Decision Decision Analysis 101Analysis 101

Stefan Tigges MD MSCRStefan Tigges MD MSCR

What is Decision What is Decision Analysis?Analysis?

Best course of action Best course of action under conditions of under conditions of uncertaintyuncertainty

Rationalize decision Rationalize decision making making

Basic conceptsBasic concepts Expected valueExpected value Decision trees/IngredientsDecision trees/Ingredients

ExamplesExamples Audience participationAudience participation

Key Concept: Key Concept: Expected ValueExpected Value

Average payoff of Average payoff of random trial random trial P x P x VV

P(outcome)P(outcome) Outcome valueOutcome value Expected value Expected value

may not be a may not be a possible outcomepossible outcome

Gambling exampleGambling example

Should I Buy a Should I Buy a Ticket?Ticket?

Wikipedia: California Lottery Mega MillionsWikipedia: California Lottery Mega Millions Minimum payoff is $12,000,000Minimum payoff is $12,000,000 P(Winning) is 1/175,711,536P(Winning) is 1/175,711,536 Cost is one dollarCost is one dollar

Should I Buy a Should I Buy a Ticket?Ticket?

Types of Expected Types of Expected ValuesValues

Expected ValueExpected Value P(outcome)P(outcome) Value of outcomeValue of outcome

DollarsDollars Years of survivalYears of survival UtilityUtility QALYQALY

Outcome: Utility Outcome: Utility Desirability of a Health Desirability of a Health

StateState

Expected Value= P(outcome) x ValueExpected Value= P(outcome) x Value

Outcome: Treatment Outcome: Treatment UtilityUtility

Decision Analysis Decision Analysis IngredientsIngredients

Comparing Comparing expected values expected values of different of different options, X vs Yoptions, X vs Y

Decision treeDecision tree OutcomesOutcomes ProbabilitiesProbabilities

Expected Value= P(outcome) x ValueExpected Value= P(outcome) x Value

Decision Tree BasicsDecision Tree Basics

TimeTime

DecisionDecisionOptionsOptionsOutcomesOutcomes

Decision Tree BasicsDecision Tree Basics

Decision Tree BasicsDecision Tree Basics

Example: R/O CADExample: R/O CAD

First Make a ChoiceFirst Make a Choice

PossibilitiesPossibilities

More PossibilitiesMore Possibilities

Final TreeFinal Tree

And the Winner And the Winner is…is…

Shortcomings of Decision Shortcomings of Decision AnalysisAnalysis

Risk AverseRisk Averse QALY (Y x U)QALY (Y x U)

Years survivalYears survival UtilityUtility

SubjectiveSubjective Doctor/patient/familyDoctor/patient/family

Other NumbersOther Numbers LiteratureLiterature UncertaintyUncertainty

Test accuracyTest accuracy CostsCosts

Sensitivity AnalysisSensitivity Analysis Technique that recognizes range Technique that recognizes range

of valuesof values ProbabilitiesProbabilities OutcomesOutcomes

TypesTypes One-WayOne-Way Two-WayTwo-Way Three-WayThree-Way

Tornado DiagramTornado Diagram

Sensitivity Analysis: Prob Sensitivity Analysis: Prob CadCad

One Way Sensitivity One Way Sensitivity AnalysisAnalysis

Range .05 to .95

Tornado DiagramTornado Diagram

Sensitivity Analysis: Cath Sensitivity Analysis: Cath MortalityMortality

One Way Sensitivity One Way Sensitivity AnalysisAnalysis

Range .000001 to .1

Two Way Sensitivity Two Way Sensitivity AnalysisAnalysis

Range Cath Mortality

.000001 to .1

Range CADProbability .05 to .95

Three Way Sensitivity Three Way Sensitivity AnalysisAnalysisSensitivity Analysis on

Mortality of Cath and Sensitivity of Cath and Sensitivity of CT

Mortality of Cath

Sens

itivi

ty o

f Cat

h

0.00 0.03 0.05 0.08 0.10

0.990

0.943

0.895

0.848

0.800

Cardiac CTCoronary Cath

Sensitivity of CT = 0.800

Sensitivity Analysis on Mortality of Cath and Sensitivity of Cath and Sensitivity of CT

Mortality of Cath

Sens

itivi

ty o

f Cat

h

0.00 0.03 0.05 0.08 0.10

0.990

0.943

0.895

0.848

0.800

Cardiac CTCoronary Cath

Sensitivity of CT = 0.848

Sensitivity Analysis on Mortality of Cath and Sensitivity of Cath and Sensitivity of CT

Mortality of Cath

Sens

itivi

ty o

f Cat

h

0.00 0.03 0.05 0.08 0.10

0.990

0.943

0.895

0.848

0.800

Cardiac CTCoronary Cath

Sensitivity of CT = 0.895

Sensitivity Analysis on Mortality of Cath and Sensitivity of Cath and Sensitivity of CT

Mortality of Cath

Sens

itivi

ty o

f Cat

h

0.00 0.03 0.05 0.08 0.10

0.990

0.943

0.895

0.848

0.800

Cardiac CTCoronary Cath

Sensitivity of CT = 0.943

Three Way Sensitivity Three Way Sensitivity AnalysisAnalysis

Do it Yourself Decision Do it Yourself Decision AnalysisAnalysis

Problem: You chooseProblem: You choose IngredientsIngredients

Decision tree: time flows left to rightDecision tree: time flows left to right ChoicesChoices OutcomesOutcomes ProbabilitiesProbabilities ValuesValues