填补支付系统的差距 - 从接受新的医疗保险账单代码的证据 Plugging Gaps i

NBERWORKINGPAPERSERIES

PLUGGINGGAPSINPAYMENTSYSTEMS:

EVIDENCEFROMTHETAKE-UPOFNEWMEDICAREBILLINGCODES

JeffreyClemens

JonathanM.Leganza

AlexMasucci

WorkingPaper31336

/papers/w31336

NATIONALBUREAUOFECONOMICRESEARCH

1050MassachusettsAvenue

Cambridge,MA02138

June2023

WethankKateAntonovics,JulianBetts,ColleenCarey,MikeGeruso,ToddGilmer,TimLayton,andGauravKhannaforhelpfulcommentsandconversations.TheviewsexpressedhereinarethoseoftheauthorsanddonotnecessarilyreflecttheviewsoftheNationalBureauofEconomic

Research.

NBERworkingpapersarecirculatedfordiscussionandcommentpurposes.Theyhavenotbeenpeer-reviewedorbeensubjecttothereviewbytheNBERBoardofDirectorsthataccompaniesofficialNBERpublications.

©2023byJeffreyClemens,JonathanM.Leganza,andAlexMasucci.Allrightsreserved.Shortsectionsoftext,nottoexceedtwoparagraphs,maybequotedwithoutexplicitpermissionprovidedthatfullcredit,including©notice,isgiventothesource.

PluggingGapsinPaymentSystems:EvidencefromtheTake-UpofNewMedicareBilling

Codes

JeffreyClemens,JonathanM.Leganza,andAlexMasucci

NBERWorkingPaperNo.31336

June2023

JELNo.H57,I11

ABSTRACT

Overthelastdecade,theU.S.MedicareprogramhasaddednewbillingcodestoenhancethefinancialrewardsforChronicCareManagementandTransitionalCareManagement.Weanalyzetheeffectsofintroducingthesenewbillingcodes.First,weprovideevidenceontheadoptionofthenewcodesbyprimarycarephysicians.Weshowthattake-upofthenewbillingcodesoccursgraduallyandexhibitssubstantialvariationacrossspaceandacrossphysiciancharacteristics.Second,weprovideevidenceonhowthenewbillingcodescanbothcomplementandsubstituteforthebillingorprovisionofotherservices.Wefocusontwocasestudies.Asacaseofcodesubstitution,weshowthatTransitionalCareManagementservicespartiallycrowdouttraditionalofficevisitsfollowinghospitaldischarges.Asacaseofcodecomplementarity,weshowthatbothTransitionalCareManagementandChronicCareManagementservicespredictincreasesinannualwellnessvisits.Overall,ouranalysishighlightshowbothnewcodetake-upfrictionsandtheimpactofnewcodebillingonexistingcodebillingcanbeimportantforassessingthetotalcostsandbenefitsofpaymentreforms.

JeffreyClemensAlexMasucci

DepartmentofEconomicsIndependentResearcher

UniversityofCalifornia,SanDiegoabmasucci@

9500GilmanDrive#0508

LaJolla,CA92093

andNBER

jeffclemens@

JonathanM.Leganza

JohnE.WalkerDepartmentofEconomics

WilburO.andAnnPowersCollegeofBusiness

ClemsonUniversity

Clemson,SC29634

UnitedStates

jleganz@

1

1Introduction

Healthcarepaymentmodelsshapethefinancialincentivesphysiciansandhospitalsfacewhiledeliveringcare.Paymentmodelscanthushaveimplicationsfortheefficiencyofthehealthsystem.Importantly,thepatternsofserviceprovisionthatconstitutecost-effectivecarearenotstatic.Efficienthealthcarewilltendtoevolvedynamicallywithapopulation’sunderlyinghealthneeds,withthedevelopmentofnewtechnologies,andwithchangesintheorganizationofmedicine.

Maintaininganefficienthealthcarepaymentmodelrequiresadaptingtothehealthcarelandscape.Tothatend,theCentersforMedicare&MedicaidServices(CMS)regularlyrevisesitsphysicianfeescheduletoincorporatenewbillingcodes.Inthispaper,weshowthattheeffectsofsuchreformscandependonarichsetoffactors.First,fornewcodestoinfluencecareprovision,theymustberecognizedandadoptedbyphysicianpractices.Second,theimpactofnewcodesonspendingandcareprovisioncandependontheextenttowhichtheysubstitutefororcomplementexistingservices.

Toprovideevidenceoncodeadoption,codesubstitution,andcodecomplementarity,weanalyzetheMedicareprogram’sintroductionofnewcodesforthemanagementofcareforpatientswithcomplexconditions.Inparticular,weanalyzethe2013introductionofnewcodesforbillingTransitionalCareManagementservicesandthe2015introductionofnewcodesforbillingChronicCareManagementservices.TheintroductionofthesecodesplayedanimportantroleinabroadereffortbyCMStoincreasethefinancialrewardstoprovidingprimarycareandimproveincentivesformanagingthecareofpatientswithhighhealthcareneeds.

Ouranalysisproceedsintwosteps.Inthefirststep,weprovideevidenceontheadoptionoftheTransitionalandChronicCareManagementcodesbyprimarycarephysicians(PCPs).Thisevidenceextendstheworkofanemergingmedicalliteraturethatalsodocumentstheuptakeofthenewcodes(Agarwaletal.,2018;Marcotteetal.,2020;Reddyetal.,2020;Agarwaletal.,2020).1Wedocumenttake-upthatoccursgraduallyovertimeandthatvariesacrossspaceandacrossphysiciancharacteristics.Overall,thepatternswedocumentareconsistentwiththeideathatthe

1Reddyetal.(2020)documenttimeseriesonChronicCareManagementbilling,andMarcotteetal.(2020)documenttimeseriesonTransitionalCareManagementbilling.Agarwaletal.(2018,2020)usedataonasampleofbeneficiariestoanalyzetake-up.Theydevelopcomplementaryfindingsbycomparingcharacteristicsofprimarycarepracticesthatbilledthenewcodestothosethatdidnot.Incontrast,weusedataonthenear-universeofMedicare-billingdoctorstoanalyzethelikelihoodofbillinganewcodebasedonphysiciancharacteristics.Oneimportantphysiciancharacteristicthatourdataallowustoanalyzeiscareerstage,whichpreviouspapershavebeenunabletoinvestigate.

2

adoptionofnewcodesrequiresphysicianstomakeinvestmentsintheirpractices’masteryofbillcoding,aformoforganizationalorentrepreneurialcapital.

Inthesecondstep,weanalyzepatternsofcomplementarityandsubstitutabilitybetweenthebillingofnewcodesandthebillingorprovisionofotherservices.Weusetworegressionframeworkstostudytheeffectsofnewcodetake-upatthecountylevel.Webeginbyusinganeventstudyframeworkthatcomparestheevolutionofoutcomesforhightake-upcountiestothatofa(matched)groupoflowtake-upcounties,beforeandaftertheintroductionofthenewbillingcodes.Wethentransitiontousingafixedeffectsframeworkthatexploitsallpanelvariationintheintensitywithwhichnewcodesarebilledacrosscounties.

Wefocusouranalysisofpatternsofcarecomplementarityandsubstitutabilityontwocasestudies.First,weshowaclearcaseofcodesubstitution.WefindthatbillingTransitionalCareManagement,whichisformanagingcareafteraninpatientdischarge,partiallycrowdsoutthebillingofstandardofficevisitsafterhospitaldischarges.Oureventstudyevidencerevealsasharpdeclineintraditionalpost-dischargeofficevisitsinhightake-upcountiescomparedtolowtake-upcountiesaftertheintroductionofthenewcodes,andourfixedeffectsestimatesimplyroughlyonelesstraditionalofficevisitforevery26additionalTransitionalCareManagementvisits.2Second,weshowacaseofcodecomplementarity.WefindthatbothTransitionalandChronicCareManagementservicespredictincreasesintheprovisionofAnnualWellnessVisits,anothertypeofcaremanagementservice.Whileoureventstudyprovideslessstrikingevidenceforthissecondcasestudy,theeventstudyandmorebasicfixedeffectsestimatorsyieldcomplementaryestimates.TheresultsindicateasubstantialcomplementaritybetweenwellnessvisitsandTransitionalCareManagementbillingandamoremodestdegreeofcomplementaritywithChronicCareManagementbilling.

Overall,ouranalysisshowsthatpatternsofcomplementarityandsubstitutabilityinbillcodingandserviceprovisioncanplayimportantrolesinshapingapaymentreform’seffects.Wefindthatnewservicecodescanbothcomplementandsubstituteforexistingservicecodes.Weemphasizetwopolicyrelevantaspectsofthesefindings.First,codesubstitutionandcode

2Byquantifyingthispartialcrowd,ourresultscomplementandareconsistentwiththepatternsofrawmeansfirstpresentedbyAgarwaletal.(2018),whoalsoshowadeclineinstandardofficevisitsafterhospitalizationsbyindividualpracticesthatbillTransitionalCareManagement.

3

complementaritycouldimpactclaims-dependentsystemsofqualitymeasurement.3Second,theexistenceofcomplementaritiesinrealserviceprovisioncanhavestraightforwardeffectsonboththecostandhealthbenefitsofintroducingnewcodes.Acomprehensiveanalysisofthecostsandbenefitsofintroducingnewcodesmustaccountforthesespillovers.

Moreover,wecontributetotheliteraturethatanalyzestheeffectsoffinancialincentivesontheservicesphysiciansprovide.Onesetofpapersestimatesstandardimpactsofreimbursementlevelsonthesupplyofservices(e.g.,Cabral,Carey,andMiller,2021;AlexanderandSchnell,2019;ClemensandGottlieb,2014;Gruber,Kim,andMayzlina,1999).Othersinvestigatemarginsincludingphysicians’preferencesovertakingnewpatients(Chen,2014;Clemens,Gottlieb,andHicks,2020;Garthwaite,2012),prescriptionpatterns(Careyetal.,2020),andchoicesoverwheretolocate(Khouryetal.,2021).Relativelyrecentresearchonthisrichvarietyofmarginsprovidesevidencethathealthcarebecomesmorewidelyaccessiblewhenphysiciansarepaidmoregenerouslytoprovideit.Stillotherresearchdemonstratesimportantrolesforadditionalfactorsincludingintrinsicmotivation(Kolstad,2013)andteamenvironments(Chan,2016).Wecontributetothisliteraturebyemphasizinghowtheeffectsofincentivesonthesupplyofservicescandependonfrictionssuchasphysicians’awarenessofthoseincentivesandonthetimehorizonsoverwhichtheyadapt.4Ouranalysispointstoanoveldimensionofphysicians’organizationalorentrepreneurialcapital:theirmasteryofthebillingsystemsthatshapetheirpractices’profitability.

2Background

2.1PrimaryCareandtheFeeforServicePaymentSystem

Primarycarephysiciansplayanimportantroleinhealthcaresystems.Theyoftenserveasinitialpointsofcontactforundiagnosedpatientsandprovidecontinuedtreatmenttopatientswithconditionsthatneedtoberegularlymanaged.Despiteplayingsuchanintegralrole,evidencehighlightshowPCPsoftenprovideservicesthatareleftoutofthePhysicianFeeSchedule(PFS).

3Forinstance,iftraditionalofficevisitsafterhospitaldischargesareincludedinqualitymeasurementsystems,andifthesesystemsarenotupdatedtoaccountfortheintroductionofnewbillingcodes,thenphysiciansbillingTransitionalCareManagementratherthantraditionalofficevisitsafterdischargesmightbenegativelyimpacted.

4Whilefrictionshavereceivedlittleattentioninpriorresearchonphysicians’laborsupply,theyhavereceivedsubstantialattentionotherlinesofwork.Frictionsplayarole,forexample,inresearchonthecausesofincompletetake-upofpublicbenefits(Aizer,2007;BhargavaandManoli,2015;ManoliandTurner,2014).Thecomplexityofphysicians’contractsandreimbursementprocedureshasalsobeenexaminedelsewhere(ClemensandGottlieb,2017;Clemens,Gottlieb,andMolnar,2017;Gottlieb,Shapiro,andDunn,2018;Dunnetal.,2021).

4

Theyarethusnotpaidinfullfortheservicestheydeliver(Gottschalketal.,2005;Farberetal.,2007;Dyrbyeetal.,2012;Tai-Sealeetal.,2017).Thenewcodesthatwestudywereintendedtoaddressthisproblem.InthefinalrulefortheMedicarePhysicianFeeSchedulefor2018,CMSstates:“Intheyearssince2012,wehaveacknowledgedtheshiftinmedicalpracticeawayfromanepisodictreatment-basedapproachtoonethatinvolvescomprehensivepatient-centeredcaremanagement,andhavetakenstepsthroughrulemakingtobetterreflectthatapproachinpaymentunderthePFS.InCY2013,weestablishednewcodestopayseparatelyfortransitionalcaremanagement(TCM)services.Next,wefinalizednewcodingandseparatepaymentbeginninginCY2015forchroniccaremanagement(CCM)services…”(CMS,2018).

Byaddingthesenewbillingcodes,CMSadjustedthePFSbyexplicitlypayingphysiciansforTCMandCCMservices.Thenewcodescaneithercompensatedoctorsmorefullyforservicestheywerealreadyprovidingorincreaseincentivesforprovidingservicesforprimarycareneedsthatwerepreviouslygoingunmet.Overall,thenewcodesaretheresultofpolicymakersaimingtomaketheprovisionofprimarycaremorefinanciallyattractive(Burtonetal.,2017),andtheycapturetheessenceofabroaderCMSagendato“improvethepaymentfor,andencouragelong-terminvestmentin,primarycareandcaremanagementservices”(CMS,2012).

2.2TransitionalCareManagement

TheTransitionalCareManagement(TCM)codesareforcaremanagementservicesprovidedtopatientsfollowingadischargeoutofaninpatientsetting,suchasahospitalorskillednursingfacility.Thegoalofthesecaremanagementservicesistoreducepreventablereadmissionsandimprovepatienthealthbybettercoordinatingtheprovisionoffollow-upcare.

CMSintroducedtwonewcodesforTCM.Billingcode99495isforTransitionalCareservicesofmoderatemedicaldecisioncomplexity.Itrequiresinitialcommunicationwiththepatient(orcaregiver)withintwodaysofthepatientdischargedateaswellasaface-to-facevisitwithin14daysofthedischarge.Billingcode99496isforTransitionalCareservicesofhighmedicaldecision-makingcomplexity.Itrequiresinitialcommunicationwithintwodaysofthedischargeaswellasaface-to-facevisitwithin7daysofthedischarge.

Thesecodeswereintroducedin2013.ReimbursementratesweresetbyCMS,takingintoconsiderationtheinputandfeedbackfromcommitteesandstakeholdersandusingsimilarexistingcodestoguidetherate-makingprocess.In2013,TCMassociatedwithcode99495paidroughly

5

$164,whichcomparesfavorablytoasimilarofficevisit($107),andTCMassociatedwithcode99496paidroughly$231,whichagainishigherthanacomparableofficevisit($143).5

2.3ChronicCareManagement

TheChronicCareManagement(CCM)codesareforcarecoordinationandcaremanagementforpatientswithmultiplechronicconditions,suchasdementia,asthma,cancer,cardiovasculardisease,ordiabetes,amongothers.ChronicconditionsarecommonamongMedicarebeneficiaries,andspendingonpatientswiththeseafflictionsissubstantial(Anderson,2010).Arecentreportfoundthat42%ofadultAmericanshadmultiplechronicconditionsandthattheprevalencewasevenhigher(81%)forAmericans65yearsandolder(Buttorffetal.,2017).

Againstthisbackdrop,CMScreatedthenewCCMcodes.Billingcode99490paysforcaremanagementofatleast20minutesofclinicalstafftimepermonth.Eligiblepatientsarethosewithmultiplechronicconditionsthatareexpectedtolastatleasttwelvemonthsoruntildeathandthatcreateasignificantriskofdeathorfunctionaldecline.CMSintroducedthiscodein2015.PaymentratesweredeterminedbyCMSwithinputfromstakeholders.Reimbursementwasroughly$43.Twoyearlater,in2017,CMSintroducedtwoadditionalCCMcodeswithhigherreimbursementrates:code99487($94),forCCMthatinvolvesmoderateorhighcomplexitymedicaldecisionmaking,andcode99489($47),foreachadditional30minutesofCCM(nomatterthecomplexity).

3Data

Tostudytheintroductionofthenewcodes,weuseseveraldatasets,primarilyfromCMS.Usingthreephysician-leveldatasets,webuildaphysicianpanelfrom2012to2018thatcontainsinformationonphysiciancharacteristicsandbilling.Wealsousethreecounty-leveldatasetsthatcontaininformationonpatientdemographics,populationhealth,andhealthcareutilization.

3.1ConstructingthePhysicianPanel

OurbasedatasetistheMedicareProviderUtilizationandPaymentData:PhysicianandOtherSupplier(MPUP).TheMPUPisaprovider-levelpanelthatcovershealthcareprofessionalswhobillservicestoMedicarePartB.Itspanstheyears2012to2018.Thedataarederivedfrom

5Wereportdollaramountsforreimbursementpurposesthatcorrespondtonationalpaymentsinanon-facilitysetting,whichcanbefoundhere:/medicare/physician-fee-schedule/search/overview.

6

administrativeclaimsdatafromCMSandallowustoobservealmostallMedicare-billingphysicians.(Physicianswhodonotbillanycodeatleast10timesinagivenyearareomittedfromthedataforthatyear.)TheMPUPcontainsuniquephysicianidentifierscalledNationalProviderIdentifiers(NPIs),informationonphysicianspecialties,andinformationonbilling.Wefocusmostlyonprimarycarephysicians(PCPs),whichwedefinetobephysicianswithaspecialtyofInternalMedicine,FamilyMedicine,GeneralPractice,orGeriatricMedicine.

WesupplementthesedatawithtwootherdatasetsfromCMS,whichwelinktotheMPUPusingtheNPIs.FromtheNationalPlanandProviderEnumerationSystem(NPPES),weobtaininformationonphysicianpracticelocation.6Thisinformationallowsustostudyphysiciangroups,whichwedefineasphysicianspracticingatthesameaddress.Then,fromthePhysicianComparedataset,wepullinformationonphysicianmedicalschoolattendanceandgraduationdates.7Weusethesedatatocategorizephysiciansbasedoncareerstage.Wedefineearly-careerPCPsasthosewhograduatedfrommedicalschool5to24yearsprior,mid-careerPCPsasthosewhograduated25to39yearsprior,andlate-careerPCPsasthosewhograduated40ormoreyearsprior.8AfteraddingtheinformationfromtheNPPESdataandthePhysicianComparedatatotheMPUP,wehaveadetailedpaneldatasetofphysiciansovertime.

3.2County-LevelData

Weusethreeadditionaldatasetsforourcounty-levelanalyses.FromtheCMSGeographicVariationPublicUseFile,weextractinformationondemographics.Specifically,weusecounty-levelvariablesthatreporttotalbeneficiarycounts,thepercentofbeneficiariesthatarefemale,thepercentofbeneficiariesthatareeligibleforMedicaid,andtheaverageageofbeneficiaries.

WealsousetheCMSChronicConditionsFiles,whichreportcounty-levelstatisticsontheprevalenceof,andMedicarespendingfor,twenty-onedifferentchronicconditions.Weusethesedatatoconstructanormalizedindexthatreflectstheoverallprevalenceofchronicconditions,whichweuseasaproxyforpatienthealth.Ourindexisbasedontheprevalenceofeightmajor

6Specifically,theNPPESdatarecordaprimarypracticelocationforeachphysician,foreachmonth.WeusepracticelocationasofDecemberforeachcalendaryear.

7CMSbeganpublishingPhysicianComparein2014.Weuseallavailabledatafrom2014through2018todefinemedicalschoolandgraduationdate.Theinformationistime-invariant,andmostphysiciansappearinallwavesofthedata,butwearemissinginformationforphysicianswhoappearinourdataonlybefore2014.

8Ourdefinitionofearly-careerPCPsisdrivenbythedata:veryfewphysiciansareassignedanNPIuntil5yearsafterfinishingmedicalschool,likelyduetotimespentinresidencies.

7

conditions(arthritis,kidneydisease,COPD,diabetes,heartfailure,hyperlipidemia,hypertension,andischemicheartdisease).SeeAppendixBfordetails.

Finally,weusetheDartmouthAtlasPost-DischargeEventsdatafrom2010to2017,whichprovidecounty-levelratesoftheincidenceofvarioushealthcarerelatedeventsexperiencedbybeneficiariesafterbeingdischargedfromthehospital.Theseratesarecalculatedasapercentageofallhospitaldischargesinthecountyineachyear.ThisdatasetprovidesakeyoutcomeforstudyingtheeffectofTransitionalCareManagement,sincethisserviceisdirectlyusedtoprovidemanagedcareforpatientsafterahospitaldischarge.

4TheTake-UpofNewMedicareBillingCodes

4.1NewCodeBillingOverTime

PanelAofFigure1plotsthetimeseriesonnationalbillingforTCMandCCMandshowsthattheadoptionofthenewcodesisagradualprocess.TotalbillingforTCM(CCM)isdefinedasthesumofthebillingforallnewcodesclassifiedasTCM(CCM).Thegraphsshowhowbillingforthenewcodesrampsupsteadilyovertime.Neithertypeofnewcodebillingseemstohaveleveledoffoverthetimehorizonofourdata.PanelBshowsasimilarpatternforthefractionofPCPsbillingthenewcodesovertime.

4.2RegionalVariationinNewCodeBilling

Thereisalsosignificantregionalvariationinthetake-upofthenewcodes.WepresentmapsofnewcodebillinginFigureA1.ThemapsplotHospitalReferralRegion(HRR)billingperPCPin2018forTCM(panelA)andCCM(panelB).TCMbillingismoreheavilyconcentratedintheNortheastandtheSoutheast.CCMbillingappearsconcentratedinsouthernregions.FigureA2assessestheextenttowhichunderlyinghealthconditionscancontributetothisregionalvariation.ThescatterplotsshowhowthebillingofTCM(panelA)andCCM(panelB)relatetotheprevalenceofchronicconditionsinHRRs.Newcodebillingiscorrelatedwithourconstructedchronicconditionindex.ThesimpleregressionmodelshowninpanelAexplains19.5%ofthevariationinHRR-levelTCMbilling,andthesimpleregressionmodelshowninpanelBexplains19.2%ofthevariationinHRR-levelCCMbilling.

8

4.3NewCodeBillingbyPhysicianCharacteristics

Table1displaysnewcodebillingratesbyphysiciancharacteristics.ThetablereportsthefractionofphysiciansbillingTCM(column1)andCCM(column2)during2018,thelastyearofourdata.PanelAdocumentsbillingratesacrossspecialtiesandshowsthatPCPsaremuchmorelikelytobillthenewcodesthannon-PCPs.

PanelBbreaksdownbillingratesbyphysiciancareerstage.Thelikelihoodofbillingthenewcodesishigherformid-careerPCPscomparedtoearly-careerorlate-careerPCPs.PanelCofFigure1providesamoregranularlookathowbillingratesvaryovercareerstage.PCPswithmoreexperiencearemorelikelytoadoptthenewcodes,untilreachingthelaterstagesoftheircareer.The“inverseU”shapeexhibitedhereconformswitheconomicintuitionforhowthepropensitytoundertakebilling-relatedinvestmentsmightvaryacrossthecareerlifecycle.Physiciansatthebeginningoftheircareersarelikelytobefacingasetofmorefundamentalbusiness-relatedinvestmentdecisionsandmaylacktheentrepreneurialcapitalnecessarytoprofitablybuildthecapacitytobillthenewcodes.ThedecliningrateofnewcodeadoptionoverthelatestofcareerstagesisconsistentwiththeideathatphysiciansapproachingretirementwillhavelesstimetocapturethereturnsoninvestmentsassociatedwithlearninghowtobillthenewcodesorhowtocarryoutproceduresthatwillqualifyasTCMorCCM.

Finally,panelsCandDofTable1breakdownbillingratesbyphysiciangroupcharacteristics.Ingeneral,weseethatPCPsbelongingtogroupsaremorelikelytobillthenewcodesthansolepractitioners,exceptforPCPsinthelargestgroups,whichisconsistentwiththeideathatlargergroupsfacemorebureaucraticbarrierstoprovidingCCM(O’Malleyetal.2017).Moreover,weseethatPCPsinPCP-onlygroupsareparticularlylikelytobillthenewcodes,whichmayreflectstrongerincentivestomakeinvestmentsinnewcodebillingforgroupscomposedentirelyofphysiciansforwhomthenewcodesaredesigned.

Overall,theevidencepresentedinthissectionprovidesinsightintohowphysiciansrespondtotheintroductionofnewbillingcodes.Wefindpatternsconsistentwiththeideathatadoptingnewcodesrequiresongoinglearningandinvestmentsrelatedtobill-codingproficiency.

5EmpiricalFrameworkforAnalyzingtheEffectsofNewCodeAdoption

Next,weinvestigatethesubstitutabilityandcomplementarityofnewcodeswithexistingcodes,usingtworegressionframeworkstoestimatetheeffectsofnewcodetake-uponthebillingor

9

provisionofotherservices.Topreventouranalysisfrombeingimpactedbyphysician-orgroup-levelspecializationorbypatientsortingacrossphysiciangroups,weconductitatthecountylevel.

First,weuseaneventstudyregressionframeworkthatcomparestheevolutionofoutcomesinplaceswithmorenewcodetake-uptothatofplaceswithlessnewcodetake-up.Highintensityadoptersareour“treatment”group,whereaslowintensityadoptersandnon-adoptersareour“control”group.Specifically,wefirstdropcountiesthatdonotmeetasizethresholdofhavingover10totalPCPsin2012.Wethenordertheremainingcountiesinoursamplebyaveragepost-implementationannualnewcodebillingperPCP.Wedefinethetophalfofthesecountiesasthetreatmentgroup,andwedefinethebottomhalfasthecontrolgroup.

Usingthisgroupingofcounties,wethenestimateregressionsoftheform:

Yc,t=∑p(t)≠−1Fp(t)TTeatmentc×EventTimep(t)+Xc,ty+ac+6t+cc,t.(1)

Inequation(1),cdenotescountiesandtdenotesyears,Yc,tisabillingorserviceprovisionoutcomevariable,TTeatmentcisanindicatorforbeingahighintensityadopterofthenewbillingcodebeinganalyzed,EventTimep(t)aredummyvariablescodedtocorrespondtothenumbersofyearsrelativetothenewcode’sintroduction(whichis2015forChronicCareManagementand2013forTransitionalCareManagement),Xc,tisavectoroftime-varyingcountycharacteristics,acarecountyfixedeffects,6tareyearfixedeffects,andcc,tisanerrorterm.Weomittheinteractionbetweenthetreatmentindicatorandtheeventtimeindicatorforthetimeperiodcorrespondingtotheyearimmediatelypriortothenewcode’sintroduction,whichwedefineasyearp(t)=−1.Thecoefficientsofinterest,Fp(t)canthusbeinterpretedasdifferentialchangesintheoutcomeofinterestfromtheyearpriortothenewcode’sintroductiontothereferenceyear.Forreferenceyearslessthan0,thepointestimatesprovideevidenceonwhetherdivergenttrendsintheoutcomeoccurredpriortothenewcode’sintroduction.Estimatesforyearsfollowingthenewcode’sintroductiontrackthedynamicswithwhic