Systematic review of disordered eating behaviors: Methodological considerations for epidemiological research

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Revista Mexicana de Trastornos Alimentarios

E-ISSN: 2007-1523

Universidad Nacional Autónoma de México

México

Ortega-Luyando, Mayaro; Alvarez-Rayón, Georgina; Garner, David M.; Amaya-Hernández, Adriana; Bautista-Díaz, María Leticia; Mancilla-Díaz, Juan Manuel Systematic review of disordered eating behaviors: Methodological considerations for

epidemiological research

Revista Mexicana de Trastornos Alimentarios, vol. 6, núm. 1, enero-junio, 2015, pp. 51-63 Universidad Nacional Autónoma de México

Tlalnepantla Edo. de México, México

Available in: http://www.redalyc.org/articulo.oa?id=425741623007

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RevistaMexicanadeTrastornosAlimentarios(2015)6,51---63

http://journals.iztacala.unam.mx/index.php/amta/

REVIEW

ARTICLE

Systematic

review

of

disordered

eating

behaviors:

Methodological

considerations

for

epidemiological

research

Mayaro

Ortega-Luyando

a_,_∗

_,

_Georgina

_{Alvarez-Rayón}

a

_,

_David

_M.

_Garner

b

_,

Adriana

Amaya-Hernández

a

_,

_María

_Leticia

_{Bautista-Díaz}

a

_,

_Juan

_Manuel

_{Mancilla-Díaz}

a a_Eating_Disorders_Laboratory,_Universidad_Nacional_Autónoma_de_México,_FES_Iztacala,_Mexico

b_River_Centre_Foundation,_Sylvania,_OH,_USA

Received19April2015;accepted26April2015 Availableonline6July2015

KEYWORDS Disorderedeating behaviors; Epidemiology; Prevalence; Women; Systematicreview

Abstract Disordered eatingbehaviors (DEB) such as dieting,fasting, laxatives or diuretics abuse,self-inducedvomitingandbingeeatingmayleadseriousphysiologicalandpsychological consequences inindividuals.Epidemiological datahelpstothe understandingofthe magni-tudeofthisproblemwithinpopulation;howeverpointprevalenceratesandthetrendofDEB arestill a subjectofconstant debate. Therefore theaim ofthisstudy is tosystematically review empirical studiesthathaveestimatedthe prevalenceofDEBinwomenandprovide somemethodologicalconsiderationsforfutureepidemiologicalstudies.Thesearchofarticles was madethroughMEDLINEandSCIENCEDIRECTdatabasesfrom2000to2013.Accordingto inclusionandexclusioncriteria20studieswerereviewed.Resultsyieldedthatthepoint preva-lencerangeofdieting(0.6---51.7%),fasting(2.1---18.5%)andbingeeating(1.2---17.3%)arehigher thanpurgativebehaviors(0---11%).HoweverfindingatrendinDEBovertimewasdifficultsince methodologiesweresignificantlydifferent.Methodologicalconsiderationsforfutureresearch inDEBareproposed.

PALABRASCLAVE Conductas

alimentarias deriesgo;

Revisiónsistemáticadelasconductasalimentariasderiesgo:consideraciones metodológicasparalainvestigaciónepidemiológica

Resumen Lasconductas alimentariasde riesgo(CAR)de lostrastornos alimentarios, tales como dieta, ayuno,abusodelaxantes o diuréticos,vómitoautoinducido yatracón,pueden

∗_{Corresponding}_author.

E-mailaddress:[email protected](M.Ortega-Luyando).

PeerReviewundertheresponsibilityofUniversidadNacionalAutónomadeMéxico.

http://dx.doi.org/10.1016/j.rmta.2015.06.001

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52 M.Ortega-Luyandoetal. Epidemiología;

Prevalencia; Mujeres;

Revisiónsistemática

causargravesconsecuenciasﬁsiológicasypsicológicasenelindividuo.Losdatosepidemiológicos ayudanalacomprensióndela magnituddeesteproblemaenla población,sinembargolas tasasdeprevalenciapuntual yla tendencia delasCARaúnsontemade constantedebate. Porlotanto,elobjetivodelpresenteestudioesrevisarsistemáticamenteestudiosempíricos queestimenla prevalenciadelasCARenmujeres yproveerconsideracionesmetodológicas parafuturainvestigaciónepidemiológica.Labúsquedadeartículosfueatravésdelasbases dedatosdeMEDLINEySCIENCEDIRECTde2000a2013.Conbaseenloscriteriosdeinclusióny exclusión20estudiosfueronanalizados.Losresultadosarrojaronqueelrangodelaprevalencia puntualparadieta(0,6-51,7%),ayuno(2,1-18,5%)yatracón(1,2-17,3%)sonmayoresqueelde lasconductaspurgativas(0-11%).Sinembargo,fuedifícilencontrarunatendenciaenlasCARa travésdeltiempodebidoaquelasmetodologíasutilizadasfueronsigniﬁcativamentediferentes. SeproponenconsideracionesmetodológicasparafuturasinvestigacionesenCAR.

Introduction

Eating disorders (ED) with higher prevalence rates are anorexianervosa(AN),bulimianervosa(BN)andbinge eat-ing disorder (BED) according to the 5th version of the DiagnosticandStatisticalManualofMentalDisorders ([DSM-5] APA, 2013). In the last two decades studies about epidemiology onED have increased significantly, however itisworthtopointoutthatthethreebasicfrequency meas-uresin this kind ofstudies areincidence, prevalenceand mortality.Incidenceexpressesthevolumeandacceleration ofnewcases----diseaseordisorder----overaspecific popula-tionandperiod,usuallyoneyear(Striegel-Moore,Franko,& Ach,2006);prevalenceratesrefertothenumberof individ-ualsinrelationtothetotalpopulationthatsufferadisease ordisorderinaspecifictime(Moreno,López,&Hernández, 2007);mortalityratespointoutthenumberofdeathscaused byaspecificdisease.Thismeasureisoftenusedasan indi-catorofillnessseverity(Rothman,2002).Allthesemeasures yieldimportantinformationthathelpsustocharacterizeED intermsofrisk,occurrenceandtrendsovertime;however thisstudywillfocusexclusivelyonprevalence,becausethis measureisessentialinplanninghealthservices,designation ofeconomicalresourcesandadministrationofmedicalcare facilities(Hoek&vanHoeken,2003;Kleinbaum,Kupper,& Morgenstern,1982).Accordingtoepidemiologicalliterature therearedifferenttypesofprevalence,(a)pointprevalence isaparticularassessmentincertainpointintime;(b)period prevalence is the percentage of cases established within a periodof time (usually 1-year period); and (c)lifetime prevalenceisdefinedasthenumberofindividuals thatat anytimehaveexperiencedadisorder(Hoek&vanHoeken, 2003;Hunter&Risebro,2011).

LifetimeprevalenceratesforAN,BNandBEDare0.9%, 1.5%and3.5%amongwomen and0.3%,0.5%and2.0% for menrespectively(,Hudson,Hiripi,Pope,& Kessler,2007). Alsothecategorycalled‘‘OtherSpeciﬁedEatingDisorders (OSED)’’includedinDSM-5,whichisappliedwhenthe indi-vidual does not meet the full criteriafor any of the ED, has a lifetime prevalence of 4---5% (Le Grange, Swanson, Crow,& Merikangas, 2012).Nevertheless it hasbeen doc-umentedthat disorderedeatingbehaviors(DEB)aremore common among community sample, such as, restrictive

dieting, fasting,self-induced vomiting, abuseof laxatives and/or diureticsandbingeeating(Garner,2008;Tam, Ng, Man, & Young, 2007). These behaviors areimportant risk factorsbecausetheyhave physiologicalcomplications,for example,delayedlineargrowthanddelayedpuberty(Daee etal.,2002); dentalerosion,mouth andesophagus ulcers andinseverecasestheonsetofesophaguscancer(Matsha etal.,2006;Mitchell,Pomeroy,&Adson,1997);ordigestive andurinaryabnormalities(Mitchelletal.,1997).However the psychological consequences areas dangerous or even morethanphysiologicalcomplicationssinceindividualswho present them at early and late adolescence not only are morelikelytodevelopanEDinadulthood,butalsobecause theseindividualsaremoresusceptibletoengageon depres-sion,low self-esteem,anxiety,substance abuseor suicide attempts (Garner & Keiper, 2010; Kotler, Cohen, Davies, Pine,&Walsh,2001;Nunes,Barros,Anselmo,Camey,&Mari, 2003;Preti,Rocchi,Sisti,Camboni,&Miotto,2011;Tylka& Mezydlo,2004).

Basedon epidemiological research, in South Australia, Hay,Mond,Buttner,and Darby(2008)assessed the preva-lenceofDEBwithwomenintwomoments,theﬁrstin1995 (M=43.4,SD=19.2years)andthesecondin2005(M=45.1, SD=24.5years)ﬁndingapointprevalenceof3.2%and7.5% inbingeeating;1.3%and2.1%inpurgingbehaviors;2.5%and 5.2%instrictdieting,respectively.Thesedatagiveevidence ofanincreaseinprevalenceofDEBovertime.

AsetofstudiescarriedoutbyKeelandcolleagues eval-uated,inalongitudinalstudy,thepointprevalenceofDEB (Heatherton, Mahamedi,Striepe,Field,& Keel,1997), BN symptoms(Keel,Heatherton,Dorer,Joiner, &Zalta,2006) andBN andOSED of BN(Keel,Gravener, Joiner, & Haedt, 2010). They reported that purging behaviors----defined as the use of vomiting, laxatives or diuretics to control weight----prevalence were 5.1% in 1982, 3.5% in 1992 and 4.3%in2002,concludingthatthesebehaviorsdidnotchange significantly across cohorts; however point prevalence in bingeeating(29.2%in1982,20%in1992and14.8%in2002) and fasting (19.6% in 1982, 12.7% in 1992 and 11.1% in 2002)decreasedsignificantlyfrom1982to2002(Keeletal., 2006).

Whenthereis amarkeduncertaintyinaspeciﬁctopic, suchastheprevalenceofDEB,itisrecommendedtocarry

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Systematicreviewofdisorderedeatingbehaviors 53 outasystematicreviewsincethiskindofstudiesgather

rele-vant,validandreliableinformationselectedunderrigorous methodological criteria that allow to discuss inconsisten-ciesamongstudiestoredesignandimprovefutureresearch (Beltrán,2005).Inthissense,someliteraturereviewshave triedtoexplaintheepidemiologyofED(from1981to2002; Hoek & van Hoeken, 2003), of OSED (among 1980---2003; Chamay-Weber, Narring,&Michaud, 2005),andcombining ED andOSEDbut onlywithSpanishpopulation (from2000 to 2010; Peláez, Raich, & Labrador, 2010). Finally to our knowledgetherearetwoextentstudiesthatcomprisedED, OSEDandDEBthatanalyzedstudiesofthelastthreedecades (Jacobi, Abascal, & Taylor, 2004) and one of them only reviewedJapanesepublications(Chisuwa&O’Dea,2010).

Basedonthesebackground,wecansummarizethat(1) DEBaremorecommonthanfullentities;(2)empirical stud-ies yield inconsistent prevalence rates and (3) literature reviewslimittheiranalysistospeciﬁcpopulationorfull enti-ties, therefore the aim of this paperis to systematically review empirical studies that have provided estimates of prevalenceoftheDEBinwomen,speciﬁcallyonrestrictive dieting,fasting, laxatives or diuretics abuse,self-induced vomiting and/orbinge eating.Particularattention willbe paid to methodological differences across studies since thesemaybelinkedtodiscrepanciesintheresultsreported. Analysisofstrengthsandlimitationsofthesestudieswillbe followedwithrecommendationsforfuturestudiesofDEB.

Several hypothesesemergedfor thisreview: (a) differ-enttypeofprevalence(point,periodandlifetime)willyield diverserates;(b)methodologicaldifferenceswillyield dif-ferentrates of prevalence and (c) restrictive dieting and bingeeatingwillbethemostprevalentDEB.

Method

AccordingtoPRISMAstatement(PreferredReportingItems forSystematicreviewsandMeta-Analyses;Moher,Liberati, Tetzlaff,&Altman,2009)onFebruary2013,asearchof arti-cleswascarriedoutthroughMEDLINEandSCIENCEDIRECT databases, using different combinations of the following key words contained in the title, abstract and/or within the article’s keywords: eating disorders, eating disorders not otherwise speciﬁed (term known as OSED in DSM-5), anorexianervosa,bulimianervosa,prevalenceandwomen. Considering thedates of previous reviewsfor the current studywereeligiblestudiespublishedbetweenJanuary2000 andJanuary2013.

Tochoosethestudiesforthisreview,theﬁrsttwoauthors determined the relevance and adequacy of each eligible paperaccordingthefollowingselectioncriteria:

Inclusion criteria: (a) studies must be based on commu-nitysampleand(b)studiesmustassessatleastoneofthe behaviorsofinterest(restrictivedieting,fasting,misuseof laxativesanddiureticsself-inducedvomitingand/orbinge eating).

Exclusion criteria: (a) studies based on clinical samples oronlyin malepopulation; (b)assessment ofexclusively otherepidemiologicalmeasures(e.g.incidenceor mortal-ity);(c)paperswritteninanyotherlanguagethanEnglish orSpanishand(d)dissertations.

Each article was analyzed using data extraction sheets, basedontheprinciplesproposedbySánchez-Sosa(2004). The data extraction sheets included thefollowing varia-bles: (a)sample (geographicalzone, age/gender,sample selection,samplesize/sample-sizepower/responserate); (b) research design; (c)instruments; and (d) prevalence rates.

Results

Searchresults

The first search yielded a total of 2024 abstracts, 1711 were excluded for: being related with the medical field, goingdeeplyinpsychiatriccomorbidityorintervention pro-grams,evaluate cognitions associated to eatingdisorders suchasbodydissatisfaction,perfectionism,thinideal inter-nalization, etc. Of the remaining 313 articles, 217 were excludedbecause:onlyincidencerateswerereported, sam-ple included only men, pregnant, or clinical cases, were dissertations, were written in a different language than Spanishor Englishandwere reviews.Ofthe remaining96 studies,76wereexcludedfor:reportingonlyAN,BNand/or OSEDprevalencerates. The20remainingstudiesthatmet inclusioncriteriafluctuatedfrom2001to2010.

Dataanalysis Sample

Geographicalzone. MostofthestudieswerefromUnited States(25%,n=5),followedby Canada,ChinaandMexico (10%,n=2eachcountry).Theremainingstudieswere car-riedoutinninedifferentcountries(seeTable1).

Settings. Thestudieswerefromtwodifferentsettings;16 (80%)fromeducationalinstitutions,and4(20%)werefrom home-settings(Hayetal.,2008;Hudsonetal.,2007;Nunes etal.,2003;Westenhoefer,2001).

Ageandgender. Morethan ahalfoftheresearchpapers (55%,n=11)workedwithadolescentsamples,whichmeans participantsagedamong11---19years,20%(n=4)ofthe stud-iesincludedadultsolderthan19yearsold(Hayetal.,2008; Hudson et al., 2007; Kiziltan, Karabudak, Ünver, Sezgin, & Ünal, 2006; Westenhoefer, 2001), and 25% (n=5) com-binedtwodifferenttypesofsample,includingadolescents andyoungadults,goingfrom10to29yearsold(Machado, Machado,Gonc¸alves,&Hoek,2007;Neumark-Sztainer,Wall, Eisenberg,Story,&Hannan,2006;Nunesetal.,2003;Tam etal.,2007;Tölgyes&Nemessury,2004).Regardingto gen-der,inthisreviewmostofstudiesincludedmenandwomen (60%,n=12);howeveritisimportanttounderlinethatgiven thepurposeofthepresentreviewwelimitthe‘‘Findings’’ sectiontoonlyfemaleprevalencerates,sincethis popula-tionpresentthehighestrisktodevelopDEB(APA,2013). Sampleselection. Fromthe20articles,12(60%)used ran-domizedsamples,4 (20%)usedconvenience samples,and other4(20%)didnotdescribethetypeofsamplingmethod theyutilized(seeTables2and3).

Sample size, sample-size power and Response rate. In this review it was observed that 75% (n=15) utilized a sample sizeless than 3000, 15% (n=3) included a sample sizeover3000 andlessthan10,000 (Ackard,Fulkerson,&

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54 M.Ortega-Luyandoetal. Table1 Classiﬁcationofstudiesaccordingtothecountry

wheretheywerepublished.

Continent Country Numberofpublications America U.S.A. 5

Mexico 2

Canada 2

Brazil 1

Trinidad&Barbados 1

Total 11(55%) Europe Germany 1 Portugal 1 Hungary 1 Total 3(15%) Asia China 2 Turkey 1

UnitedArabEmirates 1

Jordan 1

Total 5(25%)

Oceania Australia 1

Total 1(5%)

Neumark-Sztainer,2007;Hayetal.,2008;Unikel-Santocini, Bojórquez-Chapela, Villatoro-Velázquez, Fleiz-Bautista, & Medina-Mora,2006)ﬁnally10%(n=2)ofthearticles consid-eredsamplesover10,000participants(Barriguete-Meléndez etal.,2009;Forman-Hoffman,2004).Accordingto sample-size power, only two (10%) of the 20 articles, reported thisanalysis(Barriguete-Meléndezetal.,2009;Tametal., 2007). Regard response rate reported by authors, 70% (n=14)statedagoodresponserate,20%(n=4)mentioned thattheydidnotreachagoodparameterand10%(n=2)did notmentionanyresponserate.

Researchdesign

Themajorityofstudies(n=12,60%)revieweduseda cross-sectionalone-stageproceduretoevaluateDEB----usingeither self-report questionnaires or interview. Cross-sectional of two-stageprocedurewasusedby15%(n=3)ofthestudies (Bhugra, Mastrogianni, Maharajh, & Harvey, 2003; Eapen, Mabrouk,& Bin-Othman, 2006;Machado et al.,2007;see Table 3). On the other hand a signiﬁcant minority of the studies(n=5or25%)employedalongitudinalone-stage pro-cedure where follow-ups varied from 5 to 15 years (see Table2).None study useda two-stage longitudinal proce-dure.

Instruments

Tables 2 and 3 show the different measures utilized to evaluate DEB. From the 20 studies reviewed, ﬁve (25%) employedonlyself-reportquestionnaires(Crowther,Armey, Luce,Dalton, & Leahey,2008; Mousa,Al-Domi, Mashal, & Jibril,2010;Nunesetal.,2003;Tametal.,2007;Tölgyes& Nemessury,2004).The screening instrumentutilizedmost frequently among these studies was the Eating Attitudes Test,fourstudiesemployedthe26-itemversionandonethe

40-itemversion(Garner&Garﬁnkel,1979;Garner,Olmsted, Bohr, & Garﬁnkel, 1982). The Bulimic Investigatory Test, Edinburgh([BITE],Henderson&Freeman,1987)wasutilized byfourstudies(20%).

Four studies (Bhugra et al., 2003; Eapen et al., 2006; Machadoetal.,2007;Westenhoefer,2001)identiﬁedDEBby self-report measuresand byclinicalinterview.The inter-views utilized were: Those based on the 3rd Rev. ed. or the 4thed.of theDSM (APA,1987,1994),theEating Dis-orderExamination(EDE,12thed;Fairburn&Cooper,1993) andtheScheduleforAffectiveDisordersandSchizophrenia (K-SADS).

Acombinedsystemof screeninginstrumentsplus ques-tionsexprofessodevelopedbytheauthorswascarriedout inthreeinvestigations(Huon,Mingyi,Oliver,& Xiao,2002; Jonat&Birmingham,2004;Kiziltanetal.,2006).

Finallyeightinvestigations (40%) assessedDEB through NationalSurveysbutonlythreewerespecializedinEDbeing themostcommonProjectEATSurvey(Ackardetal.,2007; Jones,Bennett,Olmsted,Lawson,&Rodin,2001; Neumark-Sztaineretal.,2006).Theotherﬁvesurveyswerefocusedin differentaspectssuchasDrugandAlcoholinStudent Popula-tion,YouthRiskBehaviorsandNationalHealthbutquestions relatedtoDEBwereembeddedinthesesurveys.

Prevalence

Typeofprevalence. The majorityof studies(n=16,80%) assessedpointprevalenceofDEB,threestudies(15%;Ackard et al., 2007; Neumark-Sztainer et al., 2006; Tam et al., 2007) evaluated period prevalence and one study (5%; Bhugra et al., 2003) calculated lifetime prevalence (see Tables 2and3).Althoughfor comparisonpurposeswillbe suitabletoanalyzestudieswithsametypeofprevalence,it wasdecided toincludeall investigationsfor the analysis, since period and lifetime prevalence studies were insuf-ﬁcient tomake comparisons among them, therefore it is suggestedthatthereadertakeintoaccountthatfourstudies thatestimateddifferenttypeofprevalencewereincluded inthepresentanalysis.

Prevalence rates. For better understanding of the data studies were classified according to the research design, of the 20 papers reviewed five were longitudinal and 15 werecross-sectional.Thiswasdeterminedsincelongitudinal studiesmaysuggestatrendoftheDEBwhilecross-sectional studies onlyreportdatain onespecificpoint ofthetime, thereforetocomparedatafromthesetwotypeof studies willbespurious.Alsoitisworthtohighlightthatinthe anal-ysissectionwhentheterm‘‘paper-and-pencilinstruments’’ ismentioned,itmeansthattestssuchasself-report ques-tionnairesand/orsurveysand/orexprofessoquestionswere includedtoassessDEB.

Prevalence of restrictive dieting. Eleven of 15 cross-sectionalstudiesreportedthisbehavior;eightofthemused one-stage procedure. From these latter eight, ﬁve were from America and three from Asia. All studies from the Americancontinentutilizedpaper-and-pencilinstruments, the highest prevalence rates was reported in one study fromUnitedStatesbeing40.6%,followedbytwostudiesof Canadathatreported9.3%and23.0%.Onestudyfrom Mex-icoreported1.5%andonestudyfromBrazilreported7.8%. Otherwisestudies fromAsia usedpaper-and-pencil

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instru-Systematic review of disordered eating behaviors 55

Table2 Longitudinalstudies.

Prevalence%(onlyinwomen)

Study Country Gender Age Sample

(N) Employed instruments Typeof Prevalence Research design Res. Dieting

Fasting Laxatives Diuretics Vomiting Binge eating Trend Westenhoe-fer (2001) West Germany Men& Women Olderthan 18 18-96 1990 M(862) W(911) 1997 M(928) W(1202) -Standardized face-to-face Interview basedon DSM-IVcriteria and -10questions madebythe authors Point prevalence Long. 1stage 1990 (42.0) 1997 (35.9)* 1990 (4.4) 1997 (2.7)* 1990 (4.3) 1997 (3.1)* 1990 (1.1) 1997 (1.1) 1990 (2.0) 1997 (1.2) Decreasing (except vomiting andbinge eating) Neumark-Sztaineretal. (2006) UnitedStates ofAmerica Men& Women 1999 12-15 2004 17-20 M(1130) W(1386) ≈ -ProjectEATII Survey 1Yes/No questionper behavior Period prevalence Long. 1stage 1999 (49.7) 2004 (44.7) 1999 (21.2) 2004 (19.2) 1999 (1.8) 2004 (2.6) 1999 (2.1) 2004 (1.3) 1999 (8.2) 2004 (4.9) Relative stability Unikel-Santocini etal.(2006)

Mexico Men& Women 12-19 1997 M(4676) W(5079) 2000 M(1675) W(1611) 2003 M(1533) W(1529) -Brief questionnaire forriskyeating behaviors (Unikeletal., 2004) Point prevalence Long. 1stage 1997 (18.5) 2000 (14.7) 2003 (14.7) 1997 (18.5) 2000 (14.7) 2003 (14.7) 1997 (1.9) 2000 (7.0) 2003 (8.0)** 1997 (1.9) 2000 (7.0) 2003 (8.0)** 1997 (1.9) 2000 (7.0) 2003 (8.0)** 1997 (3.3) 2000 (7.6) 2003 (5.9)** Increasing (exceptR. Dietingand Fasting) Crowtheretal. (2008) UnitedStates ofAmerica Women x=19.1 S.D=3.29 1990-1992 (1176) 1993-1995 (1739) 1996-1998 (1926) 1999-2001 (1021) 2002-2004 (982) -Eating/Dieting Questionnaire -BULIT (Smith& Thelen,1984) -BULIT-R (Thelen, Farmer, Wonderlich& Smith,1991) Point prevalence Long. 1stage 1990-92 (6.5) ‘93-‘95 (7.4) ‘96-‘98 (7.8) ‘99-‘01 (9.1) ‘02-‘04 (8.1) 1990-92 (0.9) ‘93-‘95 (1.4) ‘96-‘98 (1.1) ‘99-‘01 (0.6) ‘02-‘04 (1.6) 1990-92 (0.4) ‘93-‘95 (1.7) ‘96-‘98 (1.5) ‘99-‘01 (2.0) ‘02-‘04 (2.7)** 1990-92 (1.8) ‘93-‘95 (2.2) ‘96-‘98 (1.6) ‘99-‘01 (1.3) ‘02-‘04 (2.3) 1990-92 (7.7) ‘93-‘95 (7.3) ‘96-‘98 (7.6) ‘99-‘01 (9.0) ‘02-‘04 (8.5) Relative stability (except diuretics)

Hayetal.(2008) Australia Men& Women 1995 x=43.4 S.D.=19 2005 x=45.1 S.D.=24.5 1995 M(1216) W(1785) 2005 M(1290) W(1757) -5questions writtenbythe author modeledon EDEitems (Fairburn& Cooper,1993) Point prevalence Long. 1stage 1995 (2.5) 2005 (5.2)** 1995 (2.5) 2005 (5.2)** 1995 (1.3) 2005 (2.1) 1995 (1.3) 2005 (2.1) 1995 (1.3) 2005 (2.1) 1995 (3.2) 2005 (7.5)** Increasing (except purgative behaviors)

Res.Dieting=RestrictiveDieting;M=Men;W=Women;x=Meanage;S.D=StandardDeviation;Long.=Longitudinal;*=Prevalenceissigniﬁcantlylowerthantimeone(p<.05);**=Prevalence issigniﬁcantlyhigherthantimeone(p<.05);≈=Samesubjectswerefollowedup;BULIT=BulimiaTest;BULIT-R=BulimiaTestRevised;EDE=EatingDisorderExamination;=Authors collapsedintoonecategorymorethanonerestrictiveorpurgativebehavior.

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56

M.

Ortega-Luyando

et

al.

Table3 Cross-sectionalstudies.

Prevalence%(onlyinwomen) Study Country Gender Age Sample

(N) Employed instruments Typeof prevalence Research design Res. Diet

Fasting Laxatives Diuretics Vomiting Binge eating Jonesetal.

(2001)

Canada Women 12-18 (1739) -DiagnosticSurvey forEatingDisorders

Point prevalence Cross-sect. 1stage 23 1.1 0.6 8.2 15 Huonetal. (2002)

China Women 12-19 (1246) -DietingStatus Measure(Strong& Huon,1997) -Questions developedby authorsaccording DSM-IVcriteria Point prevalence Cross-sect. 1stage 0.6 2.2 1.8 3.5 Bhugraetal. (2003) Trinidadand Barbados

Women 13-19 (362) -KeyquestionsofBITE -Extraquestionson DEB -BulimicDiagnostic Interviewbasedon DSM-III-R Lifetime prevalence Cross-sect. 2stage Stage1 4.1 Stage1 1.4 Stage1 8.84 Stage1 0.27 Stage1 1.93 Stage1 Stage2 3.6 Stage2 3.6 Stage2 0.27 Stage2 0.27 Stage2 0.83 Stage2 1.4 Nunesetal. (2003)

Brazil Women 12-29 (513) -EAT26 -BITE Point prevalence Cross-sect. 1stage 7.8 3.1 8.5 2.8 1.4 Forman-Hoffman (2004) UnitedStates ofAmerica Men& Women 13-19 M(7674) W(7674) -YouthRisk BehaviorSurvey (Breneretal., 2002) Point prevalence Cross-sect. 1stage 40.6 ‡ 12.6 ‡ 4.8 ‡ 4.8 ‡ Jonat& Birming-ham (2004)

Canada Men& Women 12-19 M(156) W(225) -EAT26 -Additional questions developedby authorsaboutDEB

Point prevalence Cross-sect. 1stage 9.3 8.4 8.4 8.4 17.3 Tölgyes& Nemessury (2004)

Hungary Men& Women

10-29 M(248) W(332)

-Subscaleof severityfromBITE

Point prevalence Cross-sect. 1stage 0.9 0.3 1.8 3.9 Eapenetal. (2006) UnitedArab Emirates Women 13-18 (495) -EAT-40 -Interviewbased onKSADSand DSM-IVcriteria Point prevalence Cross-sect. 2stage Stage1 — Stage1 — Stage1 — Stage1 — Stage1 — Stage2 9.1 Stage2 0 Stage2 0 Stage2 0 Stage2 3.2 Kiziltan etal. (2006)

Turkey Men& Women

18-24 M(150) W(150)

-Speciﬁcitemsfrom BITE -ExtraQuestionson Dieting Point prevalence Cross-sect. 1stage 11.3 10 0 0.7 1.3 16

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Systematic review of disordered eating behaviors 57 Table3(Continued)

Prevalence%(onlyinwomen)

Study Country Gender Age Sample

(N) Employed instruments Typeof prevalence Research design Res. Diet

Fasting Laxatives Diuretics Vomiting Binge eating Ackard etal. (2007) United Statesof America Men& Women x=14.9 S.D= 1.7 M(2377) W(2357) -ProjectEAT Survey Yes/NoQuestions developedby authorsaccording DSM-IVcriteria Period prevalence Cross-sect. 1stage 9.4 9.4 11 Hudson etal. (2007) United Statesof America Men& Women Older than18 M(1220) W(1760) -Facetoface NationalU.S. Survey -Questionsfrom theCIDI (Kessler&Üstün, 2004) Point prevalence Cross-sect. 1stage 2.5 Machado etal. (2007)

Portugal Women 12-23 (2028) -EDE-Q

(Fairburn&Beglin, 1994)

-Interviewbasedon EDE12th

(Fairburn&Cooper, 1993) Point prevalence Cross-sect. 2stage Stage1 — Stage1 1.6 Stage1 1.8 Stage1 2.9 Stage1 — Stage2 0.9 Stage2 0.3 Stage2 0.6 Stage2 0.9 Stage2 1.2 Tametal. (2007)

China Men& Women 10-21 M(1288) W(1012) -EAT26 Period prevalence Cross-sect. 1stage 51.7 ‡ 3 ‡ Barriguete-Melendez etal. (2009)

Mexico Men& Women 10-19 M(12527) W(12529) -Brief questionnairefor riskyeating behaviors Unikeletal. (2000) Point prevalence Cross-sect. 1stage 1.5 2.1 0.3 0.3 0.5 9.4 Mousaetal. (2010)

Jordan Women 10-16 (326) -EAT26

-EHQ (Greenfeld, Quinlan,Harding, Glass,&Bliss, 1987) Point prevalence Cross-sect. 1stage 7.4 7.4 11 16.9

Res.Diet=RestrictiveDieting;M=Men;W=Women;KSADS=ScheduleforAffectiveDisordersandSchizophrenia;x=Meanage;S.D=StandardDeviation;CIDI=WorldHealthOrganization CompositeInternationalDiagnosticInterview;EDE-Q=EatingDisorderExamination-Questionnaire;EDE12th=EatingDisorderExamination12thedition;EHQ=EatingHabitsQuestionnaire;

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58 M.Ortega-Luyandoetal. mentsyielding the following prevalence rates, 51.7% and

0.6%inChinaand11.3%inTurkey(seeTable3).

Table 3 shows three two-stage studies. Bhugra et al. (2003)reporteda prevalence ratein restrictive behaviors (dieting and fasting) of 3.6% in a Trinidadian population; Eapenetal.(2006)documentedinwomenfromUnitedArab Emiratesa prevalenceof 9.1%;andMachado etal.(2007) statedaprevalenceof0.9%inPortuguesepopulation.Even thoughthesestudiesusedsimilarmethodologiesthe preva-lenceratesweresubstantiallydifferent.

Paying special attention onlongitudinal studies (n=5), itwasobservedthatfourofthemassessedrestrictive diet-ing.Onlyonestudy(Westenhoefer,2001)usedface-to-face interviewwithGerman population, reporting a signiﬁcant decreaseovertheperiodsurveyed(1990---1997)goingfrom 42.0% to35.9% (p<.05). Contrary, Hay et al. (2008) used paper-and-pencil instruments, they clustered restrictive dieting and fasting, founding prevalence rates of 2.5% in 1995 and5.2% in 2005 (p<.002) in Australianpopulation. Howevertwostudiessuggestedarelativestabilityovertime usingpaper-and-pencilinstruments,onefromUnitedStates (Neumark-Sztaineretal.,2006)andtheotherfromMexico (Unikel-Santociniet al., 2006), thelatter study collapsed dietingandfastinginonecategory(seeTable2).

Fasting. Five of 15 cross-sectional studies assessed this behavior; four of them used one-stage procedure. From theselatter four,three werefrom Americaand one from Asia.Allstudiesutilizedpaper-and-pencilinstruments,the highest prevalence rates were reported in one study of UnitedStates(12.6%)andonefromTurkey(10.0%),andthe lowestprevalencerateswerereportedbyBrazil(3.1%)and Mexico(2.1%;seeTable3).

ThestudyofBhugraetal.(2003)wastheonlythatuseda two-stageproceduretoanalyzerestrictivebehaviors (diet-ing and fasting) founding a prevalence rate of 3.6% in a Trinidadianpopulation(seeTable3).

Ofﬁvelongitudinalstudiesfourassessedfasting.A statis-ticalincreaseovertimeinthisbehaviorwasreportedbyHay etal.(2008)showingprevalenceratesofrestrictive behav-iors(restrictive dieting and fasting)from 2.5% in 1995 to 5.2%in2005(p<0.001)inAustralianpopulation.Theother threelongitudinalstudieswithAmericanandMexican popu-lation(Crowtheretal.,2008;Neumark-Sztaineretal.,2006; Unikel-Santocinietal.,2006)notedafairlystabilityoverthe years(seeTable2).

Bingeeating. Twelveof15cross-sectionalstudiesreported thisbehavior;nineofthemusedone-stageprocedure.From these latter nine, ﬁve were from America, three from Asia andone fromEurope. All studies fromthe American continentutilizedpaper-and-pencilinstruments,thehighest prevalencerateswerereportedintwostudiesfromCanada being17.3%and15.0%,besidestwostudieswerecarriedout inUnited States reporting11.0% and 2.5%and ﬁnallyone study fromMexico reported9.4%. Otherwise studies from Asiausedpaper-and-pencilinstrumentsyieldingthe follow-ingprevalencerates,16.9%inJordan,16.0%inTurkeyand 3.5%in China. There is onestudy fromEurope,reporting 3.9%inHungarianpopulationusingpaper-and-pencil instru-ments(seeTable3).

Threeof15studiesusedatwo-stageprocedure.Bhugra et al. (2003) reported a prevalence rate of 1.4% in a Trinidadianpopulation;Eapen etal.(2006)documentedin

women from United Arab Emirates a prevalence of 3.2%; and Machado etal.(2007) stated aprevalence of 1.2% in Portuguesepopulation(seeTable3).

Ofﬁvelongitudinalstudiesfourassessedbingeeating.A statisticalincreaseovertimeinthisbehaviorwasreported intwostudiesusingpaper-and-pencilinstruments: Unikel-Santocinietal.(2006)reportedprevalenceratesfrom3.3% to5.9%inMexican populationandHayetal.(2008),from 3.2%to7.5%(p<0.001)inAustralianpopulation.Theother twolongitudinalstudies withAmericanandGerman popu-lation(Crowtheretal.,2008;Westenhoefer,2001)noteda fairlystabilityovertheyears(seeTable2).

Purgativebehaviors. Sixof20studies clusteredthe self-induced vomiting, abuse of laxatives and diuretics in one category, therefore the prevalence rates of these behav-iorsindividuallyis uncertain,consequentlytheprevalence analysis was made only with those studies who reported prevalencerates ofeachbehaviorandnotwiththosewho combinedmorethan onebehavior,callingthem purgative behaviors.

Abuse of laxatives. Eight of 15 cross-sectional studies assessed the useof laxatives; six of them usedone-stage procedure.Fromtheselattersix,threeofthemwerefrom America, two from Asia and one from Europe. All stud-iesfromtheAmericancontinentutilizedpaper-and-pencil instruments, the highest prevalence rates were reported by Brazil with 8.5%, while Mexico and Canada reported prevalence rates equalor less than1.1%. Otherwise stud-ies from Asia used paper-and-pencil instruments yielding the following prevalence rates, 2.2% in China and 0% in Turkey.ThereisonestudyfromEuropeperformedin Hun-garyreporting0.9%withpaper-and-pencilinstruments(see Table3).

Three of twenty studies used a two-stage procedure. Bhugraetal.(2003)reportedaprevalence rateof0.3%in a Trinidadianpopulation;Eapen etal. (2006)documented in womenfrom UnitedArabEmirates aprevalence of 0%; and Machado etal.(2007) stated aprevalence of 0.3% in Portuguesepopulation(seeTable3).

Ofﬁvelongitudinalstudiesthreeassessedtheuseof laxa-tives.OnestudyfromGermanyreportedadecreasingtrend (4.4% in 1990 and 2.7% in 1997), in contrast,two studies from United Statesfound a fairlystability over the years (seeTable2).

Abuse of diuretics. Seven of 15 cross-sectional studies assessed this behavior; five of them used one-stage pro-cedure. Fromtheselatter five,threewere fromAmerica, one from Europe and one from Asia. All studies utilized paper-and-pencilinstruments,thehighest prevalencerate was reportedby Brazil with 2.8%, while prevalence rates ofMexico,Canada,HungaryandTurkeyrangedamong0.3% and0.7%.Ontheotherhandtwostudiesusedatwo-stage procedure.ThefirstperformedinUnitedArabEmirates doc-umented aprevalence of 0% (Eapen etal., 2006)and the secondinPortugalstatedaprevalencerateof0.6%(Machado etal.,2007;seeTable3).

Of ﬁve longitudinal studies three assessed the use of diuretics. Onestudy fromGermany reportedadecreasing trend(4.3%in1990and3.1%in1997),incontrast,onestudy from UnitedStates found a fairly stabilityover ﬁve-years with prevalence rates of 2.1% in 1999 and 1.3% in 2004 (Neumark-Sztainer et al., 2006), and the other found an

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Systematicreviewofdisorderedeatingbehaviors 59 increaseinprevalenceratesrangingamong0.4%to2.7%in

atwelve-yearperiod(Crowtheretal.,2008;seeTable2). Self-inducedvomiting. Twelveof15cross-sectional stud-ies evaluatedthis behavior; nine of them used one-stage procedure. Fromtheselatter nine,four werefrom Amer-ica,onefromEuropeandfourfromAsia.Allstudiesutilized paper-and-pencilinstruments,thehighestprevalence rate werereportedbythreestudies,Mousaetal.(2010)reported aprevalence rateof11.0%inJordanian population,Jones etal. (2001) with8.2% and Jonat andBirmingham (2004) with 8.4% these latter two prevalence rates in Canadian population. In contrast Mexico, Brazil, Hungary, Turkey andChina showedrange prevalence among0.5---3.0% (see Table3).

Threestudiesusedatwo-stageprocedure.InTrinidadian (Bhugra et al.,2003),Arab (Eapen et al., 2006) and Por-tuguese(Machadoetal.,2007)populationprevalencerates werelowerthan1.0%(seeTable3).

Ofﬁvelongitudinalstudiesthreeassessedvomiting.All of them found a fairly stability over the years, one of them (Westenhoefer, 2001) with a standardized face-to-faceinterviewfoundaprevalencerateof1.1%in1990and 1997.TheothertwowerecarriedoutwithAmerican popula-tionusingpaper-and-pencilinstruments,Neumark-Sztainer etal.(2006)stated ina ﬁve-yearperiodprevalencerates of8.2%in1999and4.9%in2004andCrowtheretal.(2008) reportedprevalence ratesthatrangeamong1.8---2.3%ina twelve-yearperiod(seeTable2).

To summarize the information above it is possible to assume thatlongitudinal studies suggested astable trend for restrictive dieting,fasting, useof laxatives and vomi-tingsincetherewerenostatisticaldifferencesinprevalence ratesovertheperiodsassessed,whilethesuggestedtrend ofbingeeatinganduseofdiureticswasvariableaccording withthestatisticalanalysisreported.

Consideringtheprevalenceratesyieldedforthe20 stud-ies it was observed that restrictive dieting was the DEB withthehighest prevalence rate,followed by fastingand bingeeating,whereaspurgativebehaviorsshowedthe low-estprevalencerates.

Discussion

Themainobjectiveofthepresentpaperwasto systemati-callyreviewempiricalstudiesthathaveprovidedestimates ofprevalenceoftheDEBinwomen,aswellasmakesome recommendationsforfutureepidemiologicalstudiesofDEB. Thisreviewfoundinconsistentresultsamongstudies ana-lyzed, however this is relevant since systematic reviews provide a general view of how have been investigated theprevalenceofDEB.Thereareseveralconfounding fac-torsthatmayberesponsiblefortheseconflictingfindings. Oneexplanationisthatdifferenttypesofprevalencewere reported,supportingthefirsthypothesisofthisreviewwhich was: different typeof prevalence (point, periodand life-time)willyielddiverserates.Itiscommonthatprevalence ratesareconsiderjustasonegeneralepidemiological mea-sure,howeverthismayhavedifferenttypesandtherefore different objectives. In this literature review 80% of the studiesreportedthepointprevalenceofDEB,thisis reason-ablesinceinEDfieldthetemporalityandfrequencyinthese

behaviors(atleastduringthepastthreemonthsandtwice a week according with DSM-5) are crucial data to deter-minetheclinicalrelevance,thereforethepointprevalence considers this aspect and gives a general view about the presence or absenceof these behaviorsamong the popu-lation,allowing health servicesto provide facilities more attachedtothenecessities ofthesociety.Hence itis rec-ommendedthatbothreaderandresearcheridentifywhich kind of prevalence will be studied, since the unclearness inthisaspectmayaffectthemethodology,theresultsand mainconclusionsoftheresearch,yieldingprevalencerates overorsub-estimatednotonlyofDEBbutofanydisorder.

There is a considerable debate around the prevalence of DEB, since it is difficult to determine if these have rise,decrease or remained stableover time,this dispute isnotonlyrelatedtotypeofprevalenceissues,butalsoto differencesin methodologiesamong studies such as sam-ple features, research design and instruments, therefore thesecondhypothesisthatwasmethodologicaldifferences willyielddifferentrates ofprevalence,wasaccepted.For instance, large samples are important in epidemiological studies to be able to generalize findings; in this review 35% of the papers reported less than 1000 participants. Althoughthereisnotaconsensusaboutwhatdoesitmean ‘‘largesamples’’,Jacobi,Hayward,deZwaan,Kraemer,and Agras(2004)havesuggestedforbetterestimationsof preva-lencerates,asamplesizeofatleast3000subjectswithina community-basedstudy.Howeverthesizeisnotenoughto assuretherepresentativenessofthesample,alsoitis nec-essarytoconsiderthemethodofsampleselectionandthe responserate.Thegoldstandardprocedureinepidemiology forsampleselectionistherandomizedmethods,andPunch (2003)establishedthatgoodresponseratesinfacetoface surveysgoesfrom80%to85%,questionnairessentbymail startingfrom60%,byonlineof30%ormoreandinclassroom bypaperstartingfrom50%.Accordingtotheseassumptions itisworth tohighlightthat inthisreview mostof studies accomplishedwiththesetwolattercriteria,howeverthese criteriamustbeachievedinallepidemiologicalresearches, sincethesearekeyfeaturesthatwillreflectmorerealand certainprevalenceratesamongthepopulationstudied.

Regarding toresearch design, both cross-sectional and longitudinalstudiesyieldrelevantinformation,forinstance, cross-sectionalstudies allowtopredict strategiesfor pre-vention and intervention programs; however longitudinal studiesmaysuggest a trendof theseDEBand asan addi-tionalgoodness, to acknowledge if the strategies carried outby health services areimpacting positivelyover time inpopulation.Thereforeitis suggestedfor future investi-gationsto considerperform longitudinal studies eventhe enormoustimeandcoststhatthisdesignrequires, coincid-ingwithJacobi,Hayward, etal.(2004)whomentionthat theﬁrststep inidentifying riskfactors shouldbe through longitudinalstudies.

Thelastmethodologicalconfoundingfactorinthisreview has todo with instruments, highlighting twoaspects: (a) type of question and (b) answer option. The ﬁrst point ariseswhenwereanalyzedthedifferentquestionsutilized to estimate the point prevalence of DEB. In this analy-sis were identiﬁed questions such as ‘‘Do you currently diet/binge/vomittwiceaweek...?’’,‘‘duringthepastsix months orin the past 1year doyou...?’’and ‘‘have you

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60 M.Ortega-Luyandoetal. ever...?’’,inwhichwasobservedtemporaldifferencesthus

differenttypesofprevalence.Forinstancetwostudies car-ried out in the same country with similar sample sizes andsimilarparticipants’ features,found prevalence rates extremelydiscrepant.Huonetal.(2002)assessedthe preva-lencerateofrestrictivedietingthroughquestionsthatrefer tothecurrentmomentfinding0.6%,whileTametal.(2007) evaluatedthesamebehaviorwithquestionsthatenquired participantstothinkinthepastyear,yielding51.7% suggest-ingthat the temporalityexpressed implicitlyin questions haveasignificantinfluencein theprevalence rates. More-over it is common touse screening instruments toassess prevalence rates; howeverit is not enough tocount with awiderecognizedinstrument, itis necessary tocarefully selectitemsthatreflectthepresenceofthebehaviorand nottheattitudetowardthebehavior.Forexample,itis bet-tertoselectitemssuchas‘‘Ivomitaftereating’’instead of‘‘Iwouldliketovomitaftereating’’.

Thesecondpointtodiscussconcerninginstrumentsisthe useofLikertscalestoidentifytheDEB,sincecriteriawere notspecifiedtoconsiderpresenceorabsenceofthe behav-iors,whichiscrucialfactorinepidemiologicalresearch.For example,inaLikertscalewithfiveansweroptions(always, usually,sometimes,rarelyandnever),rigorouscriteriamay limitpresenceas‘‘always’’and absenceas‘‘never’’,but less exigent criteria may considermore than one answer option.Thisaspectwasundervaluedsincealmostanystudy specifiedmeticulouslyhowthepresenceorabsenceofDEB wasestablished.

Datacollectionisoneofthemethodologicalprocedures moreimportantinanyresearch,becausethisstageallows responding research questions proposed (Singh, 2006), therefore,theselectionoftheinstrumentmustbeadecision carefullytakensincethisincisesintheresultsofresearch. To this respect, paper-and-pencil instruments are useful toolsinepidemiological researchtocollect largeamounts ofinformationatalowcostperrespondent, notwithstand-ingthe instrument selectedneed tocover twoimportant conditions: validity and reliability in speciﬁc populations (Bhattacherjee,2012).

Accordingtothe resultsof thisreview restrictive diet-ingandbingeeatingwerewithinthemoreprevalentDEB, supporting thelast hypothesis formulated for thisreview. Thisﬁndingcouldbeinﬂuencedbythelastconfounding fac-torthathastodowithculturalissues.Toillustratethis,we canobservethatWestenhoefer(2001)inalongitudinalstudy foundadecreaseinmostofDEB,onepossibleexplanation that he proposes is that Germany is considered a coun-trywherepeopleismoreawareabouthealthandwellness issues;supporting thisproposal, theInternational Markets Bureau(2010)mentionthatexpertsandmediahaveworked togethertowarn population about health riskscaused by thepracticeofDEB,makingthewellbeingasalifestyleand marketingconcept.Incontrast,Nunesetal.(2003)reported oneof the highest prevalence rates in laxatives (8.5%) in Brazilianpopulation,accordingtotheauthorsthismaybe duetoBrazilianswomenhavemoreaccesstodietpillsthan womeninother countries,thesepillsareeachtimemore accessible toadolescentssincemedical prescription is no neededtoobtainthem,andthefactthatmediapromotes themas‘‘softornaturalweightcontrolmethods’’increase the desire to consume these products. Besides, Brazil is

considered one of the countries with the highest beauty standards,henceoneofthecountrieswheremorecosmetic surgeriesareperformedperyearintheworld(International SocietyofAestheticPlasticSurgery,2013)thismaycausea strongsocialpressureinwomen,pushingthemtoconsume productsthatwillhelpthemtoreach‘‘theperfectbody’’. Otherstudythatreﬂectsculturalaspectsinprevalencerates is the one carried out by Kiziltan et al. (2006) in Turkish population; theyreportedhigh prevalencerates infasting (10%) andbinge eating(16%). Onepossible explanation is thatfastingisabehaviorperformedbyMuslimsgirlsfor reli-giousreasons;itisknownthatlongperiodswithouteating mayleadanincreasedamountoffoodintakeandthismay bemisunderstoodasabingeeating,yieldinghighprevalence rates(Peláezetal.,2005).Thisunderlinestheimportanceto adaptculturallytheinstrumentstodetectwhenthepractice ofDEBistrulypathologicalandnotperformedforreligious, culturalorhealthpurposes.

The analysis carried out in this literature review add knowledge to understand the differences among studies about prevalence rates of DEB, howeversome limitations shouldbeconsider:(1)maleprevalencerateswerenot ana-lyzed,itissuggestedthatfutureresearchaddressthisaspect since thereis evidence thatthe practice of these behav-iorsarebecomingmorepopularamongadolescentboysand young men (Fortes et al., 2013; Petrie et al., 2008), (2) the search review wasperformed only in two data bases (MEDLINE and SCIENCE DIRECT), it is suggested that fur-therresearchincludedinformationfromothersourcessuch as books, dissertations, articles in different languages or indexedindifferentdatabasestoenrichtheknowledgein epidemiologicalﬁeldofED,(3)excessiveexerciseisalsoa relevantDEBbutwasnotincludedinthisreview,sofurther researchshould study it sincethereis evidence that it is associatedwithmuscledysmorphia(Haleetal.,2013)and (4) although thisstudy wasdesign asa systematicreview itispossibletoalsoconsideritasaﬁrstapproximationof a meta-analysis,sinceaccordingwithCrombie andDavies (2005)thevalidityofameta-analysisdependsonthequality ofthesystematicreviewonwhichitisbased,thereforeitis suggestedthatfutureresearchesgivecontinuitytothiswork toprovidemoredetailedandaccurateinformationonDEB, followingcriteriaproposedbyPRISMAstatement(Preferred ReportingItemsforSystematicreviewsandMeta-Analyses; Moheretal.,2009).

Themainstrengthofthispaperisthemeticulous anal-ysis performed in each article; this allowed deriving the following methodological considerations for epidemiologi-calresearchinED,whichwillcontributetodescribemore accuratelytherealstateofthepopulationstudy,aswellas tohaveagreaterscientiﬁcrigor:

(1) Sample. It is suggested for future studies to take intoaccounttherepresentativeness ofthe population preferablythroughrandomizedmethods,ifitisnot pos-sible toachieve this criteria, Jacobi,Hayward, et al. (2004)recommendacommunitysamplesizeatleastof 3000 participants, whichmay or may notbe selected randomly.Alsoitisimportanttohaveagoodresponse rate;itissuggestedtofollowthecriteriaproposedby Punch(2003).

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Systematicreviewofdisorderedeatingbehaviors 61 (2) Researchdesign.Iftheaimofresearchistoknow the

pointprevalenceofDEBandED,itissuggestedtousea cross-sectional design. Howeverifthe purpose of the study is to determine if prevalence rates have rise, decreaseorremainstableovertime,longitudinaldesign isthemostsuitabletoclarifythisconstantdiscussionin specializedliterature.

(3) Instruments.Thereareinstrumentsdeveloped specifi-callytoassessDEBwithepidemiologicalaims(Ferreira &Veiga,2008;Hay,1998;Unikel,Bojorquez,&Carreño, 2004).Accordingtothisreview,theEATwasthemost widely used instrument to assess the prevalence of DEB,howeverthisinstrumentwascreatedtomeasure attitudes and behaviors common among ED, not for epidemiologicalpurposes.Independentlyofthe instru-mentsutilizeditisnecessary toconsiderthreecrucial points:(1) The instruction should encourage the par-ticipanttoanswer thinkingin the past threemonths, given the frequency proposed by DSM-5; (2) If the answer options of the instrument have a Likert scale is imperative that the authors explain which answer option(s)was/werechosen for‘‘presence’’andwhich for ‘‘absence’’of DEB;and (3)Frequency parameters aredeterminantinED, theseshould bereflectedalso inepidemiologicaldata;forinstancetoengagein vomi-tinganaverageof1---3timesperweekduringthepast threemonthsisenoughtoconsideritasanindicatorof presenceofthisDEB,thereforeitisnecessarytospecify whatdoes itmean‘‘rarely,sometimes,often, usually, always’’sinceeachparticipantmayattributedifferent frequencytoeachansweroptionandatthesametime wecanpreventtheoverestimationofprevalencerates. IftheLikert scale goesfrom‘‘never’’to‘‘always’’it is suggested to consider the following frequency for each answer option: never=absence; rarely=once a monthorless;sometimes=twoormoretimesamonth; often=once a week; usually=two-six times a week; always=onceadayormore.

Ethical

disclosures

Protection of human and animal subjects.The authors declare thatthe procedures followedwere in accordance with the regulations of the responsible Clinical Research EthicsCommitteeandinaccordancewiththoseoftheWorld MedicalAssociationandtheHelsinkiDeclaration.

Conﬁdentialityofdata.Theauthorsdeclarethattheyhave followed the protocolsof their work center onthe publi-cation of patient data and that all the patients included inthestudyhavereceivedsufﬁcientinformationandhave giventheirinformedconsentinwritingtoparticipateinthat study.

Righttoprivacyandinformedconsent.Theauthorsmust haveobtainedtheinformedconsentofthepatientsand/or subjectsmentionedinthearticle.Theauthorfor correspon-dencemustbeinpossessionofthisdocument.

Conﬂict

of

interest

Theauthorsdeclarenoconﬂictofinterest.

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Systematic review of disordered eating behaviors: Methodological considerations for epidemiological research

REVIEW

ARTICLE

Systematic

review

of

disordered

eating

behaviors:

Methodological

considerations

for

epidemiological

research

Mayaro

Ortega-Luyando

,

Georgina

Alvarez-Rayón

,

David

M.

Garner

,

Adriana

Amaya-Hernández

,

María

Leticia

Bautista-Díaz

,

Juan

Manuel

Mancilla-Díaz

Introduction

Method

Results

Discussion

Sponsors

Ethical

disclosures

Conﬂict

of

interest

References

_,

_Georgina

_{Alvarez-Rayón}

_,

_David

_M.

_Garner

_,

_,

_María

_Leticia

_{Bautista-Díaz}

_,

_Juan

_Manuel

_{Mancilla-Díaz}