ContentslistsavailableatSciVerseScienceDirect
Drug
and
Alcohol
Dependence
jo u r n al h om epa g e : w w w . e l s e v i e r . c o m / l o c a t e / d r u g a l c d e p
Social
rank
and
inhalant
drug
use:
The
case
of
lanc¸
a
perfume
use
in
São
Paulo,
Brazil
Zila
M.
Sanchez
a,∗,
Ana
R.
Noto
b,
James
C.
Anthony
caDepartmentofPreventiveMedicine,UniversidadeFederaldeSaoPaulo,RuaBorgesLagoa,1341,SaoPaulo04038-034,Brazil
bDepartmentofPsychobiology,UniversidadeFederaldeSaoPaulo,RuaNapoleãodeBarros,1058,SaoPaulo04024-002,Brazil
cDepartmentofEpidemiologyandBiostatistics,CollegeofHumanMedicine,MichiganStateUniversity,909FeeRoadRoomB601,EastLansing,MI48824,USA
a
r
t
i
c
l
e
i
n
f
o
Articlehistory:
Received9August2012 Receivedinrevisedform 16November2012 Accepted3December2012
Available online 29 December 2012
Keywords:
Inhalants Adolescents Epidemiology Brazil Schoolsurvey
a
b
s
t
r
a
c
t
Background:Lancaperfume(chloroform/ether)isaninhalantusedmainlybyhighersocialclassstudents inBrazil.Inlightofthesocialandepidemiologicalfeaturesoflancause,supply,anddistribution,this investigationtestshypothesesaboutthedegreetowhichuseofinhalantlancamightbeoccurringin clusters,consistentwithsocialsharinganddiffusion,andmightshowadirectassociationwithsocial rankevenwithintherelativelyprivilegedsocialcontextofprivateschoolsinalargemega-cityofLatin America.
Methods:Epidemiologicself-reportsurveydatawerefromalargerepresentativesampleofurban post-primaryprivateschoolstudentsinSãoPaulocity,Brazil,in2008.Newlyincidentlancausewasstudied, firstwithestimatesofclusteringfromthealternatinglogisticregressions(ALR)andthenwithconditional logisticregressionstoprobeintothehypothesizeddirectsocialrankassociation.
Results:ALRdisclosedaclusteringofnewlyincidentlancauserswithinprivateschoolclassrooms (pair-wiseoddsratio(PWOR)=2.1;95%CI=1.3,3.3;p=0.002)aswellasclustersofrecentlyactivelancause (PWOR=1.9;95%CI=1.1,3.3;p=0.02).Occurrenceoflancausewithinprivateschoolclassroomswas directlyassociatedwithsocialrank(oddsratio(OR)=0.2;95%CI=0.1,0.8;p=0.03inthecontrastof low-estsocio-economicstatus(SES)versushighestSESstratawithinclassrooms).Thereafter,studyofother drugsdisclosedsimilarpatterns.
Conclusions:Theclusteringestimatesareconsistentwithconceptsofperson-to-personsharingoflanca withinprivateschoolclassroomsaswellasotherdynamicprocessesthatmightpromotelancaclusters inthiscontext.Anobserveddirectassociationwithsocialrankisnotspecifictolancause.DirectSES estimatesacrossabroadprofileofdrugcompoundssuggestscausalprocessesoverandabovethemore specificinitiallyhypothesizedsocialrankgradientsinthelancadiffusionprocess.Anovelfacetofthe evidenceisgreateroccurrenceofdruguseamongthehighersocialrankprivateschoolstudents,which shouldbeofinterestinthesocialsciencecommunity.
© 2012 Elsevier Ireland Ltd.
1. Introduction
InBrazil,traditionallyalowincomecountrythatisnow con-solidatingitsuppermiddle-incomerank(WorldBank,2011),and inmega-citySaoPaulo,themedicalandpublichealth communi-tiesfirstbecameawareof‘lanca’asaformofillegaldrugusemany yearsago.‘Lanca’isaninhalantdrugknowncolloquiallyas‘lanc¸a perfume’or‘loló’,traffickedlargelyinBrazilandArgentina,where itsuseisillegal(Mesquitaetal.,1998).Chloroformand/orether areprimaryconstituentingredientstypicallyrequiredtoproduce
∗Correspondingauthorat:DepartmentofPreventiveMedicine,Universidade FederaldeSaoPaulo,RuaBorgesLagoa,1341,1oandar,SãoPaulo04038-034,Brazil.
Tel.:+551155764876.
E-mailaddress:zila.sanchez@gmail.com(Z.M.Sanchez).
thisinhalantdruginsmallbottlesorflasks,orinmetalcapsules manufacturedforblackmarketretailsale,oftencontainingcereal ethanolandacandybesidestheetherorchloroformformulation (often,ethylchloride).In2004,theBrazilianfederalpoliceseized 70,000bottlesoflanca(Duarteetal.,2011).In thiscontext,we notethatinhalantdrugusehasbeenagenerallyneglectedtopic intheworldliteratureofpublichealth,althoughinhalant drug-takinghasadverseconsequencessuchasneurocognitivetoxicities (Balster,1997;Balsteretal.,2009).
In epidemiological field surveys conducted during the past 30years,therehasbeenageneralover-representationofhigher socialstatusindividualsamonglancausersforreasonsexplained below(e.g.,medicalstudentsinuniversity).Wenote,however,that Carlini-CotrimandCarlini(1988)foundlimitedlancauseamong 9–18yearoldlowsocio-economicstatus(SES)studentsasearlyas twodecadesago.
0376-8716© 2012 Elsevier Ireland Ltd.
http://dx.doi.org/10.1016/j.drugalcdep.2012.12.001
Open access under the Elsevier OA license.
MorerecentstudiesinBrazildisclosenoteworthyoccurrence oflanca useamong university students, includingmedical stu-dents,amongwhomanestimated20–50%havetriedit,withmost ofthesestudentsfromhigherSESstrata(Carvalhoetal.,2008). Lancausealsohasbeenobservedatthepre-universitylevel.Among theyoungerstudentsanestimated10–15%havetriedanyinhalant drug,andanestimated50%oftheinhalantusershavetriedlanca (Carlinietal.,2011;Galdurozetal.,2005).
Thepublishedepidemiologicalstudiesofdrugusepointtoward aneventualgreaterconcentrationofusersamongthelowersocial strata,withrecentillustrationsinfieldsurveyresearchoncocaine, althoughthebaseofevidenceis largelyfromtheUnitedStates andEurope[e.g.,seeMiechandChilcoat,2007).Formulatedwith anappreciationofthesupplyanddistributionoflancaproducts throughpeergroupsandsocialnetworksinBrazil,ourviewthat lancausemightbeoccurringatgreaterfrequencyamonghigher socialstatusindividualsinBrazilrunscountertothisaccumulated evidence.
Thegeneralover-representationof lancauseamong medical anduniversitystudentsofhighersocialrankmightbeexplainedby thecompound’snature,itssupplyanddistributionchains,andits cost,aswellasthegeneralepidemiologyofdruguseinBrazil,where itseemsthatwealthierpeopleareover-representedamongusersof allillegaldrugtypes(Carlinietal.,2011).Inthisrespect,earlyfield inquiriesaboutlancaidentifiedepidemiologicaldetailsofinterest. First,unlikemostinhalants,anduntiltheveryrecentInternetsales, lancahasnotbeenaswidelyavailableasotherinhalantsthattend tobeubiquitousinBrazilianhouseholds(e.g.,glueandnailpolish). Second,beforerecentInternetsalesofcommerciallymanufactured lanca,studentsatuniversityorinmedicalschoolsproducedlanca aftergainingaccesstoasupplyofchloroformorether,whichare compoundsmorewidelyavailableinmedicalschoolinstructional laboratoriesandsomeuniversitychemistrylabs,ascomparedto moretightlycontrolledchemistrylabsatsecondaryschoollevels. Thatis,incontrasttorelativelyopenaccesstootherinhalantssuch asglueornailpolish,lancahistoricallyhashadamorerestricted supplyanddistributionchain,leadingbackwardtothe university-levellaboratorystudentswhooftensuppliedthecompound for partieswithfriends(Mesquitaetal.,1998).
Withsocialdiffusionmodelsinmind,andinlightofthesocial andepidemiologicalfeaturesoflancause,supply,anddistribution, weanticipated that lancausewouldshow pronounced cluster-ingwithinrelativelyprivilegedenvironmentsoftheurbanprivate schoolclassroom,thatis,withoccurrenceofnewlyincidentlanca usebeingdependentuponthesocialrankvariationswithin class-rooms,andwithevidenceofwithin-classroomclusteringoflanca useasestimatedusing analternating logisticregressions (ALR) approach.WhenALRestimatesfailtodisclose tangiblelevelsof clustersofdrugusewithinclassrooms,thenullevidencemakesit moredifficulttoargueforperson-to-personsocialdiffusionofdrug usewithinthesegroups(BobashevandAnthony,2000;Delvaetal., 2000;PetronisandAnthony,2000).
Inadditiontoourexpectationofwithin-classroomclustersof newlyincidentlancause, wepositeda directsocialrank gradi-entbasedonanhistoricallygeneralover-representationoflanca useamong thewell-to-do inBrazil, even withintheprivileged classroomsofprivateschool,wherethereisresidual heterogene-ity in social rank levels, as shown in the empirically derived distributionsofthepresentinvestigation.In ordertostudythis aspectofsocialrankgradientsinlancaepidemiology,weturned totheconditionalformoflogisticregression(CLR), whichholds constant all socially sharedcharacteristics of school and class-roomenvironment,viamatching,evenwhenthesecharacteristics have not been measured explicitly, in order to focus estima-tion on individual-level characteristics such as person’s social rank.
Thisstudyisfocusedonhypothesesaboutnewlyincidentdrug use;weadvancenohypothesesaboutpersistenceofuse,nordrug usedisorders.Nonetheless,forcompleteness,wehavestudiedtwo formsoflancainvolvement:(a)newlyincidentlancausewithin thetwoyearspriortosurveyasamanifestationofitsincidence and(b)recentlyactiveuseoflancainthemonthpriortosurvey asamanifestationofitsprevalence.Inrelationtorecentlyactive or‘prevalent’useoflanca,theinfluenceofsocialrankmightbe expressedoneitherduration(persistence)ofuseonceitstarts,or onincidencerates,orboth[giventhatoddsoflancauseinagiven monthwillvaryasafunctionofduration(persistence)ofuseas wellasnewonsets].Bystudyingonsetsoflancausewithintwo yearspriortosurvey,wesoughttostudythemostnewlyincident lancausers;thosestartingtouselancainthepastmonthoryear weretooscarcewhenonsetswerelimitedinthisfashion.Assuch, thestudysampleofnewlyincidentlancausersspecifiedinrelation totwoyearspriortosurveyprovidessomedegreeofcontrolover theissueofpersistenceinthatmanyuserstryadrugonceandthen donotpersist,asdescribedrecentlyinrelationtotobaccosmoking byBarondessetal.(2010).
Insummary, thisinvestigationoriginatedasanefforttotest hypotheses aboutwhetherthe diffusionof lanca withinhigher socialstatusstudentsmightyieldwithin-classroomclusteringand adirectassociationbetweensocialrankandoccurrenceoflancause withinthesocialcontextofprivateschoollifeinBrazil’smega-city SaoPaulo,wherealmostallofthestudentsarefromthe middle-highersocialranks.Theinvestigationhasdevelopedintoamore comprehensiveresearchprojectontheclusteringandoccurrence oflancausewithintheprivateschoolclassroom,asoneexampleof amicro-socialenvironmentorecologicalnichewithmanysocially sharedfacets.Otherdrugsareconsideredsolelyforcomparative purposesinrelationtothesocialrankhypotheses,andwithsome degreeofexpectationthatdirectsocialrankrelationshipsmightbe foundforsomedrugsinthiscontext(e.g.,lanca),butnotforalcohol, tobacco,orubiquitousinhalantssuchasglueornailpolish.Aswe shallsee,theepidemiologicalevidenceofthisstudyspeaksclearly toquestionsaboutwhetherlancauseclusterswithinprivateschool classroomsandwhetherthereisadirectsocialrankgradientinthat specificcontext;itleavesuncertaintywithrespecttosomeofthe aspectsoftheunderlyingmechanismsorprocessesthatmightgive risetotheclusteringortosocialrankrelationships.Thestudy evi-denceisboundedbyexperiencesofprivateschoolstudents,and inferencesshouldnotbeextendedtootherpopulations.Wedraw thereader’sattentiontothefactthatmorethan80%ofstudentsin SaoPaulo(andinBrazil)attendpublicschools.
2. Materialsandmethods
2.1. Studydesignandsampleselection
Inthis study,theresearchdesign isthat ofa crosssectional surveyofschool-attendingyouthsinSãoPaulo,Brazil,with class-roomsurveydatacollectedin2008fromasampleofthecity’s823 privateschools.Thestudy’stargetpopulationwasdesignedasa representativesampleof8thto12thgradestudentsinthese pri-vateschools,withtwostepprobabilityselectionsuchthatschools weresampledinrelationtostrata(e.g.,numberofclassrooms),and thenclassroomsweresampled;allstudentsinsampledclassrooms wereaskedtoparticipate.ForthisstudyofSESitwasnecessary toexcludethe14%of student-participants who hadmissing or invalidresponsestotheSESassessmentdescribedbelow,yielding ananalysissampleof4476students.
oftheoriginallysampledschoolsconsented;threewerereplaced. (Forcomparison,theMTFreportindicatesthatinsomeyearsonly 50–55%ofthesampledschoolsconsenttoparticipateintheseUS surveys;Johnstonetal.,2009).
The protocol was reviewed and approved by the UNIFESP ResearchEthicsCommittee(Protocol#0930/07).Therewere pro-visionsforparticipantstoparticipateanonymously,todeclineto participate,andtoleavequestionsunanswered.
2.2. Assessmentplan
Anonymous standardized self-reported questionnaire data were gathered by a trained team of assessors (graduate stu-dents)whoworkedineachclassroom,collectively,withnoteacher present.Theassessorsexplainedstudyobjectivesanddistributed questionnaires,withclosedformquestionsadaptedfrom standard-izedWorldHealthOrganizationitems(Smartetal.,1980).
2.3. Keyresponsevariables
Thekey response variables in thisstudy indexuseof lanca, inhalants (other than lanca),tobacco, alcohol, and internation-ally regulateddrugs (IRD), such as cocaine and cannabis, with discriminationofnewlyincidentusersandrecentlyactiveusers. Newlyincidentuserswereidentifiedbytakingdifferencesbetween questionnaire-elicitedageatfirstdruguseandtheageonthe sur-veydate,witharequirementthatthisdifferenceshouldbeequal to0or1,asdescribedinpreviousresearcharticles(O’Brienand Anthony,2009;Stoneetal.,2007).Recentlyactivedrugusershad usedinthemonthpriortoassessment.
2.4. Covariatesunderstudy
Thesocialrankmeasureusedinthisresearchisknownasthe ABEPindex,developedbytheAssociac¸ãoBrasileiradeEmpresasde Pesquisa(ABEP,2008)andusedinmanytypesofeconomic,social, andhealthstudiesinBrazil.Weconsideredbutthenrejectedthe ideaofa modelre-specificationwithadditionalindividual-level covariatessuchasthestudent’sacademicperformance,because inthecross-sectionalcontextthesecharacteristicsmightbea con-sequenceofdruguserather thanadeterminantofdruguse,or theymightnotqualifyastruly‘independent’variablesbyvirtue ofsharedcommoncausesinthis context.In contrast,theABEP socialrankmeasureisconstructedsothatitalmostcertainlydoes notdependuponthestudent’sdrugexperiences.Rather,theABEP indexhasmoretodowiththecharacteristicsofthestudent’s fam-ilyoforigin,theparents,possessionofvarioustypesofhousehold goods(e.g.,televisionsets),andnumberofhousekeepers,largely uninfluencedbystudentbehaviorssuchasdruguse,asexplained below.
StandardABEPvaluesrangefromA1(thetoprank)toE.Inthis studysample,duetotheprivilegednatureofprivatesecondary schoolsinBrazil,only5%ofthestudentswerefoundtobeinthe lowersocialrankswithABEPvaluesofCorDorE.Accordingly, thestudyanalysesconsideredfiveorderedABEPSEScategories: A1,A2,B1,B2,versusC/D/Ecombined.Meanfamilyincome(MFI) attheE-leveloftheABEPindexisverylow(belowa‘livingwage’ levelconsideredacceptableforfamiliesintheUS),whereasa D-levelfamilyenjoysanMFIvalueroughly1.5timestheE-levelMFI. TheC-levelMFIisroughly2–3timestheE-levelvalue.Relativeto theE-levelMFI,thecorrespondingratiosforthehigherlevelsare asfollows:A1:MFI27timesgreaterthanE-levelMFI;A2,17times; B1:9times;B2:5times.
TheguidingconceptualmodelwasoneinwhichtheSES-lanca association in specific and the SES-drug association in general might be direct, as a manifestation of the types of processes
describedinthispaper’sintroduction,withtheexceptionsasnoted (alcohol,tobacco,andinhalantsotherthanlanca).Nonetheless,due tothepossibilityofimbalanceacrossthedrug-SESsubgroups,the regressionmodelsincludetermsforageandsexaswell.Asnoted above,forthisresearchonSES,itwasnecessarytoexclude stu-dentswithmissingorinvalidSESdata.Otherwise,withrespectto keyvariablesunderstudy,therewasamodestdegreeofmissing and/orinvaliddata,withgenerally0.5–2%missing.Forexample, 0.5%ofthestudentshadmissingorinvaliddataonlifetime his-toryofdrinkingalcohol,whereas2%ofthestudentshadmissingor invaliddataonageandsex.
2.5. Analysisapproach
In standard “explore, analyze, explore” cycles, the first exploratory steps involved descriptive cross tabulations. Ini-tialanalyze/estimationstepsinvolved fittingalternatinglogistic regressionmodelswithcovariatestoestimatePWORfor within-classroomclusteringofdrugoutcomes,followedbyALRforboth classrooms and schools. Thereafter, we estimatedhypothesized ABEP-drugassociationsusingconditionallogisticregressions(CLR) forwithin-classroommatcheddata.Post-estimationexploratory stepsincludedchecksonregressionmodelassumptions.
SASPROCGENMOD(V9)yieldsALRmodelswithPWOR parame-terstoaddresssurveydesigneffects(BobashevandAnthony,2000). Stata(V11)yieldsCLR models,withsvysetfor complexsample designvarianceand95%confidenceinterval(CI)estimation.
3. Results
Table 1 describes the study sample for drugs and covari-ates understudyinterms of unweightedcounts,weightedand unweightedproportions,and 95% CI. Toillustrate, among 4476 privateschoolstudents,464youthswereatABEPtoprank(A1); correspondingnumbersforlowerrankswere1492,1439,833,and 248,respectively.
Withandwithoutcovariatetermsforage,sex,andSES,lanca useshowedmoderatewithin-classroomclustering.Toillustrate, PWORestimatesforclusteringofnewlyincidentlancauseandof recentlyactivelancausewere2.1(95%CI=1.3,3.3;p=0.002)1.9 (95%CI=1.1,3.3;p=0.02),respectively,datanotshowninatable). Thethree-levelALR(studentswithinclassroomswithinschools) disclosednoresidualschool-levelclusteringoflancause,oncethis classroom-levelclusteringwastakenintoaccount(p>0.05;data notshowninatable).
ALRandCLRmodelsconfirmedhypothesesaboutSESandnewly incidentlancause,withandwithoutageandsexterms.To illus-trate,foryouthsinthelowerABEPranks(C/D/E),theoddsofrecent onsetoflancausewasanestimatedone-fifthoftheoddsobserved foryouthsinthetopmostABEPrank(A1)–i.e.OR=0.2, irrespec-tiveofcovariateadjustment(Table2,p=0.02;Table3,p=0.03). Tables2and3alsoshowthattheORpointestimatesfolloweda directgradientacrosstheA2,B1,andB2subgroups.Asreported inTables4and5,thelancaORestimatesforrecentlyactive(i.e., prevalent)usecanbeseentobenotappreciablydifferentfrom cor-respondingestimatesfornewlyincidentlancause.TheA1versus C/D/Econtrastsaredirect,andfollowageneraldirectgradientfrom topSESacrosslowerABEPvalues.
Table1
Descriptionofthestudysampleintermsofunweighteddata,weightedprevalenceproportions,and95%CI.DatafromSaoPauloCityprivateschoolsurvey,Brazil,2008 (n=4476).
N % % 95%CI
Unweighted Weighted Min Max
SES
A1(highestrank) 464 10 11 7 16
A2 1492 33 34 30 39
B1 1439 32 32 28 35
B2 833 19 18 15 23
C/D/E 248 6 5 4 7
Sex
Male 2135 48 50 47 52
Female 2269 52 50 47 52
Grade
8th 1065 24 23 18 28
9th 1014 23 21 18 26
10th 829 19 20 16 25
11th 865 19 19 15 23
12th 703 15 17 13 21
Agegroup
12thru14 1943 44 41 34 51
15thru17 2331 53 55 46 65
18andup 128 3 4 2 5
Newlyincidentuseof
Lanca Yes 45 1 1 1 2
No 4431 99 99 98 99
Inhalant Yes 245 6 6 5 8
No 3864 94 94 92 95
Alcohol Yes 888 51 52 48 55
No 863 49 48 45 52
Tobacco Yes 421 11 11 9 13
No 3363 89 89 87 91
IRD Yes 80 2 2 1 2
No 3909 98 98 97 99
Recentlyactiveuseof
Lanca Yes 94 2 2 1 3
No 4370 98 98 97 99
Inhalant Yes 62 2 2 1 3
No 4304 98 98 97 99
Alcohol Yes 1803 40 40 36 45
No 2659 60 60 55 64
Tobacco Yes 466 10 11 9 13
No 4002 90 89 87 91
IRD Yes 332 7 7 6 9
No 4144 93 93 91 94
SES:socialrankaccordingtoABEPclassification.
Table2
UnadjustedoddsratiosestimatedfromconditionallogisticregressionforSESinrelationtonewlyincidentdruguse,withclassroom-levelmatching.DatafromSaoPaulo Cityprivateschoolsurvey,Brazil,2008(n=4476).
NewlyIncident (nb) Pr SES A1 A2 B1 B2 CDE
na 464 1492 1439 833 248
Useoflanca 94 11.7% OR ref 0.8 0.5 0.4 0.2
95%CI 0.4,1.7 0.2,1.1 0.2,0.9 0.1,0.8
p 0.60 0.10 0.04 0.02
Useofinhalantdrugsotherthanlanca 62 14.5% OR ref 0.7 0.6 0.5 0.3
95%CI 0.4,1.1 0.3,0.9 0.3,0.9 0.1,0.7
p 0.100 0.020 0.010 0.005
Drinkingofalcoholicbeverages 1083 14.1% OR ref 0.6 0.5 0.6 0.7
95%CI 0.4,0.9 0.3,0.7 0.3,0.9 0.4,1.3
p 0.010 0.001 0.010 0.400
Smokingoftobacco 466 16.1% OR ref 0.6 0.6 0.4 0.4
95%CI 0.4,0.8 0.4,0.8 0.3,0.7 0.2,0.8
p 0.002 0.004 <0.001 0.008
UseofinternationallyregulateddrugsIRD 332 19.9% OR ref 0.4 0.3 0.3 Nonewlyincidentusers
95%CI 0.2,0.9 0.1,0.7 0.1,0.8
p 0.020 0.005 0.010
SES:socialrankaccordingtoABEPclassification;na:unweightednumberofyouthsateachfamilySESrank;OR:oddsratioestimatefromconditionalformoflogistic
regression,noothercovariatesinthemodel,where‘ref’indicatesthatthehighestsocialrankservedasthereferencecategoryforestimationoftheoddsratios;CI:confidence interval;p:p-valueunderthenullhypothesisofnoassociationbetweenSESanddruguseoccurrenceasstudiedhere;nb:unweightednumberofdrug-usingyouthsinthe
Table3
Covariate-adjustedoddsratiosestimatedfromconditionallogisticregressionforSESinrelationtonewlyincidentdruguse,withclassroom-levelmatchingandcovariate adjustmentforsexandage.DatafromSaoPauloCityprivateschoolsurvey,Brazil,2008(n=4476).
NewlyIncident SES A1 A2 B1 B2 CDE
Useoflanca OR ref 0.9 0.6 0.4 0.2
95%CI 0.4,1.9 0.2,1.3 0.2,1.1 0.1,0.8
p 0.70 0.20 0.10 0.03
Useofinhalantdrugsotherthanlanca OR ref 0.7 0.6 0.5 0.3
95%CI 0.4,1.1 0.3,0.9 0.3,0.9 0.1,0.7
p 0.100 0.020 0.020 0.003
Drinkingofalcoholicbeverages OR ref 0.6 0.5 0.6 0.7
95%CI 0.4,0.9 0.3,0.8 0.3,0.9 0.4,1.4
p 0.020 0.002 0.020 0.400
Smokingoftobacco OR ref 0.6 0.6 0.5 0.4
95%CI 0.4,0.8 0.4,0.8 0.3,0.7 0.2,0.8
p 0.003 0.004 0.001 0.004
UseofinternationallyregulateddrugsIRD OR ref 0.5 0.3 0.4 Nonewlyincidentusers
95%CI 0.2,0.9 0.1,0.7 0.2,0.9
p 0.040 0.008 0.030
SES:socialrankaccordingtoABEPclassification;OR:oddsratioestimatefromconditionalformoflogisticregression,withageandsexascovariatesinthemodel,where‘ref’ indicatesthatthehighestsocialrankservedasthereferencecategoryforestimationoftheoddsratios;CI:confidenceinterval;p:p-valueunderthenullhypothesisofno associationbetweenSESanddruguseoccurrenceasstudiedhere.
Table4
UnadjustedoddsratiosestimatedfromconditionallogisticregressionforSESinrelationtorecentlyactive(pastmonth)druguse,withclassroom-levelmatching.Datafrom privateschoolsurvey,SaoPaulo,Brazil,2008.
Recentlyactive SES A1 A2 B1 B2 CDE
Useoflanca OR ref 0.8 0.5 0.4 0.2
95%CI 0.4,1.7 0.2,1.1 0.2,0.9 0.1,0.8
p 0.50 0.09 0.04 0.02
Useofinhalantdrugsotherthanlanca OR ref 0.9 1.2 0.9 1.1
95%CI 0.4,2.0 0.5,3.1 0.3,2.7 0.2,4.6
p 0.7 0.6 0.9 0.9
Drinkingofalcoholicbeverages OR ref 0.8 0.6 0.5 0.5
95%CI 0.6,0.9 0.4,0.7 0.4,0.7 0.4,0.8
p 0.020 <0.001 <0.001 0.001
Smokingoftobacco OR ref 0.6 0.5 0.3 0.4
95%CI 0.4,0.8 0.3,0.7 0.2,0.5 0.2,0.8
p 0.003 <0.001 <0.001 0.004
UseofinternationallyregulateddrugsIRD OR ref 0.6 0.4 0.4 0.3
95%CI 0.4,0.9 0.2,0.5 0.3,0.7 0.1,0.5
p 0.010 <0.001 <0.001 <0.001
SES:socialrankaccordingtoABEPclassification;OR:oddsratioestimatefromconditionalformoflogisticregression,noothercovariatesinthemodel,where‘ref’indicates thatthehighestsocialrankservedasthereferencecategoryforestimationoftheoddsratios;CI:confidenceinterval;p:p-valueunderthenullhypothesisofnoassociation betweenSESanddruguseoccurrenceasstudiedhere.
Table5
Covariate-adjustedoddsratiosestimatedfromconditionallogisticregressionforSESinrelationtorecentlyactive(pastmonth)druguse,withclassroom-levelmatching. Datafromprivateschoolsurvey,SaoPaulo,Brazil,2008.
Recentlyactive SES A1 A2 B1 B2 CDE
Useoflanca OR ref 0.9 0.6 0.4 0.2
95%CI 0.4,1.8 0.3,1.3 0.2,1.1 0.1,0.8
p 0.60 0.10 0.07 0.03
Useofinhalantdrugsotherthanlanca OR ref 0.9 1.2 1.0 1.3
95%CI 0.4,2.0 0.5,3.0 0.3,3.0 0.3,5.7
p 0.7 0.6 0.9 0.7
Drinkingofalcoholicbeverages OR ref 0.8 0.6 0.5 0.5
95%CI 0.6,1.01 0.4,0.8 0.4,0.7 0.4,0.8
p 0.060 <0.001 <0.001 <0.001
Smokingoftobacco OR ref 0.6 0.5 0.3 0.4
95%CI 0.5,0.9 0.3,0.7 0.2,0.5 0.2,0.7
p 0.006 <0.001 <0.001 0.002
UseofinternationallyregulateddrugsIRD OR ref 0.7 0.4 0.4 0.3
95%CI 0.5,0.9 0.3,0.6 0.3,0.7 0.1,0.5
p 0.030 <0.001 0.001 <0.001
differentforthelowestsocialrankyouthsascomparedtothe high-estsocialrankyouthsintheirmatchedclassrooms(Tables2and3). Tables4and5provideasimilarpatternoffindingsforrecently activeuseofthesedrugcompounds,withthecomplexitythatthe observedprevalentuseroddsratiosdonotclarifywhetherthe asso-ciationsunderstudyhavetodowithsocialrankandbecominga druguserversussocialrankversussocialrankandpersistingin druguse,giventhatprevalenceofdrugusevariesasafunctionof boththeincidenceofbecomingauser,aswellasthedurationofuse onceithasstarted.Nonetheless,theseestimatesarepresentedfor readersnotaccustomedtothedistinctionbetweenincidenceand prevalence,andwhomightnotappreciatethatprevalence relation-shipsfailtoclarifywhethertheprocessesunderstudyaredynamic inrelationtotheirinfluenceon(orassociationwith)becominga druguserversuswhethertheprocessesunderstudyarestaticin relationtotheirinfluenceon(orassociationwith)durationofdrug useonceitstarts.
4. Discussion
4.1. Recapofmainfindings
Withrespecttothelancausephenomenoninthisurbancontext ofBrazil,threesubstantivefindingsemergefromthiswork.First, ashypothesized,viaALRmodeling, wehavediscovered within-classroomclustersoflancause,consistentwiththeoriginalconcept oflancaasadrugpassedfrompeertopeerwithinsocialgroups. Second,viaCLRmodeling,wehavediscoveredevidencethatlanca involvementmaydependuponsocialrank,suchthatlowersocial rankstudentswithinprivilegedprivateschoolsofBrazilareless likelytobecomenewlyincidentusersoflancaandarelesslikely tohaveused lancarecently.Third,theobserveddirect associa-tionlinkingsocialranktolanca involvementisnot likelytobe due tobackground confounding by age,sex, or sociallyshared within-classroomcharacteristicssuchasdrugpreventionprogram variables,localattitudes,orculturalnormsofintolerancefordrug use.Therealsowasasocialrankgradientfortheuseofinhalants otherthanlancaandfortobaccosmoking,aswellasasocialrank gradientforcannabisandotherIRD,butnotfordrinkingalcohol. Here,wemustofferareminderaboutthisstudy’sboundariesof inference.ThelowerSESstudentswhoattendprivateschoolsin SaoPaulocannotberegardedasarandomsampleofalllowerSES youthsinthecity.Itfollowsthattheboundariesofinferencemust besetinrelationtoschoolcontextandwhatwehavecalledthe ‘ecologicalniche’oftheprivateschoolenvironment.
4.2. Researchissues
AsdiscussedbyPetronisandAnthony(2003)andmorerecently byKarriker-Jaffe(2011),justascorrelationdoesnotimply causa-tion,theclusteringofdrugusewithinageographicalareaorwithin aclassroomdoesnot implyhandtohandsharingofdrugsor a socialdiffusionor‘contagion’process.Whenthereisgeographical concentrationofdrugusingbehavior,onepotentialexplanation isa‘birdsofafeatherflocktogether’process,asdiscussedinthis study’sintroduction.Thisparticularprocess wouldnot seemto operatewhenclassroomclusteringofdruguseisobserved,except when students self-select their classrooms, which was not the caseinthisstudy.However,schoolsareknownto‘track’students, makingclassroomsmorehomogeneouswithrespecttoobserved characteristicssuchas studentachievement test scoresor past violationsofschoolrules(e.g.,withrespecttodisruptivebehavior). Wedonotbelievethatthistypeofschool-driventrackingprocess hasproducedtheobservedwithin-classroomclustersofdrugusein thisstudy,butwedonothavefirmevidenceagainstthispossibility.
Forthisreason,thisstudy’sclusteringestimatesrepresenta mod-est step forward in our understanding of the epidemiology of lancaandotherdruguse.Futureresearchcanattempttoclarify thedegreetowhich theclustering isdue tosocial diffusionor peer-to-peerdrugsharingprocesses,versusalternativeprocesses suchasschool-driventrackinginclassroomassignments.
Innewandmoreprobingresearch,amixedmethodsapproach combiningquantitativesurveyanalysiswithqualitative interview-ing and social network analysis may help clarify the dynamic processesthatproducelancaclusteringand theobservedsocial rankgradient (Tashakkoriand Teddlie,2010).Nevertheless,the clusteringevidencecoupledwiththeevidenceofadirectSES-lanca associationlendsomesupporttoourhypothesisthatlancause fol-lowsasocialrankgradientperhapsduetoselectivesharingoflanca withinthehighersocialrankpeergroups.
Ethnographershaveinvestigatedhowdrugusingcontextsare associatedwithdrugpreferencesandpracticesofdruguse.Zinberg (1984)inastudyamongheroinuserspointedtotheimportanceof whathecalled“set”(thesocialgroupanditsnormsandvalues)and “setting”(thesocialcontextsofuse),whichjointlycandetermine anindividual’sdrugusepractices,inadditiontodrugeffectsperse. Fletcheretal.(2009)notethatdrugusemayenhancepeergroup affiliationprocessesbyhelpingnewmembersexpressa charac-teristicthatisvaluedwithinthesocialgroup.Bishopetal.(2005) joinBurke(2004)infocusingattentiononprocessesofidentity formationduringsocialinteractionswithclassmates.
Thisstudy’sevidenceonthegeneraldirectsocialrankgradient foralldrugs(otherthanalcohol)bringstomindanotherprocess thatmightbedescribedasaformofthe‘healthystudent’effect, somewhatanalogoustoa‘healthyworker’effectinoccupational epidemiology(Shah,2009).Namely,whenstudyingthehealthof employedworkersversustheunemployed,theworkersoftenhave betterhealthstatus(i.e.,morehealthythantheirunemployedpeers inthehomeneighborhoodenvironment).Byanalogy,onemight thinkthatalowersocialrankstudentwhohadtoworkhardto beadmittedtoaprivateschoolinBrazilwouldalsohavehealth advantagesascomparedtolowersocialrankstudentsnot admit-tedtoprivateschoolsandalsoascomparedtohighersocialrank studentswhose admissiontoprivateschoolaccompaniedother privilegesofhighersocial rankofthefamilyoforigin,withless demandforexceptionallyadaptationattheleveloftheindividual’s prioracademicperformanceandbehavior.Inthisstudy,wecannot makeacomparisonoflowersocialrankstudentsinprivateversus non-privateschools,butwecandrawthecontrastofhigherversus lowersocialrankstudentswithintheprivateschoolenvironment. Ifthereisapronounced‘healthystudent’effectinthelowersocial rankstudentsinprivateschoolascomparedtothehighersocial rankstudentsinthesameprivateschool,thenitmightbemanifest inageneralpatternofdirectassociationlinkingsocialranklevels withoccurrenceofanyandallofthedrugcompoundsunderstudy, i.e.,nospecificityofthisdirectassociationwithlancaonly.
beencarriedoutusingepidemiologicalsamplesofpublicschool students,withoutcoverageofprivateschools.Infutureresearchon lanca,wehopetocombinecoverageofprivateandpublicschools inthesameepidemiologicalfieldsurveyoperationinBrazil.
4.3. Limitations
Despitetheimportantresultsfound,afewlimitationsshould bementioned.Somedegreeofnon-participationanddata miss-ingnessexcludedsomestudentsfromtheanalysis.Howeverthe levelsofparticipationwerelargerthanthoseobtainedin compa-rableUSsurveys(Johnstonetal.,2009).Additionally,assessment of drug involvement by self-report questionnaires is standard practiceglobally,butalternativessuchastoxicologicalassaysare notavailableforlancause.Hence,theremaybesomedegreeof misclassification,andperhapslowersocialrankstudentswereless likelytodisclosedrugusingbehaviorsgenerally,withtheexception ofalcoholinvolvement.Theanonymousnatureofthesurveyand theabsenceoftheteacherfromtheclassroomshouldhavehelped topromoteresponsevalidity.
Thenumberoflowsocialrankstudentsrelativetohighsocial rankstudentsconstrainedourabilitytoconductdetailedanalyses forcomparisonsamongtheextremeSESpositions(AandE).Larger samplesizesonthescaleofanationalsurveymayhelpusinfuture researchonthistopic.
Notwithstandinglimitationssuchasthese,thereisreasonto reflect upon theimplications ofthis research. Ifsuccessful,the projectmayprovidesomedegreeofguidanceforfuturetheoryand fieldstudiesonthetopicofsocialstatusanddiffusionofdrug-taking behaviorinsociety.
Wealsowouldliketonotethatthisstudywasdesignedasan efforttounderstandpriorfindingsontheepidemiologyoflancause insurveysofmedicalandotheruniversitystudents,almostallof whomattendedprivateschools.Therefore,wetookastepbackinto theecologicalnicheoftheprivateschoolsrepresentedinour sam-ple,anddidnotextendtherangeofschoolstoencompasspublic schoolstudents,whereagreaterproportionoflowSESstudentscan befound.Theresultingdiscoveriesarepertinentandvalidforthe ecologicalnicheoftheprivateschoolenvironment,andwemust appreciatethatthelowerSESstudentsinthisparticular ecologi-calnichearenotbyanymeansarandomsampleofalllowerSES studentsinBrazil.ByextendingthislineofresearchtostudySES anddruguseinallpublicandprivateschools,anullrelationship ortheexpectedinverseSESrelationshipmaybefound.Thisfuture discoverywillnotmeanthatthecurrentstudyevidenceisinvalid orbiased.Rather,suchafindingmaywellremindusofthe impor-tanceoftheecologicalnicheorschoolcontextwhenweseekto understandepidemiologicalpatternsofyouthfuldruguse.
4.4. Conclusions
Insummary,wesetouttodiscoverwhethertherewouldbe classroom level clustering of lanca use among private school studentsof theSaoPauloMega-CityinBrazil,and whetherthe occurrenceoflancausemightfollowasocialrankgradientamong privateschoolstudentsinBrazil,withanexpectationthatnewly incidentlancawouldvarybysocialrank.Theresultingevidence onSES-lancainspecificandSES-drugsingeneralcanbeusedto promoteseverallinesofmoreprobingresearchonthese associa-tionsandtheunderlyingprocessessuchassocialsharingofdrugs withinpeergroupsand social networks,aswellasphenomena suchasapossible“healthystudent”effectasmightaccountforthe observeddirectSESassociationinthecontextofprivateschools inBrazil.Giventhisstudy’sfocusedhypothesesonnewlyincident drug use, one direction for future research might involve new hypothesesaboutpersistenceofuseordrugusedisorders,how
theymightclusterwithinclassrooms andschools,and whether theyshowdifferentrelationshipswithsocialrank.
Roleoffundingsource
FundingforthisstudywasprovidedbyFAPESP(Fundac¸aode AmparoàPesquisadoEstadodeSaoPaulo)#07/50007-0and# 08/54737-6andAFIP(Associac¸aoFundodeIncentivoaPesquisa). FAPESPandAFIPhadnofurtherroleinstudydesign;inthe col-lection,analysisandinterpretationofdata;inthewritingofthe report;andinthedecisiontosubmitthepaperforpublication.
Contributors
Sanchez: statistical analysis, discussion and drafting of the manuscript.
Noto:surveyconcept,designandsupervision
Anthony:analysisconceptualization,datainterpretation, dis-cussionanddraftingofthemanuscript.
All authors contributed to and have approved the final manuscript.
Conflictofinterest
Alltheauthorsdeclarethattheyhavenoconflictsofinterest.
Acknowledgements
The authorsacknowledgeJohn Troost for hishelp withSAS management.AlsowethankFAPESPthatfundedapostdoctoral researchinternshipattheMichiganStateUniversityforthefirst authorsupervisedbythelastauthor.
AppendixA. Supplementarydata
Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.drugalcdep.2012.12.001.
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