系统评价和荟萃分析的首选报告项目-PRISsMAa声明

researchmethods&reporting

Preferredreportingitemsforsystematicreviewsandmeta-analyses:thePRISMAstatement

DavidMoher,12AlessandroLiberati,34JenniferTetzlaff,1DouglasGAltman,5forthePRISMAGroup

DavidMoherandcolleaguesintroducePRISMA,anupdateoftheQUOROMguidelinesforreportingsystematicreviewsandmeta-analyses

1OttawaMethodsCentre,OttawaHospitalResearchInstitute,Ottawa,Ontario,Canada

2DepartmentofEpidemiologyandCommunityMedicine,FacultyofMedicine,UniversityofOttawa,Ottawa,Ontario,Canada

3UniversitàdiModenaeReggioEmilia,Modena,Italy

4CentroCochraneItaliano,IstitutoRicercheFarmacologicheMarioNegri,Milan,Italy

5CentreforStatisticsinMedicine,UniversityofOxford,Oxford,UK

Correspondenceto:

dmoher@ohri.ca

Accepted:5June2009

Citethisas:BMJ2009;339:b2535

doi:10.1136/bmj.b2535

Systematicreviewsandmeta-analyseshavebecomeincreasinglyimportantinhealthcare.Cliniciansreadthemtokeepuptodatewiththeirspecialty,12andtheyareoftenusedasastartingpointfordevelopingclinicalpracticeguidelines.Grantingagenciesmayrequireasystematicreviewtoensurethereisjustifica-tionforfurtherresearch,3andsomemedicaljournalsaremovinginthisdirection.4Aswithallresearch,thevalueofasystematicreviewdependsonwhatwasdone,whatwasfound,andtheclarityofreporting.Aswithotherpublications,thereportingqualityofsystematicreviewsvaries,limitingreaders’abilitytoassessthestrengthsandweaknessesofthosereviews.

Severalearlystudiesevaluatedthequalityofreviewreports.In1987Mulrowexamined50reviewarticlespublishedinfourleadingmedicaljournalsin1985and1986andfoundthatnonemetalleightexplicitscientificcriteria,suchasaqualityassessmentofincludedstudies.5In1987Sacksandcolleaguesevalu-atedtheadequacyofreportingof83meta-analyseson23characteristicsinsixdomains.6Reportingwas

generallypoor;betweenoneand14characteristicswereadequatelyreported(mean7.7,standarddevia-tion2.7).A1996updateofthisstudyfoundlittleimprovement.7

In1996,toaddressthesuboptimalreportingofmeta-analyses,aninternationalgroupdevelopedaguidancecalledtheQUOROMstatement(QUalityOfReportingOfMeta-analyses),whichfocusedonthereportingofmeta-analysesofrandomisedcontrol-ledtrials.8Inthisarticle,wesummarisearevisionoftheseguidelines,renamedPRISMA(PreferredReportingItemsforSystematicreviewsandMeta-Analyses),whichhavebeenupdatedtoaddresssev-eralconceptualandpracticaladvancesinthescienceofsystematicreviews(seebox).

Terminology

Theterminologyusedtodescribeasystematicreviewandmeta-analysishasevolvedovertime.OnereasonforchangingthenamefromQUOROMtoPRISMAwasthedesiretoencompassbothsystematicreviews

ConceptualissuesintheevolutionfromQUOROMtoPRISMA

Completingasystematicreviewisaniterativeprocess

Theconductofasystematicreviewdependsheavilyonthescopeandqualityofincludedstudies:thussystematicreviewersmayneedtomodifytheiroriginalreviewprotocolduringitsconduct.Anysystematicreviewreportingguidelineshouldrecommendthatsuchchangescanbereportedandexplainedwithoutsuggestingthattheyareinappropriate.ThePRISMAstatement(items5,11,16,and23)acknowledgesthisiterativeprocess.AsidefromCochranereviews,allofwhichshouldhaveaprotocol,onlyabout10%ofsystematicreviewersreportworkingfromaprotocol.9Withoutaprotocolthatispubliclyaccessible,itisdifficulttojudgebetweenappropriateandinappropriatemodifications.

Conductandreportingofresearcharedistinctconcepts

Thisdistinctionis,however,lessstraightforwardforsystematicreviewsthanforassessmentsof

thereportingofanindividualstudy,becausethereportingandconductofsystematicreviewsare,bynature,closelyintertwined.Forexample,thefailureofasystematicreviewtoreporttheassessmentoftheriskofbiasinincludedstudiesmaybeseenasamarkerofpoorconduct,giventheimportanceofthisactivityinthesystematicreviewprocess.10

Study-levelversusoutcome-levelassessmentofriskofbias

Forstudiesincludedinasystematicreview,athoroughassessmentoftheriskofbiasrequiresbothastudy-levelassessment(suchasadequacyofallocationconcealment)and,forsomefeatures,anewerapproachcalledoutcome-levelassessment.Anoutcome-levelassessmentinvolvesevaluatingthereliabilityandvalidity

ofthedataforeachimportantoutcomebydeterminingthemethodsusedtoassessthemineachindividualstudy.11Thequalityofevidencemaydifferacrossoutcomes,evenwithinastudy,suchasbetweenaprimaryefficacyoutcome,

whichislikelytobecarefullyandsystematicallymeasured,andtheassessmentofseriousharms,12whichmayrelyonspontaneousreportsbyinvestigators.Thisinformationshouldbereportedtoallowanexplicitassessmentoftheextenttowhichanestimateofeffectiscorrect.11

Importanceofreportingbiases

Differenttypesofreportingbiasesmayhampertheconductandinterpretationofsystematicreviews.Selectivereportingofcompletestudies(suchaspublicationbias),13aswellasthemorerecentlyempiricallydemonstrated“outcomereportingbias”withinindividualstudies,1415shouldbeconsideredbyauthorswhenconductingasystematicreviewandreportingitsresults.Althoughtheimplicationsofthesebiasesontheconductandreportingofsystematicreviewsthemselvesareunclear,someresearchhasidentifiedthatselectiveoutcomereportingmayoccuralsointhecontextofsystematicreviews.16

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Table1|Checklistofitemstoincludewhenreportingasystematicreviewormeta-analysis

Reportedonpage

Section/topic

ItemNo

Checklistitem

No

Title

Title

1

Identifythereportasasystematicreview,meta-analysis,orboth

Abstract

Structuredsummary

2

Provideastructuredsummaryincluding,asapplicable,background,objectives,

datasources,studyeligibilitycriteria,participants,interventions,studyappraisal

andsynthesismethods,results,limitations,conclusionsandimplicationsofkey

findings,systematicreviewregistrationnumber

Introduction

Rationale

3

Describetherationaleforthereviewinthecontextofwhatisalreadyknown

Objectives

4

Provideanexplicitstatementofquestionsbeingaddressedwithreferenceto

participants,interventions,comparisons,outcomes,andstudydesign(PICOS)

Methods

Protocolandregistration

5

Indicateifareviewprotocolexists,ifandwhereitcanbeaccessed(suchas

webaddress),and,ifavailable,provideregistrationinformationincluding

registrationnumber

Eligibilitycriteria

6

Specifystudycharacteristics(suchasPICOS,lengthoffollow-up)andreport

characteristics(suchasyearsconsidered,language,publicationstatus)used

ascriteriaforeligibility,givingrationale

Informationsources

7

Describeallinformationsources(suchasdatabaseswithdatesofcoverage,

contactwithstudyauthorstoidentifyadditionalstudies)inthesearchand

datelastsearched

Search

8

Presentfullelectronicsearchstrategyforatleastonedatabase,includingany

limitsused,suchthatitcouldberepeated

Studyselection

9

Statetheprocessforselectingstudies(thatis,screening,eligibility,included

insystematicreview,and,ifapplicable,includedinthemeta-analysis)

Datacollectionprocess

10

Describemethodofdataextractionfromreports(suchaspilotedforms,

independently,induplicate)andanyprocessesforobtainingandconfirming

datafrominvestigators

Dataitems

11

Listanddefineallvariablesforwhichdataweresought(suchasPICOS,funding

sources)andanyassumptionsandsimplificationsmade

Riskofbiasinindividualstudies

12

Describemethodsusedforassessingriskofbiasofindividualstudies

(includingspecificationofwhetherthiswasdoneatthestudyoroutcome

level),andhowthisinformationistobeusedinanydatasynthesis

Summarymeasures

13

Statetheprincipalsummarymeasures(suchasriskratio,differenceinmeans).

Synthesisofresults

14

Describethemethodsofhandlingdataandcombiningresultsofstudies,if

done,includingmeasuresofconsistency(suchasI2statistic)foreachmeta-

analysis

Riskofbiasacrossstudies

15

Specifyanyassessmentofriskofbiasthatmayaffectthecumulativeevidence

(suchaspublicationbias,selectivereportingwithinstudies)

Additionalanalyses

16

Describemethodsofadditionalanalyses(suchassensitivityorsubgroup

analyses,meta-regression),ifdone,indicatingwhichwerepre-specified

Results

Studyselection

17

Givenumbersofstudiesscreened,assessedforeligibility,andincludedinthe

review,withreasonsforexclusionsateachstage,ideallywithaflowdiagram

Studycharacteristics

18

Foreachstudy,presentcharacteristicsforwhichdatawereextracted(suchas

studysize,PICOS,follow-upperiod)andprovidethecitations

Riskofbiaswithinstudies

19

Presentdataonriskofbiasofeachstudyand,ifavailable,anyoutcome-level

assessment(seeitem12).

Resultsofindividualstudies

20

Foralloutcomesconsidered(benefitsorharms),presentforeachstudy(a)

simplesummarydataforeachinterventiongroupand(b)effectestimatesand

confidenceintervals,ideallywithaforestplot

Synthesisofresults

21

Presentresultsofeachmeta-analysisdone,includingconfidenceintervalsand

measuresofconsistency

Riskofbiasacrossstudies

22

Presentresultsofanyassessmentofriskofbiasacrossstudies(seeitem15)

Additionalanalysis

23

Giveresultsofadditionalanalyses,ifdone(suchassensitivityorsubgroup

analyses,meta-regression)(seeitem16)

Discussion

Summaryofevidence

24

Summarisethemainfindingsincludingthestrengthofevidenceforeachmain

outcome;considertheirrelevancetokeygroups(suchashealthcareproviders,

users,andpolicymakers)

Limitations

25

Discusslimitationsatstudyandoutcomelevel(suchasriskofbias),andat

reviewlevel(suchasincompleteretrievalofidentifiedresearch,reporting

bias)

Conclusions

26

Provideageneralinterpretationoftheresultsinthecontextofotherevidence,

andimplicationsforfutureresearch

Funding

Funding

27

Describesourcesoffundingforthesystematicreviewandothersupport(such

assupplyofdata)androleoffundersforthesystematicreview

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andmeta-analyses.WehaveadoptedthedefinitionsusedbytheCochraneCollaboration.17Asystematicreviewisareviewofaclearlyformulatedquestionthatusessystematicandexplicitmethodstoidentify,select,andcriticallyappraiserelevantresearch,andtocollectandanalysedatafromthestudiesthatareincludedinthereview.Statisticalmethods(meta-analysis)mayormaynotbeusedtoanalyseandsummarisetheresultsoftheincludedstudies.Meta-analysisreferstotheuseofstatisticaltechniquesinasystematicreviewtointegratetheresultsofincludedstudies.

DevelopingthePRISMAstatement

three-daymeetingwasheldinOttawa,Canada,inJune2005with29participants,includingreviewauthors,methodologists,clinicians,medicaleditors,andaconsumer.TheobjectiveoftheOttawameetingwastoreviseandexpandtheQUOROMchecklistandflowdiagramasneeded.

Theexecutivecommitteecompletedthefollowingtasksbeforethemeeting:asystematicreviewofstudiesexaminingthequalityofreportingofsystematicreviews;acomprehensiveliteraturesearchtoidentifymethodo-logicalandotherarticlesthatmightinformthemeeting,especiallyinrelationtomodifyingchecklistitems;andaninternationalsurveyofreviewauthors,consumers,andgroupscommissioningorusingsystematicreviewsandmeta-analyses(includingtheInternationalNetworkofAgenciesforHealthTechnologyAssessmentandtheGuidelinesInternationalNetwork)toascertainviewsofQUOROM,includingthemeritsoftheexistingchecklistitems.Theresultsoftheseactivitieswerepresenteddur-ingthemeetingandaresummarisedonthePRISMAwebsite,/.

Onlyitemsdeemedessentialwereretainedoraddedtothechecklist.Someadditionalitemsareneverthelessdesirable,andreviewauthorsshouldincludethese,ifrelevant.18Forexample,itisusefultoindicatewhetherthesystematicreviewisanupdateofapreviousreview19andtodescribeanychangesinproceduresfromthosedescribedintheoriginalprotocol.

Shortlyafterthemeeting,adraftofthePRISMA

Identification

Noofrecordsidentified

Noofadditionalrecords

throughdatabasesearching

identifiedthroughothersources

Screening

Noofrecordsafterduplicatesremoved

Noofrecordsscreened

Noofrecordsexcluded

Eligibility

Nooffull-textarticles

Nooffull-textarticles

assessedforeligibility

excluded,withreasons

Included

Noofstudiesincludedinqualitativesynthesis

Noofstudiesincludedinquantitativesynthesis(meta-analysis)

Flowofinformationthroughthedifferentphasesofasystematicreview

checklistwascirculatedtothegroup,includingthoseinvitedtothemeetingbutunabletoattend.Adispo-sitionfilewascreatedcontainingcommentsandrevi-sionsfromeachrespondent,andthechecklistwassubsequentlyrevised11times.Thegroupapprovedthechecklist,flowdiagram,andthissummarypaper.

Althoughnodirectevidencewasfoundtosupportretainingoraddingsomeitems,evidencefromotherdomainswasbelievedtoberelevant.Forexample,item5asksauthorstoprovideregistrationinformationaboutthesystematicreview,includingaregistrationnumberifavailable.Althoughsystematicreviewregis-trationisnotyetwidelyavailable,2021theparticipatingjournalsoftheInternationalCommitteeofMedicalJournalEditors22nowrequireallclinicaltrialstoberegisteredinanefforttoincreasetransparencyandaccountability.23Thoseaspectsarealsolikelytoben-efitsystematicreviewers,possiblyreducingtheriskofanexcessivenumberofreviewsaddressingthesamequestion2425andprovidinggreatertransparencywhenupdatingsystematicreviews.

ThePRISMAstatement

ThePRISMAstatementconsistsofa27itemchecklist(table1)andafourphaseflowdiagram(figure)(alsoavailableasextraitemsonforresearcherstodownloadandre-use).TheaimofthePRISMAstate-mentistohelpauthorsimprovethereportingofsys-tematicreviewsandmeta-analyses.Wehavefocusedonrandomisedtrials,butPRISMAcanalsobeusedasabasisforreportingsystematicreviewsofothertypesofresearch,particularlyevaluationsofinterventions.PRISMAmayalsobeusefulforcriticalappraisalofpublishedsystematicreviews.However,thePRISMAchecklistisnotaqualityassessmentinstrumenttogaugethequalityofasystematicreview.

FromQUOROMtoPRISMA

ThenewPRISMAchecklistdiffersinseveralrespectsfromtheQUOROMchecklist,andtable2liststhesubstantivespecificchanges.Generally,thePRISMAchecklist“decouples”severalitemspresentintheQUOROMchecklistand,whereapplicable,severalchecklistitemsarelinkedtoimproveconsistencyacrossthesystematicreviewreport.

Theflowdiagramhasalsobeenmodified.Beforeincludingstudiesandprovidingreasonsforexcludingothers,thereviewteammustfirstsearchthelitera-ture.Thissearchresultsinrecords.Oncetheserecordshavebeenscreenedandeligibilitycriteriaapplied,asmallernumberofarticleswillremain.Thenumberofincludedarticlesmightbesmaller(orlarger)thanthenumberofstudies,becausearticlesmayreportonmultiplestudiesandresultsfromaparticularstudymaybepublishedinseveralarticles.Tocapturethisinformation,thePRISMAflowdiagramnowrequestsinformationonthesephasesofthereviewprocess.

Endorsement

ThePRISMAstatementshouldreplacetheQUOROMstatementforthosejournalsthathaveendorsed

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Table2|SubstantivespecificchangesbetweentheQUOROMchecklistandthePRISMAchecklist(atickindicatesthepresenceofthetopicinQUOROMorPRISMA)

Section/topicanditem

PRISMA

QUOROM

Comment

Abstract

√

√

QUOROMandPRISMAaskauthorstoreportanabstract.However,PRISMAisnotspecificaboutformat

Introduction:

Objective

√

Thisnewitem(4)addressestheexplicitquestionthereviewaddressesusingthePICOreportingsystem(whichdescribestheparticipants,

interventions,comparisons,andoutcome(s)ofthesystematicreview),togetherwiththespecificationofthetypeofstudydesign(PICOS);

theitemislinkedtoitems6,11,and18ofthechecklist

Methods:

Protocol

√

Thisnewitem(5)asksauthorstoreportwhetherthereviewhasaprotocolandifsohowitcanbeaccessed

Search

√

√

AlthoughreportingthesearchispresentinbothQUOROMandPRISMAchecklists,PRISMAasksauthorstoprovideafulldescriptionofat

leastoneelectronicsearchstrategy(item8).Withoutsuchinformationitisimpossibletorepeattheauthors’search

 Assessmentofriskofbias

√

√

Renamedfrom“qualityassessment”inQUOROM.Thisitem(12)islinkedtoreportingthisinformationintheresults(item19).Thenew

inincludedstudies

conceptof“outcomelevel”assessmenthasbeenintroduced

 Assessmentofriskofbias

√

Thisnewitem(15)asksauthorstodescribeanyassessmentsofriskofbiasinthereview,suchasselectivereportingwithintheincluded

acrossstudies

studies.Thisitemislinkedtoreportingthisinformationintheresults(item22)

Discussion

√

√

AlthoughbothQUOROMandPRISMAchecklistsaddressthediscussionsection,PRISMAdevotesthreeitems(24-26)tothediscussion.In

PRISMAthemaintypesoflimitationsareexplicitlystatedandtheirdiscussionrequired

Funding

√

Thisnewitem(27)asksauthorstoprovideinformationonanysourcesoffundingforthesystematicreview.

QUOROM.WehopethatotherjournalswillsupportPRISMA;theycandosobyregisteringonthePRISMAwebsite.Toemphasisetoauthorsandotherstheimpor-tanceoftransparentreportingofsystematicreviews,weencouragesupportingjournalstoreferencethePRISMAstatementandincludethePRISMAwebaddressintheirinstructionstoauthors.Wealsoinviteeditorialorgani-sationstoconsiderendorsingPRISMAandencourageauthorstoadheretoitsprinciples.

ThePRISMAexplanationandelaborationpaper

InadditiontothePRISMAstatement,asupportingexplanationandelaborationdocumenthasbeenpro-duced26followingthestyleusedforotherreportingguidelines.27‑29Theprocessofcompletingthisdocumentincludeddevelopingalargedatabaseofexemplarstohighlighthowbesttoreporteachchecklistitem,andidentifyingacomprehensiveevidencebasetosupporttheinclusionofeachchecklistitem.Theexplanationandelaborationdocumentwascompletedafterseveralfacetofacemeetingsandnumerousiterationsamongseveralmeetingparticipants,afterwhichitwassharedwiththewholegroupforadditionalrevisionsandfinalapproval.Finally,thegroupformedadisseminationsubcommitteetohelpdisseminateandimplementPRISMA.

Discussion

Thequalityofreportingofsystematicreviewsisstillnotoptimal.930‑34Inarecentreviewof300systematicreviews,fewauthorsreportedassessingpossiblepublica-tionbias,9eventhoughthereisoverwhelmingevidenceforitsexistence13anditsimpactontheresultsofsystem-aticreviews.35Evenwhenthepossibilityofpublicationbiasisassessed,thereisnoguaranteethatsystematicreviewershaveassessedorinterpreteditappropriately.36Althoughtheabsenceofreportingsuchanassessmentdoesnotnecessarilyindicatethatitwasnotdone,report-inganassessmentofpossiblepublicationbiasislikelytobeamarkerofthethoroughnessoftheconductofthesystematicreview.

Severalapproacheshavebeendevelopedtoconductsystematicreviewsonabroaderarrayofquestions.Forexample,systematicreviewsarenowconductedtoinves-

tigatecosteffectiveness,37diagnostic38orprognosticques-tions,39geneticassociations,40andpolicymaking.41ThegeneralconceptsandtopicscoveredbyPRISMAarerelevanttoanysystematicreview,notjustthosesum-marisingthebenefitsandharmsofahealthcareinterven-tion.However,somemodificationsofthechecklistitemsorflowdiagramwillbenecessaryinparticularcircum-stances.Forexample,assessingtheriskofbiasisakeyconcept,buttheitemsusedtoassessthisinadiagnosticreviewarelikelytofocusonissuessuchasthespectrumofpatientsandtheverificationofdiseasestatus,whichdifferfromreviewsofinterventions.Theflowdiagramwillalsoneedadjustmentswhenreportingmeta-analysisofindividualpatientdata.42

WehavedevelopedanexplanatorydocumenttoincreasetheusefulnessofPRISMA.26Foreachchecklistitem,thisdocumentcontainsanexampleofgoodreport-ing,arationaleforitsinclusion,andsupportingevidence,includingreferences,wheneverpossible.Webelievethisdocumentwillalsoserveasausefulresourceforthoseteachingsystematicreviewmethodology.Weencouragejournalstoincludereferencetotheexplanatorydocu-mentintheirinstructionstoauthors.

Likeanyevidencebasedendeavour,PRISMAisalivingdocument.Tothisendweinvitereaderstocommentontherevisedversion,particularlythenewchecklistandflowdiagram,throughthePRISMAweb-site.WewillusesuchinformationtoinformPRISMA’scontinueddevelopment.

Contributors:See.

Funding:PRISMAwasfundedbytheCanadianInstitutesofHealthResearch;UniversitàdiModenaeReggioEmilia,Italy;CancerResearchUK;ClinicalEvidenceBMJKnowledge;theCochraneCollaboration;andGlaxoSmithKline,Canada.ALisfunded,inpart,throughgrantsoftheItalianMinistryofUniversity(COFIN-PRIN2002prot2002061749andCOFIN-PRIN2006prot2006062298).DGAisfundedbyCancerResearchUK.DMisfundedbyaUniversityofOttawaResearchChair.Noneofthesponsorshadanyinvolvementintheplanning,execution,orwritingofthePRISMAdocuments.Nofunderplayedaroleindraftingthismanuscript.

Competinginterests:Nonedeclared.

Provenanceandpeerreview:Notcommissioned;externallypeerreviewed.InordertoencouragedisseminationofthePRISMAstatement,thisarticle

isfreelyaccessibleonandwillalsobepublishedinPLoSMedicine,AnnalsofInternalMedicine,JournalofClinicalEpidemiology,andOpenMedicine.Theauthorsjointlyholdthecopyrightofthisarticle.Fordetailsonfurtheruse,seethePRISMAwebsite(/).

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JoannaBriggsInstitute.Protocols&workinprogr