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Page, Matthew J, McKenzie, Joanne E, Bossuyt, Patrick M et al. (23 more authors) (2021)
The PRISMA 2020 statement : An updated guideline for reporting systematic reviews.
Journal of Clinical Epidemiology. ISSN 0895-4356
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Journal of Clinical Epidemiology xxx (xxxx) xxx
ORIGINAL ARTICLE
The PRISMA 2020 statement: An updated guideline for reporting
systematic reviews
Matthew J. Page
a , ∗
, Joanne E. McKenzie
a
, Patrick M. Bossuyt
b
, Isabelle Boutron
c
,
Tammy C. Hoffmann
d
, Cynthia D. Mulrow
e
, Larissa Shamseer
f , g
, Jennifer M. Tetzlaff
h
,
Elie A. Akl
i , j
, Sue E. Brennan
a
, Roger Chou
k
, Julie Glanville
l
, Jeremy M. Grimshaw
m , n , o
,
Asbjørn Hróbjartsson
p , q
, Manoj M. Lalu
r , s , t
, Tianjing Li
u , v
, Elizabeth W. Loder
w , x
,
Evan Mayo-Wilson
y
, Steve McDonald
a
, Luke A. McGuinness
z
, Lesley A. Stewart
aa
,
James Thomas
ab
, Andrea C. Tricco
ac , ad , ae
, Vivian A. Welch
af , ag
, Penny Whiting
z
,
David Moher
ah , ai
a
School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia
b
Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Amsterdam University Medical Centres, University of Amsterdam, Amsterdam,
The Netherlands
c
Université de Paris, Centre of Epidemiology and Statistics (CRESS), Inserm, F 75004, Paris, France
d
Institute for Evidence-Based Healthcare, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, Australia
e
University of Texa s Health Science Center at San Antonio, San Antonio, TX, USA
f
Knowledge Translation Program, Li Ka Shing Knowledge Institute, Toronto, Canada
g
School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, Canada
h
Evidence Par tn ers, Ottawa, Canada
i
Clinical Research Institute, American University of Beirut, Beirut, Lebanon
j
Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada
k
Department of Medical Informatics and Clinical Epidemiology, Oregon Health & Science University, Portland, OR, USA
l
Yor k Health Economics Consortium (YHEC Ltd), University of Yor k, Yor k, UK
m
Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
n
School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada
o
Department of Medicine, University of Ottawa, Ottawa, Canada
p
Centre for Evidence-Based Medicine Odense (CEBMO) and Cochrane Denmark, Department of Clinical Research, University of Southern Denmark,
JB Winsløwsvej 9b, 3
rd Floor, 5000 Odense, Denmark
q
Open Patient data Exploratory Network (OPEN), Odense University Hospital, Odense, Denmark
r
Department of Anesthesiology and Pai n Medicine, The Ottawa Hospital, Ottawa, Canada
Conflict of interest: All authors have completed the ICMJE uniform disclosure form at
http:// www.icmje.org/ conflicts- of- interest/ and declare: EL is
head of research for the BMJ ; MJP is an editorial board member for PLOS Medicine ; ACT is an associate editor and MJP, TL, EMW, and DM are
editorial board members for the Journal of Clinical Epidemiology ; DM and LAS were editors in chief, LS, JMT, and ACT are associate editors, and
JG is an editorial board member for Systematic Reviews . None of these authors were involved in the peer review process or decision to publish. TCH
has received personal fees from Elsevier outside the submitted work. EMW has received personal fees from the American Journal for Public Health , for
which he is the editor for systematic reviews. VW is editor in chief of the Campbell Collaboration, which produces systematic reviews, and co-convenor
of the Campbell and Cochrane equity methods group. DM is chair of the EQUATOR Network, IB is adjunct director of the French EQUATOR Centre
and TCH is co-director of the Australasian EQUATOR Centre, which advocates for the use of reporting guidelines to improve the quality of reporting in
research articles. JMT received salary from Evidence Partners, creator of DistillerSR software for systematic reviews; Evidence Partners was not involved
in the design or outcomes of the statement, and the views expressed solely represent those of the author.
Provenance and peer review: Not commissioned; externally peer reviewed.
Funding: There was no direct funding for this research. MJP is supported by an Australian Research Council Discovery Early Career Researcher
Awa rd (DE200101618) and was previously supported by an Australian National Health and Medical Research Council (NHMRC) Early Career Fellowship
(1088535) during the conduct of this research. JEM is supported by an Australian NHMRC Career Development Fellowship (1143429). TCH is supported
by an Australian NHMRC Senior Research Fellowship (1154607). JMT is supported by Evidence Partners Inc. JMG is supported by a Tier 1 Canada
Research Chair in Health Knowledge Transfer and Uptake. MML is supported by The Ottawa Hospital Anaesthesia Alternate Funds Association and a
Faculty of Medicine Junior Research Chair. TL is supported by funding from the National Eye Institute (
UG1EY020522 ), National Institutes of Health,
United States. LAM is supported by a National Institute s for Health Research Doctoral Research Fellowship (
DRF-2018-11-ST2-048 ). ACT is supported
by a Tier 2 Canada Research Chair in Knowledge Synthesis. DM is supported in part by a University Research Chair, University of Ottawa. The funders
had no role in considering the study design or in the collection, analysis, interpretation of data, writing of the report, or decision to submit the article
for publication.
∗Corresponding author.
E-mail address:
matthew.page@monash.edu (M.J. Page).
https://doi.org/10.1016/j.jclinepi.2021.03.001
0895-4356/© 2021 Published by Elsevier Inc.
Please cite this article as: M.J. Page et al., The PRISMA 2020 statement: An updated guideline for reporting systematic reviews, Journal of Clinical
Eid il htt //di /10 1016/j j li i 2021 03 001
2 M.J. Page et al. / Journal of Clinical Epidemiology xxx (xxxx) xxx
ARTICLE IN PRESS
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s
Clinical Epidemiology Program, Blueprint Translational Research Group, Ottawa Hospital Research Institute, Ottawa, Canada
t
Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada
u
Department of Ophthalmology, School of Medicine, University of Colorado Denver, Denver, Colorado, United State
v
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
w
Division of Headache, Department of Neurology, Brigham and Women ’s Hospital, Harvard Medical School, Boston, MA, USA
x
Head of Research, The BMJ , London, UK
y
Department of Epidemiology and Biostatistics, Indiana University School of Public Health-Bloomington, Bloomington, IN, USA
z
Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
aa
Centre for Reviews and Dissemination, University of Yo rk , Yo rk , UK
ab
EPPI-Centre, UCL Social Research Institute, University College London, London, UK
ac
Li Ka Shing Knowledge Institute of St. Michael’s Hospital, Unity Health Toronto, Toronto, Canada
ad
Epidemiology Division of the Dalla Lana School of Public Health and the Institute of Health Management, Policy, and Evaluation, University of
Toronto, Toronto, Canada
ae
Queen’s Collaboration for Health Care Quality Joanna Briggs Institute Centre of Excellence, Queen’s University, Kingston, Canada
af
Methods Centre, Bruyère Research Institute, Ottawa, Ontario, Canada
ag
School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, Canada
ah
Centre for Journalology, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
ai
School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, Canada
Available online xxx
Abstract
The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, published in 2009, was designed
to help systematic reviewers transparently report why the review was done, what the authors did, and what they found. Over the past
decade, advances in systematic review methodology and terminology have necessitated an update to the guideline. The PRISMA 2020
statement replaces the 2009 statement and includes new reporting guidance that reflects advances in methods to identify, select, appraise,
and synthesise studies. The structure and presentation of the items have been modified to facilitate implementation. In this article, we
present the PRISMA 2020 27-item checklist, an expanded checklist that details reporting recommendations for each item, the PRISMA
2020 abstract checklist, and the revised flow diagrams for original and updated reviews. © 2021 Published by Elsevier Inc.
Keywords: Systematic review; Meta-analysis; Reporting guideline; Transparency; Reproducibility; Checklist
1. Introduction
Systematic reviews serve many critical roles. They can
provide syntheses of the state of knowledge in a field, from
which future research priorities can be identified; they can
address questions that otherwise could not be answered by
individual studies; they can identify problems in primary
research that should be rectified in future studies; and they
can generate or evaluate theories about how or why phe-
nomena occur. Systematic reviews therefore generate vari-
ous types of knowledge for different users of reviews (such
as patients, healthcare providers, researchers, and policy
makers) [1 , 2] . To ensure a systematic review is valuable
to users, authors should prepare a transparent, complete,
and accurate account of why the review was done, what
they did (such as how studies were identified and selected)
and what they found (such as characteristics of contributing
studies and results of meta-analyses). Up-to-date reporting
guidance facilitates authors achieving this [3] .
The Preferred Reporting Items for Systematic reviews
and Meta-Analyses (PRISMA) statement published in 2009
(hereafter referred to as PRISMA 2009)
[4–10] is a report-
ing guideline designed to address poor reporting of system-
atic reviews [11] . The PRISMA 2009 statement comprised
a checklist of 27 items recommended for reporting in sys-
tematic reviews and an “explanation and elaboration” paper
[12–16] providing additional reporting guidance for each
item, along with exemplars of reporting. The recommenda-
tions have been widely endorsed and adopted, as evidenced
by its copublication in multiple journals, citation in over
60 000 reports (Scopus, August 2020), endorsement from
almost 200 journals and systematic review organizations,
and adoption in various disciplines. Evidence from obser-
vational studies suggests that use of the PRISMA 2009
statement is associated with more complete reporting of
systematic reviews [17–20] , although more could be done
to improve adherence to the guideline [21] .
Many innovations in the conduct of systematic reviews
have occurred since publication of the PRISMA 2009 state-
ment. For example, technological advances have enabled
the use of natural language processing and machine learn-
ing to identify relevant evidence [22–24] , methods have
been proposed to synthesise and present findings when
meta-analysis is not possible or appropriate [25–27] , and
new methods have been developed to assess the risk of bias
in results of included studies [28 , 29] . Evidence on sources
of bias in systematic reviews has accrued, culminating in
the development of new tools to appraise the conduct of
Please cite this article as: M.J. Page et al., The PRISMA 2020 statement: An updated guideline for reporting systematic reviews, Journal of Clinical
Epidemiology, https:// doi.org/ 10.1016/ j.jclinepi.2021.03.001
M.J. Page et al. / Journal of Clinical Epidemiology xxx (xxxx) xxx 3
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systematic reviews [30 , 31] . Terminology used to describe
particular review processes has also evolved, as in the
shift from assessing “quality” to assessing “certainty” in
the body of evidence [32] . In addition, the publishing
landscape has transformed, with multiple avenues now
available for registering and disseminating systematic re-
view protocols
[33 , 34] , disseminating reports of systematic
reviews, and sharing data and materials, such as preprint
servers and publicly accessible repositories. To capture
these advances in the reporting of systematic reviews
necessitated an update to the PRISMA 2009 statement.
Box Summary points
• To ensure a systematic review is valuable to users,
authors should prepare a transparent, complete, and
accurate account of why the review was done, what
they did, and what they found.
• The PRISMA 2020 statement provides updated re-
porting guidance for systematic reviews that reflects
advances in methods to identify, select, appraise,
and synthesise studies.
• The PRISMA 2020 statement consists of a 27-item
checklist, an expanded checklist that details report-
ing recommendations for each item, the PRISMA
2020 abstract checklist, and revised flow diagrams
for original and updated reviews.
• We anticipate that the PRISMA 2020 statement will
benefit authors, editors, and peer reviewers of sys-
tematic reviews, and different users of reviews, in-
cluding guideline developers, policy makers, health-
care providers, patients, and other stakeholders.
2. Development of PRISMA 2020
A complete description of the methods used to develop
PRISMA 2020 is available elsewhere [35] . We identified
PRISMA 2009 items that were often reported incompletely
by examining the results of studies investigating the trans-
parency of reporting of published reviews [17 , 21 , 36 , 37] .
We identified possible modifications to the PRISMA 2009
statement by reviewing 60 documents providing reporting
guidance for systematic reviews (including reporting
guidelines, handbooks, tools, and meta-research studies)
[38] . These reviews of the literature were used to inform
the content of a survey with suggested possible modifi-
cations to the 27 items in PRISMA 2009 and possible
additional items. Respondents were asked whether they
believed we should keep each PRISMA 2009 item as is,
modify it, or remove it, and whether we should add each
additional item. Systematic review methodologists and
journal editors were invited to complete the online survey
(110 of 220 invited responded). We discussed proposed
content and wording of the PRISMA 2020 statement, as
informed by the review and survey results, at a 21-member,
2-day, in-person meeting in September 2018 in Edinburgh,
Scotland. Throughout 2019 and 2020, we circulated an
initial draft and five revisions of the checklist and expla-
nation and elaboration paper to coauthors for feedback. In
April 2020, we invited 22 systematic reviewers who had
expressed interest in providing feedback on the PRISMA
2020 checklist to share their views (via an online survey)
on the layout and terminology used in a preliminary
version of the checklist. Feedback was received from 15
individuals and considered by the first author, and any
revisions deemed necessary were incorporated before the
final version was approved and endorsed by all coauthors.
3. The PRISMA 2020 statement
3.1. Scope of the guideline
The PRISMA 2020 statement has been designed pri-
marily for systematic reviews of studies that evaluate
the effects of health interventions, irrespective of the de-
sign of the included studies. However, the checklist items
are applicable to reports of systematic reviews evaluat-
ing other interventions (such as social or educational in-
terventions), and many items are applicable to system-
atic reviews with objectives other than evaluating inter-
ventions (such as evaluating an etiology, prevalence, or
prognosis). PRISMA 2020 is intended for use in system-
atic reviews that include synthesis (such as pairwise meta-
analysis or other statistical synthesis methods) or do not
include synthesis (for example, because only one eligible
study is identified). The PRISMA 2020 items are rele-
vant for mixed-methods systematic reviews (which include
quantitative and qualitative studies), but reporting guide-
lines addressing the presentation and synthesis of qual-
itative data should also be consulted [39 , 40] . PRISMA
2020 can be used for original systematic reviews, up-
dated systematic reviews, or continually updated (“living”)
systematic reviews. However, for updated and living sys-
tematic reviews, there may be some additional consider-
ations that need to be addressed. Where there is rele-
vant content from other reporting guidelines, we reference
these guidelines within the items in the explanation and
elaboration paper [41] (such as PRISMA-Search [42] in
items 6 and 7, Synthesis without meta-analysis (SWiM)
reporting guideline [27] in item 13d). Box 1 includes
a glossary of terms used throughout the PRISMA 2020
statement.
Box 1 Glossary of terms
Systematic review —A review that uses explicit, sys-
tematic methods to collate and synthesise findings of
studies that address a clearly formulated question
[43]
Please cite this article as: M.J. Page et al., The PRISMA 2020 statement: An updated guideline for reporting systematic reviews, Journal of Clinical
Epidemiology, https:// doi.org/ 10.1016/ j.jclinepi.2021.03.001
4 M.J. Page et al. / Journal of Clinical Epidemiology xxx (xxxx) xxx
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Statistical synthesis —The combination of quantita-
tive results of two or more studies. This encompasses
meta-analysis of effect estimates (described below)
and other methods, such as combining P values, cal-
culating the range and distribution of observed effects,
and vote counting based on the direction of effect (see
McKenzie and Brennan
[25] for a description of each
method)
Meta-analysis of effect estimates —A statistical
technique used to synthesise results when study effect
estimates and their variances are available, yielding a
quantitative summary of results [25]
Outcome —An event or measurement collected for
participants in a study (such as quality of life, mor-
tality)
Result —The combination of a point estimate
(such as a mean difference, risk ratio, or propor-
tion) and a measure of its precision (such as a confi-
dence/credible interval) for a particular outcome
Report —A document (paper or electronic) supply-
ing information about a particular study. It could be
a journal article, preprint, conference abstract, study
register entry, clinical study report, dissertation, un-
published manuscript, government report, or any other
document providing relevant information
Record —The title or abstract (or both) of a report
indexed in a database or website (such as a title or
abstract for an article indexed in Medline). Records
that refer to the same report (such as the same journal
article) are “duplicates”; however, records that refer to
reports that are merely similar (such as a similar ab-
stract submitted to two different conferences) should
be considered unique.
Study —An investigation, such as a clinical trial,
that includes a defined group of participants and one
or more interventions and outcomes. A “study” might
have multiple reports. For example, reports could in-
clude the protocol, statistical analysis plan, baseline
characteristics, results for the primary outcome, re-
sults for harms, results for secondary outcomes, and
results for additional mediator and moderator analyses
PRISMA 2020 is not intended to guide systematic
review conduct, for which comprehensive resources are
available
[43-46] . However, familiarity with PRISMA 2020
is useful when planning and conducting systematic reviews
to ensure that all recommended information is captured.
PRISMA 2020 should not be used to assess the conduct
or methodological quality of systematic reviews; other
tools exist for this purpose
[30 , 31] . Furthermore, PRISMA
2020 is not intended to inform the reporting of system-
atic review protocols, for which a separate statement is
available (PRISMA for Protocols (PRISMA-P) 2015
statement [47 , 48] ). Finally, extensions to the PRISMA
2009 statement have been developed to guide reporting of
network meta-analyses [49] , meta-analyses of individual
participant data [50] , systematic reviews of harms [51] ,
systematic reviews of diagnostic test accuracy studies
[52] , and scoping reviews [53] ; for these types of reviews
we recommend authors report their review in accordance
with the recommendations in PRISMA 2020 along with
the guidance specific to the extension.
4. How to use PRISMA 2020
The PRISMA 2020 statement (including the checklists,
explanation and elaboration, and flow diagram) replaces
the PRISMA 2009 statement, which should no longer be
used. Box 2 summarizes noteworthy changes from the
PRISMA 2009 statement. The PRISMA 2020 checklist in-
cludes seven sections with 27 items, some of which include
sub-items (
Table 1 ). A checklist for journal and conference
abstracts for systematic reviews is included in PRISMA
2020. This abstract checklist is an update of the 2013
PRISMA for Abstracts statement [54] , reflecting new and
modified content in PRISMA 2020 (
Table 2 ). A template
PRISMA flow diagram is provided, which can be modified
depending on whether the systematic review is original or
updated (
Fig. 1 ).
Box 2 Noteworthy changes to the PRISMA
2009 statement
• Inclusion of the abstract reporting checklist within
PRISMA 2020 (see item #2 and Table 2 ).
• Movement of the ‘Protocol and registration’ item
from the start of the Methods section of the check-
list to a new Other section, with addition of a sub-
item recommending authors describe amendments
to information provided at registration or in the pro-
tocol (see item #24a-24c).
• Modification of the ‘Search’ item to recommend au-
thors present full search strategies for all databases,
registers and websites searched, not just at least one
database (see item #7).
• Modification of the ‘Study selection’ item in the
Methods section to emphasize the reporting of how
many reviewers screened each record and each re-
port retrieved, whether they worked independently,
and if applicable, details of automation tools used
in the process (see item #8).
• Addition of a subitem to the ‘Data items’ item rec-
ommending authors report how outcomes were de-
fined, which results were sought, and methods for
selecting a subset of results from included studies
(see item #10a).
Please cite this article as: M.J. Page et al., The PRISMA 2020 statement: An updated guideline for reporting systematic reviews, Journal of Clinical
Epidemiology, https:// doi.org/ 10.1016/ j.jclinepi.2021.03.001
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• Splitting of the ‘Synthesis of results’ item in the
Methods section into six subitems recommend-
ing authors describe: the processes used to decide
which studies were eligible for each synthesis; any
methods required to prepare the data for synthe-
sis; any methods used to tabulate or visually dis-
play results of individual studies and syntheses; any
methods used to synthesise results; any methods
used to explore possible causes of heterogeneity
among study results (such as subgroup analysis,
meta-regression); and any sensitivity analyses used
to assess robustness of the synthesized results (see
item #13a-13f).
• Addition of a subitem to the ‘Study selection’ item
in the Results section recommending authors cite
studies that might appear to meet the inclusion cri-
teria, but which were excluded, and explain why
they were excluded (see item #16b).
• Splitting of the ‘Synthesis of results’ item in the
Results section into four subitems recommending
authors: briefly summaries the characteristics and
risk of bias among studies contributing to the syn-
thesis; present results of all statistical syntheses
conducted; present results of any investigations of
possible causes of heterogeneity among study re-
sults; and present results of any sensitivity analyses
(see item #20a-20d).
• Addition of new items recommending authors re-
port methods for and results of an assessment of
certainty (or confidence) in the body of evidence
for an outcome (see items #15 and #22).
• Addition of a new item recommending authors de-
clare any competing interests (see item #26).
• Addition of a new item recommending authors indi-
cate whether data, analytic code and other materials
used in the review are publicly available and if so,
where they can be found (see item #27).
We recommend authors refer to PRISMA 2020 early
in the writing process, because prospective considera-
tion of the items may help to ensure that all the items
are addressed. To help keep track of which items have
been reported, the PRISMA statement website (
http://
www.prisma-statement.org/) includes fillable templates of
the checklists to download and complete (also available
in the Appendix). We have also created a web appli-
cation that allows users to complete the checklist via
a user-friendly interface [58] (available at https://prisma.
shinyapps.io/ checklist/ and adapted from the Transparency
Checklist app [59] ). The completed checklist can be ex-
ported to Word or PDF. Editable templates of the flow
diagram can also be downloaded from the PRISMA state-
ment website.
We have prepared an updated explanation and elabora-
tion paper, in which we explain why reporting of each item
is recommended and present bullet points that detail the re-
porting recommendations (which we refer to as elements)
[41] . The bullet-point structure is new to PRISMA 2020
and has been adopted to facilitate implementation of the
guidance
[60 , 61] . An expanded checklist, which comprises
an abridged version of the elements presented in the ex-
planation and elaboration paper, with references and some
examples removed, is available in the Appendix. Consult-
ing the explanation and elaboration paper is recommended
if further clarity or information is required.
Journals and publishers might impose word and section
limits, and limits on the number of tables and figures al-
lowed in the main report. In such cases, if the relevant
information for some items already appears in a publicly
accessible review protocol, referring to the protocol may
suffice. Alternatively, placing detailed descriptions of the
methods used or additional results (such as for less criti-
cal outcomes) in supplementary files is recommended. Ide-
ally, supplementary files should be deposited to a general-
purpose or institutional open-access repository that pro-
vides free and permanent access to the material (such as
Open Science Framework, Dryad, figshare). A reference
or link to the additional information should be included in
the main report. Finally, although PRISMA 2020 provides
a template for where information might be located, the
suggested location should not be seen as prescriptive; the
guiding principle is to ensure the information is reported.
5. Discussion
Use of PRISMA 2020 has the potential to benefit many
stakeholders. Complete reporting allows readers to assess
the appropriateness of the methods, and therefore the trust-
worthiness of the findings. Presenting and summarizing
characteristics of studies contributing to a synthesis allows
healthcare providers and policy makers to evaluate the ap-
plicability of the findings to their setting. Describing the
certainty in the body of evidence for an outcome and the
implications of findings should help policy makers, man-
agers, and other decision makers formulate appropriate rec-
ommendations for practice or policy. Complete reporting
of all PRISMA 2020 items also facilitates replication and
review updates, as well as inclusion of systematic reviews
in overviews (of systematic reviews) and guidelines, so
teams can leverage work that is already done and decrease
research waste [36 , 62 , 63] .
We updated the PRISMA 2009 statement by adapting
the EQUATOR Network’s guidance for developing health
research reporting guidelines [64] . We evaluated the
reporting completeness of published systematic reviews
[17 , 21 , 36 , 37] , reviewed the items included in other doc-
uments providing guidance for systematic reviews [38] ,
surveyed systematic review methodologists and journal
editors for their views on how to revise the original
Please cite this article as: M.J. Page et al., The PRISMA 2020 statement: An updated guideline for reporting systematic reviews, Journal of Clinical
Epidemiology, https:// doi.org/ 10.1016/ j.jclinepi.2021.03.001
6 M.J. Page et al. / Journal of Clinical Epidemiology xxx (xxxx) xxx
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Table 1. PRISMA 2020 item checklist
Section and topic Item # Checklist item Location where
item is reported
Title
Tit le 1 Identify the report as a systematic review.
Abstract
Abstract 2 See the PRISMA 2020 for Abstracts checklist ( Tabl e 2 ).
Introduction
Rationale 3 Describe the rationale for the review in the context of existing knowledge.
Objectives 4 Provide an explicit statement of the objective(s) or question(s) the review addresses.
Methods
Eligibility criteria 5 Specify the inclusion and exclusion criteria for the review and how studies were
grouped for the syntheses.
Information
sources
6 Specify all databases, registers, websites, organisations, reference lists and other
sources searched or consulted to identify studies. Specify the date when each source
was last searched or consulted.
Search strategy 7 Present the full search strategies for all databases, registers and websites, including
any lters and limits used.
Selection
process
8 Specify the methods used to decide whether a study met the inclusion criteria of the
review, including how many reviewers screened each record and each report retrieved,
whether they worked independently, and if applicable, details of automation tools
used in the process.
Data collection
process
9 Specify the methods used to collect data from reports, including how many reviewers
collected data from each report, whether they worked independently, any processes
for obtaining or conrming data from study investigators, and if applicable, details of
automation tools used in the process.
Data items 10a List and dene all outcomes for which data were sought. Specify whether all results
that were compatible with each outcome domain in each study were sought (e.g. for
all measures, time points, analyses), and if not, the methods used to decide which
results to collect.
10b List and dene all other variables for which data were sought (e.g. participant and
intervention characteristics, funding sources). Describe any assumptions made about
any missing or unclear information.
Study risk of
bias assessment
11 Specify the methods used to assess risk of bias in the included studies, including
details of the tool(s) used, how many reviewers assessed each study and whether they
worked independently, and if applicable, details of automation tools used in the
process.
Effect measures 12 Specify for each outcome the effect measure(s) (e.g., risk ratio, mean difference) used
in the synthesis or presentation of results.
Synthesis
methods
13a Describe the processes used to decide which studies were eligible for each synthesis
(e.g., tabulating the study intervention characteristics and comparing against the
planned groups for each synthesis (item #5)).
13b Describe any methods required to prepare the data for presentation or synthesis, such
as handling of missing summary statistics, or data conversions.
13c Describe any methods used to tabulate or visually display results of individual studies
and syntheses.
13d Describe any methods used to synthesise results and provide a rationale for the
choice(s). If meta-analysis was performed, describe the model(s), method(s) to
identify the presence and extent of statistical heterogeneity, and software package(s)
used.
13e Describe any methods used to explore possible causes of heterogeneity among study
results (e.g., subgroup analysis, metaregression).
13f Describe any sensitivity analyses conducted to assess robustness of the synthesised
results.
Reporting bias
assessment
14 Describe any methods used to assess risk of bias due to missing results in a synthesis
(arising from reporting biases).
( continued on next page )
Please cite this article as: M.J. Page et al., The PRISMA 2020 statement: An updated guideline for reporting systematic reviews, Journal of Clinical
Epidemiology, https:// doi.org/ 10.1016/ j.jclinepi.2021.03.001
M.J. Page et al. / Journal of Clinical Epidemiology xxx (xxxx) xxx 7
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Table 1 ( continued )
Section and topic Item # Checklist item Location where
item is reported
Certainty
assessment
15 Describe any methods used to assess certainty (or condence) in the body of evidence
for an outcome.
Results
Study selection 16a Describe the results of the search and selection process, from the number of records
identied in the search to the number of studies included in the review, ideally using
a ow diagram (see
Fig. 1 ).
16b Cite studies that might appear to meet the inclusion criteria, but which were
excluded, and explain why they were excluded.
Study
characteristics
17 Cite each included study and present its characteristics.
Risk of bias in
studies
18 Present assessments of risk of bias for each included study.
Results of
individual
studies
19 For all outcomes, present, for each study: (a) summary statistics for each group
(where appropriate) and (b) an effect estimate and its precision (e.g.,
condence/credible interval), ideally using structured tables or plots.
Results of
syntheses
20a For each synthesis, briey summarise the characteristics and risk of bias among
contributing studies.
20b Present results of all statistical syntheses conducted. If meta-analysis was done,
present for each the summary estimate and its precision (e.g., condence/credible
interval) and measures of statistical heterogeneity. If comparing groups, describe the
direction of the effect.
20c Present results of all investigations of possible causes of heterogeneity among study
results.
20d Present results of all sensitivity analyses conducted to assess the robustness of the
synthesised results.
Reporting biases 21 Present assessments of risk of bias due to missing results (arising from reporting
biases) for each synthesis assessed.
Certainty of
evidence
22 Present assessments of certainty (or condence) in the body of evidence for each
outcome assessed.
Discussion
Discussion 23a Provide a general interpretation of the results in the context of other evidence.
23b Discuss any limitations of the evidence included in the review.
23c Discuss any limitations of the review processes used.
23d Discuss implications of the results for practice, policy, and future research.
Other information
Registration and
protocol
24a Provide registration information for the review, including register name and
registration number, or state that the review was not registered.
24b Indicate where the review protocol can be accessed, or state that a protocol was not
prepared.
24c Describe and explain any amendments to information provided at registration or in the
protocol.
Support 25 Describe sources of nancial or nonnancial support for the review, and the role of the
funders or sponsors in the review.
Competing
interests
26 Declare any competing interests of review authors.
Availability of
data, code, and
other materials
27 Report which of the following are publicly available and where they can be found:
template data collection forms; data extracted from included studies; data used for all
analyses; analytic code; any other materials used in the review.
Please cite this article as: M.J. Page et al., The PRISMA 2020 statement: An updated guideline for reporting systematic reviews, Journal of Clinical
Epidemiology, https:// doi.org/ 10.1016/ j.jclinepi.2021.03.001
8 M.J. Page et al. / Journal of Clinical Epidemiology xxx (xxxx) xxx
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Table 2. PRISMA 2020 for Abstracts checklist
∗
Section and topic Item # Checklist item
Title
Tit le 1 Identify the report as a systematic review.
Background
Objectives 2 Provide an explicit statement of the main objective(s) or question(s) the review
addresses.
Methods
Eligibility criteria 3 Specify the inclusion and exclusion criteria for the review.
Information sources 4 Specify the information sources (e.g. databases, registers) used to identify studies
and the date when each was last searched.
Risk of bias 5 Specify the methods used to assess risk of bias in the included studies.
Synthesis of results 6 Specify the methods used to present and synthesise results.
Results
Included studies 7 Give the total number of included studies and participants and summarise relevant
characteristics of studies.
Synthesis of results 8 Present results for main outcomes, preferably indicating the number of included
studies and participants for each. If meta-analysis was done, report the summary
estimate and condence/credible interval. If comparing groups, indicate the direction
of the effect (i.e. which group is favoured).
Discussion
Limitations of evidence 9 Provide a brief summary of the limitations of the evidence included in the review
(e.g., study risk of bias, inconsistency and imprecision).
Interpretation 10 Provide a general interpretation of the results and important implications.
Other
Funding 11 Specify the primary source of funding for the review.
Registration 12 Provide the register name and registration number.
∗This abstract checklist retains the same items as those included in the PRISMA for Abstracts statement published in 2013
[54] , but has
been revised to make the wording consistent with the PRISMA 2020 statement and includes a new item recommending authors specify the
methods used to present and synthesise results (item #6).
PRISMA statement [35] , discussed the findings at an
in-person meeting, and prepared this document through
an iterative process. Our recommendations are informed
by the reviews and survey conducted before the in-person
meeting, theoretical considerations about which items
facilitate replication and help users assess the risk of bias
and applicability of systematic reviews, and coauthors’
experience with authoring and using systematic reviews.
Various strategies to increase the use of reporting
guidelines and improve reporting have been proposed.
They include educators introducing reporting guidelines
into graduate curricula to promote good reporting habits
of early career scientists [65] ; journal editors and reg-
ulators endorsing use of reporting guidelines [18] ; peer
reviewers evaluating adherence to reporting guidelines
[61 , 66] ; journals requiring authors to indicate where in
their manuscript they have adhered to each reporting item
[67] ; and authors using online writing tools that prompt
complete reporting at the writing stage [60] . Multipronged
interventions, where more than one of these strategies is
combined, may be more effective (such as completion of
checklists coupled with editorial checks) [68] . However, of
31 interventions proposed to increase adherence to report-
ing guidelines, the effects of only 11 have been evaluated,
mostly in observational studies at high risk of bias due to
confounding [69] . It is therefore unclear which strategies
should be used. Future research might explore barriers and
facilitators to the use of PRISMA 2020 by authors, editors,
and peer reviewers, designing interventions that address
the identified barriers, and evaluating those interventions
using randomized trials. To inform possible revisions to
the guideline, it would also be valuable to conduct think-
aloud studies [70] to understand how systematic reviewers
interpret the items, and reliability studies to identify items
where there is varied interpretation of the items.
We encourage readers to submit evidence that informs
any of the recommendations in PRISMA 2020 (via the
PRISMA statement website: http://www.prisma-statement.
org/). To enhance accessibility of PRISMA 2020, several
translations of the guideline are under way (see available
translations at the PRISMA statement website). We en-
courage journal editors and publishers to raise awareness
of PRISMA 2020 (for example, by referring to it in
journal “Instructions to authors”), endorsing its use, advis-
Please cite this article as: M.J. Page et al., The PRISMA 2020 statement: An updated guideline for reporting systematic reviews, Journal of Clinical
Epidemiology, https:// doi.org/ 10.1016/ j.jclinepi.2021.03.001
M.J. Page et al. / Journal of Clinical Epidemiology xxx (xxxx) xxx 9
ARTICLE IN PRESS
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Fig. 1. PRISMA 2020 ow diagram template for systematic reviews. The new design is adapted from ow diagrams proposed by Boers [55] ,
Mayo-Wilson et al.
[56] and Stovold et al. [57] . The boxes in gray should only be completed if applicable; otherwise they should be removed
from the ow diagram. Note that a “report” could be a journal article, preprint, conference abstract, study register entry, clinical study report,
dissertation, unpublished manuscript, government report or any other document providing relevant information.
ing editors and peer reviewers to evaluate submitted sys-
tematic reviews against the PRISMA 2020 checklists, and
making changes to journal policies to accommodate the
new reporting recommendations. We recommend existing
PRISMA extensions
[47 , 49–53 , 71 , 72] be updated to reflect
PRISMA 2020 and advise developers of new PRISMA
extensions to use PRISMA 2020 as the foundation
document.
6. Conclusion
We anticipate that the PRISMA 2020 statement will
benefit authors, editors, and peer reviewers of systematic
reviews, and different users of reviews, including guideline
developers, policy makers, healthcare providers, patients,
and other stakeholders. Ultimately, we hope that uptake of
the guideline will lead to more transparent, complete, and
accurate reporting of systematic reviews, thus facilitating
evidence based decision making.
Dedication
We dedicate this paper to the late Douglas G Altman
and Alessandro Liberati, whose contributions were funda-
mental to the development and implementation of the orig-
inal PRISMA statement.
Acknowledgments
We thank the following contributors who completed the
survey to inform discussions at the development meeting:
Xavier Armoiry, Edoardo Aromataris, Ana Patricia Ayala,
Ethan M Balk, Virginia Barbour, Elaine Beller, Jesse A
Berlin, Lisa Bero, Zhao-Xiang Bian, Jean Joel Bigna, Fer-
rán Catalá-López, Anna Chaimani, Mike Clarke, Tammy
Clifford, Ioana A Cristea, Miranda Cumpston, Sofia Dias,
Corinna Dressler, Ivan D Florez, Joel J Gagnier, Chantelle
Garritty, Long Ge, Davina Ghersi, Sean Grant, Gordon
Guyatt, Neal R Haddaway, Julian PT Higgins, Sally
Hopewell, Brian Hutton, Jamie J Kirkham, Jos Kleijnen,
Julia Koricheva, Joey SW Kwong, Toby J Lasserson,
Julia H Littell, Yoon K Loke, Malcolm R Macleod,
Chris G Maher, Ana Marušic, Dimitris Mavridis, Jessie
McGowan, Matthew DF McInnes, Philippa Middleton,
Karel G Moons, Zachary Munn, Jane Noyes, Barbara
Nußbaumer-Streit, Donald L Patrick, Tatiana Pereira-
Cenci, Ba’ Pham, Bob Phillips, Dawid Pieper, Michelle
Pollock, Daniel S Quintana, Drummond Rennie, Melissa
L Rethlefsen, Hannah R Rothstein, Maroeska M Rovers,
Rebecca Ryan, Georgia Salanti, Ian J Saldanha, Margaret
Sampson, Nancy Santesso, Rafael Sarkis-Onofre, Jelena
Savovi´c, Christopher H Schmid, Kenneth F Schulz, Guido
Schwarzer, Beverley J Shea, Paul G Shekelle, Farhad
Please cite this article as: M.J. Page et al., The PRISMA 2020 statement: An updated guideline for reporting systematic reviews, Journal of Clinical
Epidemiology, https:// doi.org/ 10.1016/ j.jclinepi.2021.03.001
10 M.J. Page et al. / Journal of Clinical Epidemiology xxx (xxxx) xxx
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Shokraneh, Mark Simmonds, Nicole Skoetz, Sharon E
Straus, Anneliese Synnot, Emily E Tanner-Smith, Brett D
Thombs, Hilary Thomson, Alexander Tsertsvadze, Peter
Tugwell, Tari Turner, Lesley Uttley, Jeffrey C Valentine,
Matt Vassar, Areti Angeliki Veroniki, Meera Viswanathan,
Cole Wayant, Paul Whaley, and Kehu Yang. We thank the
following contributors who provided feedback on a prelim-
inary version of the PRISMA 2020 checklist: Jo Abbott,
Fionn Büttner, Patricia Correia-Santos, Victoria Freeman,
Emily A Hennessy, Rakibul Islam, Amalia (Emily) Kara-
halios, Kasper Krommes, Andreas Lundh, Dafne Port
Nascimento, Davina Robson, Catherine Schenck-Yglesias,
Mary M Scott, Sarah Tanveer and Pavel Zhelnov. We
thank Abigail H Goben, Melissa L Rethlefsen, Tanja
Rombey, Anna Scott, and Farhad Shokraneh for their
helpful comments on the preprints of the PRISMA 2020
papers. We thank Edoardo Aromataris, Stephanie Chang,
Toby Lasserson and David Schriger for their helpful peer
review comments on the PRISMA 2020 papers.
Author contributions
JEM and DM are joint senior authors. MJP, JEM, PMB,
IB, TCH, CDM, LS, and DM conceived this paper and
designed the literature review and survey conducted to in-
form the guideline content. MJP conducted the literature
review, administered the survey and analysed the data for
both. MJP prepared all materials for the development meet-
ing. MJP and JEM presented proposals at the development
meeting. All authors except for TCH, JMT, EAA, SEB,
and LAM attended the development meeting. MJP and
JEM took and consolidated notes from the development
meeting. MJP and JEM led the drafting and editing of the
article. JEM, PMB, IB, TCH, LS, JMT, EAA, SEB, RC,
JG, AH, TL, EMW, SM, LAM, LAS, JT, ACT, PW, and
DM drafted particular sections of the article. All authors
were involved in revising the article critically for important
intellectual content. All authors approved the final version
of the article. MJP is the guarantor of this work. The corre-
sponding author attests that all listed authors meet author-
ship criteria and that no others meeting the criteria have
been omitted.
Patient and public involvement
Patients and the public were not involved in this
methodological research. We plan to disseminate the re-
search widely, including to community participants in ev-
idence synthesis organisations.
Supplementary materials
Supplementary material associated with this article can
be found, in the online version, at doi:
10.1016/j.jclinepi.
2021.03.001
.
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