The Cochrane Collaboration’s tool for assessing risk
上传者:黄斐|上传时间:2015-05-05|密次下载
The Cochrane Collaboration’s tool for assessing risk
Cochrane Collaboration’s tool for assessing risk of bias
BMJ2011;343:d5928doi:10.1136/bmj.d5928
Page1of9
RESEARCHMETHODS&REPORTING
ofbiasinrandomised
内容需要下载文档才能查看trials
OPENACCESS
Flaws in the design, conduct, analysis, and reporting of randomised trials can cause the effect ofan intervention to be underestimated or overestimated.The Cochrane Collaboration’s tool forassessing risk of bias aims to make the process clearer and more accurate
JulianPTHigginsseniorstatistician,DouglasGAltmandirector,PeterCGøtzschedirector,4567PeterJüniheadofdivision,DavidMoherseniorscientist,AndrewDOxmanseniorresearcher,89JelenaSavovi?postdoctoralfellow,KennethFSchulzvicepresident,LauraWeeksresearch58associate,JonathanACSterneprofessorofmedicalstatisticsandepidemiology,CochraneBiasMethodsGroup,CochraneStatisticalMethodsGroup
MRCBiostatisticsUnit,InstituteofPublicHealth,CambridgeCB20SR,UK;2CentreforStatisticsinMedicine,UniversityofOxford,Oxford,UK;3TheNordicCochraneCentre,RigshospitaletandUniversityofCopenhagen,Denmark;4InstituteofSocialandPreventiveMedicine,UniversityofBern,Switzerland;5ClinicalEpidemiologyProgram,OttawaHospitalResearchInstitute,Ottawa,Ontario,Canada;6DepartmentofEpidemiologyandCommunityMedicine,FacultyofMedicine,UniversityofOttawa,Canada;7PreventiveandInternationalHealthCareUnit,NorwegianKnowledgeCentrefortheHealthServices,Oslo,Norway;8DepartmentofSocialMedicine,UniversityofBristol,Bristol,UK;9FHI,ResearchTrianglePark,NorthCarolina,USA1123
Randomisedtrials,andsystematicreviewsofsuchtrials,providethemostreliableevidenceabouttheeffectsofhealthcareinterventions.Providedthatthereareenoughparticipants,randomisationshouldensurethatparticipantsintheinterventionandcomparisongroupsaresimilarwithrespecttobothknownandunknownprognosticfactors.Differencesinoutcomesofinterestbetweenthedifferentgroupscantheninprinciplebeascribedtothecausaleffectoftheintervention.1
Causalinferencesfromrandomisedtrialscan,however,beunderminedbyflawsindesign,conduct,analyses,andreporting,leadingtounderestimationoroverestimationofthetrueinterventioneffect(bias).2However,itisusuallyimpossibletoknowtheextenttowhichbiaseshaveaffectedtheresultsofaparticulartrial.(whichassesstrialswithoutproducingascore).4-7Untilrecently,Cochranereviewsusedavarietyofthesetools,mainlychecklists.8In2005theCochraneCollaboration’smethodsgroupsembarkedonanewstrategyforassessingthequalityofrandomisedtrials.Inthispaperwedescribethecollaboration’snewriskofbiasassessmenttool,andtheprocessbywhichitwasdevelopedandevaluated.DevelopmentofriskassessmenttoolSystematicreviewsaimtocollateandsynthesiseallstudiesthatmeetprespecifiedeligibilitycriteria3usingmethodsthatattempttominimisebias.Toobtainreliableconclusions,reviewauthorsmustcarefullyconsiderthepotentiallimitationsoftheincludedstudies.Thenotionofstudy“quality”isnotwelldefinedbutrelatestotheextenttowhichitsdesign,conduct,analysis,andpresentationwereappropriatetoansweritsresearchquestion.Manytoolsforassessingthequalityofrandomisedtrialsareavailable,includingscales(whichscorethetrials)andchecklistsInMay2005,16statisticians,epidemiologists,andreviewauthorsattendedathreedaymeetingtodevelopthenewtool.Beforethemeeting,JPTHandDGAcompiledanextensivelistofpotentialsourcesofbiasinclinicaltrials.Theitemsonthelistweredividedintosevenareas:generationoftheallocationsequence;concealmentoftheallocationsequence;blinding;attritionandexclusions;othergenericsourcesofbias;biasesspecifictothetrialdesign(suchascrossoverorclusterrandomisedtrials);andbiasesthatmightbespecifictoaclinicalspecialty.Foreachofthesevenareas,anominatedmeetingparticipantpreparedareviewoftheempiricalevidence,adiscussionofspecificissuesanduncertainties,andaproposedsetofcriteriaforassessingprotectionfrombiasasadequate,inadequate,orunclear,supportedbyexamples.Correspondence to: J P T Higgins julian.higgins@mrc-bsu.cam.ac.uk.Further details on the items included in risk assessment tool (see http://wendang.chazidian.com/content/343/bmj.d5928/suppl/DC1)
No commercial reuse: See rights and reprints http://wendang.chazidian.com/permissionsSubscribe:
内容需要下载文档才能查看http://wendang.chazidian.com/subscribe
Cochrane Collaboration’s tool for assessing risk of bias
BMJ2011;343:d5928doi:10.1136/bmj.d5928Page2of9
Duringthemeetingdecisionsweremadebyinformalconsensusregardingitemsthatweretrulypotentialbiasesratherthansourcesofheterogeneityorimprecision.Potentialbiaseswerethendividedintodomains,andstrategiesfortheirassessmentwereagreed,againbyinformalconsensus,leadingtothecreationofanewtoolforassessingpotentialforbias.Meetingparticipantsalsodiscussedhowtosummariseassessmentsacrossdomains,howtoillustrateassessments,andhowtoincorporateassessmentsintoanalysesandconclusions.Minutesofthemeetingweretranscribedfromanaudiorecordinginconjunctionwithwrittennotes.Afterthemeeting,pairsofauthorsdevelopeddetailedcriteriaforeachincludediteminthetoolandguidanceforassessingthepotentialforbias.Documentsweresharedandfeedbackrequestedfromthewholeworkinggroup(includingsixwhocouldnotattendthemeeting).Severalemailiterationstookplace,whichalsoincorporatedfeedbackfrompresentationsoftheproposedguidanceatvariousmeetingsandworkshopswithintheCochraneCollaborationandfrompilotworkbyselectedreviewteamsincollaborationwithmembersoftheworkinggroup.Thematerialswereintegratedbytheco-leadsintocomprehensiveguidanceonthenewriskofbiastool.ThiswaspublishedinFebruary2008andadoptedastherecommendedmethodthroughouttheCochraneCollaboration.9facts,includingverbatimquoteswherepossible.Thesourceofthisinformationshouldbestated,andwhenthereisnoinformationonwhichtobaseajudgment,thisshouldbestated.Thesecondpartofthetoolinvolvesassigningajudgmentofhigh,low,orunclearriskofmaterialbiasforeachitem.Wedefinematerialbiasasbiasofsufficientmagnitudetohaveanotableeffectontheresultsorconclusionsofthetrial,recognisingthesubjectivityofanysuchjudgment.DetailedcriteriaformakingjudgmentsabouttheriskofbiasfromeachoftheitemsinthetoolareavailableintheCochraneHandbook.13Ifinsufficientdetailisreportedofwhathappenedinthetrial,thejudgmentwillusuallybeunclearriskofbias.Ajudgmentofunclearriskshouldalsobemadeifwhathappenedinthetrialisknownbuttheassociatedriskofbiasisunknown—forexample,ifparticipantstakeadditionaldrugsofunknowneffectivenessasaresultofthembeingawareoftheirinterventionassignment.Werecommendthatjudgmentsbemadeindependentlybyatleasttwopeople,withanydiscrepanciesresolvedbydiscussioninthefirstinstance.
Evaluationphase
Athreestageprojecttoevaluatethetoolwasinitiatedinearly2009.Aseriesoffocusgroupswasheldinwhichreviewauthorswhohadusedthetoolwereaskedtoreflectontheirexperiences.Findingsfromthefocusgroupswerethenfedintothedesignofquestionnairesforuseinthreeonlinesurveysofreviewauthorswhohadusedthetool,reviewauthorswhohadnotusedthetool(toexplorewhynot),andeditorialteamswithinthecollaboration.Weheldameetingtodiscussthefindingsfromthefocusgroupsandsurveysandtoconsiderrevisionstothefirstversionoftheriskofbiastool.Thiswasattendedbysixparticipantsfromthe2005meetingand17others,includingstatisticians,epidemiologists,coordinatingeditorsandotherstaffofCochranereviewgroups,andtheeditorinchiefoftheCochraneLibrary.Someoftheitemsinthetool,suchasmethodsforrandomisation,requireonlyasingleassessmentforeachtrialincludedinthereview.Forotheritems,suchasblindingandincompleteoutcomedata,twoormoreassessmentsmaybeusedbecausetheygenerallyneedtobemadeseparatelyfordifferentoutcomes(orforthesameoutcomeatdifferenttimepoints).However,werecommendthatreviewauthorslimitthenumberofassessmentsusedbygroupingoutcomes—forexample,assubjectiveorobjectiveforthepurposesofassessingblindingofoutcomeassessmentoras“patientreportedat6months”or“patientreportedat12months”forassessingriskofbiasduetoincompleteoutcomedata.EvaluationofinitialimplementationThefirst(2008)versionofthetoolwasslightlydifferentfromtheonewepresenthere.The2008versiondidnotcategorisebiasesbythesixdomains(selectionbias,performancebias,etc);hadasingleassessmentforblinding;andexpressedriskofbiasintheformat‘”yes,”“no,”or“unclear”(referringtolackofarisk)ratherthanaslow,high,orunclearrisk.The2010evaluationoftheinitialversionfoundwideacceptanceoftheneedfortheriskofbiastool,withaconsensusthatitrepresentsanimprovementovermethodspreviouslyrecommendedbytheCollaborationorwidelyusedinsystematicreviews.Participantsinthefocusgroupsnotedthatthetooltooklongertocompletethanpreviousmethods.Of187authorssurveyed,88%tooklongerthan10minutestocompletethenewtool,44%longerthan20minutes,and7%longerthananhour,but83%consideredthetimetakenacceptable.Therewasconsensusthatclassifyingitemsinthetoolaccordingtocategoriesofbias(selectionbias,performancebias,etc)wouldhelpusers,soweintroducedthese.Therewasalsoconsensusthatassessmentofblindingshouldbeseparatedintoblindingofparticipantsandhealthprofessionals(performancebias)andblindingofoutcomeassessment(detectionbias)andthatthephrasingofthejudgmentsaboutriskshouldbechangedtolow,high,andunclearrisk.Thedomainsreportedtobethemostdifficulttoassesswereriskofbiasduetoincompleteoutcomedataandselectivereportingofoutcomes.Therewasagreementthatimprovedtrainingmaterialsandavailabilityofworkedexampleswouldincreasethequalityandreliabilityofbiasassessments.TheriskofbiastoolAtthe2005workshoptheparticipantsagreedthesevenprinciplesonwhichthenewriskofbiasassessmenttoolwasbased(box).Theriskofbiastoolcoverssixdomainsofbias:selectionbias,performancebias,detectionbias,attritionbias,reportingbias,andotherbias.Withineachdomain,assessmentsaremadeforoneormoreitems,whichmaycoverdifferentaspectsofthedomain,ordifferentoutcomes.Table1?http://wendang.chazidian.com.Foreachiteminthetool,theassessmentofriskofbiasisintwoparts.Thesupportforjudgmentprovidesasuccinctfreetextdescriptionorsummaryoftherelevanttrialcharacteristiconwhichjudgmentsofriskofbiasarebasedandaimstoensuretransparencyinhowjudgmentsarereached.Forexample,theitemaboutconcealmentoftherandomisedallocationsequencewouldprovidedetailsofwhatmeasureswereinplace,ifany,http://wendang.chazidian.comrmationforthesedescriptionswilloftencomefromasinglepublishedtrialreportbutmaybeobtainedfromamixtureoftrialreports,protocols,publishedcommentsonthetrial,andcontactswiththeinvestigators.Thesupportforthejudgmentshouldprovideasummaryofknown
No commercial reuse: See rights and reprints http://wendang.chazidian.com/permissionsSubscribe:http://wendang.chazidian.com/subscribe
Cochrane Collaboration’s tool for assessing risk of bias
BMJ2011;343:d5928doi:10.1136/bmj.d5928Page3of9
Principlesforassessingriskofbias
1.Donotusequalityscales
Qualityscalesandresultingscoresarenotanappropriatewaytoappraiseclinicaltrials.Theytendtocombineassessmentsofaspectsofthequalityofreportingwithaspectsoftrialconduct,andtoassignweightstodifferentitemsinwaysthataredifficulttojustify.Boththeoreticalconsiderations10andempiricalevidence11suggestthatassociationsofdifferentscaleswithinterventioneffectestimatesareinconsistentandunpredictable
2.Focusoninternalvalidity
Theinternalvalidityofastudyistheextenttowhichitisfreefrombias.Itisimportanttoseparateassessmentofinternalvalidityfromthatofexternalvalidity(generalisabilityorapplicability)andprecision(theextenttowhichstudyresultsarefreefromrandomerror).Applicabilitydependsonthepurposeforwhichthestudyistobeusedandislessrelevantwithoutinternalvalidity.Precisiondependsonthenumberofparticipantsandeventsinastudy.Asmalltrialwithlowriskofbiasmayprovideveryimpreciseresults,withawideconfidenceinterval.Conversely,theresultsofalargetrialmaybeprecise(narrowconfidenceinterval)buthaveahighriskofbiasifinternalvalidityispoor
3.Assesstheriskofbiasintrialresults,notthequalityofreportingormethodologicalproblemsthatarenotdirectlyrelatedtoriskofbias
Thequalityofreporting,suchaswhetherdetailsweredescribedornot,affectstheabilityofsystematicreviewauthorsandusersofmedicalresearchtoassesstheriskofbiasbutisnotdirectlyrelatedtotheriskofbias.Similarly,someaspectsoftrialconduct,suchasobtainingethicalapprovalorcalculatingsamplesize,arenotdirectlyrelatedtotheriskofbias.Conversely,resultsofatrialthatusedthebestpossiblemethodsmaystillbeatriskofbias.Forexample,blindingmaynotbefeasibleinmanynon-drugtrials,anditwouldnotbereasonabletoconsiderthetrialaslowqualitybecauseoftheabsenceofblinding.Nonetheless,manytypesofoutcomemaybeinfluencedbyparticipants’knowledgeoftheinterventionreceived,andsothetrialresultsforsuchoutcomesmaybeconsideredtobeatriskofbiasbecauseoftheabsenceofblinding,despitethisbeingimpossibletoachieve
4.Assessmentsofriskofbiasrequirejudgment
Assessmentofwhetheraparticularaspectoftrialconductrendersitsresultsatriskofbiasrequiresbothknowledgeofthetrialmethodsandajudgmentaboutwhetherthosemethodsarelikelytohaveledtoariskofbias.Wedecidedthatthebasisforbiasassessmentsshouldbemadeexplicit,byrecordingtheaspectsofthetrialmethodsonwhichthejudgmentwasbasedandthenthejudgmentitself
5.Choosedomainstobeassessedbasedonacombinationoftheoreticalandempiricalconsiderations
Empiricalstudiesshowthatparticularaspectsoftrialconductareassociatedwithbias.212However,thesestudiesdidnotincludeallpotentialsourcesofbias.Forexample,availableevidencedoesnotdistinguishbetweendifferentaspectsofblinding(ofparticipants,healthprofessionals,andoutcomeassessment)andisverylimitedwithregardtohowauthorsdealtwithincompleteoutcomedata.Theremayalsobetopicspecificanddesignspecificissuesthatarerelevantonlytosometrialsandreviews.Forexample,inareviewcontainingcrossovertrialsitmightbeappropriatetoassesswhetherresultswereatriskofbiasbecausetherewasaninsufficient“washout”periodbetweenthetwotreatmentperiods
6.Focusonriskofbiasinthedataasrepresentedinthereviewratherthanasoriginallyreported
Somepapersmayreporttrialresultsthatareconsideredasathighriskofbias,forwhichitmaybepossibletoderivearesultatlowriskofbias.Forexample,apaperthatinappropriatelyexcludedcertainpatientsfromanalysesmightreporttheinterventiongroupsandoutcomesforthesepatients,sothattheomittedparticipantscanbereinstated
7.Reportoutcomespecificevaluationsofriskofbias
Someaspectsoftrialconduct(forexample,whethertherandomisedallocationwasconcealedatthetimetheparticipantwasrecruited)applytothetrialasawhole.Forotheraspects,however,theriskofbiasisinherentlyspecifictodifferentoutcomeswithinthetrial.Forexample,allcausemortalitymightbeascertainedthroughlinkagestodeathregistries(lowriskofbias),whilerecurrenceofcancermighthavebeenassessedbyadoctorwithknowledgeoftheallocatedintervention(highriskofbias)
Presentationofassessments
Resultsofanassessmentofriskofbiascanbepresentedinatable,inwhichjudgmentsforeachitemineachtrialarepresentedalongsidetheirdescriptivejustification.Table2?presentsanexampleofariskofbiastableforonetrialincludedinaCochranereviewoftherapeuticmonitoringofantiretroviralsforpeoplewithHIV.14Risksofbiasduetoblindingandincompleteoutcomedatawereassessedacrossalloutcomeswithineachincludedstudy,ratherthanseparatelyfordifferentoutcomesaswillbemoreappropriateinsomesituations.this,reviewauthorsmustdecidewhichdomainsaremostimportantinthecontextofthereview,ideallywhenwritingtheirprotocol.Forexample,forhighlysubjectiveoutcomessuchaspain,blindingofparticipantsiscritical.Thewaythatsummaryjudgmentsofriskofbiasarereachedshouldbeexplicitandshouldbeinformedbyempiricalevidenceofbiaswhenitexists,likelydirectionofbias,andlikelymagnitudeofbias.Table3?providesasuggestedframeworkformakingsummaryassessmentsoftheriskofbiasforimportantoutcomeswithinandacrosstrials.
Presentingriskofbiastablesforeverystudyinareviewcanbecumbersome,andwesuggestthatillustrationsareusedtosummarisethejudgmentsinthemainsystematicreviewdocument.Thefigure?providesanexample.Herethejudgmentsapplytoallmeta-analysesinthereview.Analternativewouldbetoillustratetheriskofbiasforaparticularmeta-analysis(orforaparticularoutcomeifastatisticalsynthesisisnotundertaken),showingtheproportionofinformationthatcomesfromstudiesatlow,unclear,orhighriskofbiasforeachiteminthetool,amongstudiescontributinginformationtothatoutcome.AssessmentsofriskofbiasandsynthesisofresultsSummaryassessmentsoftheriskofbiasforanoutcomewithineachtrialshouldinformthemeta-analysis.Thetwopreferableanalyticalstrategiesaretorestricttheprimarymeta-analysistostudiesatlowriskofbiasortopresentmeta-analysesstratifiedaccordingtoriskofbias.Thechoicebetweenthesestrategiesshouldbebasedonthecontextoftheparticularreviewandthebalancebetweenthepotentialforbiasandthelossofprecisionwhenstudiesathighorunclearriskofbiasareexcluded.Meta-regressioncanbeusedtocompareresultsfromstudiesathighandlowriskofbias,butsuchcomparisonslackpower,15
andlackofasignificantdifferenceshouldnotbeinterpretedasimplyingtheabsenceofbias.SummaryassessmentofriskofbiasTodrawconclusionsabouttheoverallriskofbiaswithinoracrosstrialsitisnecessarytosummariseassessmentsacrossitemsinthetoolforeachoutcomewithineachtrial.Indoing
No commercial reuse: See rights and reprints http://wendang.chazidian.com/permissionsAthirdstrategyistopresentameta-analysisofallstudieswhileprovidingasummaryoftheriskofbiasacrossstudies.However,Subscribe:http://wendang.chazidian.com/subscribe
Cochrane Collaboration’s tool for assessing risk of bias
BMJ2011;343:d5928doi:10.1136/bmj.d5928Page4of9
thisrunstheriskthatbiasisdownplayedinthediscussionandconclusionsofareview,sothatdecisionscontinuetobebased,atleastinpart,onflawedevidence.Thisriskcouldbereducedbyincorporatingsummaryassessmentsintobroader,butexplicit,measuresofthequalityofevidenceforeachimportantoutcome,forexampleusingtheGRADEsystem.16Thiscanhelptoensurethatjudgmentsabouttheriskofbias,aswellasotherfactorsaffectingthequalityofevidence(suchasimprecision,heterogeneity,andpublicationbias),areconsideredwheninterpretingtheresultsofsystematicreviews.1718Developmentmeetingparticipants(May2005):DougAltman(co-lead),GerdAntes,ChrisCates,JonDeeks,PeterGøtzsche,JulianHiggins(co-lead),SallyHopewell,PeterJüni(organisingcommittee),SteffLewis,PhilippaMiddleton,DavidMoher(organisingcommittee),AndyOxman,KenSchulz(organisingcommittee),NandiSiegfried,JonathanSterne,SimonThompson.Othercontributorstotooldevelopment:HildaBastian,RachelleBuchbinder,IainChalmers,MirandaCumpston,SallyGreen,PeterHerbison,VictorMontori,HannahRothstein,GeorgiaSalanti,GuidoSchwarzer,IanShrier,JayneTierney,IanWhiteandPaulaWilliamson.
Evaluationmeetingparticipants(March2010):DougAltman(organisingcommittee),ElaineBeller,SallyBell-Syer,ChrisCates,RachelChurchill,JuneCody,JonathanCook,ChristianGluud,JulianHiggins(organisingcommittee),SallyHopewell,HayleyJones,PeterJ?ni,MonicaKjeldstrøm,TobyLasserson,AllysonLipp,LaraMaxwell,JoanneMcKenzie,CraigRamsey,BarneyReeves,JelenaSavovi?(co-lead),JonathanSterne(co-lead),DavidTovey,LauraWeeks(organisingcommittee).
Othercontributorstotoolevaluation:IsabelleBoutron,DavidMoher(organisingcommittee),LucyTurner.
Funding:ThedevelopmentandevaluationoftheriskofbiastoolwasfundedinpartbyTheCochraneCollaboration.TheviewsexpressedinthisarticlearethoseoftheauthorsandnotnecessarilythoseofTheCochraneCollaborationoritsregisteredentities,committeesorworkinggroups..JPTHwasalsofundedbyMRCgrantnumberU.1052.00.011.DGAwasfundedbyCancerResearchUKgrantnumberC-5592.DMwasfundedbyaUniversityResearchChair(UniversityofOttawa).TheCanadianInstitutesofHealthResearchprovidesfinancialsupporttotheCochraneBiasMethodsGroup.
Competinginterests:http://wendang.chazidian.com/coi_disclosure.pdf(availableonrequestfromthecorrespondingauthor)anddeclaresupportfromtheCochraneCollaborationforthedevelopmentandevaluationofthetooldescribed;theyhavenofinancialrelationshipswithanyorganisationsthatmighthaveaninterestinthesubmittedworkinthepreviousthreeyearsandnootherrelationshipsoractivitiesthatcouldappeartohaveinfluencedthesubmittedwork.
Provenanceandpeerreview:Notcommissioned;externallypeerreviewed.
1KleijnenJ,GøtzscheP,KunzRH,OxmanAD,ChalmersI.Sowhat’ssospecialaboutrandomisation?In:MaynardA,ChalmersI,eds.Non-randomreflectionsonhealthservicesresearch:onthe25thanniversaryofArchieCochrane’sEffectivenessandEfficiency.BMJBooks,1997:93-106.WoodL,EggerM,GluudLL,SchulzK,JüniP,AltmanDG,etal.Empiricalevidenceofbiasintreatmenteffectestimatesincontrolledtrialswithdifferentinterventionsandoutcomes:meta-epidemiologicalstudy.BMJ2008;336:601-5.EggerM,DaveySmithG,AltmanDG,eds.Systematicreviewsinhealthcare:meta-analysisincontext.BMJBooks,2001.MoherD,JadadAR,NicholG,PenmanM,TugwellP,WalshS.Assessingthequalityofrandomizedcontrolledtrials—anannotatedbibliographyofscalesandchecklists.ControlledClinTrials1995;12:62-73.JüniP,AltmanDG,EggerM.Systematicreviewsinhealthcare:assessingthequalityofcontrolledclinicaltrials.BMJ2001;323:42-6.WestS,KingV,CareyTS,LohrKN,McKoyN,SuttonSF,etal.Systemstoratethestrengthofscientificevidence.Evidencereport/technologyassessmentno47.AHRQpublicationNo02-E016.AgencyforHealthcareResearchandQuality,2002.CroweM,SheppardL.Areviewofcriticalappraisaltoolsshowtheylackrigor:alternativetoolstructureisproposed.JClinEpidemiol2011;64:79-89.LundhA,GøtzschePC.RecommendationsbyCochraneReviewGroupsforassessmentoftheriskofbiasinstudies.BMCMedResMethodol2008;8:22.HigginsJPT,GreenS,eds.Cochranehandbookforsystematicreviewsofinterventions.Wiley,2008.GreenlandS,O’RourkeK.Onthebiasproducedbyqualityscoresinmeta-analysis,andahierarchicalviewofproposedsolutions.Biostatistics2001;2:463-71.JüniP,WitschiA,BlochR,EggerM.Thehazardsofscoringthequalityofclinicaltrialsformeta-analysis.JAMA1999;282:1054-60.GluudLL.Biasinclinicalinterventionresearch.AmJEpidemiol2006;163:493-501.HigginsJPT,AltmanDG.Assessingriskofbiasinincludedstudies.In:HigginsJPT,GreenS,eds.Cochranehandbookforsystematicreviewsofinterventions.Wiley,2008:187-241.KredoT,VanderWaltJ-S,SiegfriedN,CohenK.TherapeuticdrugmonitoringofantiretroviralsforpeoplewithHIV.CochraneDatabaseSystRev2009;3:CD007268.HigginsJPT,ThompsonSG.Controllingtheriskofspuriousfindingsfrommeta-regression.StatMed2004;23:1663-82.DiscussionDiscrepanciesbetweentheresultsofdifferentsystematicreviewsexaminingthesamequestion1920andbetweenmeta-analysesandsubsequentlargetrials21haveshownthattheresultsofmeta-analysescanbebiased,whichmaybepartlycausedbybiasedresultsinthetrialstheyinclude.Webelieveourriskofbiastoolisoneofthemostcomprehensiveapproachestoassessingthepotentialforbiasinrandomisedtrialsincludedinsystematicreviewsormeta-analyses.Inclusionofdetailsoftrialconduct,onwhichjudgmentsofriskofbiasarebased,providesgreatertransparencythanpreviousapproaches,allowingreaderstodecidewhethertheyagreewiththejudgmentsmade.Thereiscontinuinguncertainty,andgreatvariationinpractice,overhowtoassesspotentialforbiasinspecificdomainswithintrials,howtosummarisebiasassessmentsacrosssuchdomains,andhowtoincorporatebiasassessmentsintometa-analyses.Arecentstudyhasfoundthatthetooltakeslongertocompletethanothertools(theinvestigatorstookameanof8.8minutesperpersonforasinglepredeterminedoutcomeusingourtoolcomparedwith1.5minutesforapreviousratingscaleforqualityofreporting).22Thereliabilityofthetoolhasnotbeenextensivelystudied,althoughthesameauthorsobservedthatlargereffectsizeswereobservedonaverageinstudiesratedasathighriskofbiascomparedwithstudiesatlowriskofbias.22Byexplicitlyincorporatingjudgmentsintothetool,weacknowledgethatagreementsbetweenassessorsmaynotbeashighasforsomeothertools.However,wealsoexplicitlytargettheriskofbiasratherthanreportedcharacteristicsofthetrial.Itwouldbeeasiertoassesswhetheradrop-outrateexceeds20%thanwhetheradrop-outrateof21%introducesanimportantriskofbias,butthereisnoguaranteethatresultsfromastudywithadrop-outratelowerthan20%areatlowriskofbias.Preliminaryevidencesuggeststhatincompleteoutcomedataandselectivereportingarethemostdifficultitemstoassess;kappameasuresofagreementof0.32(fair)and0.13(slight)respectivelyhavebeenreportedforthese.22Itisimportantthatguidanceandtrainingmaterialscontinuetobedevelopedforallaspectsofthetool,butparticularlythesetwo.Wehopethatwidespreadadoptionandimplementationoftheriskofbiastool,bothwithinandoutsidetheCochraneCollaboration,willfacilitateimprovedappraisalofevidencebyhealthcaredecisionmakersandpatientsandultimatelyleadtobetterhealthcare.Improvedunderstandingofthewaysinwhichflawsintrialconductmaybiastheirresultsshouldalsoleadtobettertrialsandmorereliableevidence.Riskofbiasassessmentsshouldcontinuetoevolve,takingintoaccountanynewempiricalevidenceandthepracticalexperienceofauthorsofsystematicreviews.Contributors:Allauthorscontributedtothedraftingandeditingofthemanuscript.JPTH,DGA,PCG,PJ,DM,ADO,KFSandJACScontributedtothechapterintheCochraneHandbookforSystematicReviewsofInterventionsonwhichthepaperisbased.JPTHwillactasguarantor.
No commercial reuse: See rights and reprints http://wendang.chazidian.com/permissions23456789101112131415Subscribe:http://wendang.chazidian.com/subscribe
Cochrane Collaboration’s tool for assessing risk of bias
BMJ2011;343:d5928doi:10.1136/bmj.d5928Page5of9
Summarypoints
Systematicreviewsshouldcarefullyconsiderthepotentiallimitationsofthestudiesincluded
TheCochraneCollaborationhasdevelopedanewtoolforassessingriskofbiasinrandomisedtrials
Thetoolseparatesajudgmentaboutriskofbiasfromadescriptionofthesupportforthatjudgment,foraseriesofitemscoveringdifferentdomainsofbias
16
17
18
19
20
21GuyattGH,OxmanAD,VistGE,ZunzR,Falck-YtterY,Alonso-CoelloP,etal.GRADE:anemergingconsensusonratingqualityofevidenceandstrengthofrecommendations.BMJ2008;336:924-6.SchünemannHJ,OxmanAD,HigginsJPT,VistGE,GlasziouP,GuyattGH,etal.Presentingresultsand“Summaryoffindings”tables.In:HigginsJPT,GreenS,eds.Cochranehandbookforsystematicreviewsofinterventions.Wiley,2008:335-8.SchünemannHJ,OxmanAD,VistGE,HigginsJPT,DeeksJJ,GlasziouP,etal.Interpretingresultsanddrawingconclusions.In:HigginsJPT,GreenS,eds.Cochranehandbookforsystematicreviewsofinterventions.Wiley,2008:359-87.LeizoroviczA,HaughMC,ChapuisFR,SamamaMM,BoisselJP.Lowmolecularweightheparininpreventionofperioperativethrombosis.BMJ1992;305:913-20.NurmohamedMT,RosendaalFR,BullerHR,DekkerE,HommesDW,VandenbrouckeJP,etal.Low-molecular-weightheparinversusstandardhepariningeneralandorthopaedicsurgery:http://wendang.chazidian.comncet1992;340:152-6.LelorierJ,BenhaddadA,LapierreJ,DerderianF.Discrepanciesbetweenmeta-analysesandsubsequentlargerandomized,controlledtrials.NEnglJMed1997;337:536-42.22HartlingL,OspinaM,LiangY,DrydenDM,HootonN,KrebsSJ,etal.Riskofbiasversusqualityassessmentofrandomisedcontrolledtrials:crosssectionalstudy.BMJ2009;339:b4012.Accepted:22July2011Citethisas:BMJ2011;343:d5928Thisisanopen-accessarticledistributedunderthetermsoftheCreativeCommonsAttributionNon-commercialLicense,whichpermitsuse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited,theuseisnoncommercialandisotherwiseincompliancewiththelicense.See:http://wendang.chazidian.com/licenses/by-nc/2.0/andhttp://wendang.chazidian.com/licenses/by-nc/2.0/legalcode.
No commercial reuse: See rights and reprints http://wendang.chazidian.com/permissionsSubscribe:http://wendang.chazidian.com/subscribe
下载文档
热门试卷
- 2016年四川省内江市中考化学试卷
- 广西钦州市高新区2017届高三11月月考政治试卷
- 浙江省湖州市2016-2017学年高一上学期期中考试政治试卷
- 浙江省湖州市2016-2017学年高二上学期期中考试政治试卷
- 辽宁省铁岭市协作体2017届高三上学期第三次联考政治试卷
- 广西钦州市钦州港区2016-2017学年高二11月月考政治试卷
- 广西钦州市钦州港区2017届高三11月月考政治试卷
- 广西钦州市钦州港区2016-2017学年高一11月月考政治试卷
- 广西钦州市高新区2016-2017学年高二11月月考政治试卷
- 广西钦州市高新区2016-2017学年高一11月月考政治试卷
- 山东省滨州市三校2017届第一学期阶段测试初三英语试题
- 四川省成都七中2017届高三一诊模拟考试文科综合试卷
- 2017届普通高等学校招生全国统一考试模拟试题(附答案)
- 重庆市永川中学高2017级上期12月月考语文试题
- 江西宜春三中2017届高三第一学期第二次月考文科综合试题
- 内蒙古赤峰二中2017届高三上学期第三次月考英语试题
- 2017年六年级(上)数学期末考试卷
- 2017人教版小学英语三年级上期末笔试题
- 江苏省常州西藏民族中学2016-2017学年九年级思想品德第一学期第二次阶段测试试卷
- 重庆市九龙坡区七校2016-2017学年上期八年级素质测查(二)语文学科试题卷
- 江苏省无锡市钱桥中学2016年12月八年级语文阶段性测试卷
- 江苏省无锡市钱桥中学2016-2017学年七年级英语12月阶段检测试卷
- 山东省邹城市第八中学2016-2017学年八年级12月物理第4章试题(无答案)
- 【人教版】河北省2015-2016学年度九年级上期末语文试题卷(附答案)
- 四川省简阳市阳安中学2016年12月高二月考英语试卷
- 四川省成都龙泉中学高三上学期2016年12月月考试题文科综合能力测试
- 安徽省滁州中学2016—2017学年度第一学期12月月考高三英语试卷
- 山东省武城县第二中学2016.12高一年级上学期第二次月考历史试题(必修一第四、五单元)
- 福建省四地六校联考2016-2017学年上学期第三次月考高三化学试卷
- 甘肃省武威第二十三中学2016—2017学年度八年级第一学期12月月考生物试卷
网友关注
- 2019北京公务员考试常识判断40000问(八十九)
- 2019北京公务员考试常识判断40000问(九十三)
- 2019北京公务员考试常识判断40000问(一百零四)
- 2019北京公务员考试申论题库:公布失信人名单与信用建设
- 2019北京公务员考试常识判断40000问(八十六)
- 2019北京公务员考试常识判断40000问(八十三)
- 2019北京公务员考试常识判断40000问(一百零五)
- 2019北京公务员考试申论题库:文化遗产传承和保护
- 2019北京公务员考试公安专业科目考试模拟题(6)
- 2019北京公务员考试常识判断40000问(一百一十)
- 2019北京公务员考试常识判断40000问(一百零九)
- 2019北京公务员考试行测题库:资料分析练习题(一)
- 2019北京公务员考试常识判断40000问(八十四)
- 2019北京公务员考试常识判断40000问(九十)
- 2019北京公务员考试常识判断40000问(九十四)
- 2019北京公务员考试常识判断40000问(一百)
- 2019北京公务员考试常识判断40000问(八十二)
- 2019北京公务员考试常识判断40000问(九十五)
- 2019北京公务员考试公安基础模拟题
- 2019北京公务员考试行测题库:常识判断练习题
- 2019北京公务员考试行测题库:言语理解练习题答案(二)
- 2019北京公务员考试常识判断40000问(八十一)
- 2019北京公务员考试常识判断40000问(九十八)
- 2019北京公务员考试常识判断40000问(九十七)
- 2019北京公务员考试行测题库:言语理解练习题答案
- 2019北京公务员考试常识判断40000问(一百零七)
- 2019北京公务员考试公安专业科目考试模拟题(4)
- 2019北京公务员考试常识判断40000问(一百零八)
- 2019北京公务员考试行测题库:常识判断练习题答案
- 2019北京公务员考试行测题库:资料分析练习题(二)
网友关注视频
- 沪教版牛津小学英语(深圳用) 四年级下册 Unit 7
- 沪教版牛津小学英语(深圳用)五年级下册 Unit 1
- 外研版英语七年级下册module3 unit1第二课时
- 外研版英语七年级下册module3 unit2第一课时
- 河南省名校课堂七年级下册英语第一课(2020年2月10日)
- 冀教版小学数学二年级下册第二单元《有余数除法的简单应用》
- 苏科版数学 八年级下册 第八章第二节 可能性的大小
- 苏科版八年级数学下册7.2《统计图的选用》
- 沪教版牛津小学英语(深圳用) 四年级下册 Unit 4
- 精品·同步课程 历史 八年级 上册 第15集 近代科学技术与思想文化
- 化学九年级下册全册同步 人教版 第25集 生活中常见的盐(二)
- 化学九年级下册全册同步 人教版 第22集 酸和碱的中和反应(一)
- 【部编】人教版语文七年级下册《老山界》优质课教学视频+PPT课件+教案,安徽省
- 第12章 圆锥曲线_12.7 抛物线的标准方程_第一课时(特等奖)(沪教版高二下册)_T274713
- 冀教版小学数学二年级下册第二周第2课时《我们的测量》宝丰街小学庞志荣.mp4
- 沪教版八年级下册数学练习册21.4(1)无理方程P18
- 沪教版牛津小学英语(深圳用) 四年级下册 Unit 12
- 【部编】人教版语文七年级下册《逢入京使》优质课教学视频+PPT课件+教案,安徽省
- 二年级下册数学第二课
- 第五单元 民族艺术的瑰宝_15. 多姿多彩的民族服饰_第二课时(市一等奖)(岭南版六年级上册)_T129830
- 【获奖】科粤版初三九年级化学下册第七章7.3浓稀的表示
- 沪教版八年级下册数学练习册20.4(2)一次函数的应用2P8
- 沪教版八年级下册数学练习册一次函数复习题B组(P11)
- 北师大版小学数学四年级下册第15课小数乘小数一
- 沪教版牛津小学英语(深圳用) 四年级下册 Unit 3
- 外研版英语七年级下册module3 unit2第二课时
- 【部编】人教版语文七年级下册《泊秦淮》优质课教学视频+PPT课件+教案,湖北省
- 沪教版八年级下册数学练习册21.3(3)分式方程P17
- 3.2 数学二年级下册第二单元 表内除法(一)整理和复习 李菲菲
- 三年级英语单词记忆下册(沪教版)第一二单元复习
精品推荐
- 2016-2017学年高一语文人教版必修一+模块学业水平检测试题(含答案)
- 广西钦州市高新区2017届高三11月月考政治试卷
- 浙江省湖州市2016-2017学年高一上学期期中考试政治试卷
- 浙江省湖州市2016-2017学年高二上学期期中考试政治试卷
- 辽宁省铁岭市协作体2017届高三上学期第三次联考政治试卷
- 广西钦州市钦州港区2016-2017学年高二11月月考政治试卷
- 广西钦州市钦州港区2017届高三11月月考政治试卷
- 广西钦州市钦州港区2016-2017学年高一11月月考政治试卷
- 广西钦州市高新区2016-2017学年高二11月月考政治试卷
- 广西钦州市高新区2016-2017学年高一11月月考政治试卷
分类导航
- 互联网
- 电脑基础知识
- 计算机软件及应用
- 计算机硬件及网络
- 计算机应用/办公自动化
- .NET
- 数据结构与算法
- Java
- SEO
- C/C++资料
- linux/Unix相关
- 手机开发
- UML理论/建模
- 并行计算/云计算
- 嵌入式开发
- windows相关
- 软件工程
- 管理信息系统
- 开发文档
- 图形图像
- 网络与通信
- 网络信息安全
- 电子支付
- Labview
- matlab
- 网络资源
- Python
- Delphi/Perl
- 评测
- Flash/Flex
- CSS/Script
- 计算机原理
- PHP资料
- 数据挖掘与模式识别
- Web服务
- 数据库
- Visual Basic
- 电子商务
- 服务器
- 搜索引擎优化
- 存储
- 架构
- 行业软件
- 人工智能
- 计算机辅助设计
- 多媒体
- 软件测试
- 计算机硬件与维护
- 网站策划/UE
- 网页设计/UI
- 网吧管理