INTRODUCTION
Randomised controlled trials, when appropriately designed, conducted and reported,
represent the gold standard in evaluating healthcare interventions. However, randomised
trials can yield biased results if they lack methodological rigour.[1] To assess a
trial accurately, readers of a published report need complete, clear and transparent
information on its methodology and findings. Unfortunately, attempted assessments
frequently fail because authors of many trial reports neglect to provide lucid and
complete descriptions of that critical information.[2–4]
That lack of adequate reporting fuelled the development of the original CONSORT (Consolidated
Standards of Reporting Trials) statement in 1996[5] and its revision five years later.[6–8]
While those statements improved the reporting quality for some randomised controlled
trials,[9
10] many trial reports still remain inadequate.[2] Furthermore, new methodological
evidence and additional experience has accumulated since the last revision in 2001.
Consequently, we organised a CONSORT Group meeting to update the 2001 statement.[6–8]
We introduce here the result of that process, CONSORT 2010.
INTENT OF CONSORT 2010
The CONSORT 2010 Statement is this paper including the 25 item checklist in the [Table
1] and the flow diagram [Figure 1]. It provides guidance for reporting all randomised
controlled trials, but focuses on the most common design type—individually randomised,
two group, parallel trials. Other trial designs, such as cluster randomised trials
and non-inferiority trials, require varying amounts of additional information. CONSORT
extensions for these designs,[11
12] and other CONSORT products, can be found through the CONSORT website (http://www.consort-statement.org).
Along with the CONSORT statement, we have updated the explanation and elaboration
article,[13] which explains the inclusion of each checklist item, provides methodological
background and gives published examples of transparent reporting.
Figure 1
Flow diagram of the progress through the phases of a parallel randomised trial of
two groups (that is, enrolment, intervention allocation, follow-up and data analysis).
Table 1
CONSORT 2010 checklist of information to include when reporting a randomised trial
(for a downloadable version of this checklist see Text S1 or the CONSORT website)*
Section/Topic
Item no.
Checklist Item
Reported on page no.
Title and abstract
1a
Identification as a randomised trial in the title
1b
Structured summary of trial design, methods, results and conclusions (for specific
guidance see CONSORT for abstracts[21
31])
Introduction
Background and objectives
2a
Scientific background and explanation of rationale
2b
Specific objectives or hypotheses
Methods
Trial design
3a
Description of trial design(such as parallel, factorial) including allocation ratio
3b
Important charges to methods after trial commencement (such as eligibility criteria),
with reasons
Participations
4a
Eligibility criteria for participants
4b
Settings and locations where the data were collected
Interventions
5
The interventions for each group with sufficient details to allow replication, including
how and when they were actually administered
Outcomes
6a
Completely defined pre-specified primary and secondary outcome measures, including
how and when they were assessed
6b
Any changes to trial outcomes after the trial commenced, with reasons
Sample size
7a
How sample size was determined
7b
When applicable, explanation of any interim analyses and stopping guidelines
Randomisation
Sequence generation
8a
Method used to generate the random allocation sequence
8b
Type of randomisation, details of any restriction (such as blocking and block size)
Allocation concealment mechanism
9
Mechanism used to implement the random allocation sequence (such as sequentially numbered
containers), describing any steps taken to conceal the sequence until interventions
were assigned
Implementation
10
Who generated the random allocation sequence, who enrolled participants, and who assigned
participants to interventions
Blinding
11a
If done, who was blinded after assignment to interventions (for example, participants,
care providers, those assessing outcomes) and how
11b
If relevant, description of the similarity of interventions
Statistical methods
12a
Statistical methods used to compare groups for primary and secondary outcomes
12b
Methods for additional analyses, such as subgroup analyses and adjusted analyses
Results
Participant flow (a diagram is strongly recommended)
13a
For each group, the numbers of participants who were randomly assigned, received intended
treatment, and were analysed for primary outcome
13b
For each group, losses and exclusions after randomisation, together with reasons
Recruitment
14a
Dates defining the periods of recruitment and follow-up
14b
Why the trial ended or was stopped
Baseline data
15
A table showing baseline demographic and clinical characteristics for each group
Number analysed
16
For each group, number of participants (denominator) included in each analysis and
whether the analysis was by original assigned groups
Outcomes and estimation
17a
For each primary and secondary outcomes, results for each group, and the estimated
effect size and its precision (such as 95% confidence interval)
17b
For binary outcomes, presentation of both absolute and relative effect sizes in recommended
Ancillary analyses
18
Results of any other analyses perform, including subgroup analyses and adjusted analyses,
distinguishing pre-specified from exploratory
Harms
19
All important harms or unintended effects in each group (for specific guidance see
CONSORT for harms[28])
Discussion
Limitations
20
Trial limitations, addressing sources of potential bias, imprecision, and, if relevant,
multiplicity of analyses
Generalisability
21
Generalisability (external validity, applicability) of trial findings
Interpretation
22
Interpretation consistent with results, balancing benefits and harms, and considering
other relevant evidence
Other information
Registration
23
Registration number and name of trial registry
Protocol
24
Where the full trial protocol can be accessed, if available
Funding
25
Sources of funding and other support (such as supply of drugs), role of funders
*
We strongly recommend reading this statement in conjunction with the CONSORT 2010
Explanation and Elaboration[13] for important clarifications, on all the items. If
relevant, we also recommend reading CONSORT extensions for cluster randomised trials[11],
non-inferiority and equivalence trials[12], nonpharmacological treatments[32], herbal
interventions[33], and pragmatic trials[34]. Additional extensions are forthcoming:
for those and for up to date references relevant to this checklist, see http://www.consort-statement.org
Diligent adherence by authors to the checklist items facilitates clarity, completeness
and transparency of reporting. Explicit descriptions, not ambiguity or omission, best
serve the interests of all readers. Note that the CONSORT 2010 Statement does not
include recommendations for designing, conducting and analysing trials. It solely
addresses the reporting of what was done and what was found.
Nevertheless, CONSORT does indirectly affect design and conduct. Transparent reporting
reveals deficiencies in research if they exist. Thus, investigators who conduct inadequate
trials, but who must transparently report, should not be able to pass through the
publication process without revelation of their trial’s inadequacies. That emerging
reality should provide impetus to improved trial design and conduct in the future,
a secondary indirect goal of our work. Moreover, CONSORT can help researchers in designing
their trial.
BACKGROUND TO CONSORT
Efforts to improve the reporting of randomised controlled trials accelerated in the
mid-1990s, spurred partly by methodological research. Researchers had shown for many
years that authors reported such trials poorly and empirical evidence began to accumulate
that some poorly conducted or poorly reported aspects of trials were associated with
bias[14] Two initiatives aimed at developing reporting guidelines culminated in one
of us (DM) and Drummond Rennie organising the first CONSORT statement in 1996.[5]
Further methodological research on similar topics reinforced earlier findings[15]
and fed into the revision of 2001.[6–8] Subsequently, the expanding body of methodological
research informed the refinement of CONSORT 2010. More than 700 studies comprise the
CONSORT database (located on the CONSORT website), which provides the empirical evidence
to underpin the CONSORT initiative.
Indeed, CONSORT Group members continually monitor the literature. Information gleaned
from these efforts provides an evidence base on which to update the CONSORT statement.
We add, drop, or modify items based on that evidence and the recommendations of the
CONSORT Group, an international and eclectic group of clinical trialists, statisticians,
epidemiologists and biomedical editors. The CONSORT Executive (KFS, DGA, DM) strives
for a balance of established and emerging researchers. The membership of the group
is dynamic. As our work expands in response to emerging projects and needed expertise,
we invite new members to contribute. As such, CONSORT continually assimilates new
ideas and perspectives. That process informs the continually evolving CONSORT statement.
Over time, CONSORT has garnered much support. More than 400 journals, published around
the world and in many languages, have explicitly supported the CONSORT statement.
Many other healthcare journals support it without our knowledge. Moreover, thousands
more have implicitly supported it with the endorsement of the CONSORT statement by
the International Committee of Medical Journal Editors (http://www.icmje.org). Other
prominent editorial groups, the Council of Science Editors and the World Association
of Medical Editors, officially support CONSORT. That support seems warranted: when
used by authors and journals, CONSORT seems to improve reporting.[9]
DEVELOPMENT OF CONSORT 2010
Thirty one members of the CONSORT 2010 Group met in Montebello, Canada, in January
2007 to update the 2001 CONSORT statement. In addition to the accumulating evidence
relating to existing checklist items, several new issues had come to prominence since
2001. Some participants were given primary responsibility for aggregating and synthesising
the relevant evidence on a particular checklist item of interest. Based on that evidence,
the group deliberated the value of each item. As in prior CONSORT versions, we kept
only those items deemed absolutely fundamental to reporting a randomised controlled
trial. Moreover, an item may be fundamental to a trial but not included, such as approval
by an institutional ethical review board, because funding bodies strictly enforce
ethical review and medical journals usually address reporting ethical review in their
instructions for authors. Other items may seem desirable, such as reporting on whether
on-site monitoring was done, but a lack of empirical evidence or any consensus on
their value cautions against inclusion at this point. The CONSORT 2010 Statement thus
addresses the minimum criteria, although that should not deter authors from including
other information if they consider it important.
After the meeting, the CONSORT Executive convened teleconferences and meetings to
revise the checklist. After seven major iterations, a revised checklist was distributed
to the larger group for feedback. With that feedback, the executive met twice in person
to consider all the comments and to produce a penultimate version. That served as
the basis for writing the first draft of this paper, which was then distributed to
the group for feedback. After consideration of their comments, the executive finalised
the statement.
The CONSORT Executive then drafted an updated explanation and elaboration manuscript,
with assistance from other members of the larger group. The substance of the 2007
CONSORT meeting provided the material for the update. The updated explanation and
elaboration manuscript was distributed to the entire group for additions, deletions
and changes. That final iterative process converged to the CONSORT 2010 Explanation
and Elaboration.[13]
CHANGES IN CONSORT 2010
The revision process resulted in evolutionary, not revolutionary, changes to the checklist
[Table 1] and the flow diagram was not modified except for one word [Figure 1]. Moreover,
because other reporting guidelines augmenting the checklist refer to item numbers,
we kept the existing items under their previous item numbers except for some renumbering
of items 2 to 5. We added additional items either as a sub-item under an existing
item, an entirely new item number at the end of the checklist, or (with item 3) an
interjected item into a renumbered segment. We have summarised the noteworthy general
changes in Box 1 and specific changes in Box 2. The CONSORT website contains a side
by side comparison of the 2001 and 2010 versions.
Box 1.
Noteworthy General Changes in CONSORT 2010 StatemeWe simplified and clarified the
wording, such as in items 1, 8, 10, 13, 15, 16, 18, 19 and 21.
We improved consistency of style across the items by removing the imperative verbs
that were in the 2001 version.
We enhanced specificity of appraisal by breaking some items into sub-items. Many journals
expect authors to complete a CONSORT checklist indicating where in the manuscript
the items have been addressed. Experience with the checklist noted pragmatic difficulties
when an item comprised multiple elements. For example, item 4 addresses eligibility
of participants and the settings and locations of data collection. With the 2001 version,
an author could provide a page number for that item on the checklist, but might have
reported only eligibility in the paper, for example and not reported the settings
and locations. CONSORT 2010 relieves obfuscations and forces authors to provide page
numbers in the checklist for both eligibility and settings.
Box 2.
Noteworthy Specific Changes in CONSORT 2010 StatementItem 1b (title and abstract)
– We added a sub-item on providing a structured summary of trial design, methods,
results and conclusions and referenced the CONSORT for abstracts article.[21]
Item 2b (introduction) – We added a new sub-item (formerly item 5 in CONSORT 2001)
on “Specific objectives or hypotheses”.
Item 3a (trial design) – We added a new item including this sub-item to clarify the
basic trial design (such as parallel group, crossover, cluster) and the allocation
ratio.
Item 3b (trial design) – We added a new sub-item that addresses any important changes
to methods after trial commencement, with a discussion of reasons.
Item 4 (participants) – Formerly item 3 in CONSORT 2001.
Item 5 (interventions) – Formerly item 4 in CONSORT 2001. We encouraged greater specificity
by stating that descriptions of interventions should include “sufficient details to
allow replication”.[3]
Item 6 (outcomes) – We added a sub-item on identifying any changes to the primary
and secondary outcome (endpoint) measures after the trial started. This followed from
empirical evidence that authors frequently provide analyses of outcomes in their published
papers that were not the prespecified primary and secondary outcomes in their protocols,
while ignoring their prespecified outcomes (that is, selective outcome reporting).[4
22] We eliminated text on any methods used to enhance the quality of measurements.
Item 9 (allocation concealment mechanism) – We reworded this to include mechanism
in both the report topic and the descriptor to reinforce that authors should report
the actual steps taken to ensure allocation concealment rather than simply report
imprecise, perhaps banal, assurances of concealment.
Item 11 (blinding) – We added the specification of how blinding was done and, if relevant,
a description of the similarity of interventions and procedures. We also eliminated
text on “how the success of blinding (masking) was assessed” because of a lack of
empirical evidence supporting the practice as well as theoretical concerns about the
validity of any such assessment.[23
24]
Item 12a (statistical methods) – We added that statistical methods should also be
provided for analysis of secondary outcomes.
Sub-item 14b (recruitment) – Based on empirical research, we added a sub-item on “Why
the trial ended or was stopped”.[25]
Item 15 (baseline data) – We specified “A table” to clarify that baseline and clinical
characteristics of each group are most clearly expressed in a Table.
Item 16 (numbers analysed) – We replaced mention of “intention to treat” analysis,
a widely misused term, by a more explicit request for information about retaining
participants in their original assigned groups.[26]
Sub-item 17b (outcomes and estimation) – For appropriate clinical interpretability,
prevailing experience suggested the addition of “For binary outcomes, presentation
of both relative and absolute effect sizes is recommended”.[27]
Item 19 (harms) – We included a reference to the CONSORT paper on harms.[28]
Item 20 (limitations) – We changed the topic from “Interpretation” and supplanted
the prior text with a sentence focusing on the reporting of sources of potential bias
and imprecision.
Item 22 (interpretation) – We changed the topic from “Overall evidence.” Indeed, we
understand that authors should be allowed leeway for interpretation under this nebulous
heading. However, the CONSORT Group expressed concerns that conclusions in papers
frequently misrepresented the actual analytical results and that harms were ignored
or marginalised. Therefore, we changed the checklist item to include the concepts
of results matching interpretations and of benefits being balanced with harms.
Item 23 (registration) – We added a new item on trial registration. Empirical evidence
supports the need for trial registration and recent requirements by journal editors
have fostered compliance.[29]
Item 24 (protocol) – We added a new item on availability of the trial protocol. Empirical
evidence suggests that authors often ignore, in the conduct and reporting of their
trial, what they stated in the protocol.[4
22] Hence, availability of the protocol can instigate adherence to the protocol before
publication and facilitate assessment of adherence after publication.
Item 25 (funding) – We added a new item on funding. Empirical evidence points toward
funding source sometimes being associated with estimated treatment effects.[30]
IMPLICATIONS AND LIMITATIONS
We developed CONSORT 2010 to assist authors in writing reports of randomised controlled
trials, editors and peer reviewers in reviewing manuscripts for publication and readers
in critically appraising published articles. The CONSORT 2010 Explanation and Elaboration
provides elucidation and context to the checklist items. We strongly recommend using
the explanation and elaboration in conjunction with the checklist to foster complete,
clear and transparent reporting and aid appraisal of published trial reports.
CONSORT 2010 focuses predominantly on the two group, parallel randomised controlled
trial, which accounts for over half of trials in the literature.[2] Most of the items
from the CONSORT 2010 Statement, however, pertain to all types of randomised trials.
Nevertheless, some types of trials or trial situations dictate the need for additional
information in the trial report. When in doubt, authors, editors and readers should
consult the CONSORT website for any CONSORT extensions, expansions (amplifications),
implementations, or other guidance that may be relevant.
The evidence based approach we have used for CONSORT also served as a model for development
of other reporting guidelines, such as for reporting systematic reviews and meta-analyses
of studies evaluating interventions,[16] diagnostic studies,[17] and observational
studies.[18] The explicit goal of all these initiatives is to improve reporting. The
Enhancing the Quality and Transparency of Health Research (EQUATOR) Network will facilitate
development of reporting guidelines and help disseminate the guidelines: http://www.equator-network.org
provides information on all reporting guidelines in health research.
With CONSORT 2010, we again intentionally declined to produce a rigid structure for
the reporting of randomised trials. Indeed, SORT[19] tried a rigid format and it failed
in a pilot run with an editor and authors.[20] Consequently, the format of articles
should abide by journal style, editorial directions, the traditions of the research
field addressed and, where possible, author preferences. We do not wish to standardise
the structure of reporting. Authors should simply address checklist items somewhere
in the article, with ample detail and lucidity. That stated, we think that manuscripts
benefit from frequent subheadings within the major sections, especially the methods
and results sections.
CONSORT urges completeness, clarity and transparency of reporting, which simply reflects
the actual trial design and conduct. However, as a potential drawback, a reporting
guideline might encourage some authors to report fictitiously the information suggested
by the guidance rather than what was actually done. Authors, peer reviewers and editors
should vigilantly guard against that potential drawback and refer, for example, to
trial protocols, to information on trial registers and to regulatory agency websites.
Moreover, the CONSORT 2010 Statement does not include recommendations for designing
and conducting randomised trials. The items should elicit clear pronouncements of
how and what the authors did, but do not contain any judgments on how and what the
authors should have done. Thus, CONSORT 2010 is not intended as an instrument to evaluate
the quality of a trial. Nor is it appropriate to use the checklist to construct a
“quality score.”
Nevertheless, we suggest that researchers begin trials with their end publication
in mind. Poor reporting allows authors, intentionally or inadvertently, to escape
scrutiny of any weak aspects of their trials. However, with wide adoption of CONSORT
by journals and editorial groups, most authors should have to report transparently
all important aspects of their trial. The ensuing scrutiny rewards well conducted
trials and penalises poorly conducted trials. Thus, investigators should understand
the CONSORT 2010 reporting guidelines before starting a trial as a further incentive
to design and conduct their trials according to rigorous standards.
CONSORT 2010 supplants the prior version published in 2001. Any support for the earlier
version accumulated from journals or editorial groups will automatically extend to
this newer version, unless specifically requested otherwise. Journals that do not
currently support CONSORT may do so by registering on the CONSORT website. If a journal
supports or endorses CONSORT 2010, it should cite one of the original versions of
CONSORT 2010, the CONSORT 2010 Explanation and Elaboration and the CONSORT website
in their “Instructions to authors.” We suggest that authors who wish to cite CONSORT
should cite this or another of the original journal versions of CONSORT 2010 Statement
and, if appropriate, the CONSORT 2010 Explanation and Elaboration.[13] All CONSORT
material can be accessed through the original publishing journals or the CONSORT website.
Groups or individuals who desire to translate the CONSORT 2010 Statement into other
languages should first consult the CONSORT policy statement on the website.
We emphasise that CONSORT 2010 represents an evolving guideline. It requires perpetual
reappraisal and, if necessary, modifications. In the future we will further revise
the CONSORT material considering comments, criticisms, experiences and accumulating
new evidence. We invite readers to submit recommendations via the CONSORT website.