上海交通大学医学院2012级研究生课程循证医学临床经济学评价（课件）

ToolsforDecisionMakingEconomicevaluationofHealthInterventionsShiRongShanghaiJiaoTongUniversityToolsforDecisionMakingPARTI.

OpportunitycostTomakeachoicemeansoptforsomethingandgiveupanotheropportunity.=>Everychoiceinvolvesacost.Theeconomistsusethetermofopportunitycosttoemphasisthiscost.Opportunitycost:thebestalternativeforegone.PARTI.

OpportunitycostTomakExampleYouhave1,000€Youhave3options:—A/EPI15livessaved—B/DOTS20livessaved—C/Fluconazol5livessavedWhatistheopportunitycostofchoosing(1)A,(2)Band(3)C?ExampleYouhave1,000€YouhaMarginality:thequestionisnot“tostudyornot”,but“howmanyhourspercourse”?HoursinstudyResult520/1001050/1001570/1002080/1002585/1003086/100Marginality:thequestionisMarginalityfortheconsumerItdependsalsoonthequantityIhavealready!Beforebuying/consumingoneunit,Iconsiderwhatutilitybringsthissupplementaryunit.Economistsconsidersthatmarginalutilityisdecreasing:thenextunitbringslessutilitythanthepreviousone.MarginalityfortheconsumerItChoice:theexampleoftheMoHInmanysituations,decisionisnotonmyownresourcesalongmyownpreferences.Example:MusttheMoHputitsnext$incondoms,drugsforopportunisticdiseasesorARV?Howtocomparemarginalbenefitandmarginalcost?=>Cost-effectivenessstudy!Choice:theexampleoftheMoHPARTⅡ.

COSTANALYSIS

PARTⅡ.

COSTANALYSIS

1.Theuseofcostinformation4reasonstostudycosts:

—toplanabudgetandstaywithinin(accountable);—tocompareefficiencyofdifferentfacilities(toidentifyopportunitiesofrationing);—tofixpricesofaservice(allocatecosttogoodsandservicesproduced);—toprioritizebetweendifferentinterventions.=>Avitalmanagerialtool!1.Theuseofcostinformation2.Therelationbetweencostandoutput:afewdefinitionsOutput:goodsorservicesproducedbyafirm.Fixedcosts:costincurredonceyoustartaspecificproduction,butwhichisnotrelatedtothequantityofoutput.Variablecosts:directlyrelatedtothequantityofoutput.2.TherelationbetweencostanAfewdefinitionsTotalcost:foragivenoutput,FC+VC;Itisdeterminedbythecurrentstateoftechnique&knowledge,costsoftheinputsandquantityofoutput.Averagecost:Totalcost/output.Marginalcost:increaseincostduetotheproductionofonemoreunitofoutput.AfewdefinitionsTotalcost:fAnumeric&graphicexample#ofnursesDischargedTFCTVCTCAFCAVCACmCpatients0025002501402502505006.256.2512.56.2521002505007502.557.54.17313025075010001.925.777.698.334150250100012501.676.678.3312.55160250125015001.567.819.3825Marginalcost=(totalcostn+1-totalcostn)/(quantityn+1-quantityn)Anumeric&graphicexampleMarginalityindecisionmaking:

anexampleImagineyouarethemanagerofahealthcenter.Yourclinicisopenfrom8a.m.to15a.m.6daysaweek.Partofthepopulationcomplainsabouttheseopeninghours.Youconsidertoextendtheopeningofyourfacility.Youwonderifitisrelevantornot.MarginalityindecisionmakingCostsoftheHealthCenter

CostNowNow+Now+Option1Options1&2Building(%)200200200Equipment(%)100100200Vehicles(%)100100150Support(%)200200300Runningcosts(%)200250250Staff(%)5006001,500Drugs5007501,000Total1,8002,2003,600Output(consult.)600800900

CostsoftheHealthCenter4.AllocatingtheoverheadcostsSomeinputsaresharedbydifferentoutputs.There’saneedtosplitthecostsperoutput.INPUTALLOCATIONKEYVehicles=>DistancetraveledEquipment=>TimeusedBuildingspace=>Space/timeusedStaff=>timeworkedSupplies=>Volume/weightused4.Allocatingtheoverheadcos5.AssessingcostsforeconomicevaluationImagineyouareinchargedofthemalariacontrolprograminadistrict.Providethelistofallthecostsoftheprogram.Usethetypologycapital/recurrentcosts.Table6.4Mustincludethecostscoveredbythesocietyasawhole.=>Muchbroaderthanbudgeting,efficiencycomparisonandpricing.Figure6.45.AssessingcostsforeconomiAfewdefinitionsDirectcosts:resourcesusedinthedesign,implementation,receiptandcontinuationofahealthintervention.Actualsumsofmoneyarehandedoverinpayment.Indirectcosts:thevalueofresourcesexpendedbypatientsandtheircarerstoenableindividualstoreceiveanintervention.Nomoneyispaidover.Intangiblecosts:non-financialcostssuchasanxiety,painattributabletotheprogram.AfewdefinitionsDirectcosts:Sometips…Directcostsareeasytovalue.Useactualexpendituresorconsumption(Don’tincludestock!)UsesamplingExcludetransfers.Indirectcostsaremoredifficult.Canbethemajorcostincurredbythehouseholds!Usesurveyandproxies.Intangibleareverydifficult.Thinkalsotoside-effectsoftheintervention!Don’tinvesttoomuchtimeincostsofsmallamounts!Sometips…DirectcostsareeasClassifythefollowingcostsofanAIDS/HIVprojectDrugstotreattheopportunisticdiseases.Timeofcarerdoingpsychologicalsupporttothepatienttocontinuetheirtreatment.FeelingofshameanddespairoftheAIDSpatient.Taxifaretocometotheconsultation.Absenteeismofthepatientonherjobthedaysshegoestothehealthcenter.Doctortimeforconsultation.ClassifythefollowingcostsoComparingdifferentinterventionsMaketheperspectiveexplicit:costfortheprovider,thehealthsector,thehouseholdorthewholesociety?Keepthepossibilitytopresentseparatelythecostsaccordingtotheperspectives(splitbysources).Omitcommoncosts(costssharedbyalltheoptionsunderconsideration).Comparingdifferentinterventi6.Takingtimeintoconsideration:6.1.DiscountingYouareamanager.Youarelookingatthefuture.Youhavelimitedresourcestocarryoutsomeinterventions.Youhavereliableinformationonfuturecostsandbenefitsofthedifferentoptions.Youhavetoidentifythebestallocationofcurrentandfutureresources.Ex:privateinvestment.6.TakingtimeintoconsideratiTimepreferenceDoyouprefertohave100$todayor100$inoneyear?Doyouprefertopay100$todayor100$inoneyear?Peopleusuallyworth1$todaymorethan1$tomorrow:—inflation—preferenceforpresent.TimepreferenceDoyouprefertApreferenceforthepresentTimepreference:People’spreferenceforconsumption(oruseofresources)nowratherthanlaterbecausetheyvaluepresentconsumptionmorethanthesameconsumptioninthefuture.Itwouldexisteveninaworldofzeroinflationandnobankinterest.ApreferenceforthepresentTi5reasonsforapositiverateoftimepreferenceImpatience,short-termviewoflife,‘livingfortodayratherthaninthefuture’.Futureisuncertain.“Abirdinthehandisworthtwointhebush”.Positiveeconomicgrowth.Wewillbemorewealthyinthefuture+decreasingmarginalutilityofwealth=>1$today>1$inthefuture.5reasonsforapositiverate5reasonsforapositiverateoftimepreferenceSincemostindividualhaveapositiverateoftimepreference,onecanobtainapositivereturnwhenmakingarisklessinvestment.Ihavemyowninvestmentopportunities(toincreasemyfuturewell-beingbyusingresourcestoday).Toseizetheseopportunities,Ineedtheresourcesnow!5reasonsforapositiverateWhentoconsidertimepreferenceineconomicevaluation?Whenever:—costsoccurindifferentyears—outcomesoccurindifferentyears—bothcostsandoutcomesoccurindifferentyears.—differentinterventionsarecompared.Usuallycostscomeatanearlystage,benefitscomelater.WhentoconsidertimepreferenDiscountingBecausecosts(andoutcomes)usuallyoccurindifferenttimeperiods,andbecausethevaluesofthesecosts(andoutcomes)aredifferentfordifferentyearsduetotimepreference,itisimportanttoadjustcosts(andoutcomes)tocommonyear.DiscountingBecausecosts(andCostsandbenefitsof5-yearintervention

Year1Year2Year3Year4Year5TotalBenefits01240100135287Costs10050505010260NetBenefits-100-38-105012527Costsandbenefitsof5-yeariDiscountedcosts&benefitsofa5-yearintervention

Year1Year2Year3Year4Year5TotalBenefits01240100135287Costs10050505010260Discount10.910.830.750.68factorPresent011337592211ValueofBPresent1004541387231ValueofCNet-100-34-83785-20benefitsDiscountedcosts&benefitsofDefinitionsDiscounting:isamethodforadjustingthevalueofcostsandoutcomeswhichoccurindifferenttimeperiodsintoacommontimeperiod,usuallythepresent.Presentvalue:thevaluenowoffuturecostsorbenefitsadjustedforthefactthattheyoccurinthefuturebydiscountingatagivenrate.DefinitionsDiscounting:isamHowthediscountfactoriscalculated?Thediscountrate(δ)istherateatwhichfuturecostsandoutcomesarediscountedtoaccountfortimepreference.Ifthediscountrateis5%,forthe1styear,thediscountfactorwillbe:1/(1+0.05)=0.9524;forthe2ndyear:1/(1+0.05)2=0.9070;forthe3rdyear:1/(1+0.05)3=0.8638;andsoon.HowthediscountfactoriscalDiscounting:theformulasFormulaforoneyear:

NPV(Ci)=Ci*discountfactor—ifthecostisincurredattheendoftheyear,thediscountfactoris1—ifthecostisincurredatthebeginningoftheyear,thediscountfactoris(1+δ)i(1+δ)i-11Discounting:theformulasFormuDiscounting:theformulasFormulaforaseriesoffuturecosts:—ifthecostisincurredattheendoftheyear,NPV(Ci)=∑

—ifthecostisincurredatthebeginningoftheyear,

NPV(Ci)=∑nni=1nCi(1+δ)ini=1Ci(1+δ)i-1Discounting:theformulasFormuExampleIf,wehave3years,withC1=20,C2=30andC3=50,thentheformulaNPV(Ci)=∑becomesNPV(C

)=++(costincurredatthebeginningoftheyear)nni=1Ci(1+δ)i-120(1+δ)0

(1+δ)1

30(1+δ)2

50ExampleIf,wehave3years,wiExerciseWhatistheNPVofeachdistributionofcosts?(δ=0.06,costsatthebeginningoftheyear)

2004200520062007Option1100200300400Option25003002000Option30001000ExerciseWhatistheNPVofeacDiscountingwithtablesTablesexist.Inthetable,Nstartsat1.

•l=nextyearifthecostisincurredatthebeginningoftheyear;

•l=thiscurrentyear,ifthecostisincurredtheendoftheyear.DiscountingwithtablesTablesWhatisthesocialrateoftimepreference?Indevelopedcountries,economistsuseadiscountratebetween3and5%.Indevelopingcountries,thediscountratemustbehigher(“higherurgencyofneeds”):theWorldBankusesaratearound10%.Localrealinterestrate(i.e.inflationtakenaway)canalsobeusedasthesocialdiscountrate=>δ=r.WhatisthesocialrateoftimExerciseWhatistheactualizedcostofthisprogram?(δ=10%;costsassumedasincurredatthebeginningoftheyears)Year1Year2Year3Motocycle1,50000Benzine300300300Vaccine400400400Ice505050Nurse1,0001,0001,000ExerciseWhatistheactualizedSensitivityanalysisThisproceedsby:—identifyinguncertainparameters,—drawingupthemostrealisticrangeofvaluesforthem,—insertingtheseintothefinalcalculationofcostsandbenefits,—consideringtheeffectofchangingthevaluesonthefinaloutcome.SensitivityanalysisThisproceConsequencesIfthefinalvalueofthedecisionalcriterionissignificantlyalteredandthevalueofthevariableisgenuinelyuncertain,theconclusionwillbeshowntobeweakbysuchsensitivityanalysis.Ifthesensitivityanalysisshowsthatthefinalvalueremainsquitethesame,theconclusionisreinforced.ConsequencesIfthefinalvalueExample:costsof2programsDiscountrate3%5%10%1800usd(year10)1550usd(year5)Choice?Example:costsof2programsDiPARTⅢ.

COST-EFFECTIVENESS

ANALYSISThebestuseofscarceresourcesContentofthissession:CostbenefitAnalysisCosteffectivenessAnalysis

—exerciseCostutilityAnalysisOthercriteriathanefficiencyPARTⅢ.

COST-EFFECTIVENESS

AN1stProposal:Cost-BenefitAnalysis“Investing€1millionininterventionXwillyieldasocialbenefitof€1,2million”.“ThesameamountininterventionYwillyieldasocialbenefitof€1,1million”.“ThesameamountininterventionZwillyieldasocialbenefitof€0,9million”.1stProposal:Cost-BenefitAn1stProposal:Cost-BenefitAnalysisCBA:methodofeconomicevaluationwherethemonetaryvalueoftheresourcesconsumedbyahealthintervention(costs)iscomparedwiththemonetaryvalueoftheoutcomes(benefits)achievedbytheintervention.Methodusedfordamp,highway,tunnel…1stProposal:Cost-BenefitAnCBAGreatquality:thenumeratorandnominatorareinthesameunit.=>Itispossibletocompareallthepublicintervention.Ex:isitbettertobuildabridge,usethesamebudgetforeducationorforthecontrolofadisease.Drawback:manyoutcomesaredifficulttovalueinmonetaryterms.CBAGreatquality:thenumeratoHowtocomparebenefitstocost?Thenetbenefits:TotalBenefits–TotalCostsofanintervention.InterventionrelevantifNetBenefit>0Benefit–CostRatio:TotalBenefit/TotalCostsInterventionrelevantifBCR>1HowtocomparebenefitstocosExampleBenefitCostsNetBCR(NPV,€)(NPV,€)BenefitsOption14,5005,000-5000.9Option24,5003,6009001.25Option345,50036,0009,0001.25ExampleBeneHealthbenefitsinmonetaryvalue?Howtogiveamonetaryvaluetothebenefitsbroughtbyanintervention?Thereare3typesofbenefits:

—direct:savingsinfuturecostsofprevention,treatment,controlwhichwouldbeincurredbythehealthserviceorpatientsorsocietyatlarge.—indirect:avoidedcostsintermsofproductionorproductivitylosses.—intangible:avoidedcostsintermsoflossofqualityoflife.HealthbenefitsinmonetaryvaIndirectbenefitHowtovalueinmoneytermstheyears/qualityoflifesavedbyanintervention?“Lifehasnoprice”…butithasanopportunitycost!Bettertosaveababy,anadultoraneldery?IndirectbenefitHowtovalueiWhichmonetaryvalueforlife?Asktousersthemselves:WillingnessToPaySurvey.“Ask”tothemarket(other!):valuationofthelifeofsomebodyaccordingtohisreturntothesociety=>HumanCapital:salary“Ask”tothepoliticians:studythereveleadpreferencesinpoliticaldecisions.Whichmonetaryvalueforlife?TosummarizeTooambitiousforhealthintervention.Goodmethodwhentheindirectcostsareanimportantpartoftheproblemforthesociety.Example:adiseasewhichgeneratemanyproductionlosses.Itistheonlyrelevantmethodifyouwanttocompareaninterventioninhealthandaninterventioninanothersector(cation).TosummarizeTooambitiousfor2ndProposal:Cost-Effectiveness“Investing€1millionininterventionXwillallowtovaccinate123,000children”.“Withthesameamount,interventionYmayfinance1,931,000malariachloroquinetreatments”.“ThesameamountininterventionZwillprevent76,000prematureddeaths”.2ndProposal:Cost-Effectivene2ndProposal:Cost-EffectivenessEffectsaremeasuredinnonmonetaryvalues,Naturalunits.Principle:wehavetoidentifytheeffectwewanttostudy.Forexample,tocomparetwostrategiesofvaccination,wewillcomparecostperchildcompletelyvaccinated.Itisnotalwayseasytochose!2ndProposal:Cost-EffectiveneBreastCancerScreening:Whichcosttominimize?Screeningcost/screenedwoman?Screeningcost/positivecasedetected?Scr.&Treatmentcost/+casedetected?Scr.&Tmentcost/true+casedetected?Scr.&Tmentcost/deathaverted?Scr.&Tmentcost/yearoflifeextended?=>Theformulationofcostsdependsonthewayweformulatetheissue!BreastCancerScreening:WhichTosummarize:strengthsofCEAItissimple.Formanyhealthinterventions,itismorerelevantthanCBA.Itisaveryhandymethodtocomparetwointerventionswhichtackleasamehealthissue.IfCEAisenoughforthepoliticalobjectiveofyourstudy,goforit.Tosummarize:strengthsofCEAToSummarize:weaknessesifCEAManyinterventionshavenumerouseffects,includingintermsofhealth.WithCEA,weneglectotherimportantoutcomes.Possibilitiesforcomparisonarelimitediftheeffectivenessismeasuredwithatoospecificmeasurement.Weneedatooltobeabletocompare,forexample,aSTDproject(adults)andaMCHone(mothers&babies).ToSummarize:weaknessesifCE3rdProposal:Cost-UtilityAnalysis“Investing€1millionininterventionXwillallowtosave53,000QALYs”.“ThesameamountininterventionYwillsave49,760DALYs”.3rdProposal:Cost-UtilityAn3rdProposal:Cost-UtilityAnalysisCostUtilityAnalysisisaformofevaluationthatfocusesparticularattentiononthequalityofthehealthoutcomeproducedoravertedbyahealthprogram.CUAhasbeendevelopedtoconsiderthewholesetofhealtheffectsdeliveredbyanintervention.Outcome:compositemeasureofhealtheffects.3rdProposal:Cost-UtilityAnCUAprincipleSomeofthesedifferentoutcomesaremoreimportant&morevalued(bytheillpersonthanothers=>Aweightingmethodisnecessary.Otherobjective:thecomprehensivenesswithhealtheffectswillmakepossibletocompareprogramstacklingdifferentdiseases.CUAprincipleSomeofthesedifWhenCUAshouldbeused?Whenhealth-relatedqualityoflifeistheimportantoutcome.Ex:arthritis.Itisamatterofphysicalfunction,socialfunctionandpsychologicalwell-being.Whenhealth-relatedqualityoflifeisanimportantoutcome.Ex:neonatalintensivecareforvery-low-birth-weightinfants.Notonlysurvivalinimportant,butalsoqualityoffuturelife.WhenCUAshouldbeused?WhenhWhenCUAshouldbeused?Whentheprogramaffectsbothmorbidityandmortalityandyouwishtohaveacommonunitofoutcomethatcombineseffects.Ex:cancertreatmentsimprovelongevityandlong-termqualityoflife,butdecreasequalityoflifeduringthetreatmentprocessitself.Whenyoucomparedisparateprograms.WhenCUAshouldbeused?WhentStep1:BurdenoftheDiseaseObjective:toassessthequalityandquantityoflifelostbecauseofadiseaseA.1ststep:

toknowthe“lifeflow”inqualitative(onascalefrom0to1)andquantitativeterms(numberofexpectedyears)forapersonwithagivendiseaseversus“normallife”.Wegettheindividualburdenofthedisease.Step1:BurdenoftheDiseaseOQuantityandqualityoflifelostbecauseofadisease(QALYs)1/Scientistshavedefinedarangeofstatesofhealth.Multi-attributescaleshavebeendeveloped.2/Panelsofindividualsgavethe“utility”or“preferences”foreachcategoryofhealthstatus.0=death,1=fullhealth;Example:QWB3/Foradisease,oneestimatesthenumberofyearsineachcategoryof“healthstatus”andwecanapplytheweight.QuantityandqualityoflifelTheGlobalBurdenofDiseasesExercisedonejointlybytheWHOandtheWBtoidentifythediseaseshavingthehighestburdenontheWorld(WDR1993）。TheyhaveusedameasureeasierthanQALYs:internationalDALYs(DisabilityAdjustedLifeYears).Applicationto107healthdisorders,distinctionpercontinentandgender.TheGlobalBurdenofDiseasesEAfewfigures(WHO2000)TotallostDALYsin1999:1438bilions.66%ofDALYsarelostbecauseofaprematuredeath,34%becauseofindividuals.Diarrhoea+childhood&perinataldiseases+malaria+RTI=26.1%Africa(10%ofworldpopulation):26%oflostDALYs.Afewfigures(WHO2000)TotalMeasuringgainsQALYsandDALYsaredifferentmathematicaltransformationsmeasuringhealthoutcome.Theycombinethechangeinqualityoflifeandthechangeinlifeexpectancycausedbyanintervention,Supposeamedicineallowsapatienttolive5moreyearsbutonlyinastateofhealththatisconsideredhalfasgoodasaperfecthealth.Thenthegainis5*5=2.5QALEsMeasuringgainsQALYsandDALYsCostUtilityAnalysisForagivenintervention,itisthenpossibletoassessthespecifichealthbenefit.Itispossibletocomparedifferentinterventions,tacklingsamediseasesorverydifferentones.CompareeffectivenessCompareefficiency(=CUA)CostUtilityAnalysisForagivExerciseA€10,000investmentinprogramKgeneratesagainof532QALYs.Cost-UtilityofK:€18.8/savedQALYA€23,000INPROGRAMlYIELDSAGAINOF1,687QALYs.Cost-UtilityofL:€13.6/savedQALY.Ifthebudgetislimitedto€25,000,thebestoptionis…ExerciseA€10,000investmentiDALYsQALYsisatechniquetoocomplexfordevelopingcountries.=>needforsomethingmorepragramticforprioritysettinginDCsettings.DALYshavebeendevelopedasajointeffortbyHarvard,theWorldBankandtheWHO.DALYsQALYsisatechniquetooHowtocalculateDALYs?DALYsarethesumofthepresentvalueoffutureyearsoflifetimelostthroughprematuremortality,andthepresentvalueofyearsoffuturelifetimeadjustedfortheaverageseverity(frequency&intensity)ofanymentalorphysicaldisabilitycausedbyadiseaseorinjury.HowtocalculateDALYs?DALYsaToolsforDecisionMakingEconomicevaluationofHealthInterventionsShiRongShanghaiJiaoTongUniversityToolsforDecisionMakingPARTI.

OpportunitycostTomakeachoicemeansoptforsomethingandgiveupanotheropportunity.=>Everychoiceinvolvesacost.Theeconomistsusethetermofopportunitycosttoemphasisthiscost.Opportunitycost:thebestalternativeforegone.PARTI.

OpportunitycostTomakExampleYouhave1,000€Youhave3options:—A/EPI15livessaved—B/DOTS20livessaved—C/Fluconazol5livessavedWhatistheopportunitycostofchoosing(1)A,(2)Band(3)C?ExampleYouhave1,000€YouhaMarginality:thequestionisnot“tostudyornot”,but“howmanyhourspercourse”?HoursinstudyResult520/1001050/1001570/1002080/1002585/1003086/100Marginality:thequestionisMarginalityfortheconsumerItdependsalsoonthequantityIhavealready!Beforebuying/consumingoneunit,Iconsiderwhatutilitybringsthissupplementaryunit.Economistsconsidersthatmarginalutilityisdecreasing:thenextunitbringslessutilitythanthepreviousone.MarginalityfortheconsumerItChoice:theexampleoftheMoHInmanysituations,decisionisnotonmyownresourcesalongmyownpreferences.Example:MusttheMoHputitsnext$incondoms,drugsforopportunisticdiseasesorARV?Howtocomparemarginalbenefitandmarginalcost?=>Cost-effectivenessstudy!Choice:theexampleoftheMoHPARTⅡ.

COSTANALYSIS

PARTⅡ.

COSTANALYSIS

1.Theuseofcostinformation4reasonstostudycosts:

—toplanabudgetandstaywithinin(accountable);—tocompareefficiencyofdifferentfacilities(toidentifyopportunitiesofrationing);—tofixpricesofaservice(allocatecosttogoodsandservicesproduced);—toprioritizebetweendifferentinterventions.=>Avitalmanagerialtool!1.Theuseofcostinformation2.Therelationbetweencostandoutput:afewdefinitionsOutput:goodsorservicesproducedbyafirm.Fixedcosts:costincurredonceyoustartaspecificproduction,butwhichisnotrelatedtothequantityofoutput