JPediatr(RioJ).2015;91(1):1---3
www.jped.com.br
EDITORIAL
A
sequel
of
the
International
Study
of
Asthma
and
Allergies
in
Childhood
or
a
prelude
to
the
Global
Asthma
Network?
夽
,
夽夽
Uma
sequência
do
Estudo
Internacional
de
Asma
e
Alergias
na
Infância
ou
um
prelúdio
da
Global
Asthma
Network?
Luis
Garcia-Marcos
a,b,∗,
Rosa
Pacheco-Gonzalez
a,baRespiratoryMedicineandAllergyUnits,ArrixacaChildren’sUniversityHospital,UniversityofMurcia,Murcia,Spain bIMIB-ArrixacaResearchInstitute,Murcia,Spain
Asthma is one of the most prevalent chronic diseases, affecting over 334 million individuals worldwide.1 A very
different distribution of its prevalence around the world was described by the International Study of Asthma and Allergies in Childhood (ISAAC).2,3 This enormous research
program has been surveying the prevalence and risk fac-torsforasthma,rhinoconjunctivitis,andeczemagloballyfor threedecades,andhasprovidedalargebodyof epidemio-logicalinformationwhichwasexpectedtoyieldnewclues abouttheetiologyoftheseconditions.However,thelatest survey,ISAACphasethree,wasconductedtenyearsago,and sincethen,nootherhasbeenperformedworldwide. Fortun-ately,some researchershave used thesame methodology
DOIoforiginalarticle:
http://dx.doi.org/10.1016/j.jped.2014.05.002
夽 Pleasecitethisarticleas:Garcia-MarcosL,Pacheco-González
R.AsequeloftheInternational StudyofAsthmaandAllergiesin Childhoodora preludetotheGlobal AsthmaNetwork?JPediatr (RioJ).2015;91:1---3.
夽夽
SeepaperbySoléetal.,inpages30---5.
∗Correspondingauthor.
E-mail:lgmarcos@um.es(L.Garcia-Marcos).
tostudy these conditionslocally, comparing the newand thepreviousdatawheneveravailable.4---11 Soléetal.have
updatedthesedatainBrazil.12
Their study provides valuable information about the prevalence of asthma, rhinoconjunctivitis,and eczema in Brazilian adolescents.Comparing to datafrom nineyears ago, rhinoconjunctivitis and eczema prevalences are still increasing, in contrast to that of asthma, which shows a declining trend.13,14 Unfortunately, only seven of the 21
BrazilianISAACcentersparticipatedinthisstudy;theoverall results,iftheyhadcomefromthewhole21centers,could havebeendifferent,evensignificantlyso.
An increase in asthma prevalence should have been expected in the age group of the aforementioned study, consideringthehighproportion(24.4%)of6-7year-age chil-drenpresentingasthmasymptomsatISAACphasethree.13,14
However,acohorteffecthasnotoccurred.
The authorsdiscusssome factorsthat have changedin theirenvironmentinrecentyears,whichcouldhaveleadto thedecreaseinasthmaprevalence.Someofthesechanges are related to dissemination of asthma knowledge, such astheimplementationof managementprograms or diffu-sionofmedicalguidelinesandconsensusstatements.Those couldbefactorsassociatedwiththeincreasedfrequencyof
http://dx.doi.org/10.1016/j.jped.2014.09.001
2 Garcia-MarcosL,Pacheco-GonzalezR
diagnosisand thereduction ofitsseverity, astheauthors state.Moreover,thosefactorscouldbealsoresponsiblefor thestabilization ofasthmaprevalenceduetotheboostin primaryprevention.Astheyalsodiscuss,the standardiza-tion of asthma therapy could be a protective factor for decreasing asthma morbidity and mortality, but not for prevalencereduction.
Anotherinteresting factor, discussed bythe authors,is the improvement of Brazilian economy. The economical factorwasproposedinISAACphasethreeasapossible expla-nationtothelarge differencesinprevalencebetweenthe collaboratingcenters. This hypothesis emergedasasthma prevalencewasthoughttobemoreelevatedindeveloped countries,in particular in English-speaking countries,and lowerin developing countries.Surprisingly, theincreasing trendin developing countries wasnot observed in devel-opedcountries.Asaconsequence,itwasproposedthatthe asthma prevalence hadreached aplateau in high income countries(higherprevalence),while inlow income(lower prevalence)countries,it wasstillincreasing.13,15 The fact
thatasthmaprevalencehascontinuedtodecreaseforthe last nine years, while Brazilian economy has improved considerably, could indicate that asthma prevalence has reachedaplateauinthatcountry,asitoccurredwithhigh incomecountriesinISAACphasethree.However,thisfactor doesnotappeartofullyexplainthesituation.Itisimportant tohighlightthat,contrarytothegeneralhypothesisfromthe ISAACstudy,Malloletal.observed,inamulticentrestudyin LatinAmerica,thathigherprevalenceofasthmasymptoms were observed in areas of lower socioeconomic status.16
Thus,socioeconomiclevelappearstobeafactorrelatedto asthmaetiology.However,asincomedatais notavailable atindividuallevel,itsrealeffectcannotbeelucidated.It ispossible that thesocioeconomic statusis just amarker ofrural/urbanenvironment.Inprevious studies,thesame Braziliangroupconfirmedthatlivinginaruralenvironment wasaprotectivefactorforasthmainBrazil.14---17
ISAAC phase three listed other risk factors that could influencetheprevalenceofallergicconditions,suchas envi-ronmentalpollution.However,Anderson etal.18 couldnot
relatean increasein theprevalence ofasthma, rhinocon-junctivitis, and eczema with air pollution levels on a worldwideanalysis.Soléetal.12suggestthatpollutioncould
be a factor related to the increase in the prevalence of rhinoconjunctivitis and eczema in their region, based on their previous study where pollutant levels were associ-ated with the prevalence of asthma, rhinoconjunctivitis, andeczema.19Supportingtheirresult,adifferentstudy
con-ductedinAltaFloresta(southeastoftheBrazilianAmazon) concludedthatasthma prevalenceinthatregionisoneof thehighest in thecountry (21.4%),which couldbe linked withthehighconcentrationofoutbreaksofbiomassburnings inthearea,althoughthisargumentwasnotconfirmed.4Solé
etal.12alsomentionthatairpollutionhasbeenmonitored
inthepastyearsintwoBrazilianregions,andconsequently betterairqualityhasbeenachieved.Thisshouldhavebeen translatedintoa decrease in theprevalence of rhinocon-junctivitis and eczema in those two areas but not in the others,accordingtotheauthors.However,theresultsdonot corroboratethisstatement.Theinfluenceofenvironmental pollutionshouldbeanalyzedindetailtoconfirmitsimpact inthesediseases.Anotherfactorthatmight beassociated
totheinceptionoftheseconditionsis dietaryhabits.Fast food consumption appearstobe a riskfactor for asthma, whilefruitsandvegetablesconsumptionmayactas protec-tivefactors.20Unfortunately,Soléetal.didnotanalyzethis
possibilityintheirarticle.
Insummary, thestudy by Solé et al.,published in the current issue of Jornal de Pediatria, is a very interest-ing article, updating the data onthe prevalence asthma, rhinoconjunctivitis, and eczema in Brazil. Similar studies shouldbe conductedinmore regionsaround theworldto comparewiththeprevioustrends,andtochecktheriskor protectivefactorsthatwerereported.Fortunately,nowthat theISAACprogramhasended,theGlobalAsthmaNetwork willprovidesuchdatainthenewfuture.Inthemeantime, Soléetal.12anticipatedalargeamountofepidemiological
data,whichcanhelptoexplainthelocalenvironmental fac-torsand,furthermore,toclarifythesituationofuncertainty about thecauseof theseallergicconditions.Thequestion stands:isthisasequeloftheInternationalStudyofAsthma andAllergiesinChildhood(ISAAC)orapreludetotheGlobal AsthmaNetwork(GAN)?
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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