Examining Frailty Phenotype Dimensions in the Oldest Old

Nevertheless, there is not a gold standard to study frailty. Several studies have used Fried's frailty phenotype (Fried et al., 2001), which ... ThisarticleispartoftheResearchTopic PhysicalandCognitiveFrailtyintheElderly:AnInterdisciplinaryApproach Viewall 13 Articles Articles MartinaAmanzio DepartmentofPsychology,UniversityofTurin,Italy LuZhang WallaceH.CoulterDepartmentofBiomedicalEngineering,CollegeofEngineering,GeorgiaInstituteofTechnology,UnitedStates GiuseppeLiotta UniversityofRomeTorVergata,Italy Theeditorandreviewers'affiliationsarethelatestprovidedontheirLoopresearchprofilesandmaynotreflecttheirsituationatthetimeofreview. Abstract Introduction MaterialsandMethods Results Discussion DataAvailabilityStatement EthicsStatement AuthorContributions Funding ConflictofInterest Acknowledgments References SuggestaResearchTopic> DownloadArticle DownloadPDF ReadCube EPUB XML(NLM) Supplementary Material Exportcitation EndNote ReferenceManager SimpleTEXTfile BibTex totalviews ViewArticleImpact SuggestaResearchTopic> SHAREON OpenSupplementalData ORIGINALRESEARCHarticle Front.Psychol.,26March2020 |https://doi.org/10.3389/fpsyg.2020.00434 ExaminingFrailtyPhenotypeDimensionsintheOldestOld SaraAlves1,2*,LaetitiaTeixeira1,2,OscarRibeiro3,4andConstançaPaúl1,2 1AbelSalazarInstituteofBiomedicalSciences—UniversityofPorto(ICBAS.UP),Porto,Portugal 2CenterforHealthTechnologyandServicesResearch(CINTESIS.ICBAS),Porto,Portugal 3CenterforHealthTechnologyandServicesResearch(CINTESIS.UA),UniversityofAveiro,Aveiro,Portugal 4DepartmentofEducationandPsychology,UniversityofAveiro,Aveiro,Portugal Introduction:Frailtyhasbeenstudiedamongtheoldpopulationduetoitsassociationwithnegativeoutcomes.Presentlythereisnogoldstandardformeasuringfrailty,butseveralstudieshaveusedthefrailtyphenotypeofFriedconsistingoffivecomponents(weakness,slowness,unintentionalweightloss,exhaustion,andlowphysicalactivity)thatclassifyindividualsasrobust,pre-frail,orfrail,dependingonthenumberofcomponentsaffected,respectively,zero,oneortwo,andthreeormore.Thisstudyaimstoexplorethespecificcontributionofeachofthesecomponentstothefrailtyphenotypeinasampleofoldestoldcommunity-dwellingindividuals. MaterialsandMethods:Individualsaged80+yearsoldlivinginthecommunity(N=142)participatedinthisstudy.Sociodemographicdata(age,sex,educationallevel,andmaritalstatus)andFried’sfrailtyphenotypewerecollected.Descriptiveanalysissummarizedsociodemographicinformationandthefrailtycomponents.Multiplecorrespondenceanalysis(MCA)wasperformedtodetectandexplorerelationshipsbetweenfrailty’sfivecomponents. Results:Participantshadameanageof88.07years(SD=5.30years)andweremainlywomen(73.9%).Themajorityofthesamplewereconsideredfrail(71.8%)andpre-frail(24.7%),andthemostrecurrentcomponentforbothgroupswasslowness.FromtheMCAanalysis,atwo-dimensionsolutionwasconsideredthemostadequate,with53.47%ofvarianceexplained.Dimension1(32.21%ofvarianceexplained)showedweaknessasthemostdiscriminantcomponent;dimension2(21.26%ofvarianceexplained)showedunintentionalweightlossasthemostdiscriminantcomponent. Discussion:Resultsrevealedahighnumberofpre-frailandfrailparticipants.MCAprovedtoaddanimportantunderstandinginexaminingthefrailtyphenotype;itrevealedweaknessasthemostdiscriminantcomponentfordimension1,suggestingahighassociationwiththefrailtyphenotype.MCAalsoidentifiedtwomainfeaturesoffrailty:onerelatedwithphysicalfeatures(motorbehavioralandgripstrength)includingweakness,lowphysicalactivity,andslowness;andthesecondrelatedwithintrinsicconditions(unintentionalweightlossandexhaustion). Conclusion:Thisstudycorroboratestheneedofadifferentiatedapproachtothefrailtyphenotypeamongveryoldindividuals,bringingforconsiderationthespecificinfluenceofitscomponents. Introduction Worldwidetrendsshowanincreasingandfastagingpopulation.Alongerlifeexpectancycontributestotheincreaseofindividualsaged80yearsandolder—theoldestoldpopulation.InPortugal,oldestoldindividualsconstitute5.0%(532,219)ofthetotalpopulation(10,562,178)and26.5%ofthepopulationaged65+(2,010,064)(Brandãoetal.,2017).Trendsshowthatlivinglongermayleadtoalongperiodofdisabilityandfrailtywithincreasingcaredemands(Alvesetal.,2016). Frailtyhasbeenwidelystudiedamongtheoldpopulationduetoitsrelationwithnegativeoutcomessuchasfalls,institutionalization,hospitalization,anddeath.Nevertheless,thereisnotagoldstandardtostudyfrailty.SeveralstudieshaveusedFried’sfrailtyphenotype(Friedetal.,2001),whichdefinesfrailtyasthepresenceoffivecomponents:weakness,slowness,exhaustion,lowphysicalactivity,andunintentionalweightloss.Accordingtothisperspective,individualscanbeclassifiedasrobust,pre-frail,orfraildependingonthenumberofcomponentsthattheyscore(0components,1–2components,or≥3components,respectively). Previousresearchhasshownthatthereisasignificantassociationbetweenincreasedageandfrailty,revealingthatthemajorityoffrailindividualsaretheoldestones(e.g.,Friedetal.,2001;DuarteandPaúl,2015;Careyetal.,2018;Lewisetal.,2018).Fried’soriginalstudyinparticularshowedthatindividualsaged80+yearsoldrepresented34.8%ofthefrailsample.Thisnumbercouldbehigherbecausethereisalargedifferencebetweenthenumberofindividualsassessedunderandabovethe80yearsoldthreshold(4,636versus681participants).Whenanalyzingspecificallytheproportionoffrailindividualsbasedonagegroupsunderandabove80years,Fried’soriginalstudyrevealedthat18.8%ofindividualsaged80andoverwerefrailincontrastwith5.2%offrailindividualsbelowthatage(lessthanone-thirdofthefrailoldestoldparticipants).Alongwiththisdiscrepancy,thestudydidnotreportinformationontheproportionofpre-frailindividualsingroupsunderandabove80years,northeproportionofcomponentsimpactedbasedonpre-frailandfrailcondition. Recentstudiesthatusedthefrailtyphenotyperevealedthattheproportionoffrailtyamongoldestoldindividualsisparticularlyhigh(DuarteandPaúl,2015;Bienieketal.,2016)incomparisonwithyoungeroldindividuals(e.g.,frailtyprevalenceincreasedwithagefrom31.7%inthe60–69agegroupto67.6%inthe90+agegroup,andfrom22.5%inthe50–65agegroupto60.4%inthe75+agegroup,respectively).Theseresultsseemtoindicatethatthefrailconditionisveryfrequentamongoldestoldindividualsandsuggeststhatthefrailtyphenotypeprovideslowvariabilitywithintheoldestoldsubgrouponcealargeproportionofoldestoldindividualsarefrail.Otherstudieshavealreadyanalyzedthecomponentsofthefrailtyphenotypeandshowedsomeresultsinrelationtocharacteristicssuchasage(Hoogendijketal.,2015),gender(Bienieketal.,2016),disability(Papachristouetal.,2017),andmortality(Papachristouetal.,2017).Nevertheless,thesestudiesdidnotinformabouttheweight/contributionofeachcomponentforthefrailtyphenotype,anditwouldbeimportanttounderstandifallcomponentscontributeequally(ornot)tothefrailtyconditionandhowtheyinterrelatewitheachother. Intheoldestoldgroup,duetothelargeproportionofindividualsclassifiedasfrail(lowvariability),itwouldbecrucialtodeterminewhichcomponentsofthefrailtyphenotypecontributethemosttoestablishthefrailtycondition.Determiningsuchweightswouldhelptomakefrailtyscreeningmoreefficientandmoretargetable,sincethesuccessofinterventions,consideringfrailtyasareversiblecondition,maydependonthespecificcomponentstobeaddressed.ThisstudyaimstoexplorethestructureofthefrailtyphenotypeofFriedandthecontributionofeachofitscomponentsinasampleofoldestoldcommunity-dwellingindividualsbyusingmultiplecorrespondenceanalysis(MCA). MaterialsandMethods Design Anon-probabilisticsamplewasrecruitedfromJuneof2017toAugustof2018,intheMetropolitanAreaofPorto(NorthofPortugal).RecruitmentwasbasedonthereferralofindividualsbylocalNGOs—non-governmentalorganizations(e.g.,daycentersandhomeservices)andbyusingasnowballstrategy(BiernackiandWaldorf,1981),whichallowedtheidentificationofcasesofinterestamongpeoplewhoknewotherswithsimilarcharacteristicsandthereforewithinthescopeoftheresearch.Atwo-stageprocesswasused:first,NGOswereinvitedtoparticipateintheproject.Thosethatagreedtoparticipateidentifiedpossibleparticipantsaccordingtoasetofinclusioncriteria(peopleaged80+yearsoldandlivinginthecommunityintheMetropolitanAreaofPorto).Thesecretaryofeachorganizationthencontactedeachpotentialparticipantinordertoaskforauthorizationforsharingpersonaldatawiththeresearchteam.Afterthispreliminaryconsent,theresearchteamcontactedthesubjectsandprovidedamoredetaileddescriptionofthestudy,namely,itsobjectivesandconditions.Thosewillingtoparticipatewereinterviewedface-to-face.Iftheoldestoldpersonhadnocognitiveabilitytorespond(e.g.,peoplewithdementia),permissiontoparticipatewasobtainedbythelegalrepresentative.Allparticipantssignedaninformedconsentform:onefortheresearcher/interviewerandtheotherfortheparticipant.ThestudywasapprovedbytheEthicalCommitteeoftheInstituteofBiomedicalSciencesofAbelSalazar,UniversityofPorto(processno.188/2017),andauthorizedbythePortugueseDataProtectionAuthority(approvalno.1338/2017). Measures –Sociodemographicinformation:age,sex,educationlevel,andmaritalstatus. –Phenotypeoffrailty:weassessedfivecomponentsaccordingthedefinitionofphysicalfrailtyproposedbyFriedetal.(2001):(i)weakness,(ii)slowness,(iii)unintentionalweightloss,(iv)exhaustion,and(v)lowphysicalactivity.Regardingthefrailtyphenotype,participantswereconsidered“frail”iftheyfulfilledthreeormorecriteria,“pre-frail”iftheyfulfilledoneortwo,and“robust”ifnoneofthecriteriawasfulfilled.Themetricswereslightlychangedfollowingtheproceduresusedinsimilarstudieswithveryoldindividuals(e.g.,Gonzalez-Pichardoetal.,2013;Nyuntetal.,2017).Inparticular: (i)Weaknesswasmeasuredusinghandgripstrength[dynamometer(Takeidynamometer,T.K.K.5401,Japan)].Gripstrengthwastestedtwoconsecutivetimesonboththerightandlefthands.Analysisusedtheaveragepeakvalueacrossbothhands,andthethirdquartilewasconsideredtoclassifyparticipantsaccordingtotheirweakness;participantswithvalues<13.6kgwereconsideredweakandwerecategorizedas1,andthosewhoobtainedvalues≥13.6kgwerecategorizedas0,meaningtheywerenotweak(highstrength). (ii)SlownesswasevaluatedusinggaitspeedbytheTimed“UpandGo”test(PodsiadloandRichardson,1991).Thepatientmuststandupfromanarmchair,walk3m,turnaround,walkbacktothechair,andsitdown.Iftheparticipantstook16.8ormoreseconds[Portuguesecutoffforpeople80yearsandolder(Almeidaetal.,2017)]toperformthetesttheywereconsideredtohavelowmobilityandcategorizedas1.Participantswhowerenotabletodothewalkingtestwerealsocategorizedas1(lowmobility).Participantswhoperformedthetestinlessthan16.8swerecategorizedas0,meaninggoodmobility. (iii)Unintentionalweightlosswasevaluatedusingstep2oftheMalnutritionUniversalScreeningTool(Bapen,2003).Eachparticipantansweredaboutthetotalunplannedweightlossinthepast3–6monthsconsideringthetotalofhisorherweight.Initiallythequestionwasscoredas0forweightloss<5%,1forweightlossbetween5and10%,and2forweightloss>10%ofthetotalofweight.Answerswerethenrecodedas0forweightloss<5%and1forweightloss≥5%. (iv)Exhaustionwasassessedusingthequestion“Inthislastmonth,doyoufeelthatyouhavelessenergytodothethingsyouwant?,”whichwascategorizedas0=noexhaustionor1=yesexhaustion. (v)Lowphysicalactivitywasassessedbythequestion“Howoftendoyoupracticeanyofthefollowingactivities(dancing,walking,farmerwork,orgardening)?”(Duarteetal.,2014).Answersrangedfromonetofour,respectively,never/almostnever,uptothreetimesamonth,onceaweek,andmorethanonceaweek.Answerswerethenrecodedas0ifanswerswere“onceaweek”or“morethanonceaweek,”meaningtheywereactive,and1foranswers“never/almostnever”or“uptothreetimesamonth,”whichwereconsiderednotactive. StatisticalAnalysis Thedescriptiveanalysissummarizedsamplecharacteristicsconsideringsociodemographicaspects,thecomponentsoffrailty,andtheclassificationoffrailtyaccordingtoFried’sphenotype(Friedetal.,2001).Resultsweredisplayedusingabsoluteandrelativefrequenciesorcentrallocationanddispersionmeasures,accordingtothetypeofvariable.Todetectandexplorerelationshipsbetweenthefivecomponentsoffrailty(activevariables),age,sex,andeducation(supplementaryvariables),aMCAwasperformedusingRsoftwareandthepackagesFactoMineRandfactoextra.Supplementaryvariablesarenotusedforthedeterminationoftheprincipaldimensions.TheircoordinatesarepredictedusingonlytheinformationprovidedbytheperformedMCAonactivevariables,i.e.,thefivecomponentsoffrailty(Lêetal.,2008). Multiplecorrespondenceanalysisisamultivariatetechniquedesignedtodiscoverbothinterrelationsandintra-relationsoftwoormorecategoricalvariablesbyreviewingtheclosenessandremotenessbetweenthevariables,whichallowstheanalysisofpatternsofrelationshipsofseveralcategoricaldependentvariables.MCAfacilitatestheinterpretationofcategoricalvariablesinthecrosstablesprovidinginformationaboutthesimilarities,divergences,andassociationsbetweentherowandcolumnvariables.InMCA,somediscriminationmeasuresareusuallyanalyzedsuchasinertia,whichmeasureshowfarthecategoriesarespreadoutfromtheorigin,andtheeigenvalues,whicharethepercentageofinertiaexplained.MCAalsoallowsthegraphicalrepresentationoftheassociationsinalower-dimensionalspace,aidingtheinterpretationofresults.Eachvariableisrepresentedwithadotinamulti-dimensionalspace.DotsclosetotheXorYaxesarehighlyrelatedwiththerespectivedimension,andthoseclosetoeachotherareconsideredsimilartoorrelatedtoeachother,dependingontheareastheyfallinto.Similarly,dotsfarfromeachotherareconsideredtobeunrelated(Greenacre,1988;Anderson,1994).Todefinethenumberofdimensionstoretain,thefollowingcriteria/considerationswereemployed:(i)inclusionofMCAdimensionswithinertiaabove0.2and(ii)screetest(Hairetal.,1998).IninterpretingthediscriminationmeasuresandthevisualoutputsfromMCA,theaimshouldbetoidentifythosecomponentsthatclustertogether. Results Participants(N=142)hadameanageof88.07years(SD=5.30years)andweremainlywomen(73.9%),andthemajorityhadaloweducationallevel(34.5%wereilliterate,and65.5%hadoneormoreyearsofschool)(Table1).Accordingtothefrailtyphenotype(Table2),5(3.5%)individualswereconsideredrobust,35(24.7%)werepre-frail,and102(71.8%)frail. TABLE1 Table1.Sociodemographicinformationaboutparticipants. TABLE2 Table2.Phenotypeoffrailtyassessment. Consideringthephenotypecomponentsofthetotalsample,93participants(65.5%)revealedweakness,122(85.9%)revealedslowness,74(52.1%)reportedexhaustion,113(79.6%)reportedlowphysicalactivity,and21(14.8%)revealedunintentionalweightloss.Specifically,fromthepre-frailparticipants,13scoredononecomponent(representing9.2%ofthetotalofthesampleand37.1%ofthepre-frailindividuals),and22scoredontwocomponents(representing15.5%ofthetotalofthesampleand62.9%ofthepre-frailindividuals).Themostrelevantcomponentwasgaitspeed(65.7%),followedbyphysicalactivity(54.3%). Consideringtheparticipantslabeledasfrail,50participantsscoredonthreecomponents(35.2%ofthetotalofthesampleand49.0%ofthefrailindividuals),44scoredonfour(31.0%ofthetotalofthesampleand43.2%ofthefrailindividuals),and8scoredonfivecomponents(5.6%ofthetotalofthesampleand7.8%ofthefrailindividuals).Likewise,inparticipantslabeledaspre-frail,themostrelevantcomponentsweregaitspeed(97.1%)andphysicalactivity(92.2%). Ourresultsalsoshowedthatofthe62participantsexcludedfromtheanalysis,32werecompletelyunabletocooperateduetocognitiveimpairment(e.g.,dementiacases,stroke),and23duetodisability(e.g.,strokeconsequences,severehearingimpairment)thathampereddatacollectionofsomecomponentsoffrailty.Theothersevenexcludedparticipantsshowedtirednessorrefusaltoperformthesomecomponentassessment. FromtheMCAanalysis,atwo-dimensionsolutionwasconsideredthemostadequate(Table3).Thefirstandseconddimensionsshowed,respectively,0.32and0.21ofinertia(Table3).Thefirstdimensionexplained32.21%ofthevariance,anddimensiontwoexplained21.26%ofthevariance(Figure1).Together,bothdimensionsexplained53.47%ofthevariance(Table3).Table4describestheMCAdimensiondiscriminationmeasures.Fordimension1—labeledbyusasthefunctionaldimension—themostdiscriminantvariableswereweakness,followedbylowphysicalactivityandbyslowness.Regardingdimension2—labeledbyusastheintrinsicconditiondimension—themostdiscriminantvariableswereunintentionalweightlossandexhaustion(Table4).ConsideringthesociodemographicvariablestestedinMCA(age,sex,andeducationlevel),weverifiedaslightrelationofeachofthemwiththetwodimensions.Agewasalmostexclusivelyrelatedwithdimension2,andsexandeducationlevelwithdimension1(Table4andFigure1). TABLE3 Table3.Inertiaandeigenvaluesonthedimensionsofmultiplecorrespondenceanalysis(MCA). FIGURE1 Figure1.Multiplecorrespondenceanalysis(MCA)dimensiondiscriminationmeasures. TABLE4 Table4.MCAdimensiondiscriminationmeasures. Discussion Inaccordancewithpreviousstudies(Lewisetal.,2018),ourfindingsrevealedahighnumberofwomenandwidow(ed)participants.Theeducationlevelamongthisgroupisverylow(orinexistent),whichiswhyweconsideredparticipantswhowereilliterateversusthosewhoattendedschoolfor1yearormore.ThislastcharacteristicisstillexpressedintheoldestoldPortuguesepopulation,asformaleducationbecamemandatoryonlyin1950formenandin1960forwomen,justifyingthehighnumberofparticipantswithloweducationallevelandwhowereilliterate(Palmaetal.,2003). Concerningthefrailtycondition,fivekeyaspectsemergedfromourresults.First,weobservedagreatnumberofpre-frailandfrailsubjects.Frailindividualsrepresentedmorethantwo-thirdsofthetotalsample(71.8vs.24.6%ofpre-frail).Theseresultsareinaccordancewithotherstudies(DuarteandPaúl,2015;Lewisetal.,2018),whichalsohadagreatnumberoffrailoldestoldindividualsintheirsamples,highlightingthelowdifferentiation(almostallfrailpersons)providedbythefrailtyphenotypeofFriedamongoldestoldindividualsandemphasizingtheneedtobetterunderstanditscomponents. Second,thenumberoffrailtycomponentsimpaired(Table2)providedusefulinformationonthe“level”offrailtywithinboththepre-frailandfrailgroups.Specifically,inthefirstgroup,weobservedthatparticipantsscoredmostlyintheupperlimitofthepre-frailcondition(i.e.,twocomponents),whereasinthesecondgroup,wefoundthatparticipantsscoredmostlyinthelowerandmiddlelimitoffrailty(i.e.,threeandfourcomponents,representingatotalof92.2%offrailparticipants). Third,themethodologicalapproachusingMCAforthestudyoffrailtycomponentsprovedtoaddanimportantunderstandingforthestudyoffrailtyintheoldestoldparticipants.Ononehand,itrevealedweaknessasthemostdiscriminantcomponentforfunctionaldimension(withhighervarianceexplained,Figure1),evidencedbythefactthatamongthefivecomponentsoffrailty,weaknesswastheonewiththehighestassociationwiththefrailtyphenotype.Ontheotherhand,MCAidentifiedtwomainfeaturesoffrailty:onemorerelatedwithfunctionality/physicalfeatures(motorbehavioralandgripstrength)composedofweakness,lowphysicalactivity,andslowness;andasecondonerelatedwithintrinsicconditions(unintentionalweightlossandexhaustion).Thepresenceofafunctionaldimensionrelatedwithphysicalfeaturesmightsuggestthatthesecomponentsarepotentiallymoremodifiablethanthetwoothercomponentsfromtheintrinsicconditiondimension(unintentionalweightlossandexhaustion).Thisdistinctionofthetwofrailtydimensionsmaybeakeyaspectforcustomizedinterventionssinceitwouldhelptobetterdefinepathwaysaswellastounderstandtheeffectofinterventionsonindividualcomponentsoffrailtyaswellasintheoverallcondition.Theliteraturehasshownahighnumberofstudiesanalyzingtheeffectofinterventionsonimprovingthefrailtycondition(Cesarietal.,2015;DeLabraetal.,2015;Apostoloetal.,2018),althoughfewhaveevaluatedtheeffectofindividualandcombinedinterventionsincomponentsoffrailtyphenotypeand/orinreversingfrailty.Arecentstudy(Liaoetal.,2019)testingtheeffectoftwoexerciseinterventionsinpre-frailandfrailolderindividualsprovedthatbothinterventionswereeffectiveforweakness,slowness,andphysicalactivity(functionaldimension)butnotforexhaustionandweightloss(intrinsicconditiondimension),corroboratingourresults.ApreviousstudybyNgetal.(2015)thatconductedarandomizedcontrolledtrialamongolderadultstoverifytheeffectsofnutritional,physical,cognitive,andcombinedinterventionsonfrailtyreversalfoundthatthecomponentsoffrailtybenefitfromtargetedinterventionssuchasphysical,nutritional,andcognitive,andespeciallycombinedones.Acombinedinterventionseemedtoproducethebesteffectsinalmostallcomponentsoffrailty,exceptforweightlost,whichpresentedsomechangeintheshortandmiddletermdependingontheinterventionanalyzedbutwithoutlong-lastingeffects.Improvementsdecreasedat12months,whatevertheinterventionperformed,whichmaysuggestthatthiscomponentiseffectivelyanintrinsicaspectandmoredifficulttochange.Theseresultsmayalsohavetwomainimplicationsintheinterpretationoffrailty:(i)itspotentialofreversibility(Canevellietal.,2017),sincecomponentsfromfunctionalconditionmayhavehigherreversalratesthanintrinsicconditioncomponents(probablylesschangeableorurgingothertypesofintervention,including,namely,nutrition,cognition,andsocial);and(ii)itsrelationwithpracticalaspects,namely,intermsofindividuals’assessment(greaterattentiontocomponentsoffrailtyratherthantotheoverallscore)andindefiningandcustomizinginterventions(suitabilityandadequacy). Fourth,theslightassociationofsociodemographicvariableswiththetwodimensionssuggestedthatthisapproachoffrailtyshowedverylittleassociationwithsociodemographicaspectsnotcorroboratingpreviousstudies(Bienieketal.,2016;Nyuntetal.,2017;Papachristouetal.,2017;Lewisetal.,2018),whichshouldbethesubjectoffurtherresearch,consideringthesetwodimensionsofthefrailtyphenotypeandacrossdifferentagegroups.Thisstudyanalyzedonlytheoldestoldpeoplewithverylowvariabilityineducationlevelandhealthcondition,asreferredtointheLimitationssection. Fifth,moreattentionshouldbegiventothegreatnumberofindividualsexcludedfromthetotalsample.Participantswereexcludedduetotheirtotalorpartialinabilitytoperformthetestofcomponentsoffrailty(duetoauditorydeficits,consequencesofstroke,anddementia,amongothers).AccordingtoLewisetal.(2018),thefrailtyphenotypeofFriedrequiresacertainleveloffunctioning,whichisinaccordancewithwhatweobservedinourstudyoncewehadtoexcludefromouranalysisahighnumberofindividuals(55individualswereconsideredasnothavingthat“certainlevel”offunctioning).InFried’soriginalstudy,that“certainlevel”offunctioningwasassured,definingasetofexclusioncriteria(e.g.,historyofParkinson’sdisease,stroke,dementia),missinginformationabouttheexcludedparticipantsintermsofdisabilitylevel(totalorpartial),andthecomponentsimpaired.Probably,atthisadvancedage,manyoftheparticipantswerealreadydependent(withanirreversibleconditionandnotfrail).Thisshouldbefurtherexploredsothatthefrailtyconditionbecomesmoreclearandusefultoinforminterventions.Thedistinctionbetweentheinabilitytoperformacertaintaskorrequirementandamissingvalueseemscrucialtofullyunderstandthefrailtycondition. Overall,theresultsobtainedinthisstudysubstantiatetheneedofadiscriminantapproachtothefrailtyphenotype,namely,amongveryoldindividuals,bringingintoconsiderationthespecificrelevanceofthedifferentcomponentsoffrailty(functionaldimensionandintrinsiccondition).Thesubdivisionofthefrailtyphenotypeintotwodimensionsmayhelpprofessionalstoidentifyifthefrailconditionismorerelatedwithphysicalfeaturesorwithintrinsicaspects,leadingtothecustomizationofinterventionsandbearinginmindthatfunctionalaspectsarepotentiallymoremodifiablethanintrinsicones. Limitations Somelimitationsmustbementioned.First,ourstudymightbenefitfromanotherreferenceprocessforparticipants.TheidentificationofthetargetpopulationthroughNGOscouldcontributetohigherparticipantsdisabilitylevels.Second,thisstudyincludedveryoldindividuals(meanageof88years),whocouldhaveahigherincidenceofhealth-relatedproblems.WethereforesuggestfurtherstudiesamongotheryoungeragegroupstotestMCAandtoverifyifthetwo-dimensionapproachtofrailtyremainsuseful.FurtherresearchshouldalsoconsiderstudyingfrailtyinthosewhocannotbefullyassessedbymeansofFried’sfrailtyphenotype.Inparticular,somestudies(Ravindrarajahetal.,2013;Payneetal.,2017)demonstratedthatthoseparticipantswhocannotcompletetheFriedphenotyperequirementsshouldbeconsideredfrailordependent(irreversiblecondition)andhadahighermortalityratethanthosewhocouldbeassessed.Despitetheselimitations,ourresultsmayrepresentanimprovementtothestudyandconceptualizationofthefrailtyphenotypeaswellastotheplanningofinterventionsforpre-frailandfrailindividuals. DataAvailabilityStatement ThestudywasapprovedbytheEthicalCommitteeoftheInstituteofBiomedicalSciencesofAbelSalazar,UniversityofPorto(processNo.188/2017)andauthorizedbythePortugueseDataProtectionAuthority(approvalNo.1338/2017),guaranteeinganonymity,privacy,andconfidentiality. EthicsStatement ThestudiesinvolvinghumanparticipantswerereviewedandthestudywasapprovedbytheEthicalCommitteeoftheInstituteofBiomedicalSciencesofAbelSalazar,UniversityofPorto(processNo.188/2017)andauthorizedbythePortugueseDataProtection396Authority(approvalNo.1338/2017).Thepatients/participantsprovidedtheirwritteninformedconsenttoparticipateinthisstudy. AuthorContributions SAwasresponsibleforthestudydesign,collecting,analyzing,andinterpretingdata,andmanuscriptdraftingandrevision.LTmanaged,analyzed,andinterpretedthedata.ORwasresponsibleforstudysupervisionandmanuscriptrevision.CPwasresponsibleforstudysupervisionandmademanuscriptrevisions. Funding ThisworkwassupportedbyPh.D.gantfromtheFundaçãoparaaCiênciaeaTecnologia/PortugueseScienceandTechnologyFoundation(grantnumberSFRH/BD/108635/2015).TheresearchunitissupportedbytheFundaçãoparaaCiênciaeaTecnologia/PortugueseScienceandTechnologyFoundationintheframeworksofthe(PEst-OE/SAU/UI0688/2014andUID/IC/4255/2013)andbyEuropeanRegionalDevelopmentFund(ERDF)throughtheoperationPOCI-01-0145-FEDER-007746. ConflictofInterest Theauthorsdeclarethattheresearchwasconductedintheabsenceofanycommercialorfinancialrelationshipsthatcouldbeconstruedasapotentialconflictofinterest. Acknowledgments WewouldliketothankallNGOsthatgentlyagreedtoparticipateinthisstudy. References Almeida,S.,Marques,A.,andSantos,J.(2017).Normativevaluesofthebalanceevaluationsystemtest(BESTest),Mini-BESTest,Brief-BESTest,timedupandgotestandusualgaitspeedinhealthyolderPortuguesepeople.Rev.Portug.Med.GeralFam.2017,106–116. 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Editedby: MartinaAmanzio,UniversityofTurin,Italy Reviewedby: GiuseppeLiotta,UniversityofRomeTorVergata,Italy LuZhang,GeorgiaInstituteofTechnology,UnitedStates Copyright©2020Alves,Teixeira,RibeiroandPaúl.Thisisanopen-accessarticledistributedunderthetermsoftheCreativeCommonsAttributionLicense(CCBY).Theuse,distributionorreproductioninotherforumsispermitted,providedtheoriginalauthor(s)andthecopyrightowner(s)arecreditedandthattheoriginalpublicationinthisjournaliscited,inaccordancewithacceptedacademicpractice.Nouse,distributionorreproductionispermittedwhichdoesnotcomplywiththeseterms. *Correspondence:SaraAlves,[email protected] COMMENTARY ORIGINALARTICLE Peoplealsolookedat SuggestaResearchTopic>