Article
Reference
Course of serological tests in treated subjects with chronic Trypanosoma cruzi infection: A systematic review and meta-analysis
of individual participant data
SGUASSERO, Yanina, et al .
Abstract
Objective: To determine the course of serological tests in subjects with chronic Trypanosoma cruzi infection treated with anti-trypanosomal drugs. Methods: A systematic review and meta-analysis was conducted using individual participant data. Survival analysis and the Cox proportional hazards regression model with random effects to adjust for covariates were applied. The protocol was registered in the PROSPERO database (http://www.crd.york.ac.
uk/PROSPERO; CRD42012002162). Results: A total of 27 studies (1296 subjects) conducted in eight countries were included. The risk of bias was low for all domains in 17 studies (63.0%). Nine hundred and thirteen subjects were assessed (149 seroreversion events, 83.7% censored data) for enzyme-linked immunosorbent assay (ELISA), 670 subjects (134 events, 80.0% censored) for indirect immunofluorescence assay (IIF), and 548 subjects (99 events, 82.0% censored) for indirect hemagglutination assay (IHA). A higher probability of seroreversion was observed within a shorter time span in subjects aged 1–19 years compared to adults. The chance of seroreversion also varied according to the [...]
SGUASSERO, Yanina, et al . Course of serological tests in treated subjects with chronic Trypanosoma cruzi infection: A systematic review and meta-analysis of individual participant data. International Journal of Infectious Diseases , 2018, vol. 73, p. 93-101
DOI : 10.1016/j.ijid.2018.05.019
Available at:
http://archive-ouverte.unige.ch/unige:107120
Disclaimer: layout of this document may differ from the published version.
1 / 1
Review
Course of serological tests in treated subjects with chronic
Trypanosoma cruzi infection: A systematic review and meta-analysis of individual participant data
Yanina Sguassero
a,b,*, Karen N. Roberts
c, Guillermina B. Harvey
c, Daniel Comandé
d, Agustín Ciapponi
d, Cristina B. Cuesta
c, Emmaría Danesi
e, Camila Aguiar
f,
Ana L. Andrade
g, Ana M. de Castro
h, Marta de Lana
i, Josep M. Escribà
j, Diana L. Fabbro
k, Cloé D. Fernandes
l, Wendell S.F. Meira
m, María Flores-Chávez
n,
Alejandro M. Hasslocher-Moreno
o, Yves Jackson
p,q, Carlos D. Lacunza
r, Girley F. Machado-de-Assis
s, Marisel Maldonado
t, María M. Monje-Rumi
u, Israel Molina
v,w, Catalina Muñoz-San Martín
x,y, Laura Murcia
z,
Cleudson Nery de Castro
aa, Celeste A.N. Silveira
bb, Olga Sánchez Negrette
cc,dd, Manuel Segovia
ee, Aldo Solari
ff, Mário Steindel
gg, Mirtha L. Streiger
hh,
Ninfa Vera de Bilbao
t, Inés Zulantay
y, Sergio Sosa-Estani
b,d,iiaCentroRosarinodeEstudiosPerinatales,Rosario,Argentina
bConsejoNacionaldeInvestigacionesCientíficasyTécnicas,BuenosAires,Argentina
cFacultaddeCienciasEconómicasyEstadística,UniversidadNacionalideRosario,Argentina
dInstitutodeEfectividadClínicaySanitaria,BuenosAires,Argentina
eCentroNacionaldeInvestigaciónyDiagnósticoenEndemoepidemias(CeNDIE-ANLIS),BuenosAires,Argentina
fFaculdadedeCiênciasMédicas,UniversidadeEstadualdeCampinas,Brazil
gDepartamentodeSaúdeColetiva,InstitutodePatologiaTropicaleSaúdePública,UniversidadeFederaldeGoiás,Goiânia,Goiás,Brazil
hInstitutodePatologiaTropicaleSaúdePública,UniversidadeFederaldeGoiás,Goiânia,Goiás,Brazil
iDepartamentodeAnáliseClínica,UniversidadeFederaldeOuroPreto,Brazil
jMedicalDepartment,DoctorsWithoutBorders,Barcelona,Spain
kCentrodeInvestigacionessobreEndemiasNacionales(CIEN),FacultaddeBioquímicayCienciasBiológicas,UniversidadNacionaldelLitoral,SantaFe, Argentina
lInstitutodePesquisaBiológica,LaboratórioCentral,FundaçãoEstadualdeProduçãoePesquisaemSaúde,PortoAlegre,RS,Brazil
mDepartamentodeMicrobiologia,ImunologiaeParasitologia,UniversidadeFederaldoTrianguloMineiro,Brazil
nUnidaddeLeishmaniasis,ServiciodeParasitología,InstitutodeSaludCarlosIII,Madrid,Spain
oInstitutoNacionaldeInfectologiaEvandroChagas,Fiocruz,Brazil
pDivisionofPrimaryCareMedicine,GenevaUniversityHospitals,Geneva,Switzerland
qInstituteofGlobalHealth,UniversityofGeneva,Geneva,Switzerland
rDireccióndePrimerNiveldeAtención,ÁreaOperativaNLV,Salta,Argentina
sDepartamentodeCiênciasBásicasdaVida,UniversidadeFederaldeJuizdeFora,Brazil
tDepartamentodeMedicinaTropical,InstitutodeInvestigacionesenCienciasdelaSalud,UniversidadNacionaldeAsunción,Paraguay
uLaboratoriodePatologíaExperimental,UniversidadNacionaldeSalta,Salta,Argentina
vInfectiousDiseasesDepartment,HospitalUniversitarioValld’Hebron,Barcelona,Spain
wInternationalHealthProgramoftheCatalanInstituteofHealth,Barcelona,Spain
xLaboratoriodeEcología,FacultaddeCienciasVeterinariasyPecuarias,UniversidaddeChile,Santiago,Chile
yLaboratoriodeParasitologíaBásico-ClínicoInstitutodeCienciasBiomédicas,FacultaddeMedicina,UniversidaddeChile,Santiago,Chile
zUnidadRegionaldeMedicinaTropical,ServiciodeMicrobiología,HospitalUniversitarioVirgendelaArrixaca,ElPalmar,Murcia,Spain
aaFaculdadedeMedicina,UniversidadeCatólicadeBrasília,Brazil
bbNúcleodeMedicinaTropical,FaculdadedeMedicina,UniversidadedeBrasília,Brazil
ccCátedradeInmunología,FacultaddeCienciasAgrariasyVeterinarias,UniversidadCatólicadeSalta,Argentina
ddCátedradeQuímicaBiológica,FacultaddeCienciasExactas,UniversidadNacionaldeSalta,Argentina
eeDepartamentodeGenéticayMicrobiología,UniversidaddeMurcia,Espinardo,Murcia,Spain
ffProgramadeBiologíaCelularyMolecular,ICBM,FacultaddeMedicina,UniversidaddeChile,Santiago,Chile
ggDepartamentodeMicrobiologia,ImunologiaeParasitologia,UniversidadeFederaldeSantaCatarina,Brazil
hhCentrodeInvestigacionessobreEndemiasNacionales(CIEN),FacultaddeBioquímicayCienciasBiológicas,UniversidadNacionaldelLitoral,SantaFe,
https://doi.org/10.1016/j.ijid.2018.05.019
1201-9712/©2018PublishedbyElsevierLtdonbehalfofInternationalSocietyforInfectiousDiseases.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://
creativecommons.org/licenses/by-nc-nd/4.0/).
ContentslistsavailableatScienceDirect
International Journal of Infectious Diseases
j o u r n a l h o m ep a g e : w w w . e l s e v i e r . c o m / l o c a te / i j i d
Argentina
iiInstitutoNacionaldeParasitología,FatalaChaben-ANLIS,BuenosAires,Argentina
ARTICLE INFO Articlehistory:
Received1March2018
Receivedinrevisedform26May2018 Accepted29May2018
CorrespondingEditor:EskildPetersen,Aar- hus,Denmark
Keywords:
Trypanosomacruzi Chronicdisease Follow-upstudies Individualparticipantdata Meta-
analysis Serologictests
ABSTRACT
Objective: Todeterminethecourse ofserological tests insubjects withchronicTrypanosomacruzi infectiontreatedwithanti-trypanosomaldrugs.
Methods: A systematicreview and meta-analysiswas conductedusing individualparticipant data.
SurvivalanalysisandtheCoxproportionalhazardsregressionmodelwithrandomeffectstoadjustfor covariateswereapplied.TheprotocolwasregisteredinthePROSPEROdatabase(http://www.crd.york.ac.
uk/PROSPERO;CRD42012002162).
Results:Atotalof27studies(1296subjects)conductedineightcountrieswereincluded.Theriskofbias waslowforalldomainsin17studies(63.0%).Ninehundredandthirteensubjectswereassessed(149 seroreversion events, 83.7% censored data) for enzyme-linked immunosorbent assay (ELISA),670 subjects(134events,80.0%censored)forindirectimmunofluorescenceassay(IIF),and548subjects(99 events,82.0%censored)forindirecthemagglutinationassay(IHA).Ahigherprobabilityofseroreversion wasobservedwithinashortertimespaninsubjectsaged1–19yearscomparedtoadults.Thechanceof seroreversionalsovariedaccordingtothecountrywheretheinfectionmighthavebeenacquired.For instance,thepooledadjustedhazardratiobetweenchildren/adolescentsandadultsfortheIIFtestwas 1.54(95%confidenceinterval0.64–3.71)forcertaincountriesofSouthAmerica(Argentina,Bolivia,Chile, andParaguay)and9.37(95%confidenceinterval3.44–25.50)forBrazil.
Conclusions:Thedisappearanceofanti-T.cruziantibodieswasdemonstratedalongthecourseoffollow- up.Aninteractionbetweenageattreatmentandcountrysettingwasfound.
©2018PublishedbyElsevierLtdonbehalfofInternationalSocietyforInfectiousDiseases.Thisisanopen accessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Contents
Introduction ... 94
Methods ... 95
Studydesign ... 95
Outcomes ... 95
Datacollection ... 95
Statisticalanalysis ... 95
Results ... 96
Discussion ... 98
Acknowledgements ... 99
References ... 100
Introduction
Chagas disease is a potentially life-threatening endemic illnessinthe Latin America region(Bulla et al.,2014; Pérez- MolinaandMolina,2018).Itiscausedbyaprotozoanparasite calledTrypanosomacruzi.Thisparasitehasbeenclassifiedintosix geneticvariants withapproximate geographical distribution in domesticandwildtransmissioncycles(Zingalesetal.,2012).Itis mainlytransmittedthroughvectors(namelytriatominebugs)in impoverishedruralareas(Houwelingetal.,2016Pérez-Molinaand Molina,2018).Bloodtransfusionandcongenitaltransmissionare other mechanisms for acquiring the disease. Alternative mechanismsare accidental, oral, and via organ transplantation (Diasand Amato Neto,2011; Ministerio deSaludde laNación, 2012).
Thedurationandclinicalpresentationoftheinitialacutephase oftheinfectionmaybevariable,dependingonthepatient’sage, immunologicalstatus,presenceofcomorbidities,andthetrans- mission pathway. It usually lasts a few months and may be symptomatic(prolongedfebrilesyndrome,asthenia,hepatosple- nomegaly,andothercharacteristicbutlessfrequentsigns,suchas R-
o-
maña sign and ‘chagoma’ of inoculation) or asymptomatic (MinisteriodeSaluddelaNación,2012).
Mostsubjectswhodonotreceivespecifictreatmentduringthe acutephasegoontodevelopachronicinfection.Ifuntreated,the chronicphaseusuallycontinuesforthesubject’slifetime,and30%
to40%ofpatientswillprogresstothechronicphasewithacardiac, digestive,neurological,ormixedformat15to30yearsafterthe initialinfection.Progressiveheartfailureandsuddendeatharethe maincausesofdeathinpatientswithchronicChagasheartdisease (MinisteriodeSaluddelaNación,2012;Pérez-MolinaandMolina, 2018).
Severalsystematicreviewsontheeffectivenessoftreatmentin chronicallyinfectedsubjectshavebeenpublished(Villaretal.,2014;
Fuentesetal.,2012;Pérez-Molinaetal.,2009;VallejoandReyes, 2005).ThecurrentrecommendationoftheWorldHealthOrganiza- tion(WHO)istoofferanti-trypanosomaldrugs(benznidazoleor nifurtimox)tosubjectswithchronicTrypanosomacruziinfection, particularlythosewhoareasymptomatic(Bullaetal.,2014).Based oncurrenttechniquesandtheirattributes,thegeneralconsensusis thattreatmentsuccessisconfirmedby conversionfromapositiveto anegativeserologicalstate(seroreversion),whiletreatmentfailure is demonstratedthrougha positivemolecularorparasitological test.Theassessmentoftheresponsetotreatmentisuncertainina large number of subjects because of the long span needed to demonstratethedisappearanceofanti-T.cruziantibodies(deLana andMartins-Filho,2009;Viottietal.,2014).
* Correspondingauthorat:CentroRosarinodeEstudiosPerinatales(Argentinean CochraneCentre),Moreno878,S2000DKRRosario,Argentina.
E-mailaddress:ysguassero@crep.org.ar(Y.Sguassero).
94 Y.Sguasseroetal./InternationalJournalofInfectiousDiseases73(2018)93–101
Inthiscontext,itwassoughttoanswerthefollowingquestion:
When and to what extent does the administration of anti- trypanosomal drugs result in the negativization of serological teststhroughthecourseoffollow-up?Thepresentresearchgroup previouslypublishedaprognosticsystematicreviewoffollow-up studiesincludingchronicallyinfectedandtreatedsubjectsasafirst attempttoaddresstheresearchquestion.Theresultsofthatreview showedadynamicpatternofserologicalresponse;however,pre- plannedsecondaryanalyseswereincompleteduetothelimited utilityofaggregatedata(Sguasseroetal.,2015).Asaconsequence, ameta-analysisofindividualparticipantdata(IPD)wasconducted consideringalllaboratorytestsperformedaftertreatment(Riley etal.,2010;Stewartetal.,2015).Thepurposeofthisarticleisto presentthecourseofserologicaltestsanddescribetheeffectof explanatoryfactorsonthetimetoseroreversionintreatedsubjects with chronic Trypanosoma cruzi infection. The hypothesis was based on previous research suggesting an earlier reversion of conventionalserologytonegativeresultsintreatedsubjectswith an‘earlychronicinfection’(childrenandadolescents)comparedto thosewitha‘latechronicinfection’(adults).
Methods Studydesign
Thismeta-analysiswas performedaccording totheprotocol registeredintheinternationaldatabaseofprospectivelyregistered systematicreviews,PROSPERO(http://www.crd.york.ac.uk/PROS- PERO, registration number CRD42012002162) in March 2012 (Sguassero et al., 2012). All studies shared unidentified data;
henceindividualconsentforthereuseofparticipantdatawasnot sought.
The inclusion and exclusion criteria have been detailed elsewhere(Sguasseroetal.,2015).Cohortstudiesandrandomized controlled trials (RCTs) with follow-up data on serological, molecular, and parasitological outcomes measured in subjects withadefinitediagnosisofchronicTrypanosomacruziinfection, who received benznidazole and/or nifurtimox, were included.
Subjectsintheacutephase,childrenaged12monthsoryounger borntoinfectedmothers,immunocompromisedparticipants,and pregnantwomenwereexcluded.Twoauthors,onewithtrainingin systematicreviews(YS)andoneexpertinthefield(SSE),identified potentially eligible studies. YS also screened the references of relevantstudies.Disagreementswereresolvedbydiscussion.The electronicsearchstrategiesusedhavebeendescribedpreviously;
there was no restriction on language or year of publication (Sguasseroetal.,2015).
TheelectronicsearchesintheCochraneDatabaseofSystematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL),Database of Abstractsof Reviews ofEffects (DARE), MEDLINE(SupplementaryMaterial,AnnexA,TableS1),Embase, andLILACSwereupdatedonJuly1,2015.Threeneweligiblestudies were identified (Bianchi et al., 2015; Andrade et al., 2013; de Oliveira,2013).Inaddition,theprotocolwaspresentedtoexperts inthefieldandthreefurtherstudieswereidentifiedbycontacting the principal investigators(Morillo et al., 2015; Lacunza et al., 2015;Guhletal.,2004).
Tworeviewauthors(YSandAC)independentlyassessed the riskofbiasofincludedstudiesusingthetoolsrecommendedbythe CochraneCollaboration(Higgins and Green, 2011; Sterneetal., 2016). A data extraction template withthe following principal domainsofbiaswasused:selectionofparticipantsintothestudy, measurementoftheintervention,measurementofoutcomes,and missingdata.Thejudgmentregardingtheoverallriskofbiasfor each serologicaloutcome was rated as low,moderate, or high.
Studieswithalowriskofbiasforallkeydomainsorstudieswhere
itseemedunlikelythatbiaswouldhavealteredtheresultswere consideredtohavealowriskofbias.Studieswithariskofbiasinat leastonedomainwereconsideredtohaveanoverallriskmatching the higher level of bias identified that decreases the grade of certainty.Discrepancieswereresolvedthroughdiscussionwitha thirdauthor(SSE).
Outcomes
Primaryoutcomesweretheresultsofconventionalserological tests,suchastheenzyme-linkedimmunosorbent assay(ELISA), indirectimmunofluorescence(IIF)assay,andindirecthemaggluti- nationassay(IHA).Secondaryoutcomesweretheresultsofnon- conventional ‘in-house’ serological testsbasedonrecombinant/
syntheticor biochemicallypurifiedantigensspecificallyusedto monitorchangesafteranti-trypanosomaltreatment.Theresultsof serological tests weredichotomizedas reactive ornon-reactive (negativeresult)independentlyofeach other.Itwasdecidedto analyze thetechniques separately given thevariability of their performanceindemonstratingserologicalchangesovertime.The dependentvariablewasdefinedasthetimeelapsedfromtheend oftreatmenttothefirstnegativeresultofeachserologicaltestas measuredbytheauthors.Nocompositeoutcomesweredefinedat theprotocolstage.
Datacollection
Asystematicapproachtorequest,collect,andmanageIPDwas undertaken(Stewartetal.,2015).Allcorrespondingorprimary authorswereinvitedtoparticipateinthisresearchbye-mail.In thecaseofanon-response,thecontactdetailswerecheckedand the website of universities or other research organizations exploredtofindanewe-mailaddress.Atleastthreerounds of e-mailsperinvestigatorwerelaunchedbythesameperson(YS).
Insomecases,amemberofthereviewteam(SSE)sentaletterof invitationormadeaphonecall.Thestrategydevelopedhadthree basicsteps.Thefirste-mailintendedtopresenttheresearchand providedalinktothesystematicreviewprotocol.Theimportance of themeta-analyticalapproachwasexplainedin briefandthe investigators wereinvited toparticipate. A second e-mailwas sent to those collaborators expressing their willingness to contribute;thise-mail includedalink toa shortonlinesurvey aimedatgatheringbaselineinformation(availabilityofprimary studyprotocol,theformatofthestudydataset,thetimeneeded to send the original data, etc.), and a section toupdate their contact details. Following this, a third e-mail was sent that includedadetaileddescriptionofthepieceofinformationneeded foreachoutcomeofinterest,anagreementondatasecurityand co-authorshiptobesigned,andrecommendationsforencrypted datasharing.
Concerning the variables of interest, collaborators provided individual-leveldataatbaseline(sex,ageattreatment,ageatstudy entry,countryoforigin,thenameoftheanti-trypanosomaldrug, thedoseandlengthoftreatment)andduringthefollow-up(dates ofmeasurementsandresultsofallavailablelaboratorytests).The internal consistencyofIPD foreach studydatasetwas checked independentlybytwoauthors(YSandKR),takingintoaccountthe informationpublishedintheoriginalreports.Minorquerieswere resolved by reaching a consensus; however, any specific IPD inconsistency was resolved by seeking clarification from the collaborators (YS). Any inaccuracies or errors were properly discussedandallamendmentswereregisteredbeforemerginga studydatasetintothemasterfile(YSandKR).Missingdatawere also requested, whenever appropriate (YS). All collaborators answeredane-mail abouttheriskof reinfection intheirstudy population.
Statisticalanalysis
Theone-stageIPDmeta-analysiswasfollowedasstatedatthe protocol stage. Two functions that are dependent on time for describingthedistributionofeventtimes(thesurvivalandhazard functions)wereestimated(Pococketal.,2002;Collett,2003).The Kaplan–Meiermethodwasusedtoobtainunivariatedescriptive survivaldataontwoormoregroupsofsubjects(Collett,2003).The Coxproportionalhazardsregressionmodelwithrandomeffects was applied to adjust for pre-specified covariates of clinical relevance. In this model, the time was assembled in years as providedinmostdatasets.Theexcessriskorfrailtyfordistinct studieswasdescribed usingthevariancecomponentofrandom effects and the corresponding Kendall’s Tau coefficient (^
t
)(Therneau and Grambsch, 2000). Hazard ratios (HR) and 95%
confidenceintervals(CI)werecalculated.
Subgroup analyses were performed based onpotential pre- dictorsoftreatmentresponseinthechronicphaseofTrypanosoma cruzi infection, such as the age of the subject at treatment (children/adolescents vs. adults) and the country where the subjectwas born,asa surrogate forthelineage of theparasite (Argentina,Bolivia,Chile,andParaguayvs.Brazil)(Zingalesetal., 2012).
TakingadvantageofavailableIPDonpolymerasechainreaction (PCR) or xenodiagnosis after treatment, the study participants were assigned to the following three post-hoc categories:
‘potentialresponders’,i.e. subjectswiththreeor morenegative PCRorxenodiagnosisresults;‘uncertainresponders’,i.e.subjects withatleasttwonegativePCRorxenodiagnosisresults;and‘non- responders/potentialnon-responders’,i.e.subjectswithjustone PCRorxenodiagnosis(positiveornegative).
Theeffectoftheriskofbiaswasexploredthroughasensitivity analysis.ThesurvivalanalysesforthisstudyweredoneusingSAS version9.4.Ap-valueoflessthan0.05wasconsideredstatistically significant.Itwasnotpossibletouseaggregatedatafromstudies forwhichIPDwerenotobtainedbecausetime-to-eventanalysis requiresindividual-leveldata.
Results
A total of 24 cohort studies and three RCTs (1296 subjects) reportingonserologicaloutcomeswereincluded(Figure1;Table1 (Lacunzaetal.,2015;Molinaetal.,2014;Fabbroetal.,2014;Jackson etal.,2013;Machado-de-Assisetal.,2013;Muñozetal.,2013;Rumi et al., 2013; Aguiar et al., 2012; Machado-de-Assis et al., 2012;
Hasslocher-Moreno,2010;Murciaetal.,2010;deLanaetal.,2009;
Escribàetal.,2009;Fernandesetal.,2009;Sosa-Estanietal.,2009;
SánchezNegretteetal.,2008;deCastroetal.,2006;Flores-Chávez etal.,2006;VeradeBilbaoet al.,2006;Meiraetal.,2004;Streiger etal., 2004; Vera de Bilbao etal., 2004;Solari et al., 2001; Silveira etal., 2000;
Sosa-Estanietal.,1998;deAndradeetal.,1996;Maldonadoetal., 1995). For studies conducted before the 1990s or for whichthe
Figure1.PRISMAIPDflowdiagram.
*Numberobtainedfrompublishedreports.|Asubjectcouldhavemorethanonereasonforexclusion.IPD,individualparticipantdata;RCT,randomizedcontrolledtrial.
96 Y.Sguasseroetal./InternationalJournalofInfectiousDiseases73(2018)93–101
Table1
Studiesforwhichindividualparticipantdataonserologicaloutcomeswasprovided,categorizedbycountry,durationoffollow-up,areaofendemicity,treatment,andtypeof test(27studies,1296treatedsubjectswithchronicTrypanosomacruziinfection).
Source StudyIDa Maximum duration follow-up (months)
Areaof endemicity
Riskof reinfection
Ageat treatment (years)
Anti- trypanosomal drug
NumberoftreatedsubjectswithIPDfortime-to- eventanalysis
Totalnumber ofsubjects with serologyb Parasitological
tests
Conventional serologicaltest
Non- conventional serological test
XD PCR ELISA IIF IHA
Argentina Lacunza etal.(2015)
69 Yes No 16–34 Benznidazole – 52 38 – 39 – 39
Fabbroetal.
(2014)
401 No No 6–45 Benznidazole
and Nifurtimox
– – 47 52 52 – 52
Rumietal.
(2013)
60 Yes No 3–16 Benznidazole – 45 45 – 45 – 45
Streiger etal.(2004)
288 No No 1–14 Benznidazole
and Nifurtimox
21 – 26 48 48 – 48
Sosa-Estani etal.(2009)
144 Yes No 6–14 Benznidazole – – 16 16 16 16 –
SosaEstani etal.(1998)
48 49 46 53 53 52 53 53
Sánchez Negrette etal.(2008)
66 Yes No 19–41 Benznidazole – – 18 – 18 18 18
Totalnumberofsubjects–Argentina 255
Brazil Machado- de-Assis etal.(2013)
156 Yes No 6–37 Benznidazole – 27 26 – – 22 26
deLanaetal.
(2009) Aguiaretal.
(2012)
348 Yes No 8–56 Benznidazole – 29 29 29 – – 29
Machado- de-Assis etal.(2012)
432 Yes No 2–60 Benznidazole – 94 94 94 94 94 94
Hassslocher- Moreno (2010)
204 No No 16–56 Benznidazole 62 – – 62 – – 62
Fernandes etal.(2009)
36 Yes No 17–48 Benznidazole – 80 80 80 – – 80
deCastro etal.(2006)
44 Yes NK 23–76 Benznidazole – 37 37 37 37 – 37
Meiraetal.
(2004)
50 Yes No 10–61 Benznidazole – 31 31 – 31 – 31
Silveiraetal.
(2000)
204 Yes NK 7–12 Benznidazole
and Nifurtimox
38 28 37 37 37 – 37
deAndrade etal.(1996)
36 Yes No 8–11 Benznidazole – – 58 58 58 58 58
Totalnumberofsubjects–Brazil 454
Bolivia Flores- Chavezetal.
(2006)
12 Yes No 5–10 Benznidazole 22 33 33 22 – 33 33
Totalnumberofsubjects–Bolivia 33
Chile Muñozetal.
(2013)
57 Yes No 22–48 Nifurtimox 21 21 – 21 – – 21
Solarietal.
(2001)
36 Yes No 1–10 Nifurtimox 37 37 37 – 37 – 37
Totalnumberofsubjects–Chile 58
Honduras Escribàetal.
(2009)
51 Yes No 1–18 Benznidazole – – 227 – – – 227
Totalnumberofsubjects–Honduras 227
Paraguay Verade Bilbaoetal.
(2006)
120 Yes No 9–11 Benznidazole – – 5 5 – – 5
Verade Bilbaoetal.
(2004)
24 Yes No 7–14 Benznidazole 20 20 20 20 – – 20
Maldonado etal.(1995)
Totalnumberofsubjects–Paraguay 25
Spain Molinaetal.
(2014)
12 No No 27–60 Benznidazole – 25 26 – – – 26
30 No No 2–74 Benznidazole – 138 181 181 – – 181
primaryauthor haddied,no attempt to obtainoriginal raw data wasmade.ItwasnotpossibletoobtainIPDfrom21cohortstudies (Figure 1); some of themare known to belost (Supplementary Material,AnnexB).Threeeligiblestudiesinvolvingchildrencouldbe reachableinthefuture:twostudieswerefromColombia(n=79)and reportedupto42.0%ofseroreversionafter30monthsoftreatment, andonewasfromBrazil(n=46),whichreportedalmost20.0%of seroreversionafter24monthsoffollow-up.Regardingthestudies conductedinadultsthatmaystillbeaccessible,thepublishedrateof seroreversionrangedfrom5%after5–10yearsoftreatmentto45.0%
injustonecohortstudyreportingon55treatedsubjectslivingina non-endemic area after more than 20 years of follow-up (SupplementaryMaterial,AnnexA,TableS2).
Thetotalavailablefollow-upforserologicaloutcomeswas6847 person-years(median3.0yearsperperson,interquartilerange1.5– 7.0years).Benznidazolewasusedastheonlytreatmentofchoicein 24 out of 27 included studies. The most common duration of treatmentwas 31to60days(959subjects) (SupplementaryMaterial, AnnexA,TableS3).Mostoftheincludedstudiesreportedatleasttwo serologicaltests.Non-conventionalserologyresultswereprovided insevenstudiesandmolecularorparasitologicaltestresultswere providedin20studies(Table1).Theriskofbiaswaslowforall domainsin17studies(63.0%),moderateinfive(18.5%),andhighin anotherfive(SupplementaryMaterial,AnnexA,FigureS1).
NoissueswereencounteredwhencheckingIPDintegrity.The highestrateofmissingIPDwasaround15.0%forELISA.Sample sizesbeyond10yearsoffollow-upweresmall.Theapproachused formeasuringthevariationamongstudiesrevealedthat
t
^was0.63 forELISA,0.58forIIF,and0.47forIHA.Atotal913subjects(149seroreversionevents,83.7%censored data)wereassessed for ELISA, 670 subjects (134 events, 80.0%
censoreddata)forIIF,and548subjects(99events,82.0%censored data)forIHA.Ahigherprobabilityofseroreversionwasobserved withina shortertime spanin treatedsubjectsaged 1–19years comparedtoadults.Inthisrespect,after11–13yearsoffollow-up, therewasa0.50 probabilityofseroreversioninthesubgroupof treatedchildrenandadolescentslivinginArgentina,Bolivia,Chile, andParaguay.Whenconsideringthesametimeaftertreatmentfor the subgroup of Brazilian children and adolescents, a similar probabilityof 0.55was observed for theELISAtest. Insubjects treatedasadults,theprobabilityofseroreversionafter11yearsof treatmentwasaround0.90(Figure2).Therewerenostatistically significantdifferencesintheriskofseroreversionbetweenfemale andmalesubjectsforanyoftheserologicaltests(datanotshown).
By using non-conventional serology test results, an earlier probabilityof seroreversioncouldalsobeinferred comparedto conventionalserologyinchildrenandadolescents(Supplementary Material, Annex A, Table S4 and Figure S2). No statistically significantdifferenceamongsurvivalcurvesstratifiedbycategory usingavailablePCRorxenodiagnosisIPDwasfound(Supplemen- taryMaterial,AnnexA,TableS5andFigureS3).
TheadjustedCoxmodeldemonstratedtheinteractionbetween age at treatmentand countrysetting. The pooled adjusted HR betweensubjectsaged1–19yearsattreatmentincomparisonto adultsvariedaccordingtothecountrywheretheinfectionmight have beenacquired.In theregionof Brazil, a higher chanceof seroreversionwas foundin children and adolescentscompared toadults:HR6.60(95%CI2.03–21.42)forELISA,HR9.37(95%CI 3.44–25.50)forIIF,andHR5.55(95%CI1.46–21.11)forIHA.No statisticallysignificantdifferenceswerefoundforthiscomparison inArgentina,Bolivia,Chile,andParaguay(Table2).Thesensitivity analysiswasnotinformative(SupplementaryMaterial,AnnexA, TableS6).
Discussion
Thisappearstobethefirstmeta-analysisusingIPDinsubjects withchronicTrypanosomacruziinfectionwhohadreceivedanti- trypanosomaldrugs.Theresultsprovideanimprovedpictureof thekineticsofanti-T.cruziantibodiesindifferentcountrysettings andshowthattheserologicalcourseaftertreatmentisvariable alongthedurationoffollow-up,asreportedpreviously(deLana and Martins-Filho, 2009; Viotti et al., 2014). Nevertheless, the single-arm study design poses limitations with regard to the inferences that can be drawn from this meta-analysis. This approach relates directly to the aim of the research and the preliminarypublishedresultsshowingscatter plotsof negative serologicaltestsinnon-treatedsubjectswithchronicTrypanosoma cruziinfectionbasedonaggregatedata(Sguasseroetal.,2015).The techniques used to measure the serological course presented differences that could be explained by the affinity during the formationoftheantigen–antibodycomplex,withtheELISAtest performing better for the detection of seroreversion. This phenomenon has been described before in two RCTs in the medium-term(deAndradeetal.,1996;Sosa-Estanietal.,1998).
Non-conventional serological tests seem to detect early the disappearance of antibodies after treatment in children and adolescentscomparedtoELISA,IIFandIHAtests.
Table1(Continued)
Source StudyIDa Maximum duration follow-up (months)
Areaof endemicity
Riskof reinfection
Ageat treatment (years)
Anti- trypanosomal drug
NumberoftreatedsubjectswithIPDfortime-to- eventanalysis
Totalnumber ofsubjects with serologyb Parasitological
tests
Conventional serologicaltest
Non- conventional serological test
XD PCR ELISA IIF IHA
Murciaetal.
(2010)
Totalnumberofsubjects–Spain 207
Switzerland Jacksonetal.
(2013)
36 No No 25–59 Nifurtimox – 37 37 – – – 37
Totalnumberofsubjects–Switzerland 37
Grandtotal 1296
ELISA,enzyme-linkedimmunosorbentassay;IIF,indirectimmunofluorescenceassay;IHA,indirecthemagglutinationassay;IPD,individualparticipantdata;NK,notknown;
PCR,polymerasechainreaction;XD,xenodiagnosis.
aThestudyidentificationincludessurnameofprimaryauthorandyearofpublication.
b Theestimateofthetotalnumberofsubjectswasbasedonthetestwiththebestnumberofindividualparticipantdata.
98 Y.Sguasseroetal./InternationalJournalofInfectiousDiseases73(2018)93–101
Possible patterns of interaction with the probability of occurrenceofseroreversionwereexplored.Theageattreatment and the country setting are two variables that merit further attentionwhen assessingtreatmentsuccess duringthe chronic phase. Whereas a positive molecular or parasitological test confirms thefailureof treatment, a negativeresultcannot rule outtheabsenceofinfectionbecauseofthelackofsensitivityinthe chronicphase ofChagasdisease.Thepatternofserologyshown according to the number and results of available PCR or xenodiagnosis tests merits a more comprehensive assessment.
Thepreliminaryobservationssuggestedabettercourseintreated subjectswithpersistentparasiteclearancemeasuredbythreeor morenegativePCRorxenodiagnosistestsaftertreatment.Among otherplausibleexplanations,seroreversioninsubjectsclassifiedas
‘non-responders/potentialnon-responders’mightbeexplainedby thetransientnatureofthePCR resultsand bytheconservative approachadoptedtodefinethecategoriesonapost-hocbasis.
Thisstudyhasthefollowingstrengths.Apragmaticapproach was taken in adopting the current recommendations for IPD meta-analysis (Supplementary Material, Annex C). The rate of responsetotheinvitationtoparticipatewashighandmostofthe studiesforwhichIPDwerenotprovidedincludedadults.Therisk of bias assessment was restricted to those domains that were relevanttothemeta-analysis.Includedstudiesbenefitedfroma well-definedinterventionstatusandobjectiveoutcomemeasures, hencethemeasurementofinterventionsandthemeasurementof outcomeswerejudgedashavingalowriskofbiasinallstudies.A pilot test was conducted for the selection of the statistical methodologytoensurearigorousIPDanalysis.
Thisstudyhassomelimitations.Toberelevant,ameta-analysis shouldincludealloftheavailablestudies.Theinherentconflictsin theprovisionofIPDwereinlinewiththebarrierstodatasharing described in theliterature,includingconcerns aboutprotecting subjectconfidentialityandanonymity,lackoftime,andunavail- ableorunusabledatasets(Melloetal.,2013).Itwasnotpossibleto explorepotential sourcesofheterogeneityasplannedgiventhe lackofcomparisongroupstoestimatethehazardratiosforeach study.Somedatasetsincludedchildrenwhileothersincludedonly adults, and allstudieswereconducted ina singlecountry. The meta-analysisalsodidnotinclude sufficientIPDfromcountries where the TcI Trypanosoma cruzi lineage may be prevalent (Zingalesetal.,2012).
TheelectronicsearcheswereupdatedonAugust28,2017tofind newstudiespublishedsince thelastsearch.Atthattime, three potentially eligiblestudies reportingserologicaloutcomes (two studies includingadultsliving inArgentina and Spain,and one study including children living in Guatemala) were identified;
thesewillbeconsideredinfutureupdates.
The survival analyses may be useful in regard to current recommendations for the clinical management of chronic Trypanosomacruziinfection.Factorssuchastheageofthepatient attendingtheclinicalappointmentandtheageattreatment(time elapsedbetweentreatmentandclinicalassessment),thecountry oforigin(orthecountrywheretheinfectionwasacquired),andthe complementary assessment of conventional serology and PCR resultsarecriticaltomonitoringaftertreatment.
Theuseofparticipant-leveldatawasintendedtoovercomethe pragmaticconstraintsofanewfollow-upstudy,suchasthelong time between exposure to anti-trypanosomaldrugs and seror- eversion,theneedforappropriatesamplesizesforchildrenand adults,andadequateratesoffollow-up.Itishopedthatthisstudy providesanencouragingexampleoftheimportanceofanonym- izingand sharingIPDfor secondaryanalysis. Thisstrategymay decreasetheburdenonresearchresourcesthroughthemeaningful reuseofexistingdata.
Thenextstepswillbetodeterminethecourseofmolecularand parasitologicaltestsaftertreatmentduringchronicTrypanosoma cruziinfectionandtoconductanewanalysisusingavailableIPD accordingtothestandarddefinitionofcure(seroreversiondefined as having negative results for at least two different serology techniques)astheprimaryresult.Thetime periodcoveredwill likelybethatduringwhichhealthcareprovidersexpecttomake decisions based on official guidelines, e.g., up to 3 years.
Theultimategoalistoprovideamonitoringtooltohelpinthe assessmentoftreatmentinchronicallyinfectedpatients.
Figure2. Kaplan–Meierplotsoftheprogressionofconventionalserologyintreated subjectswithchronicTrypanosomacruziinfectionstratifiedbyageattreatmentand countrysetting,with95%confidenceintervals.Plotsshowtheproportionoftreated subjectsprogressingtowardsseroreversionaccordingto(1)ELISA,(2)IIF,and(3) IHAtestsduringthefollow-up,stratifiedbyageattreatment(1–19yearsvs.>19 years)andcountrysetting(groupA:Argentina,Bolivia,ChileandParaguayvs.group B:Brazil).
ELISA,enzyme-linkedimmunosorbentassay;IIF,indirectimmunofluorescence assay;IHA,indirecthemagglutinationassay.
