’ terms Controlled vocabularyControlled vocabulary

BI-RADS “BI-RADS “Suspicious Abnormality—Suspicious Abnormality—Biopsy Should Be ConsideredBiopsy Should Be Considered””

Fuzzy logicFuzzy logic

Remedies – axis 2Remedies – axis 2 Reason should be documentedReason should be documented

……activated protein C should not be routinely used…activated protein C should not be routinely used… ……activated protein C should not be routinely used activated protein C should not be routinely used

because of its high cost…because of its high cost… Selecting a vague term should consider the Selecting a vague term should consider the

audienceaudience The range of interpretation by the intended audienceThe range of interpretation by the intended audience Other terms with similar meaningOther terms with similar meaning Avoid terms with wide range of interpretationAvoid terms with wide range of interpretation

Limit the scope of vaguenessLimit the scope of vagueness Cigarette smoking may be hazardous to your healthCigarette smoking may be hazardous to your health Smoking causes lung cancer, heart disease, emphysema Smoking causes lung cancer, heart disease, emphysema

and may complicate pregnancyand may complicate pregnancy Clarification of deliberate vagueness should be Clarification of deliberate vagueness should be

done with author inputdone with author input

SummarySummary

Vagueness is a common problem in CPG Vagueness is a common problem in CPG

recommendationsrecommendations ““Classic” (i.e. semantic) ambiguity is uncommonClassic” (i.e. semantic) ambiguity is uncommon

Distinct forms of vagueness and ambiguity Distinct forms of vagueness and ambiguity

require specific remediesrequire specific remedies When deliberate vagueness is deemed necessary, When deliberate vagueness is deemed necessary,

end-user uncertainty should be minimizedend-user uncertainty should be minimized Clarification of deliberate vagueness must Clarification of deliberate vagueness must

consider the rationale for the vaguenessconsider the rationale for the vagueness

Everything is vague to a degree Everything is vague to a degree you do not realize till you have you do not realize till you have

tried to make it precise.tried to make it precise.

Bertrand Russell, 1918Bertrand Russell, 1918

AcknowledgementsAcknowledgements

Prof. Laurence HornProf. Laurence HornYale LinguisticsYale Linguistics

National Library of National Library of MedicineMedicine