Cost analysis of substitutive renal therapies in children 夽

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www.jped.com.br

ORIGINAL ARTICLE

Cost analysis of substitutive renal therapies in children ^夽

Maria Fernanda Carvalho de Camargo

^a

, Klenio de Souza Barbosa

^b

, Seiji Kumon Fetter

^c

, Ana Bastos

^a

, Luciana de Santis Feltran

^a

, Paulo Cesar Koch-Nogueira

^a^,∗

aHospitalSamaritano,SãoPaulo,SP,Brazil

bInstitutodeEducac¸ãoePesquisa(Insper),SãoPaulo,SP,Brazil

cFundac¸ãoGetúlioVargas(FGV),SãoPaulo,SP,Brazil

Received18October2016;accepted27February2017 Availableonline24July2017

KEYWORDS Economics;

Kidney

transplantation;

Renaldialysis;

Pediatrics

Abstract

Objective: End-stage renal disease is a health problem that consumes public and private resources.Thisstudyaimedtoidentifythecostofhemodialysis(eitherdailyorconventional hemodialysis)andtransplantationinchildrenandadolescents.

Methods: Thiswasaretrospectivecohortofpediatric patientswithEnd-stagerenaldisease whounderwenthemodialysisfollowedbykidneytransplant.Allcostsincurredinthetreatment werecollectedandthemonthlytotalcostwascalculatedperpatientandforeachrenaltherapy.

Subsequently,adynamicpaneldatamodelwasestimated.

Results: Thestudyincluded30childrenwhounderwenthemodialysis(16conventional/14daily hemodialysis) followed byrenal transplantation.The meanmonthly outlay for hemodialysis wasUSD3500andUSD1900for transplant.HemodialysiscostsaddeduptooverUSD87,000 in40monthsforconventionaldialysispatientsandUSD131,000in50monthsfordailydialysis patients.Inturn,transplantcostsin50monthsreachedUSD48,000andUSD70,000,forconven- tionalanddailydialysispatients,respectively.Forconventionaldialysispatients,transplantis lesscostlywhentherapyexceeds16months,whereasfordailydialysispatients,thethreshold isaround13months.

Conclusion: Transplantation is less expensive than dialysis in children, and the estimated thresholds indicate that renal transplant should be the preferred treatment for pediatric patients.

4.0/).

夽 Pleasecitethisarticleas:CamargoMF,BarbosaKS,FetterSK,BastosA,FeltranLS,Koch-NogueiraPC.Costanalysisofsubstitutiverenal therapiesinchildren.JPediatr(RioJ).2018;94:93---9.

∗Correspondingauthor.

E-mail:pckoch@uol.com.br(P.C.Koch-Nogueira).

https://doi.org/10.1016/j.jped.2017.05.004

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PALAVRAS-CHAVE Economia;

Transplanterenal;

Diáliserenal;

Pediatria

Análisedecustosdeterapiasrenaissubstitutivasemcrianc¸as

Resumo

Objetivo: A Doença Renalem Estágio Finaléum problemade saúdequeconsome recursos públicoseprivados.Nossoobjetivoéidentificarocustodahemodiálise(hemodiálisediariasou convencional)etransplanteemcriançaseadolescentes.

Métodos: Uma coorte retrospectivade pacientespediátricos comDoenc¸a Renalem Estágio Final(DREF)submetidosàhemodiáliseapóstransplantederim.Todososcustosincorridosno tratamentoforamcobradoseocustototalmensalfoicalculadoporpacienteeporcadaterapia renal.Então,foiestimadoummodelodinâmicocomdadosempainel.

Resultados: Estudamos 30 crianc¸as submetidas à hemodiálise (16 hemodiálises conven- cionais/14hemodiálisesdiárias)apóstransplanterenal.Ogastomédiomensalparahemodiálise foiUS$3,5mileUS$1,9milparatransplante.OscustosdehemodiálisesomammaisdeUS$87 milem 40 mesespara pacientessubmetidos ahemodiáliseconvencional (HC)e US$131mil em50mesesparapacientessubmetidosahemodiálisediária(HD).Poroutrolado,oscustos detransplanteem 50mesesatingemUS$48eUS$70mil,parapacientessubmetidosaHCe HD,respectivamente.Parapacientessubmetidosàhemodiáliseconvencional,otransplanteé menosonerosoquandoaterapiaultrapassa16meses,aopassoqueparapacientessubmetidos ahemodiálisediáriaolimiarécercade13meses.

Conclusão: Otransplanteémenoscaroqueadiáliseemcrianc¸aseoslimiaresestimadosindicam queotransplanterenaldeveserotratamentopreferencialparapacientespediátricos.

0/).

Introduction

End-stagerenaldisease(ESRD)isa disordercharacterized bytheirreversiblelossofkidneyfunction.Thediseaseisa healthproblemthatincreasesmortalityrate,causesanega- tiveimpactonthequalityoflifeofpatients,andconsumes ahigh amount of resources. Kidneytransplantation is the treatmentof choicefor ESRDinchildren, andpreemptive transplantshouldbetheﬁrsttherapeuticgoalforpediatric patientswiththiscondition.¹

InBrazil,alarge portionof thebudgetoftheBrazilian UniﬁedHealthSystem(SistemaÚnicodeSaúde[SUS])isallo- catedforrenalreplacementtherapies;increaseddemands arepredicted,duetotherisingprevalenceofthedisease.² Theincidenceandprevalence ofpediatricchronic dialysis inBrazilis6and20casespermillionage-relatedpopulation (pmarp),respectively,³ andtheincidenceofpediatrickid- neytransplantationis4pmarp.⁴Hemodialysisisthreetimes moreusedthanperitonealdialysis(75%vs.25%),andthere areregionaldifferencesinaccesstoESRDtreatment,which islowest inthe NorthandMidwestregions.^3,4 Inequalities inaccesstoESRDtreatmentarenotexclusivetoBraziland haveamacroeconomicorigin.^5---8

Given the amount of resources used in the treatment ofthedisease,variousstudiesestimatethe costsofrenal replacement therapies. In general, those studies suggest that transplanting younger and healthier individuals and eventhosewithconsiderable ESRDco-morbidities is cost- effective.^9---16

However,mostofthesestudiesarebasedondatafrom adults,and no study has analyzed the costs of childhood renalreplacement therapies in Brazil. Extrapolation from thestudies withadultsis notappropriate,sinceESRDhas

peculiaritiesin eachage range,makingtreatment inchil- drenandadolescentsalmostindividualized,andthusmore complexandexpensive.

Whenconsideringdialysistreatmentalone,recentdata indicate that daily hemodialysis promotes better out- comes for children when compared with conventional dialysis.¹⁷ Consequently, theinterestin dailyhemodialysis hasincreasedbut, todate, thecostsof thistherapyhave notbeenevaluated.

In this context, this study aimed toﬁll these gaps by identifying the costs of hemodialysis (either daily [DHD]

orconventionalhemodialysis[CHD])andtransplantationin childrenandadolescents.ThisistheﬁrstanalysisinBrazil tocompileallcostsofdifferentkidneytreatmenttherapies inchildren.

Methods

The authors report on a single-center cohort of 30 pediatric patients withESRDwho weretreated between 2007 and2013,allofwhomunderwenthemodialysisfollowedby kidney transplantationatHospital Samaritano.The conve- nience sample was drawn from the 168 pediatric kidney transplants that wereperformed during thestudy period.

Datawereretrospectivelycollectedforalltreatmentcosts including material, medicine, equipment, medical fees, administrativecosts,dailyrates ofhospitalization,physio- therapy,nutrition,nursing,administrativefees,equipment, wages,andlaboratorytests.

Themonthlytotalcostswerecalculatedforeachpatient on hemodialysisand transplantation (by the ofﬁcialprice index[IPCA]).Themeanaccumulatedcostfor eachofthe therapieswasthencalculated.

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Twodatasourceswereused:theadministrativedatabase fromtheHospital,withcostinformationfor bothtypesof therapiesandtheclassiﬁcationinbillingproceduresandthe NEFRODATAsoftware(version5.12---LifeSys,Divinópolis,MG, Brazil),withdetailedinformationonmaterialandmedicine forhemodialysis.

The main outcome was the total monthly cost per patient, adding variable costs, other variable expenses (itemsnot billedtothe patient,suchasusage of laundry facilities)andfixedcosts(administrativerates,apartments, andoperatingrooms).Aspatientswerefollowedduringdif- ferent periods, all values were converted into November 2013 U.S. dollars using the official inflation rate and the meanexchangeratefor thatmonth,¹inordertocompare costs.

Theanalysisofcostsofhemodialysiswasperformedcat- egorizing patients into two types: those who underwent CHDandthosewhounderwentdailyhemodialysisDHD,each patient belonging to only one type of treatment. In the- ory,patientsonDHDpresentdoublethedialysiscostswhen compared with those undergoing CHD, thus signiﬁcantly affectingthecosts.

Twotimevariableswereconstructed:onecalculatingthe time(months)thateachpatientspentonhemodialysisther- apyandtheothercalculatingthetransplantanddurationof follow-uptherapy.

Statisticalmethods

Descriptiveanalysis

Firstly, the evolution of the meanmonthly cost in differ- ent renaltherapies wascalculated by averagingthe total costineachmonthoverthenumberofpatients.Thevalues consideredareonlyformonthswithatleasttwopatients.

Comparisonsofgroups

Quantitative variables between the groups (DHD vs. CHD) were compared using the Mann---Whitney test, while the Wilcoxon matched-pairs test was used to compare treat- ments(hemodialysisvs.transplantation).Thechi-squaredor Fisher’sexacttestwereusedtocompareproportions.Inall tests,thelimitof5%(p<0.05)torejectthenullhypothesis wasadopted.

Subsequently, an econometric model was estimated in ordertocontrolforwithin-patientheterogeneityandgen- erate predictions as function of past values, while also quantifyingtheuncertaintywithconﬁdenceintervals.

Econometricanalysis

Sincethe30patientswereobservedoverdifferentperiodsin hemodialysisandfollowingtransplantation,theframework chosenwasthatofadynamicpanelwithasymptoticsinthe cross-sectionaldimensionandﬁxedtime.

1Inthisstudy,theIPCAinflationratewasused.BecausetheCen- tralBankusestheIPCAindexforinflationtargetingpurposes,itis regardedastheBrazilianofficialpriceindex.Themeanexchange rateforNovember2013was2.2947BRL/USD.

Taking thecross-sectional heterogeneity andthe auto- correlationintoaccount,thefollowingmodelwasformed:

y_it^j =˛+a^j_i+ˇ^j1t+ˇ^j2t²+^j1y_i,t−^j 1+2^jy_i,t−^j 2+3^jy_i,t−^j 3+ε^j_it wherejindexeswhetherthepatientwasinhemodialysisor transplantandwhether he/sheis undergoingCHD or DHD treatment.Indexireferstothepatientandt,tothetime.

Variableyitisthetotalmeanmonthlycostthatpatientihad inthet-ethmonthintreatment.

The model allows for ﬁxed effects, ai, so that each patientmight haveadifferentrecurringlevelof expenses compatible with his/her physical condition (such as age andweight)and howwell he/she responds totreatment.

Thequadratictrendcapturesthesmoothor intensefallin monthlycostsoverthedurationoftreatment. Finally,the inclusionoflaggeddependentvariablesmodelsthetemporal structure.

Theeconometricerrorsε^j_itareindependentlyandidenti- callydistributedovertimeandpatients,butrobuststandard errorsarealsoemployedforheteroscedasticity.

Asiscommoninthedynamicpanelsliterature,theinclu- sionoflaggeddependentvariablesinthemodelgenerates abiaswhentimeisfixedandthewithinorfirst-differences estimatorisused.Therefore,theestimatoremployedisthe systemGMMthatinstrumentsthetransformedendogenous variablesandthelevelendogenousvariablesbylaggedlevels andfirst-differencesofthedependentvariable.

Consideringthatthestudywasperformedthroughanal- ysisofsecondarydatafromdatabasesanddidnotrequire anyinterventionor evenanyprocedure withpatients,the ethics committee of the institution approved the project withouttheneedtoobtaininformedconsentfrompatients andparents(ProcessNo.:321.698).

Results

The study sample involved 30 children (18 boys/12 girls) whounderwenthemodialysis(16CHD/14DHD)followedby renaltransplantation. Themainetiology ofESRDwascon- genitalanomalies ofthekidney andurinarytract(CAKUT) in 18 patients (60%), and the mean age at transplanta- tionwas9years(SD=5).In25cases(83%),transplantwas fromdeceaseddonors.Themediandurationofeachtherapy was20(IQR=10---31)monthsforhemodialysis,whilemedian transplanttherapywas27(IQR=20---33)months(p=0.028).

Table1presentsthedemographicandclinicaldataofthe sample.

One observation concerning an item that was in the datasetand wasunrelated to renaltherapies (aCochlear implant, which is a high one-off cost [USD 34,900]) was dropped.Thissingleobservationwouldhaveincreasedthe meancostofhemodialysis.

Combiningthedifferentmonthlycostsperpatient,the mean cost of hemodialysis was USD 3500 and USD 1900 for transplant,according toTable 2. Half of the patients hadcost equal to or lower than USD 3300 per month for hemodialysisandUSD120fortransplant.Inturn,thehighest sumincurred inamonthwashigherfortransplant,reach- ingUSD 59,200vs.USD 22,200forHD.Thisindicatesthat,

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Table1 Demographicandclinicaldataofthestudiedsampleaccordingtotypeofdialysisbeforetransplantation.

CHD DHD p

Ageatdialysis(IQR) 10(8---11) 3(2---7) 0.032

Ageattransplantation(IQR) 12(10---14) 4(2---8) 0.007

Femalesexproportion 6/16(38%) 6/14(43%) 0.765

ESRDetiology CAKUT 9/16(56%) 9/14(64%)

Glomerular 4/16(25%) 2/14(14%) 0.880

Others 3/16(19%) 3/14(22%)

CHD,conventionalhemodialysis;DHD,dailyhemodialysis;IQR,interquartilerange;CAKUT,congenitalanomaliesofthekidneyandthe urinarytract;ESRD,end-stagerenaldisease.

Table2 Meanmonthlycostspertypeoftreatment(inthousandUSD).

Patienttype Therapy Mean SD Max

CHD Hemodialysis 2.8 2.1 22.0

Transplant 1.7 4.5 28.3

DHD Hemodialysis 4.0 2.6 22.2

Total Hemodialysis 3.5 2.7 22.2

CHD,conventionalhemodialysis;DHD,dailyhemodialysis.

overall, transplants initiallyhave highercosts, but in the longruntheyaremoreeconomical.

Subdividing the costs bybilling group, it wasobserved thatpatientsinHDhadthefollowingdistribution:(a)medi- cationsandmaterial=64%,(b)prosthesisandorthesis=15%, (c) hospital services=17% and (d) diagnostic medicine service=4%. Transplant patients costs were divided as:

(a) medications and material=49%, (b) prosthesis and orthesis=9%, (c)hospital services=35% and(d) diagnostic medicineservice=7%(p=0.014).

Analyzing separately CHD andDHD patients, themean monthlycostofDHDwashigher,atUSD4000(Table2).

It is noteworthy that transplant initially requires high expenditure,butitscostsubsequentlydecelerates,eventu- allyresultinginanoverallsavingsovertheaverageincurred forhemodialysis.Itisestimatedthattheaccumulatedcosts fortransplantcanreachUSD43,600.00intheﬁrstmonthand graduallyincreaseinthefollow-upperiod.Aftertwoyears oftreatment,theaccumulatedcostpost-transplantrisesto

betweenUSD 43,600.00andUSD65,368.00onaverage,as opposedtodoublethecostthatis observedinhemodialy- sisfor thesame period.Expenses withtransplantare,on average,alsohigherforDHDpatientsbyalmostUSD4580.

However,costsoftreatingcomplicationsaresimilarforboth groups(Table3).

Time-seriesanalysis

Fig. 1A presents the evolution of the mean monthly cost ofdifferentrenaltherapies,byaveragingthetotalsample costforeachmonth.Itshowsthathemodialysiscostsaddup tooverUSD87,000in40monthsforCHDpatientsandUSD 131,000in50monthsfor DHDpatients.Inturn,transplant costsin50monthsreachUSD48,000andUSD70,000forCHD andDHHpatients,respectively.Itisnoteworthythatthegap between thetransplantcumulativecosts forCHD patients andDHDpatientsincreaseearlypost-transplant,sincemost expensesareincurredintheﬁrstfewmonths.

Table3 Meanmonthlycostsfortypesoftreatment(inthousandUSD).

Treatment Typeofcosts CHD DHD Total

Hemodialysis Hemodialysis 1.8 3.4 2.7

Complications 3.9 2.8 3.3

Others 0.1 0.1 0.1

Transplant Transplantation 13.5 17.9 15.3

Preparationpre-Tx 0.2 0.6 0.5

Post-Txfollow-up 0.2 0.2 0.2

Complications 5.5 5.0 5.2

Others 0.2 0.3 0.3

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A _CHD

174

130

88

44

174

4 20

15

10

5

0 3

2

1

0 10 20 30

Duration of hemodialysis (months) Duration of transplant (months)

CHD DHD CHD DHD

40 50 0 10 20 30 40 50

130

88

44

0

0 5 10 15 20 25

Months in therapy

30 35 40 45 50

0 5 10 15 20 25 30 35 40 45 50 0 5

Duration of therapy (months) Months in therapy

Cumulative average costs

Transplant Hemodialysis Transplant

Transplant Hemodialysis

Hemodialysis 10 15 20 25 30 35 40 45 50

DHD 132

110

88

66

44

22

0

0 5 10 15 20 25 30 35 40 45 50

C D

B

Figure1 A,cumulativemeanmonthlycostscomparinghemodialysisandtransplant,bypatienttype(inthousandUSD);B,testing forstatisticallysigniﬁcantdifferencesincumulativecosts:CHD(inthousandUSD);C,testingforstatisticaldifferencesincumulative costs:DHD(inthousandUSD);D,evolutionofthemeanmonthlycostofhemodialysissessions(left)andfromhospitalizationdueto transplant(right),bypatienttype(inthousandUSD).

Insummary,apost-transplantthresholddurationofther- apy appear toexist, where a transplantbecomes a more economicaloptiontohemodialysis.Inordertostatistically estimatethisthreshold,takingcross-sectionalheterogene- ity into account and predicting the cost with the same temporal structure, the following section will present an econometricanalysisofthedata.

Econometricanalysis

Fig. 1B and C plots the average predicted cumulative costs and their confidence intervals at a 95% confidence level basedon thedynamic panel estimation (seeregres- sion results in the Online Appendix). Both figures clearly showthathemodialysisbecomesamorecostlyoptionafter a threshold duration of therapy. Being conservative, the thresholdisidentifiedwhenthelowerboundofhemodialysis confidenceintervalsurpassestheupperboundoftransplant confidenceinterval.

ForCHDpatients,itislesscostlytoundergotransplant whentherapyexceeds16months.Inturn,forDHDpatients, thethresholdarrivesearlier,at approximately13months.

The result is intuitive, sinceDHD requires twice asmuch materialandmedicine,thusinducingaswiftriseincost.

In both cases,the thresholdduration corresponds toa cost of around USD 44,000. It is noteworthy that a DHD patientintransplanttherapy costs USD 44,000in under5 months,butthisamountdoes notsurpassesUSD87,000in 50months.Inturn,DHDcostsadduptoUSD87,000inonly 24months(Table2).

Analysisofhemodialysisandtransplantprocedures Even though the economics of the therapies should cover all costs involved, including hospitalization due to complications and pre- and post-transplant exams, for example,itisalsointerestingtoanalyzeseparately,froma managementpointofview,hemodialysissessionsandtrans- planthospitalizationcosts.This subsectionanalyzes, from aneconomicstandpoint,theevolutionofcostsforhemodial- ysissessionsandtransplanthospitalizations.Fig.1Dpresents the monthly evolution of these costs in hemodialysis and transplant,whichdonotdivergesigniﬁcantlyfromthetotal costs for each therapy. The transplant procedure cost is almostzeroaftertheﬁrsttwomonths,contrarytohemodial- ysis.

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Discussion

Themainﬁndingofthisresearchisthattransplantinchil- dren and adolescents is an economically more attractive therapyafterarelativelyshortthresholdof time.Observ- ing30patientsfrom2007until2013andcomparingthecosts incurredinhemodialysisandtransplant,itcanbeconcluded thattransplantisamoreadvantageoustherapyfromacost standpointafter13---16monthspost-transplant.

Itis impossibletocomparethe costdifferencesamong hospitals and countries because there are regional varia- tions,butthepresentresultsareinagreementwithseveral studiesinadultsshowingthattransplantismoreeconomical whencomparedwithdialysistreatment.^13,18Onlyonestudy reportedthatdialysiswaslessexpensivethantransplanta- tion,buttheirpatientsonlyunderwenttwodialysissessions perweek. Moreover,itwasacross-sectionalstudy,andno econometrictechniquewasimplementedtomodelthecosts oftreatmentsaccordingtotheduration.¹⁹

The innovative aspect of the present research is that it was based only on pediatric patients; the findings are relevantbecausetheyextendpreviousconcepts thatwere reportedinadults.Also,thefactthatthissampleincluded childrenwhounderwentdailydialysisbeforetransplantation isoriginal.Morefrequentdialysishasthepotentialtoreduce malnutrition,cachexia,allowinggreaterdietaryfreedom²⁰; thesebenefitsmakeDHDaninterestingoptionforchildren, sinceit promotes growth and lowermorbidity.^17,21---23 The authorstookadvantageofthefactthatthiscenterregularly performsDHDinsmallchildrentostudytheeconomicimpact ofthistreatmentmodality.Tothebestoftheauthors’knowl- edge,thisisthefirsttimethatestimationofcostsofrenal replacementtherapiesincludeddailydialysis.

Although a cost-effectiveness analysis was not per- formed,it is plausibletoassume thatthis ratiowouldbe elevated,sincepediatricsolid-organtransplantsresultina survivalbeneﬁtofover25yearsintheUnitedStateswhen comparedtochildrenwhowereplacedonthewaiting list butwerenottransplanted.²⁴

Thisstudycollectedandanalyzedcostsrelatingtomate- rials,medicine,doctors,administrative,andhospitalization fees, as well as other incidentals, to establish economic parametersforanefﬁcientallocationofresourcesinrenal replacementtherapyforthepediatricpopulation.However, even if indirect costs are excluded, such as hospitaliza- tions due to complications and post-transplant consults, the meaning of the results does not change. In fact, the inference that transplant is a more economical therapy in the long run is further corroborated. Considering only hemodialysis session costs (routine exams, hemodialyzer, materials,medicine,andmedicalfees)andtransplanthos- pitalizationcosts inthis sample, thethreshold isreduced from13to16monthsto9to15months.Theseresultsare inagreement withthosebySánchez-Escuredo etal., who reportedthattransplantationresulted incostsavingseven intheﬁrstyearandwas74%lessexpensivetreatmentthan hemodialysisin the second year afterliving donor kidney transplantation.¹⁵

Thepresentdatawerebasedonmeanmonthlycosts;the problemwiththisapproachisthatthetemporaldependency ofthecostsisignored,impeding arobustinferenceanda moreinformedprediction.Estimatinganeconometricmodel

fortheevolutionofcostsallowedtocontrolwithin-patient heterogeneity and to generate predictions as function of past values, while also quantifying the uncertainty with conﬁdenceintervals.Theresultsallowedananalysisofthe costs temporal structure while also controlling for cross- section idiosyncrasiesofthe patientsusingdynamic panel datamethods.

The present results also considered the fact that CHD andDHDpatientsmaybedifferent.DHDhasbeenreported to decrease the length of hospital stay, the weekly dose of erythropoiesis-stimulating agents, and the number of antihypertensive medications when compared with conventionalhemodialysis.^13,25,26 Itis noteworthythat,in the presentsample,thecostsofDHDwerelogicallygreaterthan CHD,butthecostofcomplicationswasnumericallylower, suggesting that intensiﬁed hemodialysispromotes a lower incidenceof complications.²¹ Theseinferior complications costsaremorenotablewhenconsideringthatthepatients whounderwentDHD inthepresentstudy wereyoungerat thebeginningoftreatment.

In the 10---30 months range, the mean costs for CHD patients had a higher growth rate than DHD patients, although the overall trendremaineda decliningone.The authors concluded that this is not due to a change in the costs dynamics of a particular treatment itself, but due to the change in the sample composition, which happens naturally because patients leave treatment over time. As the sample size decreases, the cost estimates becomelesspreciseandendupreflectingindividualpatients idiosyncrasies. In particular, only half of the CHD sample was in treatment after the 20th month; therefore, the meancosts were greatlyinfluenced by anyadditional leave. The authorsconsiderthatthe presenteconometric approach improves upon the simple comparison of mean monthly(cumulative)costs,becauseitisolatestheidiosyn- crasies(fixed-effectsintheregression)andtheestimation of the dynamics parameters is less affected by sample reductions.

Thepresentresearchhaslimitationsbecauseitisaret- rospective singlecenterstudy involvingareducednumber of children for a limited period. Furthermore, the sample included only patients who underwent hemodialysis, and more studies comparing the costs of transplantation with peritoneal dialysiswould be welcome.However, the strengthofthestudyisthefactthatitaddressedasigniﬁ- cant questionfroman economicalpoint ofview,involving a developing country with limited resources, since this scenarioisnotrestrictedtoBrazil.Moreover,robustecono- metricmodelswereapplied,allowingthepredictionofthe costsforalongerperiod.

In summary, the present data suggest that treating patients under CHD for over 16 months would be more expensive than thecosts of atransplant. Likewise,trans- plantislessexpensivethantreatingpatientswithDHDfor over 14 months. Transplant becomes a more economical therapyattheUSD43,590.00threshold,becausethepostop- erativemonthsdonotgreatlyaddtothecumulativecosts.In turn,hemodialysisdemandsacontinuousmonthlyspending ofresources, reachingtwice thecumulativecostoftrans- plant after 30---40 months. Considering only hemodialysis sessionsandhospitalizationfortransplant,thethresholdis USD30,513.00.Consideringthatthesamplepatientsspent

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amediantimeof20monthsondialysis,transplantisabet- ter alternative for children undergoing substitutive renal therapies.

The thresholds estimated in this study might serve to guidepublicpolicy,indicating thatrenaltransplantshould beusedvis-à-vishemodialysisforpatientsofthepediatric populationinalongdurationtherapy.

Funding

ResearchfundedbytheBrazilianMinistryofHealththrough the‘ProgramadeApoioaoDesenvolvimentoInstitucionaldo SistemaÚnicodeSaúde--- PROADI-SUS’,protocol number:

25000.180613/2011-11.

Conﬂicts of interest

Theauthorsdeclarenoconﬂictsofinterest.

Appendix. Supplementary data

Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.jped.

2017.05.004.

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