J. Pediatr. (Rio J.) vol.91 número3

(1)

www.jped.com.br

ORIGINAL

ARTICLE

Reference

curves

of

the

body

fat

index

in

adolescents

and

their

association

with

anthropometric

variables

夽

Renata

Rago

Frignani

a

_,

_Maria

_Aparecida

_Zanetti

_Passos

a

_,

Gerson

Luis

de

Moraes

Ferrari

a,b,∗

,

Sheila

Rejane

Niskier

a

,

Mauro

Fisberg

a

_,

_Isa

_de

_Pádua

_Cintra

a

a_Division_of_Adolescent_Medicine,_Centro_de_Atendimento_e_Apoio_ao_Adolescente_(CAAA),_Department_of_Pediatrics,

UniversidadeFederaldeSãoPaulo(UNIFESP),SãoPaulo,SP,Brazil

b_Centro_de_Estudos_do_Laboratório_de_Aptidão_Física_de_São_Caetano_do_Sul_(CELAFISCS),_São_Paulo,_SP,_Brazil

Received26March2014;accepted15July2014 Availableonline2December2014

KEYWORDS

Adolescents; Sexualmaturation; Fat;

Skinfolds

Abstract

Objectives: Todevelopreferencecurvesforthebodyfatindex(BFI)inthepediatricpopulation, inadolescentsfromthecityofSãoPaulo,Brazil,andverifytheirassociationwithbodymass indexandbodyfatpercentage.

Methods: Thestudyispartoftheresearchproject‘‘NutritionalProfile ofAdolescentsfrom PublicandPrivateSchoolsofSãoPaulo’’thatwas performedin2004-2005.Atotalof4,686 adolescents(2,130boysand2,556girls)aged10-15yearsweredividedintotwogroups: 10-12and13-15yearsofage.Bodymass,height,bodymassindex,hipcircumference,bodyfat percentage,bodyfatindex,andsexualmaturationperformedbytheself-assessmentmethod (prepubertal,pubertal,andpostpubertal)wereanalyzed.ANOVAwas performed,aswellas percentiledistribution,Pearson’scorrelation,andBland-Altmanplot.

Results: Inboys,therewasanincreaseinbodymass,height,bodymassindex,andhip circum-ferencewithadvancingageandTannerstage.Ingirls,therewasanincreaseinbodyfatindex andbodyfatpercentagewithadvancingageandstageofsexualmaturation.Anassociationwas foundbetweenbodyfatindexandbodymassindex(r=0.67inboysand0.80ingirls,p<0.001) andbodyfatpercentage(r=0.71inboysand0.68ingirls,p<0.001).

Conclusion: Thebodyfatindexseemstoreflectwellthephenomenaofsexualdimorphismin adolescence,iseasytoperform,andrepresentsamethodthatshouldbeusedinpopulation samples.

夽

Pleasecitethisarticleas:FrignaniRR,PassosMA,FerrariGL,NiskierSR,FisbergM,dePáduaCintraI.Referencecurvesofthebodyfat indexinadolescentsandtheirassociationwithanthropometricvariables.JPediatr(RioJ).2015;91:248---55.

∗_{Corresponding}_author.

E-mail:[email protected](G.L.d.M.Ferrari).

http://dx.doi.org/10.1016/j.jped.2014.07.009

(2)

PALAVRAS-CHAVE

Adolescentes; Maturac¸ãosexual; Adiposidade; Pregascutâneas

Curvasdereferênciadoíndicedeadiposidadecorporaldeadolescentesesuarelac¸ão comvariáveisantropométricas

Resumo

Objetivos: Desenvolvercurvasdereferênciadoíndicedeadiposidadecorporalparapopulac¸ão pediátrica,em adolescentesdacidadedeSãoPaulo,Brasil,everificarasuarelac¸ãocomo índicedemassacorporalepercentualdegorduracorporal.

Métodos: Oestudo fazpartedoprojeto depesquisa‘‘PerfilNutricionaldeAdolescentesde escolasPúblicasePrivadasdeSãoPaulo’’realizadoem2004/2005.4.686adolescentes(2.130 meninos e 2.556 meninas) de 10-15 anos foram divididos em dois grupos: 10-12 e 13-15 anos.Massacorporal,estatura,índicedemassacorporal,circunferênciadequadril, porcent-agemdegorduracorporal,índicedeadiposidadecorporalematuraçãosexualrealizadapelo métododeautoavaliação(pré-púbere,púbereepós-púbere)foramanalisadas.FoifeitoANOVA, distribuiçãopercentilar,correlaçãodePearsoneográficodeBland-Altman.

Resultados: Nosmeninos,ocorreuaumentodamassacorporal,estatura,índicedemassa cor-poral ecircunferênciadoquadrilcomoavançodaidade eestágiodeTanner.Nasmeninas, ocorreuaumentodoíndicedeadiposidadecorporaledopercentualdegorduracorporalcom oavançodaidadeeestágiodematuração.Foiencontradaumaassociaçãoentreoíndicede adiposidadecorporalcomoíndicedemassacorporal(r=0,67nosmeninose0,80nasmeninas; p<0,001)ecomopercentualdegordura(r=0,71nosmeninose0,68nasmeninas;p<0,001). Conclusão: Oíndicedeadiposidadecorporalparecerefletirbemosfenômenosdodismorfismo sexualnaadolescência,sendoummétododefácilrealizaçãoquedeveriasermaisutilizadoem amostraspopulacionais.

Introduction

Inrecentdecades,theprevalenceof overweightand obe-sityhasincreasedalarminglyworldwide,whichisconsidered apublichealth problem.1,2 _The _period_of _greatest_risk_for

theincidenceof obesity isthetransition between

adoles-cenceandtheearlystagesofadulthoodinbothgendersand

several ethnic groups,3 _in _addition_to _also _representing _a

majorriskfactor forcardiovasculardisease.4 _Although_the

clinicalmanifestationsofthesediseasesoccurinadulthood,

studieshaveshownthatcomorbiditiessuchasdyslipidemia,

hypertension, and insulin resistance may be present as

earlyasinchildhoodandadolescence,4_and_are_responsible

for the increasedrisk of morbidity and mortalityin adult

life.5

In addition to increasing the chances of obesity in

adulthood,3,4 _the _strong _association _of _excess _weight _in

childhood with metabolic alterations (lipid profile and

blood pressure) has resulted in the development of

sev-eraltechniques(hydrostaticweighinganddual-energyX-ray

absorptiometry)toaccuratelydeterminebodyfat;however,

mostmethodsarecomplex,timeconsuming,andexpensive

toberoutinelyapplied.6,7_Thus,_{anthropometric}_assessment

constitutesanimportantdiagnosticmethod,asitiseasyto

perform,inexpensive,noninvasive, universallyapplicable,

hasgoodacceptancebythe population,andis universally

acceptedandproposedbytheWorldHealthOrganization.8,9

Inadditiontothemeasurementofbodyweightandbodyfat

percentage (BF%),the body mass index (BMI)is themost

commonlyusedapproachtocharacterizeobesityin

individ-ualsubjects.7---9

AlthoughtheBMIisusedtocharacterizebodygrowthof

children,thismeasureisroutinelyapplied,notonlyin

epi-demiologicalstudies,butalsoinclinicalpractice.1,9,10_When

usedindiscriminately,itcanleadtofalseresults,asitisa

stillcontroversialmeasure,inadditiontothefactthatitis

particularlydifficulttodeterminebodyfatinchildren.10,11

Bergman et al. proposed the Body Fat Index (BFI) for

adults,anewparametertoassessbodycompositionbased

ontwoanthropometricmeasures,botheasilyreproducible

-height,inmeters,andhipcircumference(HC),incm.7_The

BFIhasbeen developedandappliedin adultsfrom

differ-entcountries,6,7 _but _this _index _is _still _scarcely_applied _in

Brazilianadolescents.

Thus,theaimofthisstudywastodevelopBFIreference

curvesforthepediatricpopulation,usingadolescentsliving

inthecityofSãoPaulo,Brazilasmodels,aswellasverify

theirassociationwithBMIandBF%.

Methods

Studypopulationandschoolsampling

(3)

The study evaluated adolescents who were enrolled between the fifth and eighth grades from 43 randomly selectedpublicandprivateschools.Randomization consid-eredthenumberofpublicandprivateschoolsineachregion, containing at least 200 students from the fifth to eighth gradeattendingthemorningand/orafternoonshifts,anda 2:1relationofproportionality wasverifiedbetweenthem. DuethedifficultyinagreeingtoapplytheTannerstagesby theprivateschoolsandasthisinformationwasimportantfor theresearch,thefinalproportionwas4:1publictoprivate schools,representing a lossof 28%. These wererandomly selectedin 31 schools (25 public and6 private) fromthe fourregions(north,south,east,andwest)ofthecityofSão Paulo,Brazil.

This study sample was constituted by analyzing a database consisting of more than 8,020 students of both genderswhohadtomeet the followinginclusion criteria: (a)havecompletedemographicandclinicaldataavailable forthestudy(b)agebetween10and15years;(c)be regu-larlyenrolledinapublicorprivateschoolinthecityofSão Paulo;(d)andhaveaninformedconsentsignedbyaparent orguardian.ThestudyprotocolwasapprovedbytheEthics CommitteeofUNIFESP,protocolNo.0977/03.Pregnant ado-lescentswereexcludedfromthestudy.

This study included 4,686 adolescents,of whom 45.5% (n=2,130)weremalesand54.5%(n=2,556)werefemales, agedfrom10yearsandonedayto15years,11monthsand29 days,representingasamplingfractionof1.3%ofthe360,000 studentsenrolledinpublicandprivateschoolsinSãoPaulo. Noformulawasusedtoestimatethesamplesize,asa prob-abilisticapproachwasused.Datawerecollectedbetween Septemberof2004andJuneof2005.

Theagedistributionamongthefemaleandmalestudents wasrespectively,asfollows:646and554agedbetween10 and11years;1,308and1,053agedbetween12and13years; and602and523agedbetween14and15years.

Anthropometricmeasurements

Ateamoffourtrainedresearcherscoordinatedthe perfor-manceofallmeasurements;theteamwastrainedregarding thetechniquesandthestandardizationofthemethodsused, inordertoachievegreateraccuracyofthecollecteddata.

Body mass was measured on a portable digital scale (Seca®_,_CA,_USA)_with_capacity_of₁₅₀_kg._Adolescents_were

weighedonthecenteroftheplatform,inthestanding posi-tion,facingthefront,withlateralspacingbetweenthefeet andthebodyweightevenlydistributedbetweenthefeet, barefoot,wearinglightclothing,andsteadywiththearms alongsidethebody.12

Heightwasdeterminedusingadigital wallstadiometer

(Seca®_,_CA,_USA),_with_the_adolescent_barefoot_or_wearing

thinsocks and light clothes, so that the body positioning

couldbe seen by the examiner. The adolescent stood on

a flat surface withthe weightdistributed evenly on both

feet, withthe eyesperpendicular to the body. The arms

were positionedalongside the body, and the head, back,

andbuttockswereincontactwiththeverticalplate. The

measurementwasmadeduringadeepinspirationwiththe

bodyfullyerect.12

BMI wascalculated by dividing weight in kilograms by

height in square meters(kg/m2_), _according _to_the _curves

proposedbytheWorldHealthOrganization (WHO)for age

andgender.9_This_{classification}_has_been_used_to_identify_the

riskortheactualconditionofobesityinpopulations.7---9

Aninelasticmeasuringtape(Seca®_,_CA,_USA)_was_used

to measure the HC,while the adolescent maintained the

feet together and with the weight distributed evenly on

bothfeet.Themeasurementwasperformedontheareaof

greatestglutealcircumference.13_Both_HC_and_height_were

measured three times, consecutively, and the arithmetic

meanwasconsideredasthefinalvalue.Basedonthesetwo

measurementsmentioned above,theBFI wasobtained by

dividingtheHCbyheightmultipliedbythesquarerootof

height,minus18:7

BFI= HC

heightheight−18

TocalculateBF%,measurementsofthetriceps skinfold

thickness(TST),atthepointthatcompriseshalfthedistance

betweenthesuperolateralborderoftheacromionandthe

olecranon,andofthesubscapularskinfoldthickness(SST),

performedobliquelyinrelationtothelongitudinalaxisand

located2cmbelowtheinferiorangleofthescapula,were

obtained, using the equations of Slaughter et al.14 _When

interpretingtheresults,bodyfatvaluesproposedbyLohman

etal.wereconsideredacceptable.15

Sexual maturation was determined based on Tanner

pubertal staging,16 _using _the _previously _validated17

self-ratingtechnique for breast development(B1, B2,B3,B4,

andB5)forgirlsandgenitalia(G1,G2,G3,G4,andG5)for

boys, withresults grouped intoprepubertal (M1and G1),

pubertal(M2toM4andG2toG4),andpostpubertal(M5and

G5).

Forcalculation purposes,the adolescentsweredivided

accordingtothebiologicalageas:earlyadolescence:10-12

years,middleadolescence13-15years.18

Statisticalanalysis

Mean descriptive analysis and standard deviation were used.Normalityofcontinuousdatawasevaluatedusingthe Kolmogorov-Smirnovtest.Tocomparethegenderswiththe dependentvariables(bodymass,height,BMI,HC,BFI,and BF%), analysis of variance with two factors (gender with chronologicalandbiologicalage)wasapplied,followedby theBonferronimultiplecomparisonmethod.19

TodevelopBFIreferencecurves,theageofthe

adoles-centswasusedincentesimalformandtheLMSmethodwas

usedtodefinethedistributionandcutoffsofBFIaccording

togender,withthefollowingpercentilevalues:3,5,10,15,

25,50,75,85,90,95,and97.20

The Bland-Altman scatter-plot was used to verify the

absolute agreementbetween BFI and BMIand BF%.21 _This

procedureallowsvisualizingthemeandifferencesandthe

extremelimitsofagreement,incaseoftwostandard

devia-tionsofdifference.Thus,theBland-Altmanscatterplotcan

provideusefulinformationregardingtherangesofvaluesfor

whichthetwomethodsaremoreconcordant/discordant.21

(4)

Table1 Samplesize,mean,andstandarddeviationforbodymass,height,BMI,HC,BFI,andBF%ofadolescentsinSãoPaulo accordingtoageandTannerstage.

Gender Age (years) Bodymass (kg) Height (cm)

BMI(kg/m2₎ _HC_(cm) _BFI _BF%

Boys 10-12 (n=1,087)

43.11a,b ±10.61 149.60a,b ±8.17 19.09b ±3.59 79.44a,b ±8.76 25.42a,b ±3.94 20.22b ±8.89 13-15

(n=1,043)

54.75a ±12.65 163.77a ±9.20 20.26a ±3.68 86.66a ±8.88 23.40a ±3.85 18.88a ±8.06 Girls 10-12

(n=1,311)

45.08b ±10.90 151.58b ±7.79 19.46b ±3.75 83.18b ±9.34 26.55b ±3.97 20.95b ±7.55 13-15

(n=1,245)

52.84 ±10.10 159.08 ±6.34 20.84 ±3.56 90.28 ±8.02 27.04 ±3.95 23.06 ±6.85

Tannerstage Bodymass (kg)

Height (cm)

BMI (kg/m2₎

HC (cm)

BFI BF%

Boys Prepubertal (n=115)

44.01a,c,d ±12.26 149.47c,d ±8.75 19.43a ±3.87 80.72a ±9.81 26.13c,d ±3.92 21.04 ±9.34 Pubertal

(n=1,998)

49.01e ±12.98 156.84a,e ±11.13 19.67a ±3.68 83.07a ±9.49 24.36a ±4.00 19.50a ±8.48 Postpubertal

(n=17)

57.56 ±14.29 169.17a ±13.30 19.88 ±3.15 87.37 ±9.34 21.83a ±3.54 16.84a ±6.15 Girls Prepubertal

(n=115)

38.31c,d ±10.38 146.12c,d ±8.87 17.74c,d ±3.56 76.77c,d ±8.53 25.47c,d ±3.72 18.56c,d ±7.55 Pubertal

(n=2,365)

49.11e ±10.94 155.57 ±7.75 20.17e ±3.68 86.89e ±9.16 26.79e ±3.95 22.01e ±7.22 Postpubertal

(n=76)

57.21 ±10.12 158.62 ±6.97 22.68 ±3.33 93.72 ±7.96 28.96 ±3.88 26.28 ±6.63

BMI,bodymassindex;HC,hipcircumference;BFI,bodyfatindex;BF%,bodyfatpercentage. a _p_<_0.05_differences_between_the_genders.

b _p_<_0.05_differences_between_age.

c _p_<_0.05_differences_between_prepubertal_and_pubertal. d _p_<_0.05_differences_between_prepubertal_and_{postpubertal.} e _p_<_0.05_differences_between_pubertal_and_{postpubertal.}

betweenBFIwithBMIandBF%.The calculationswere per-formed usingthe SPSS,release20.0 (IBM Corp,2011. IBM SPSSStatisticsforWindows,NY,USA)andthelevelof signif-icancewassetatp<0.01.19

Results

SamplecharacterizationisshowninTable1,accordingtothe

analyzedvariables.Itispossibletoverifythatboysshowed

anincreaseinbodymass,height,BMI,andHCwithadvancing

ageandTannerstage.Asforthegirls,thesameoccurredfor

allvariablesanalyzedinthepresentstudy.

Regardinggender(Table1),itcanbeobservedthatthe

younger boys (10-12 years) had significantly lower mean

bodymass,height,HC,andBFIthangirlsof thesameage

(p<0.001).Amongtheolderadolescents(13-15years),this

occured for all variables (p<0.001). In both genders, the

youngeradolescentshadsignificantlydifferentmeanvalues

whencomparedtoolder ones (p<0.001),for allanalyzed

variables.

Table 1 results showed that, in the comparative

anal-ysis between the genders, the prepubertal adolescents

showedasignificantdifferencein bodymass,BMI,andHC

(p<0.001).Inpubertaladolescents,onlybodymassdidnot

differbetweengenders(p=0.06).As forthepostpubertal,

onlyheight,BFI,andBF%valueswerestatisticallydifferent

(p<0.001).

WhencomparingTannerstages,prepubertalboyshad

sig-nificantlylowermeanvaluesthanpubertalandpostpubertal

boysforbodymass,height,andBFI.Whencomparing

puber-talwithpostpubertalboys,meanvaluesinboyswere

signi-ficantlylowerregardingbodymassandheight(p<0.001).

Prepubertalgirlshadsignificantlylowermeanvaluesthan

pubertalandpostpubertalgirlsforallvariables(p<0.001).

Whencomparingmeanvaluesofpubertalwithpostpubertal

girls,onlyheightshowednosignificantdifference(p=0.08).

Table 2establishes the percentiles ofBFI classification

accordingtoageandTannerstageoftheadolescents.Itwas

observedthatbetweengenders,thedifferenceinvaluesin

adolescentsaged10-12 years is lowerthan in those aged

13-15years.

Itcanbeobservedthat,inthecomparisonbetween

gen-ders,fromthe3rd _percentile_to_the₇₅th _percentile,_there

wasan increase in the differenceof valuesas thesexual

developmentstageadvanced.Fromthe85th_percentile,

pre-pubescent boys had higher values than girls of the same

classification.

It can be demonstrated that BFI behavior is different

(5)

Table2 BFIaccordingtothepercentile,gender,age,andTannerstageofadolescentsinSãoPaulo,aged10-15years.

Gender Age (years)

3% 5% 10% 15% 25% 50% 75% 85% 90% 95% 97%

Boys 10-12 (n=1,087)

19.50 19.98 21.02 21.71 22.67 24.75 27.60 29.28 30.87 32.92 34.20

13-15 (n=1,043)

17.39 18.00 19.13 19.67 20.70 22.88 25.50 27.47 28.64 30.81 32.41

Girls 10-12 (n=1,311)

20.46 21.20 22.08 22.75 23.95 26.01 28.58 30.63 31.89 33.97 35.48

13-15 (n=1,245)

20.55 21.31 22.49 23.28 24.41 26.72 29.16 30.57 31.89 34.26 36.06

Gender Tanner stage

3% 5% 10% 15% 25% 50% 75% 85% 90% 95% 97%

Boys Pre (n=115)

19.62 20.28 21.85 22.34 23.22 25.73 29.09 30.31 32.01 33.48 34.76

Pubertal (n=1,998)

18.09 18.88 19.78 20.51 21.60 23.77 26.69 28.36 29.74 32.10 33.04

Post (n=17)

15.58 15.58 17.05 17.70 19.13 22.50 24.85 26.35 26.93 -

-Girls Pre (n=115)

20.56 20.94 21.51 22.10 22.94 25.09 27.26 28.87 29.84 32.23 33.36

Pubertal (n=2,365)

20.49 21.23 22.27 23.02 24.21 26.35 28.91 30.52 31.87 34.22 35.62

Post(n=76) 23.75 24.28 24.84 25.19 26.48 28.15 31.07 32.94 33.26 36.63 40.02

BFI,bodyfatindex;Pre,prepubertal;Post,postpubertal.

decreasewithadvancingage andthemeanvalues ingirls showedaslightincreasewithadvancingage(Fig.1).

Regardingtheassociationbetweenvariables,Fig.2shows

asignificantassociationofBFIwithBMIandBF%of

adoles-centsof bothgenders inthe city ofSãoPaulo (p<0.001).

Furthermore,Fig.2showstheBland-Altmanplotwithhigh

agreementofBFIwithBMIandBF%inbothgenders.Inmales,

themeandifference(BFI-BMI)wasequalto4.73±3.21,with

limitsofagreementrangingfrom11.03(+2SD)to-1.57

(-2 SD). As for BF%-BFI, the mean difference wasequal to

-4.83±6.37,withlimitsofagreementrangingfrom7.66(+

2SD)to-17.31(-2SD)(Fig.2:A,B).

For the female gender, the mean difference (BFI-BMI)

wasequalto6.65±2.43,withlimitsofagreementranging

from 11.40 (+ 2 SD) to 1.90 (-2 SD). As for BF%-BFI, the

mean differencewasequal to-4.81±5.43, withlimits of

agreement ranging from 5.84 (+ 2 SD) to -15.46 (-2 SD)

(Fig.2:C,D).

Discussion

ThisstudypresenteddataandpercentilecurvesfortheBFI ofadolescentsaged10-15years,withheightandhip circum-ference used for thisevaluation. Although this technique hasbeenvalidatedandfoundtobeextremelyusefulin epi-demiologicalstudiesofadultsduetoitseaseofuseandlow cost, Bergman etal. 7 _highlight _a _prediction _error _of _3%.

BFIisadirectestimateofBF%,andunlikeBMI,BFIprovides

Boys

Age (years) Age (years)

BFI BFI

Girls 40

35

30

25

20

15

10

10 11 12 13 14 15

97 95 90 85 75 50 25 15 10 5 3

40

35

30

25

20

15

10 11 12 13 14 15

(6)

r=0.67 (p<.001) 20

15

10

20

15

+2DP=11.03

–2DP=1.57 Average=4.73

+2DP=7.66

–2DP=17.31 Average=4.83

+2DP=5.84

–2DP=15.46 Average=4.81 +2DP=11.40

+2DP=1.90 Average=6.65

10

5

–5

–10

–15

15

10

5

–5

–10

–15

–20

–25 0 –20

–25 0 5

–5

–10 12

15 ₁₀ ₁₅ ₂₀ ₂₅ ₃₀ ₃₅ ₄₀ ₄₅

15 20 25 30 35 40 45

10

20 25 30 35 40

17 22 27 32 37

0

20

15

10

5

–5

–10 0

r=0.80 (p<.001) r=0.68 (p<.001)

Boys

Girls

BF% + BFI

BFI - BMI

(BF% + BFI)/2 (BF% + BFI)/2

(BFI+ BMI)/2 (BFI + BMI)/2

BF% + BFI

r=0.71 (p<.001)

A

C

B

D

Figure2 Bland-AltmanplottoassessthedegreeofagreementofBAIwithBMIandBF%ofadolescents(Boys:A,B;Girls:C,D) fromSãoPaulo,aged10-15years.

BF%datawithoutstatisticalcorrectionanddoesnotrequire bodymassmeasurement.7

BFI valuescan beused in obesity prevention asa tool

forspecificevaluation,whereasBMIonlyrepresentsagross

valueforbodyfatwithoutgenderandpubertalstage

differ-entiation,whichcouldeasilyleadtomisclassification.22

The present study showed that in adolescence (10-12

yearsand13-15years),statisticaldifferenceswereobserved

betweengenderandagegroupconcerningBMI,BFI,andBF%.

However,inmid-adolescence (13-15years),although boys

aretallerandhavegreaterbodymass,theyhavelowerBMI,

HC,BFI,andBF%valuesthangirlsofthesameagegroup.

BFI has been previously used and validated in

differ-entagerangesandethnicgroups.7,23_Due_to_the_increasing

prevalence of childhood obesity and the fact that the

obesepediatricpopulationhashighoddsofbecomingobese

adults,24_with_high_risk_of_{cardiovascular}_disease,_type₂

dia-betes,andhypertension,25_the_authors_consider_BFI_data_and

curvestobeveryrelevantfor pediatricpatientsaccording

toageandsexualmaturation.ForBergmanetal.,itis

crit-icaltoassessBFIbehaviorinprepubertalandpostpubertal

schoolchildren of both genders and different ethnicities.7

Thesameauthorsmakeitclearthatitisimportanttoassess

theassociationofBFIwithbodyfat,whichwasperformed

inthepresentstudy.

Oneofthesurprisingresultswasthestrongassociationof

BFIwithBF%,sotherewasnoneedtouseaspecificand/or

electronictoolforthemeasurementofBF%.Thus,evenin

environmentswhereonly thesimplestandleastexpensive

toolsareavailable (ameasuringtape),areliableestimate

ofadipositycanbeobtained.

Regardingthestagesofsexualmaturation,bothBFIand

BF% values showed similar behavior in both genders. In

boys,themeanofthesetwovariablesshowedasignificant

decrease,andingirls,themeanswerehigherwith

advanc-ingTannerstages.SimilarresultsrelatedtoBF%havebeen

demonstratedby other authors,11,26,27 _and _it _is _important

toemphasizethatduringpuberty,girlsgainmorebodyfat,

whileboysgainmoremusclemass.18

It should be emphasized that puberty is characterized

bytheappearanceofdrastichormonalchangesthatinduce

significantchangesingrowth,bonemass,andbody

composi-tion.Thesechangesareassociatedwithvariationsincertain

biochemicalparameters,whicharetrue markersthat

reg-ulateboneturnoverandleptinlevels,reflectingchangesin

bonegrowthandfatmass,respectively.28

Whenanalyzing thepercentiles ofBFIinschoolchildren

accordingtoagegroupandTannerstage,itisobservedthat

inboysthemeanvaluesdecreased withadvancing Tanner

stage,whilegirlsshowedtheoppositepattern.

TheassociationbetweenBF%andcardiovasculardisease

riskiswell-documented.3,4_However,_there_is_convincing

evi-dencethatvisceralfatcontent29_may_be_a_stronger_predictor

ofcardiovascular riskthan general adiposity,eventhough

thisstudymeasuredonlyoverallBF%.Atthistime,itisnot

possibletodetermineifBFIcanbemoreharmfulinthe

vis-ceralfat orintheliverfat,butinthefuture,itwillbeof

interesttocompareBFIwithselectedfatdeposits.

Althoughthereisnoconsensusregardingthediagnosisof

obesitythroughBF%andBFI in adolescents,someauthors

havedefined the85th _and₉₅th _percentiles _as_excess_body

(7)

Whenthe85th_and₉₅th_percentiles_of_the_BFI_were

eval-uatedaccordingtosexualmaturation,itwasobservedthat

therewasanincreaseinprepubertalandpubertalboys,of

approximately10%and 17%,respectively. As for girls,the

greatestincrease wasobserved among those classified as

postpubertal.

Thesedatademonstratetheimportanceofassessing

sex-ual maturation and its influence on body composition of

adolescents.When thegroups aged10-12yearsand13-15

yearswerecompared,boyshadagreaterincreaseintheage

group10-12years;ingirls,thegreatestincreaseoccurredin

theagegroupof13-15years.Asboyshadhigherprevalence

of excess weightin the studied population and the same

trendhasbeenobservedintheauthors’clinicalexperience,

it is considered important to use these data to evaluate

adolescentsofSãoPaulo.

Manypopulationstudies havefocused onBFIin foreign

populations and other ethnicities.23 _To _date, _no _Brazilian

studyhadshownthevaluesofBFIaccordingtogender,age,

and sexual maturation, which is essential during

adoles-cence, as thereis a widevariation of pubertal events in

individualsofthesamegenderandofthesameage.

More-over, anincrease in BMIhas been shown at each stageof

sexualmaturation30_and,_{consequently,}_this_study_offers_an

additionalcontribution tobodycompositionassessmentin

adolescents,makingtheassessmentofthisparameterinthis

agegroupmorereliable.

A limitation of the study is that by separating

adoles-centsaged10-15yearsaccordingtosexualmaturation,most

wereclassifiedaspubertal andtherewere few

prepuber-tal(predominantlymales)andpostpubertal(predominantly

females)adolescents.

Samplesizemayalsoaffecttheresults.Infuturestudies,

it willbe necessary toinclude a largersample sizein all

stagesofsexualmaturation.

This is the first study to provide data on BFI for

ado-lescentsaccordingtogender, age,andsexualmaturation,

allowingamoreappropriateassessmentforpubertalstage,

asthechronologicalageatthisstageshowsgreat

variabil-ity,therebyprovidinganimportanttoolfortheassessment

ofadiposityinadolescence.

BFI appears to reflect well the phenomena of sexual

dimorphism in adolescence, representing an

easy-to-perform method that should be used more often in

population samples; further studies may, along with the

presentwork,resultinanormalitycurve,whichwouldbe

ofgreatuseinclinicalpractice.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

Acknowledgments

TheauthorsacknowledgethesupportoftheAdolescent Divi-sion, Pediatric Department, Universidade Federal de São Paulo (Federal University of São Paulo) and the Interna-tional Life Sciences Institute (ILSI). They also thank the participants,theirparentsandguardians,theteachersand coordinatorsateachschool,andtheMunicipalGovernment ofSãoPaulo,Brazil.

References

1.MoraesFerrariGL,BraccoMM,MatsudoVK,FisbergMM. Car-diorespiratoryfitnessandnutritionalstatusofschoolchildren: 30-yearevolution.JPediatr(RioJ).2013;89:366---73.

2.InstitutoBrasileirodeGeografiaeEstatística(IBGE).Indicadores sociaismunicipais:umaanálisedosresultadosdouniversodo censodemográfico.[cited2012Jun01].Availablefrom:http:// www.ibge.gov.br/home/estatistica/populacao/censo2010/ indicadoressociaismunicipais/defaultindicadoressociais municipais.shtm

3.JuonalaM,MagnussenCG,BerensonGS,VennA,BurnsTL,Sabin MA,etal.Childhoodadiposity,adultadiposity,and cardiovas-cularriskfactors.NEnglJMed.2011;365:1876---85.

4.PintoMC,OliveiraAC.Occurrenceofchildobesityinpreschool childreninaSãoPauloday-carecenter.Einstein.2009;7:170---5.

5.CanoyD.Coronaryheartdiseaseandbodyfatdistribution.Curr AtherosclerRep.2010;12:125---33.

6.AlvimRO,Mourao-JuniorCA,OliveiraCM,KriegerJE,MillJG, PereiraAC.Bodymassindex,waistcircumference,body adi-posityindex,andriskfortype2diabetesintwopopulationsin Brazil:GeneralandAmerindian.PlosOne.2014;9:e100223.

7.BergmanRN,StefanovskiD,BuchananTA,SumnerAE,Reynolds JC,SebringNG,etal.Abetterindexofbodyadiposity.Obesity. 2011;19:1083---9.

8.ColeTJ,FlegalKM,NichollsD,JacksonAA.Bodymassindexcut offstodefinethinnessinchildrenandadolescents:international survey.BMJ.2007;335:194.

9.deOnisM,OnyangoAW,BorghiE,SiyamA,NishidaC,Siekmann J.Development ofa WHO growthreference for school-aged childrenand adolescents.Bull WorldHealth Organ.2007;85: 660---7.

10.DugganMB.Anthropometryasatoolformeasuringmalnutrition: impactofthenewWHOgrowthstandardsandreference.Ann TropPaediatr.2010;30:1---17.

11.McCarthyHD.Bodyfatmeasurementsinchildrenaspredictors forthemetabolicsyndrome:focusonwaistcircumference.Proc NutrSoc.2006;65:385---92.

12.WorldHealthOrganization.In:WHOExpertCommitteeon Physi-calStatus:theuseandinterpretationofanthropometryphysical status.Geneva:WorldHealthOrganization;1995.

13.CallawayCW,ChumleaWC,BouchardC,HimesJH,LohmanTG, Martin AD,et al. Circumferences. In: Lohman TG, Martorell R,editors.Anthropometricstandardizationreferencemanual. Champaign,IllinoisRocheAF:HumanKineticsBooks;1988.p. 39---54.

14.SlaughterMH,LohmanTG,BaileauRA,HorswillCA,StillmanRJ, VanLoanMD,etal.Skinfoldequationsforestimationofbody fatnessinchildrenandyouth.HumBiol.1988;60:709---23.

15.Lohman T, Roche A, Martorell R, editors. Anthropometric standardizationreferencemanual.Champaign,Illinois:Human KineticsBooks;1988.

16.TannerJ.M.Growthatadolescence.2nd_ed._Oxford:_Blackwell Scientific.In:MalinaRM,BouchardC.Growth,Maturation,and PhysicalActivity.Champaign:HumanKineticsBooks; 1991:11-20.

17.MatsudoSM.Self-assessment,MatsudoV.K.physicalassessment ofsexualmaturationinBrazilianboysandgirls:concordance andreproducibility.AmJHumBiol.1994;6:451---5.

18.CintraIP,FerrariGL,SoaresAC,PassosMA,FisbergM,Vitalle MS.BodyfatpercentilesofBrazilianadolescentsaccordingto ageandsexualmaturation:across-sectionalstudy.BMCPediatr. 2013;13:96.

19.FieldA.DescobrindoaestatísticausandooSPSS.2nd_ed._Porto

Alegre:Artmed;2009.

(8)

21.BlandJM,AltmandG.Statisticalmethodsforassessing agree-mentbetweentwomethodsofclinicalmeasurement.Lancet. 1986;1:307---10.

22.Ellis KJ, Abrams SA, Wong WW. Monitoring childhood obe-sity:assessmentoftheweight/heightindex.AmJEpidemiol. 1999;150:939---46.

23.UrdeaM,KolbergJ,WilberJ,GerwienR,MolerE,RoweM,etal. Validationof a multimarkermodel for assessing riskof type 2diabetesfrom afive-yearprospectivestudyof6784Danish people(Inter99).JDiabetesSciTechnol.2009;3:748---55.

24.MustA. Morbidity and mortality with elevated body weight in children and adolescents. Am J Clin Nutr. 1996;63: 445---7.

25.WilliamsCL,HaymanLL,DanielsSR,RobinsonTN,SteinbergerJ, ParidonS,etal.Cardiovascularhealthinchildhood:astatement forhealthprofessionalsfromthecommitteeonatherosclerosis, hipertension,andobesityintheyoung(AHOY)ofthecouncilon

cardiovasculardiseaseintheyoung.AmericanHeartAssociation Circulation.2002;106:143---60.

26.PapandreouD,MalindretosP,RoussoI.Firstbodyfatpercentiles for607childrenfromThessaloniki-NorthernGreece. Hippokra-tia.2010;14:208---11.

27.Kurtoglu S, Mazicioglu MM, Ozturk A, Hatipoglu N, Cicek B, UstunbasHB.BodyfatreferencecurvesforhealthyTurkish chil-drenandadolescents.EurJPediatr.2010;169:1329---35.

28.Federico G, Baroncelli GI, Vanacore T, Fiore L, Saggese G. Puberalchangesinbiochemicalmarkersofgrowth.HormRes. 2003;60:46---51.

29.Canoy D.Distributionofbodyfat and riskofcoronaryheart diseaseinmenandwomen.CurrOpinCardiol.2008;23:591---8.