nefrologia.2016;3 65:465–468Revista de la Sociedad Española de Nefrología Editorial El Kidney Donor Profile Index: ¿se puede extrapolar a nuestro entorno?. Julio Pascuala,b, ∗, María José
Trang 1nefrologia.2016;3 6(5):465–468
Revista de la Sociedad Española de Nefrología
Editorial
El Kidney Donor Profile Index: ¿se puede extrapolar a nuestro
entorno?
Julio Pascuala,b, ∗, María José Pérez-Sáeza,b
aServicio de Nefrología, Hospital del Mar, Barcelona, Spain
bInstitut Mar d’Investigacions Mediques, Barcelona, Spain
Weoftenfindourselvesfacedwiththedilemmaofwhetheror
nottoacceptanapparentlynon-optimalkidneyinapatient
who hasbeen on dialysis and wantstohave atransplant
Theassessmentofthe“quality”ofthekidneyremains
con-troversial.Thesimplestconceptisage.Donorageisafactor
limitingthesurvivalofthekidney,andalthoughweknowthat
theoldertheage,thepoorerthesurvival,1wealsoknowthat
kidneysfromolderpeoplecanbebeneficialforpatientswhen
comparedwiththeirtimeondialysiswithoutatransplant.2,3
Intheearly2000s,aconceptwasdevelopedintheUScalled
expandedcriteria donor(ECD),where inaddition toage, 3
otherclinicalvariableswereincluded:ahistoryofhighblood
pressure,apreoperativeserumcreatininetest,andcauseof
death(i.e.whether cerebrovascular orotherwise).4 AnECD
kidneyhadasurvivalbetween70%and168%worsethana
kid-neyfromastandard-criteriadonor(SCD).Foroveradecade,
everyonehasusedthisdistinction,althoughinSpainithas
neverreached the point ofdeveloping a specific informed
consentforthiskindofkidney,whichinmanyprogrammes
constituteoverhalfofthoseavailable.Inourhealthcare
set-ting,theuseoftheECD-SCDdistinctionhasbeenlimitedto
scientificissues, with no real effecton clinical care
Inter-estingly, inthe US as well as inSpain, the mostcommon
夽Pleasecitethisarticleas:PascualJ,Pérez-SáezMJ.ElKidneyDonorProfileIndex:¿sepuedeextrapolaranuestroentorno?Nefrologia 2016;36:465–468
∗ Corresponding author.
E-mailaddress:julpascual@gmail.com(J.Pascual)
reasonfornotusingaremovedkidneyisbasedonthe his-tologicalstudyinthepre-implantbiopsy,whichprovidesno parameters forthe ECD-SCD comparison.5 The correlation betweenthehistologicalfindings,particularlythepercentage
ofglomerulosclerosisandgraftandpatientsurvival,islimited anddoesnotjustifythewidespreaduseofitformaking deci-sions about the importance ofwhether or not toaccept a kidneyfortransplantation.Thesimplefactofvariationinthe findingsbetweendifferentpathologistsexaminingthebiopsy illustratesthesignificantlimitationoftheseparameters.6
Inanattempttoimprovethepredictiveabilityofthe ECD-SCD classification based on 4 variables, the US system of donationandtransplantationhasdevelopedtheKidneyDonor RiskIndex(KDRI),basedon10variables.7Thesevariables(all clinicalones)includethe4above,plusweight,height,race, historyofdiabetes,hepatitisCvirusbloodtest,andwhether thedonor’sheartstopped.TheKDRIiseasilyobtained,witha readilyavailablecalculator.8Aswasthecasewiththeconcept
ofECD,itdoesnotincludeanyclinicalparameterof donor-recipientcompatibility,noranylaboratoryparameterexcept serumcreatinine,oranyparameterregardingthekidney,such
as macroscopic appearance, arteriosclerosis or histopatho-logy Major decisions in this area should be made after a
2013-2514/©2016SociedadEspa ˜noladeNefrolog´ıa.PublishedbyElsevierEspa ˜na,S.L.U.ThisisanopenaccessarticleundertheCC BY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/)
Trang 2466 nefrologia.2016;3 6(5):465–468
Table 1 – Renal graft survival according to the Kidney
Donor Profile Index (KDPI) in the US, with transplants
performed between 2004 and 2011 10
Data(%)
morecomprehensiveanalysis.9 Theparametersincludedin
theKDRIareonlythevariousclinicalcharacteristics
signifi-cantlyrelatedtograftsurvivalinananalysisofnearly70,000
donorsusedbetweentheyears1995and2005.Interestingly,
anattempttoimproveKDRIbyaddingfactorsthatoftenare
notwellknownatthetimeofmakingthedecisiontoaccept
orrejectthekidney,suchasischaemictime,HLAmatchor
machineperfusionparameters,didnotimprovethe
discrim-inativepower.10 Theindex assignsthe valueof1.00tothe
medianvalue(50thpercentile)ofdonorsfromtheprevious
year,thusavalue<1.00indicatesthebestkidney,andavalue
>1.00,worsethanthemediankidneyfromthepreviousyear
The KDRI value estimates the risk of loss of kidney with
respecttothemediankidney,thereforeakidneywithaKDRI
valueof1.40willhaveariskofloss1.4timesabovethemedian
kidneyfromthepreviousyearintheUS
TheKidneyDonorProfileIndex(KDPI)isanaccumulated
extrapolationoftheKDRI,suchthatkidneyqualityis
trans-ferredtoascalefrom0%to100%:aKDPIof80%assignedtoa
givenkidneymeansthat80%ofthekidneysfromtheprevious
yearhavehadbettersurvivalthanactualkidney.Thehigher
theKDPI,the“worse”isthekidneyintermsofestimated
sur-vival,andviceversa(Table1 TheKDPIisnotcomparedwith
anyvalidatedstandard,butonlywithkidneystransplanted
duringtheprioryearintheUS.TheKDPIimprovesthelimited
discriminativeabilityoftheECD,byobtainingthe
informa-tionfromaCoxmodelwith10significantvariablesinsteadof
4,andinmanycases,continuousandnon-dichotomous
vari-ables.However,thevalueofC-statistic(areaunderthecurve)is
0.60,10whichconfersapoordiscriminativevalue,considering
acceptableonlybetween0.70and0.80.11Themostimportant
variableinthecalculationisage:a20-year-olddonor,of80kg
ofweight,180cmtall,white,withnohypertensionordiabetes,
whodiedbybraintraumaandhadacreatinineof0.9,hasa
KDPIvalueof2%;adonorwiththesamecharacteristicsbut
whois70yearsoldhasaKDPIvalueof82%.8Ifthatsame
70-year-olddonorhasbeenhypertensiveduringthelast6years
ofhislife(whichoccursin70%oftheSpanishpopulationof
thatage),theKDPIvalueis90%.Gender(maleorfemale)has
notbeenfoundtobesignificant intermsofdiscriminative
value,andhasnotincludedinthefinalcalculation.7,8Table2
illustratessomecases
TheKDPI,besidesbeingincorporatedasatoolto
compar-ativelyestimaterenalsurvival,KDPIhasbeenusedrecently
intheUStomatchkidneyswithaKDPI<20%(theoretically
the best) to 20% ofwaitlist recipients with a
higher-than-expectedsurvival.12Theexpectedsurvivaliscalculatedbythe
Table 2 – Examples of KDPI using the Organ Procurement and Transplantation Network’s calculator 8
a%
1 20years,weight80,height180,white,no
HTN,nodiabetes,serumCr0.9mg/dL, HCV-negative,deathbybraintrauma
2
2 47years,weight78,height173,white,no
HTN,nodiabetes,serumCr1.4mg/dL, HCV-negative,donorinasystole
61
3 54years,weight72,height166,white,
HTNfor6years,nodiabetes,serumCr 0.9mg/dL,HCV-negative,braindeath
77
4 70years,weight80,height180,white,no
HTN,nodiabetes,serumCr0.9mg/dL, HCV-negative,deathbybraintrauma
82
5 70years,weight80,height180,white,
HTNfor6years,nodiabetes,serumCr 0.9mg/dL,HCV-negative,braindeathby brainhaemorrhage
94
6 70years,weight72,height166,white,
HTNofunknownduration,noDM,serum
Cr0.9mg/dL,HCV-negative,braindeath
bybrainhaemorrhage
97
7 65years,weight78,height173,white,
HTNfor1year,nodiabetes,serumCr 1.4mg/dL,HCV-negative,postinfarct donorinasystole
97
8 65years,weight72,height166,white,
hypertensionfor6years,typeIIdiabetes for2years,serumCr0.8mg/dL, HCV-negative,braindeathbybrain haemorrhage
98
9 72years,weight72,height166,white,
hypertensionfor6years,typeIIdiabetes for2years,serumCr0.8mg/dL, HCV-negative,braindeathbybrain haemorrhage
100
10 75years,weight78,height169,white,
hypertensionfor12years,nodiabetes, serumCr1.3mg/dL,HCV-negative,brain deathbybrainhaemorrhage
100
Source: https://optn.transplant.hrsa.gov/resources/allocation-calculators/kdpi-calculator/
EstimatedPostTransplantSurvival(EPTS),whichalsoranges from0%to100%:candidateswithalowerEPTSpresumably will last moreyears with renal function For this purpose, anothercalculatorhasbeendeveloped,whichincludes4 clini-calvariables(age,yearsondialysis,diabetes[yes/no]andprior transplant[yes/no]).13 Forexample,a48-year-oldpatienton dialysisfor3years,withnodiabetesorprevioustransplants, hasaEPTSof21%,sothispatientwillnolongerbenefitfrom receivingakidneywithaKDPIvalueof<20%,sincesurvival
“wouldnotbesufficient”toobtainakidneyofsuchquality
Would the KDPI be useful in Spain?
ThemajorlimitationoftheKDPIinitsapplicationinsettings other than US is evident:it onlyestimates which percent-ageofkidneysareremovedandimplantedintheUSduring thepreviousyearareworseorbetterthanthespecifickidney
Trang 3nefrologia.2016;3 6(5):465–468 467
analysedatacurrenttime.Therefore,itcannotbe
extrapo-latedtoothercountriesortransplantprogrammeswherethe
strategiesfortheuse oforgansare notthe sameand even
clinicaloutcomesare verydifferent.14 IntheUSonly5%of
donorswhosekidneysweretransplantedin2014wereover65,
andthepercentagewasevensmallerthanduringthe10years
earlier.15InSpain,32.4%ofdonorsin2015were70yearsor
older,andonly46.8%wereunder60.16IntheUStherateof
kid-neysremovedandrejectedisveryhigh,especiallyamongECD
kidneysorwithahighKDPI(65%discardedpost-extraction
ifKDPI >90%).17 Thesepercentageshavenot changedafter
KDPIhasextendedthecriteriaforevaluation.18Althoughin
Spainthispercentageislower,19 itislikelythatthe
funda-mentaldifferencetakesplacebeforeorganextraction,since
thenumberofECDdonorsorwithahighKDPIwhoare
con-sideredvalidintheUSislowerthaninSpain,atleastforgoing
toandanalysethekidneyonceremoved.Itisinterestingto
notethatintheUS,morethan30%ofrecipientsinthewaiting
listthatare65orolderwouldnotacceptakidneywithKDPI
>85%,when100%ofpatientseligiblefortransplantswould
haveaKDPIof>85%iftheywere donors.Also,thenumber
ofpatientsinthewaitinglistis5timeshigher(86,965
candi-dates)thanthenumberoftransplantsin2013(17,600),20and
thedifferencebetweencandidatesandtransplanted
contin-uestogrow.ThemediantransplantwaitingtimeintheUS
is6.5years,andwaitlistmortalityisroughly8percentper
year.Thismeans thatapproximately50%ofcandidatesdie
beforebeingtransplanted.15InSpain,almost60%ofpatients
inthewaitinglisthaveatransplanteveryyear.21 Foryears,
therehasbeen appliedmuchwider criteria foracceptance
ofdonorsandkidneys.22Thustransplantperformancewould
notimprovebyadoptingaratingsystemfromsuchadifferent
scenario
ThequestionofusingKDPIasthemaincriteriontorule
outatransplantablekidneyalsocomesfrom theconsistent
demonstration thatthe kidneys witha high KDPI (even of
91–100%)conferssurvivalbenefitscomparedwithwaitingfor
dialysis ofa kidney witha lower KDPI23; this is similar to
whatwehaveseenwithkidneysfromelderlypatientsinour
setting.2,3
Theseradical differencesindicate that the directuse of
US-basedKDPIinSpainwould beanonadvisablepractice
Using USdonors asacomparison, eventhoughwe donot
havereliableSpanishdata,theKDPIofSpanishdonorscan
beestimatedtobe morethan 80% inmorethan half, and
closeto100%inmorethan30%.Ithasbeenrecentlydiscussed
thattheKDPIshouldbevalidatedinaEuropeanpopulation
sincevariablesareavailableinmanyregistries.24Wedonot
share this view The,onlyidea that seems validwould be
tofindkidneyqualityindexavailablebasedonknowndata
onviabilityand survival.Butsuchdatacannotbe
extrapo-latedfromsettingsthataresodifferentfromours,25asthis
oftenprovesunsuccessful.26Anentirelydifferentissuewould
betodevelopaSpanishKidneyDonorProfileIndex(SKDPI),
whichwouldnecessarilybeconstructedfromSpanishdata,
combiningclinicalvariablesfromdonorswithmedium-and
long-term outcomes in recipients Some patient registries
accumulateenoughdatatobuildindexesofthistype,which
maybemoreusefulinguidingdecisions
r e f e r e n c e s
3.Pérez-SáezMJ,ArcosE,ComasJ,CrespoM,LloverasJ,Pascual
J,CatalanRenalRegistryCommittee.Survivalbenefitfrom kidneytransplantationusingkidneysfromdeceaseddonors over75years–atimedependentanalysis.AmJTransplant
2016,http://dx.doi.org/10.1111/ajt.13800[Epubaheadofprint]
8.[accessed24Mar2016].Availablein:https://optn.transplant hrsa.gov/resources/allocation-calculators/kdpi-calculator/
10.[accessed20Mar2016].Availablein:https://optn
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12.[accessed24Mar2016].Availablein:https://optn.transplant
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13.[accessed24Mar2016].Availablein:https://optn.transplant hrsa.gov/resources/allocation-calculators/epts-calculator/
15.HartA,SmithJM,SkeansMA,GustafsonSK,StewartDE, CherikhWS,etal.Kidney.AmJTransplant.2016;16:11–46,
16.[accessed20Mar2016].Availablein:http://www.ont.es/
18.BaeS,MassieAB,LuoX,AnjumS,DesaiNM,SegevDL ChangesindiscardrateaftertheintroductionoftheKidney DonorProfileIndex(KDPI).AmJTransplant.2016,
19.[accessed24Mar2016].Availablein:http://www.ont.es/
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22.RegistroEspa ˜noldeEnfermosRenales.Informedediálisisy
trasplante2014.[accessed20Mar2016].Availablein:
http://www.ont.es/infesp/Registros/REGISTRO%20RENAL%