Begg, Colin PhD; Cho, Mildred PhD; Eastwood,
Susan ELS-D; Horton, Richard MB; Moher, David MSc; Olkin, Ingram PhD;
Pitkin, Roy MD; Rennie, Drummond MD; Schulz, Kenneth F. PhD; Simel, David
MD; Stroup, Donna F. PhD
The randomized controlled trial (RCT),
more than any other methodology, can have a powerful and immediate impact
on patient care. Ideally, the report of such an evaluation needs to convey
to the reader relevant information concerning the design, conduct, analysis,
and generalizability of the trial. This information should provide the reader
with the ability to make informed judgments regarding the internal and external
validity of the trial. Accurate and complete reporting also benefits editors
and reviewers in their deliberations regarding submitted manuscripts. For
RCTs to ultimately benefit patients, the published report should be of the
highest possible standard.
Evidence produced repeatedly over the
last 30 years indicates a wide chasm between what a trial should report and
what is actually published in the literature. In a review of 71 RCTs with
negative results published between 1960 and 1975, the authors reported that
the vast majority of them had too few patients to observe moderate or large
differences.  Twenty years later, The Journal
reported research indicating few improvements in this situation and expressed
a concern about the reporting of RCTs in general. 
In an effort to correct these and other
problems, the Standards of Reporting Trials (SORT) group met on October 7
and 8, 1993. At the conclusion of the 2-day workshop, the SORT group put
forth a new proposal for the reporting of RCTs: structured reporting. 
The proposal set out 24 essential items that needed to be included in the
report of a trial, provided empirical evidence as to why the items should
be included, and provided a format showing how they could be included.
Independently, approximately 5 months
later (March 14 to 16, 1994), another group, the Asilomar Working Group on
Recommendations for Reporting of Clinical Trials in the Biomedical Literature,
met to discuss similar challenges facing the reporting of clinical trials.
Their proposal  consisted of a checklist
of items that should be included when reporting a clinical trial, along with
a suggestion that editors add it to the Instructions for Authors.
A subsequent Editorial 
urged both groups to meet and decide which recommendations from each group's
proposal should be retained. Besides being pragmatic, this suggestion had
the potential for increasing consensus, which in turn might afford a greater
chance of improving the quality of reporting of clinical trials to a wider
On September 20, 1995, a total of 9
members (including editors, clinical epidemiologists, and statisticians)
of the SORT group and the Asilomar Working Group met in Chicago, Ill. Two
other people participated in the meeting: a journal editor (R.H.) who had
expressed interest in helping to improve the reporting of RCTs and one of
the authors (D.S.) of a trial report that used the SORT approach. 
We started the day by reviewing both
the SORT and Asilomar checklists to ascertain which items covered similar
content areas and which ones were unique. Those items having similar content
areas we then reviewed individually. We decided, a priori, to keep only those
items for which there was empirical evidence, when available, that not reporting
them resulted in bias in the estimates of the effects of interventions. We
used common sense for those items included for which there was no empirical
evidence. The selection of items was achieved using a modified Delphi process.
We also emphasized the need to keep the number of items to a minimum, while
maintaining adequate standards of reporting RCTs. We used a similar approach
in deciding which of the unique items should remain in the resulting checklist.
The day ended with a discussion on the use of the flow diagram proposed by
the SORT group and the format of a trial report. Within a week or so following
the meeting, a draft report was circulated to the entire group for further
refinement. This process was continued until we felt the report accurately
represented what had gone on during the meeting.
This meeting resulted in the Consolidated Standards of Reporting Trials (CONSORT) statement-a checklist (Table 1) and a flow diagram (Figure 1).
The checklist consists of 21 items that pertain mainly to the methods, results,
and discussion of an RCT report and identify key pieces of information necessary
to evaluate the internal and external validity of the report. We have included
at least 1 reference for each item, when appropriate (Table 1).
The flow diagram provides information about the progress of patients throughout
a 2-group parallel-design RCT, perhaps the type of trial most commonly reported.
 Appropriate adjustments will need to be
made in reports of trials with a larger number of groups or trials using
a different design.
We recommend, for example, that RCTs
should report how the allocation sequence was generated (eg, computer generated)
and concealed (eg, in sequentially numbered, opaque, sealed envelopes) until
the patient was randomized, something that is possible in all trials.  Schulz and colleagues 
have shown empirically that trials in which the allocation sequence had been
inadequately concealed yielded larger estimates of treatment effects (odds
ratios that were lower, on average, by 30%-40%) compared with trials in which
the authors reported adequate allocation concealment (ie, keeping the intervention
assignments hidden from all individuals participating in the trial until
the point of allocation). One possible interpretation is that some trials
with inadequate reporting of allocation concealment actually had faulty randomization,
and faulty randomization allowed the introduction of bias.
Although any optimally reported trial
will address the items on the checklist and embody the flow diagram, the
manner in which RCTs are reported (ie, their format) is also important. The
format we favor includes a combination of 5 new subheadings in the text of
the trial report and the use of the checklist during the journal submission
Three of the subheadings fall within
the "Methods" section of a trial report: protocol, assignment, and masking
(blinding). For example, under the subheading "assignment" the authors would
describe the unit of randomization (eg, the individual patient). The remaining
2 subheadings are included when the authors report the results: participant
flow and follow-up, and analysis. The participant flow and follow-up subheading
is used in conjunction with describing details of the flow diagram. These
5 subheadings provide readers with consistency from report to report as to
where they can expect to find relevant information. The completed checklist,
which includes all 5 subheadings, would be required for all journal submissions.
For example, corresponding authors would need to specify whether or not their
trial report described the unit of randomization, and, if so, where in the
report this is documented. We recognize that different trials, because of
unusual or complex methods, will require modifications to the reporting structure.
The advantages of the CONSORT format
include minimal change to the length and readability of the manuscript and
enhanced clarity and organization in the actual report of a trial through
the addition of the 5 new subheadings, while at the same time the information
that is submitted to editors and reviewers is maximized through the completed
checklist. This strategy avoids some of the criticisms of previously suggested
reporting formats. [3,6]
Some authors, editors, and even reviewers
may find our recommendations for the reporting of RCTs difficult and even
restrictive. Similar concerns were also raised when more informative abstracts
were first introduced.  Our separate group efforts [3,4]
and our combined effort, CONSORT, came about because of the need to provide
readers with enough valid and meaningful information concerning the design,
conduct, and analysis of RCTs.
We would be remiss if we did not evaluate
whether the CONSORT approach actually has its intended impact. Such an evaluation
should incorporate the very design we are advocating improvements to its
reporting: the RCT. The assessments need to be of both process and outcome,
such as the readability of the report and its length as well as more standard
quality assessments.  In the coming months we will work toward designing and implementing such an evaluation.
During our meeting there was unanimous agreement that the reporting of RCTs, and research in general, is frequently incomplete.  Many examples of inadequate reporting and their sequelae have been cited. [29-31]
As a result, we decided that our deliberations should be disseminated to
as wide an audience as possible in the hope that the CONSORT statement will
ultimately lead to more comprehensive and complete reporting of RCTs. We
recognize that the statement will need revision as new empirical evidence
of bias becomes available. We invite all editors and clinical trialists to
join us in using the CONSORT checklist and flow diagram. We will make the
checklist and flow diagram available to all interested journal editors who
wish to disseminate the information to their reviewers. Interested readers
can also find the checklist and flow diagram on The Journal's World Wide
Web site (http://www.ama-assn.org).
Note: Some reference citations may appear only in tables. [2-4,7-25]
Financial support for this study was
provided by Abbott Laboratories, Abbott Park, Ill, and by the Council of
Biology Editors, Northbrook, Ill.
We wish to thank all the members of
the Standards of Reporting Trials group and the Asilomar Working Group on
Recommendations for Reporting of Clinical Trials in the Biomedical Literature
who helped bring us to this point. Our sincere appreciation to the many people
who reviewed the manuscript.
Reprints: David Moher, MSc, Clinical
Epidemiology Unit, Loeb Medical Research Institute, Ottawa Civic Hospital,
1053 Carling Ave, Ottawa, Ontario, Canada K1Y 4E9 (e-mail: firstname.lastname@example.org).
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Clinical Trials; Manuscripts, Medical; Publishing; Randomized Controlled Trials; Research