Rev. Bras. Hematol. Hemoter. vol.39 número3

revbrashematolhemoter.2017;39(3):290–291

w w w . r b h h . o r g

Revista

Brasileira

de

Hematologia

e

Hemoterapia

Brazilian

Journal

of

Hematology

and

Hemotherapy

Letter

to

the

Editor

Response

to

the

assessment

of

the

Matos

&

Carvalho

index

by

Hoffmann

and

Urrechaga

DearEditor,

Hoffmann and Urrechaga evaluated the Matos & Carvalho Index(MCI),1_{howevertheyperformedtheiranalyses}

charac-terizingthepopulationdifferently fromthat usedbyus.In Matosetal.,2_{anemiawascharacterizedashemoglobin(Hb)}

<12g/dLforwomenand<13g/dLformen.3_Conversely,

Hoff-mannandUrrechagacharacterizedanemiausingthe value ofHb<13g/dL,independentofthesexofthepatients,which isnotrecommendedbytheWorldHealth Organization.3_In

addition,thecharacterizationofirondeficiencyanemia(IDA) performedinourstudywasbasedontheferritinlevel accord-ingtothegender,thatis,<6ng/mLforwomenand<28ng/mL formen.Hoffmannand UrrechagacharacterizedIDAusing ferritin <15␮g/L regardlessofgender. Thisvariation inthe definition ofcases of anemia, particularly IDA, may affect theresults,sinceinthe studyconductedbyHoffmannand Urrechaga,falsepositivewomenwithHbvaluesgreaterthan 12g/dLandlessthan13g/dLwereincludedinthestudy. More-over,womenwithIDAandferritin levels>6and<15ng/mL (falsepositive)andtruepositivemenwithferritinlevels>15 and <28ng/mLwere excluded. It is important tohighlight thatdifferentcriteriainthesampleselectionmay interfere withtheresultsofsensitivity,specificityandareaunderthe curve.

Followingtheabove,someotheraspectsdeserve clarifica-tion:

Firstly,inBrazil,somestudieshavealreadybeencarriedout todeterminethefrequencyofthe3.7kbdeletion,themain mutationcausing␣-thalassemia, withfrequenciesbetween 20%and25%beingfoundinthepopulationstudied.4,5_Despite

this high frequency, the correct diagnosis of this disorder dependsonmolecularteststhatarenotaccessibletoalarge proportion of the Brazilian population. Although used in manyclinicallaboratories,thehemoglobin(Hb)Htestshows lowsensitivity.Theprevalenceofthe␤-thalassemiatraitin BraziliscertainlylowerthanthatobservedinMediterranean countries.

DOIoforiginalarticle:http://dx.doi.org/10.1016/j.bjhh.2017.04.003.

Secondly,withregardtotheprevalenceofIDA,itispossible toobservethatthisdisorderismoreprevalentinallgroupsand agerangeswhencomparingnon-industrializedto industrial-izedcountries.6_{Thus,consideringtherealityoftheBrazilian}

population,anindexthatshowsgoodsensitivityforthe diag-nosisofIDA,acommonconditionthatcausesmicrocytosisin Brazil,wouldbeimportant.

ItshouldbenotedthattheobjectiveofMatosetal.was todevelopascreeningtoolthatcouldguidethephysicianas towhich clinicalconduct shouldbeadopted asmentioned inthediscussionofthearticle.2 _{TheinabilityoftheMCIto}

discriminatebetweenIDAandthethalassemiatrait(TT)isa limitationofthisformulaclearlydescribedinthediscussion ofthearticle.2_{However,weconsiderthatthisindexmaybe}

useful asascreeningtoolinapopulationwithsimilar epi-demiologicalcharacteristicsasthesamelaboratorydiagnostic criteriawereadoptedforIDAandtheTT.

Inorder tofurtherclarifythe usefulnessofthe MCI,we highlightpartofthediscussionbyMatosetal.2_{:“Despitethe}

revbrashematolhemoter.2017;39(3):290–291

291

With regard to the MCI using the mean corpuscular hemoglobinconcentration(MCHC),this parameteris calcu-latedbyhematology analyzers andisnotobtaineddirectly similar to the other parameters and this may weaken its discriminative value.However,all the parameters obtained directlyfromhematologyanalyzersweretestedbya profes-sionalwithrecognizedcompetenceintheareaofstatisticsat thetimeofindexdevelopmentandMCHCcombinedwiththe redbloodcellcount,providedthebestdiscriminantpower.

Finally, we agree with the comment of Hoffmann and Urrechagaregardingtherecommendationtolaboratoriesthat anynewlypublishedindexshould beusedonlyafter addi-tionalvalidationintheirownpatientpopulation.

Conflict

of

interest

Theauthorsdeclarenoconflictsofinterest.

r

e

f

e

r

e

n

c

e

s

1.HoffmannJJ,UrrechagaE.AssessmentoftheMatos&Carvalho indexfordistinguishingthalassemiafromirondeficiency anemia.RevBrasHematolHemoter.inpress.DOI: 10.1016/j.bjhh.2017.04.003.

2.MatosJF,DusseLM,BorgesKB,CastroRL,Coura-VitalW, CarvalhoMG.Anewindextodiscriminatebetweeniron deficiencyanemiaandthalassemiatrait.RevBrasHematol Hemoter.2016;38(3):214–9.

3.WorldHealthOrganization–WHO.Guidelinesfortheuseof ironsupplementstopreventandtreatirondeficiencyanemia. Availablefrom:http://www.who.int/nutrition/publications/ micronutrients/anaemiairondeficiency/1-57881-020-5/en/

4.SonatiMF,FarahSB,RamalhoAS,CostaFF.Highprevalenceof ␣-thalassemiainablackpopulationofBrazil.Hemoglobin. 1991;15(4):309–11.

5.SouzaAE,CardosoGL,TakanashiSY,GuerreiroJF. ␣-thalassemia(3.7kbdeletion)inapopulationfromthe BrazilianAmazonregion:Santarém,ParáState.GenetMolRes. 2009;8(2):477–81.

6.WorldHealthOrganization–WHO.Irondeficiencyanaemia: assesment,preventionandcontrol.Aguideforprogramme managers;2001.Availablefrom:http://www.who.int/nutrition/ publications/micronutrients/anaemiairondeficiency/WHO NHD01.3/en/

JanuáriaF.Matosa,b,∗,LuciM.S.Dusseb,KarinaB.G.Borgesb,

RicardoL.V.deCastroc_{,WendelCoura-Vital}d_,

MariadasG.Carvalhob

a_{InstitutoFederalMinasGerais(IFMG),OuroPreto,MG,Brasil}

b_{UniversidadeFederaldeMinasGerais(UFMG),BeloHorizonte,}

MG,Brasil

c_{HospitalOdilonBehrens,BeloHorizonte,MG,Brasil}

d_{UniversidadeFederaldeOuroPreto,OuroPreto,MG,Brasil}

∗_{Corresponding author at: Instituto Federal de Minas Gerais,}

CampusOuroPreto,RuaPandiáCalógeras,898,Bauxita, 35400-000OuroPreto,MG,Brazil.

E-mailaddress:januaria.matos@ifmg.edu.br(J.F.Matos).

Received9April2017 Accepted24April2017 1516-8484/

©2017Associac¸ ˜aoBrasileiradeHematologia,Hemoterapiae TerapiaCelular.PublishedbyElsevierEditoraLtda.Thisisan openaccessarticleundertheCCBY-NC-NDlicense(http:// creativecommons.org/licenses/by-nc-nd/4.0/).

http://dx.doi.org/10.1016/j.bjhh.2017.04.004