国会预算办公室-气候变化引起的极端温度对医疗保险人群的影响：初步结果（英）

congressionalBudgetoffice

NonprtisanAnaysisforthecongress

EffectsofExtremeTemperatures

FromClimateChangeontheMedicare

Population:PreliminaryResultsMay31,2024

PresentationattheAssociationofEnvironmentalandResourceEconomistsSummerConference

JaredJageler,DavidAdler,NoeliaDuchovny,andEvanHerrnstadt

MicroeconomicStudiesDivisionandHealthAnalysisDivision

Forinformationabouttheconference,see

/summer

.

Introduction

Climatechangeisexpectedtoincreaseaveragetemperaturesandaffectthe

frequencyofextremelyhotandcolddays.

Theneteffectsofthosechangingtemperaturesonhealthandfederalhealthcare

spendingareuncertain:

.Extremeheatandcoldareassociatedwitharangeofnegativehealtheffects.

.Spendingandutilizationcouldincreaseordecreasedependingonhowhealtheffectsandbehaviorrespondtoextremetemperatures.

.Mortalitycouldincrease(becauseofmorehotdays)ordecrease(becauseoffewercolddays).

Thoseeffectsmaybepronouncedamongelderlypopulations,withimplications

forthefederalbudgetrelatedtoMedicareenrolleesandspending.

Theinformationinthispresentationispreliminaryandisbeingcirculatedtostimulatediscussionandcriticalcomment.1

ResearchQuestions

TheCongressionalBudgetOfficeusesacompletenationwidedatasetofMedicarebeneficiariestoexaminehealthcareutilizationandspendingaswellasmortality.

Inparticular,CBOinvestigatesthesequestions:

.Whatistheeffectofextremetemperaturesonemergencydepartment(ED)visits,EDspending,andmortalityamongMedicarebeneficiaries?

.Howwillthoseoutcomesbeaffectedbyprojectedtemperaturesresultingfromclimatechange,afterincorporatingtheeffectsofadaptation?

Thisresearchispreliminary,andtheresultsaresubjecttochange.

Adaptationreferstohowareaswithdifferentclimatesrespondtoincreasingtemperaturesdifferently,suchasbyinstallingmoreairconditioning.2

RelatedResearch

.Nationwidestudiesontheeffectsofclimatechangeonmortality

-Heutel,Miller,andMolitor(2021)

-Carletonandothers(2022)

.Otherrecentresearchonhealthcareutilization(EDvisits)andmortalityinCaliforniahospitals:

-White(2017)

-Gouldandothers(2024)

.AstudyestimatingtheeffectsofexposuretoparticulatepollutiononsimilaroutcomesintheMedicarepopulation

-Deryuginaandothers(2019)

3

Overview:EconometricEstimates

Veryhotdayscausemore

EDvisitsandhigherED

spending.Bycontrast,verycolddayscauseareductioninEDvisitsandasmaller

reductioninEDspending.

Mortalityishigheronboth

veryhotandverycolddays.

Thecurrentestimatesshowtheeffectofweatheronlyonoutcomesforthesamedayandthefollowingtwodays,whichcouldexcludesome

delayedandcompensatoryeffects.

CBOplanstoexplorelongerwindowsinfutureversions

ofthisanalysis,whichcouldchangetheresults.

Overall,CBOfindsadailyweightedaverageof11deaths,156EDvisits,and$388,000inspendingper100,000Medicareenrollees.ED=emergencydepartment.4

MedicareandClimateData

MedicareOutcomes

.DailycountsofEDvisitsandspendingbyzipcode(2000to2019)forfee-for-service(FFS)enrollees

–Alsodisaggregatedtoinpatient(IP)andoutpatient(OP)visitsandspending;IPinvolvesanovernighthospitalstay,butOPdoesnot

.Dailydeathsbyzipcodeper100,000enrollees(2000to2019)

–IncludesFFSandMedicareAdvantage

Weather

.DailyaveragetemperatureandprecipitationfromtheNationalOceanicandAtmosphericAdministration’snClimGrid-Daily(2000to2019)

.TheNationalAeronauticsandSpaceAdministration’sEarthExchangeGlobalDailyDownscaledProjections(through2099)

–25-kilometerx25-kilometergrid

–Dailyprojectionsofaveragetemperature

.Botharematchedtozipcodetabulationareas(ZCTAs)andweightedbyinversedistancetoZCTAcentroid

Dailyaveragetemperatureisthesimplemeanofdailyminimumandmaximumtemperatures.5

EstimatingHomogeneousEffectsofTemperatureBins

yisty=βbtempbisty+yxit+aid+δsy+Eisty

.yistyisthethree-daysumofthehealthoutcome(EDvisitsorEDspendingper100,000MedicareFFSenrollees,ormortalityper100,000Medicareenrollees)inZCTAi,instates,ondatet,inyeary.

.βbarecoefficientsofinterest.

.tempbistyarethedailyaverage5degreesFahrenheittemperaturebinsfrom0to100(60to65degreesFahrenheitistheomittedcategory),wherebindexesthebins.

.xitisavectorofcontrolsfordailyprecipitationandfullyinteractedtwo-andseven-daytemperaturelagsplusleads.

.aidandδsyareZCTA-day-of-yearandstate-yearfixedeffects.EachobservationisweightedbyZCTAMedicareenrollment.StandarderrorsareclusteredbyZCTA.

MedicaredataareaggregatedtothezipcodeandtemperaturedatatotheZCTA.Thoselevelsarenearlyidentical,butCBOperformsacrosswalkbetweenthetwotostayattheZCTAlevel.6

ChangeinThree-DayEmergencyDepartmentVisitsper100,000Fee-for-ServiceMedicareEnrollees

AllEDvisitsincreasewith

higher-temperaturedays.

EDvisitsdecreasewith

coolertemperaturesinthe

shortterm.OPvisitsdrive

thateffect,becauseIPvisitsaremorecomplexand

thereforemoreunavoidable.

ED=emergencydepartment;IP=inpatient;OP=outpatient;ZCTA=zipcodetabulationarea.7

ChangeinThree-DayEmergencyDepartmentSpendingper100,000Fee-for-ServiceMedicareEnrollees

EDspendinggenerallyincreases

withhighertemperatures.The

increaseisgreaterforIPvisitsthanforOPvisits,whichisconsistent

withthegreatercomplexityandcostofIPvisits(whichthereforeresultinahospitalstay).

Oncolddays,anincreaseinIP

spendingdrivesanoverallincreaseinEDspending.OPspending

decreasesslightlyoncolddays,

suggestingthatthedecreaseinEDvisitsmayhavebeenconcentratedinlower-costvisits.

ED=emergencydepartment;IP=inpatient;OP=outpatient;ZCTA=zipcodetabulationarea.8

UsingDifferencesinLocalAverageClimatetoAccountforAdaptation

Extremetemperaturesdonotaffectallareasequallybecauseofdifferent

levelsofadaptation:Forexample,a

dailytemperatureof90degrees

FahrenheitislikelytobemoreharmfulinMinneapolisthaninDallas.

CBOcapturesthatdifferenceby

allowingtheeffectofeachtemperaturebintodifferonthebasisofaZCTA’s

averageclimate.

CBOcomputestheaverageannual

coolingdegreedays(CDDs)foreachZCTAandestimatesaseparatelinearsplineinCDDsforeachtemperaturebin.AnnualCDDscapturehowoftenandbyhowmuchthedaily

temperaturesurpassed65degreesFahrenheit.

CDDs=coolingdegreedays;ED=emergencydepartment.9

ChangeinThree-DayInpatientandOutpatientEmergencyDepartmentVisitsforThreeIllustrativeCities

DespitetheoverallpatternoffewerEDvisitsoncolddays,placeswithwarmerclimatesexperiencemoreEDvisits

whenthetemperatureis

below20degreesFahrenheit.Placeswithmildandcold

climatesexperiencemoreEDvisitsonhotdays.

ED=emergencydepartment.10

ChangeinThree-DayInpatientandOutpatientEmergencyDepartmentSpendingforThreeIllustrativeCities

Spendingincreases

substantiallyatthe

extremes,withsignificantheterogeneitybyclimate.

ED=emergencydepartment.11

ProjectingtheEffectsofClimateChange

CBOcomputestheprojectedchangeinthefuturetemperaturedistribution

relativetothe2015–2019averageandappliesthatchangetotheagency’s

historicalweatherdata.

Toaccountforadaptation,CBOallowsaZCTA’stemperatureresponsetovaryinthefutureonthebasisofitsprojectedCDDsusingsplineestimates.

Forexample,Minneapolisisgradually

allowedtohaveatemperature

responseby2075thatapproachestheresponseofWashington,DC,today.

CBO’scentralclimatescenariois

SSP2-4.5,buttheagencyalsopresentscaseswithlow(SSP1-2.6)andhigh

(SSP3-7.0)emissionsandwarming.

CBOtakestheunweightedaverageofNEX-GDDPdailydownscaledprojectionsfrommodelsreportingafullyearofprojections.Dallas’sCDDsin2075areestimatedtobe3300,

exceedingthelimitsofthisfigure.CDDs=coolingdegreedays;ED=emergencydepartment;SSP=sharedsocioeconomicpathway.

12

ProjectedChangeinAnnualEmergencyDepartmentVisitsper100,000MedicareEnrollees

AverageannualEDvisitsper

100,000enrolleesfrom2030to2075areprojectedtoincreasebyanaverageof250under

SSP2-4.5.Underalternative

scenarios,thosevisitsare

projectedtoincreaseby175

(SSP1-2.6)to285(SSP3-7.0).

Withoutadaptation,average

annualEDvisitsareprojectedtoincreaseby415per100,000enrollees.

ThefigureshowsthechangeinIPandOPvisitsrelativetothe2015-2019average.ED=emergencydepartment;SSP=sharedsocioeconomicpathway.13

ProjectedChangeinAnnualEmergencyDepartmentSpendingper100,000MedicareEnrollees

AverageannualEDspendingper100,000enrolleesfrom2030to

2075isprojectedtodecreaseby

anaverageof$750,000under

SSP2-4.5.TheprojecteddecreaseinEDspendingisdrivenbya

decreaseof$870,000inOP

spendingthatispartiallyoffsetbyanincreaseof$120,000inIP

spending.

Underalternativescenarios,

averageannualEDspendingper100,000enrolleesisprojectedtodecreaseby$510,000(SSP1-2.6)to$810,000(SSP3-7.0).Withoutadaptation,averageannualED

spending(IPandOP)isprojected

toincreaseby$48,000per100,000enrollees.

ThefigureshowsthechangeinIPandOPspendingrelativetothe2015-2019average.SSP=sharedsocioeconomicpathway.14

PreliminaryProjectedOutcomeSummaryforSSP2-4.5,2030to2075

.AverageannualEDvisits(IPandOP)areprojectedtoincreaseby235,000peryearfrom2030to2075.

-About1percentoftotal2019EDvisits

.CumulativechangesinEDspending(IPandOP)through2075areprojectedtodecreasebyroughly$7billion.

-Anincreaseofabout$1.1billioninOPspendingandadecreaseofabout$8.1billioninIPspending

-Anaverageannualdecreaseof$700million,orabout1percentoftotal2019EDspending

.Cumulativemortalitythrough2075isprojectedtodecreasebyroughly320,000.

-Anaverageannualdecreaseofabout32,000,orabout2percentoftotal2019Medicaremortality

TotalcumulativechangesarebasedonMedicareenrolleeprojectionsandonthesumoffive-yearincrementalestimatesfrom2030to2075.15

NextSteps

.Extendtheoutcomeobservationwindowtoa28-daysum

.Examinedifferencesinmortalityeffectsbys