CONSORT 2010 Statement: updated guidelines for reporting parallel group randomised trials
BMJ 2010; 340 doi: https://doi.org/10.1136/bmj.c332 (Published 24 March 2010) Cite this as: BMJ 2010;340:c332
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Colagiuri and Benedetti, in their Rapid Response, wrote that we
ignored a growing body of research that stresses the importance of
evaluating blinding, yet they did not describe how that research supports
their views. We did not ignore that research. We just came to a different
interpretation than Colagiuri and Benedetti, considering the totality of
evidence.
We anticipated that some researchers might question the reasoning
behind CONSORT 2010 removing mention of how the success of blinding might
have been evaluated. Thus, with the simultaneous publication of CONSORT
2010 in 9 journals on March 24, 2010, that same day we also published a
Comment in the online version of The Lancet that explained our reasoning.
It was subsequently published in print on April 3, 2010.(1) We direct
Colagiruri, Benedetti, and other readers to that Comment for our
rationale, and for some potential alternatives to tests of blindness.(1)
Readers should recognize that CONSORT only addresses reporting.
CONSORT has not addressed conduct thus far, and will not directly
recommend specific conduct in the future. In other words, CONSORT 2010
does not recommend for or against testing the success of blinding, and
does not proscribe, or even recommend against, the reporting of such
testing.
The CONSORT Group is only able to include a minimal set of items in
the checklist for reporting a randomized trial, and we strive to be
evidence-based wherever possible. In this case, we believe that the
methods used in assessing the success of blinding have interpretational
difficulties, leading us to question their usefulness in many
circumstances. While such tests could be beneficial for certain trials,
our judgment reflects a broad appraisal that, in general, reporting tests
of blindness does not cross our minimal reporting criteria threshold.
We emphasize that CONSORT 2010 is a generic minimum, indicating those
aspects of a trial we would expect to see in all trial reports. Trialists
should transparently and clearly describe their trial, and that may
include additional information in their trial report. Those who have
assessed the success of blinding should certainly feel free to report
their findings.
Kenneth F. Schulz, PhD
Douglas G. Altman, DSc
David Moher, PhD
Reference List
1. Schulz KF, Altman DG, Moher D, Fergusson D. CONSORT 2010 changes
and testing blindness in RCTs. Lancet 2010;375(9721):1144-6.
Competing interests:
None declared
Competing interests: No competing interests
To the Editor – The CONSORT 2010 Statement for reporting parallel
group randomised trials(1) and its accompanying ‘Explanation and
elaboration’(2) (currently online ahead of print) have recently been
published in BMJ and elsewhere. Notably, the item concerning blinding
(Item 11) no longer recommends that trialists report on whether or not
blinding has been maintained. We believe that this significant change is
unwarranted and imprudent, as it ignores a growing body of research that
stresses the importance of evaluating blinding(3-9).
The value of blinding is uncontroversial and is noted in the
explanation and elaboration of the CONSORT 2010 Statement. The controversy
lies in how the success of blinding should be assessed. In contrast to the
previous revision(10), the CONSORT 2010 Statement no longer advocates
reporting on the success of blinding via assessing guesses about
participants’ treatment allocation and comparing these guesses across the
treatment arms. The rationale provided by the authors for this is that
“because participants and healthcare providers will usually know whether
the participant has experienced the primary outcome, this makes it
difficult to determine if their responses reflect failure of blinding or
accurate assumptions about the efficacy of the intervention”(2: p13).
These two alternatives are not, however, mutually exclusive. Accurate
assumptions about the efficacy of the intervention are a possible reason
that blinding may fail, not an alternative to failed blinding.
For example, a participant may assume that Treatment X is superior to
Treatment Y and know that she has been allocated to receive one of those
two treatments. If that participant experiences and notices improvement as
a result of her treatment, then she will likely believe that she has been
allocated to Treatment X. If another participant holding the same
assumption experiences no improvement as a result of her treatment, then
he will likely believe that he has been allocated to Treatment Y. If this
pattern is repeated for other participants in the trial and Treatment X is
actually superior to treatment Y, then a test of blinding will almost
certainly reveal that blinding has failed. The CONSORT 2010 Statement
authors(1-2) suggest that this invalidates the test of blinding. However,
a test of blinding simply evaluates the pattern of guesses about treatment
allocation across treatment groups. While the reason that blinding has
failed in this case is due to the improvement that some but not other
participants experienced, it does not alter the fact that the pattern of
participants’ guesses about their treatment allocation differed across
treatment groups and that these differences may introduce bias into the
trial. The same applies for healthcare providers, assessors, and others
involved in the trial.
The CONSORT 2010 Statement(1) proposes that trialists should explain
the measures adopted to attempt to blind participants, healthcare
providers, and assessors more fully as an alternative to testing for
blinding. Explaining the method adopted to attempt to blind participants
no better indicates whether blinding was successful or not than explaining
the design of a RCT indicates whether one treatment is more effective than
the other. To achieve both, trialists must assess the outcomes of these
procedures. As far as blinding is concerned, comparing guesses about
treatment allocation is the only valid way to achieve this.
The fact that guesses about treatment allocation are influenced by
whether or not participants observe improvement does, of course, lead to
an unsatisfactory situation whereby more efficacious treatments will often
lead to failed blinding(4,8,11). This is not, however, a failure of tests
of blinding, but rather a methodological limitation to the process of
blinding. Avoiding reporting on tests of blinding simply ignores, rather
than addresses this limitation. Even worse, avoiding reporting on tests of
blinding provides trialists and readers with no information about whether
or not the results may have been biased by guesses about treatment
allocation.
Testing for blinding is the only valid way to determine whether a
trial is blind. Trialsists conducing RCTs should, therefore, report on the
success of blinding. In situations where blinding is successful, trialists
and readers can be confident that guesses about treatment allocation have
not biased the trial’s outcome. In situations where blinding fails,
trialists and readers will have to evaluate whether or not bias may have
influenced the trial’s outcomes. Importantly, however, in the second
situation, while trialists are unable to label their trial as blind, the
failure of blinding should not be taken as definitive evidence that bias
occurred. Instead, trialists should provide a rationale as to why the test
of blinding was unsuccessful and a statement on whether or not they
consider the differences between treatment arms to be valid.
References
1. Schulz KF, Altman DG, Moher D, for the CONSORT Group. CONSORT 2010
Statement: updated guidelines for reporting parallel group randomised
trials. BMJ 2010;340:698-702.
2. Moher D, Hopewell S, Schulz KF, Montori V, Gotzsche PC, Devereaux
PJ, et al. CONSORT 2010 Explanation and Elaboration: updated guidelines
for reporting parallel group randomised trials. BMJ 2010;340(mar23_1):c869
-.
3. Benedetti F. The importance of considering the effects of
perceived group assignment in placebo-controlled trials. Eval. Health
Prof. 2005;28:5-6.
4. Colagiuri B, Boakes RA. Perceived treatment, feedback, and placebo
effects in double-blind RCTs: An experimental analysis. Psychopharmacology
(Berl.) 2010;208:433-41.
5. Finniss DG, Benedetti F. Mechanisms of the placebo response and
their impact on clinical trials and clinical practice. Pain 2005;114(1-
2):3-6.
6. Park J, Bang H, Canette I, Park J, Bang H, Canette I. Blinding in
clinical trials, time to do it better. Complement. Ther. Med.
2008;16(3):121-3.
7. Karanicolas PJ, Bhandari M, Taromi B, Akl EA, Bassler D, Alonso-
Coello P, et al. Blinding of outcomes in trials of orthopaedic trauma: an
opportunity to enhance the validity of clinical trials. Journal of Bone
& Joint Surgery - American Volume 2008;90(5):1026-33.
8. Colagiuri B, Morley KC, Boakes RA, Haber PS. Expectancy in double-
blind placebo-controlled trials: An example from alcohol dependence.
Psychother. Psychosom. 2009;78:167-71.
9. Hróbjartsson A, Forfang E, Haahr MT, Als-Nielsen B, Brorson S.
Blinded trials taken to the test: an analysis of randomized clinical
trials that report tests for the success of blinding. Int. J. Epidemiol.
2007;36(3):654-63.
10. Moher D, Schulz KF, Altman DG. The CONSORT Statement: Revised
recommendations for improving the quality of parallel-group randomized
trials. JAMA 2001;285(15):1987-81.
11. Sharpe L, Ryan B, Allard S, Sensky T. Testing for the integrity
of blinding in clinical trials: How valid are forced choice paradigms?
Psychother. Psychosom. 2003;72(3):128-31.
Competing interests:
None declared
Competing interests: No competing interests
Progress in healthcare depends on the application of innovation from
many types of biomedical research. While appropriate design, conduct and
analysis are key characteristics of quality, a critical aspect of
translating findings to healthcare is clear and transparent reporting.
The first CONSORT statement was published in 1996 [1] and revised in
2001. [2-4] The aim then, and now, was to improve how randomised
controlled trials (RCTs) are reported so that they can be accurately
assessed by readers, editors and reviewers. Some success has been
achieved and the reporting of some RCTs is excellent. [5, 6] Despite
CONSORT statement has been around for 14 years, complete and clear
information on all aspects of all RCTs is still missing from many reported
studies. [7]
How does the 2010 statement [8] differ from the 2001 version? [2-4]
There are general and specific improvements. Wording was simplified and
clarified, and consistency in language improved. Some items have been
split into sub-items to avoid confusion. Specific changes include
requiring a description of how blinding is done, but eliminating the need
to explain how its success was determined, since research has raised
questions about the validity of such estimates. Numbers for “intention-to
-treat” analysis are no longer required because the authors consider this
term widely misused. Instead, they ask for the number of participants in
each analysis and whether the analysis was by original assigned group.
These are just some examples of changes in the CONSORT 2010 checklist [8]
which was described as a “service history” for RCTs. [9]
In the CONSORT 2010 statement, [8] the text on how the success of
blinding was evaluated has been removed. This seems to be opposite to the
views advocated by other investigators. [10, 11] This issue has been
discussed briefly in the separate explanatory paper. [12] Researchers,
however, may want to read a more fuller explanation of the rationale for
removal of the sub-item on testing for blinding in the commentary by
Schulz et al. [13]
The revised statement [8] alone will not improve reporting of RCTs.
To be effective, the CONSORT statement must be used in practice, which
will require commitments from authors, editors and peer reviewers.
With more complete reporting, the whole process of evaluating the
quality of research should be easier. In my work as a systematic
reviewer, it is such a joy to come across a clearly reported trial when
abstracting data.
1 Begg C, Cho M, Eastwood S, Horton R, Moher D, Olkin I, et al.
Improving the quality of reporting of randomized controlled trials. The
CONSORT statement. JAMA 1996;276:637-9.
2 Moher D, Schulz KF, Altman DG. The CONSORT statement: revised
recommendations for improving the quality of reports of parallel-group
randomised trials. Lancet 2001;357:1191-4.
3 Moher D, Schulz KF, Altman DG; CONSORT Group. The CONSORT
statement: revised recommendations for improving the quality of reports of
parallel-group randomized trials. Ann Intern Med 2001;134:657-62.
4 Moher D, Schulz KF, Altman D; CONSORT Group. The CONSORT statement:
revised recommendations for improving the quality of reports of parallel-
group randomized trials. JAMA 2001;285:1987-91.
5 Plint AC, Moher D, Morrison A, Schulz K, Altman DG, Hill C, et al.
Does the CONSORT checklist improve the quality of reports of randomised
controlled trials? A systematic review. Med J Aust 2006;185:263-7.
6 Hopewell S, Dutton S, Yu L-M, Chan A-W, Altman DG. The quality of
reports of randomised trials in 2000 and 2006: comparative study of
articles indexed in PubMed. BMJ 2010;340:c723.
7 Chan AW, Altman DG. Epidemiology and reporting of randomised
trials published in PubMed journals. Lancet 2005;365:1159-62.
8 Schulz KF, Altman DG, Moher D. CONSORT 2010 statement: updated
guidelines for reporting parallel group randomised trials. BMJ
2010;340:c332.
9 Williams HC. Cars, CONSORT 2010, and Clinical Practice. Trials
2010;11:33.
10 Fergusson D, Glass KC, Waring D, Shapiro S. Turning a blind eye:
the success of blinding reported in a random sample of randomised, placebo
controlled trials. BMJ 2004;328:432.
11 Kolahi J, Bang H, Park J. Towards a proposal for assessment of
blinding success in clinical trials: up-to-date review. Community Dent
Oral Epidemiol 2009;37:477-84.
12 Moher D, Hopewell S, Schulz KF, Montori V, Gøtzche PC, Devereaux
PJ, et al. CONSORT 2010 Explanation and Elaboration: updated guidelines
for reporting parallel group randomised trials. BMJ 2010;340:c869.
13 Schulz KF, Altman DG, Moher D, Fergusson D. CONSORT 2010 changes
and testing blindness in RCTs. Lancet 2010;375:1144-6.
Competing interests:
None declared
Competing interests: No competing interests
The work of the CONSORT group has been one of the most
important editorial developments of the past 30 years, but I
think it should concentrate much more on implementation.
At the moment the group seems to be spending its time
developing ever more refined versions of its statement, while
the world goes on failing to implement its advice. It is of
course much easier to develop advice than make it happen, but
100% of studies including the 10 most essential requirements
would be better than 30% implementing 25. I suggest that the
group makes implementation its top priority, which may mean
including some different sorts of people.
It seems odd as well that in this electronic age the statement
was reproduced in nine journals. Surely it needs to be in only
one place, and the journals could add value commenting on the
statement and directing readers to the one place.
Competing interests:
I'm a board member of the
Public Library of
Science, was the editor
of the BMJ, and am a
friend of many members of
the CONSORT group
Competing interests: No competing interests
The revised CONSORT guideline is a welcome contribution to attempts
to
make reporting of research more robust.[1] However, the fact that it
entirely
omits any mention of guest or ghost authorship is cause for concern.
There is now increasing awareness of the extent to which people who
have
not contributed to a paper are credited as authors (guest authorship) and
those who have contributed are not (ghost authorship).[2] Such deceptive
practice is unethical and can weaken otherwise strong evidence:
"Transparent
and complete identification of contributors to research publication is
essential to scientific integrity."[3]
In CONSORT 2010's checklist of information that must be included when
reporting a trial, the first item mentioned is "Title and abstract"; the
second
is "Introduction". Why is no reference made to the importance of honest
attribution of authorship? The guidelines of the International Committee
of
Medical Journal Editors (ICMJE) state that “All persons designated as
authors
should qualify for authorship, and all those who qualify should be
listed”,
and strict criteria are provided for what constitutes authorship.[4] Given
that
CONSORT goes into so much detail about what should be included in a
report, it is surprising that no mention is made of the importance of
accurate
authorship reporting.
CONSORT 2010 correctly states that "readers of a published report
need
complete, clear and transparent information on its methodology and
findings." They also need to know who actually wrote the research report.
Given that its aim is to encourage “lucid and complete descriptions…of
critical information”, CONSORT should at the very least refer authors to
the
ICMJE guidelines.
Dr David Shaw, Lecturer in Ethics, University of Glasgow
References
1. Schulz KF, Altman DG, Moher D. CONSORT 2010 Statement: updated
guidelines for reporting parallel group randomised trials. BMJ
2010;340:c332
2. Wislar J, Flanagin A, Fontanarosa PB, DeAngelis CD. Prevalence of
honorary
and ghost authorship in 6 general medical journals, 2009 [abstract]. Sixth
International Congress on Peer Review and Biomedical Publication;
September 10-12, 2009; Vancouver.
3. Murray S, Brophy J, Palepu A. Open Medicine’s ghost and guest
authorship
policy. Open Medicine 2010; 4(1).
http://www.openmedicine.ca/article/view/378/296 (accessed 30/3/10)
4. International Committee of Medical Journal Editors. Uniform
Requirements
for Manuscripts Submitted to Biomedical Journals: Ethical Considerations
in
the Conduct and Reporting of Research: Authorship and Contributorship.
http://www.icmje.org/ethical_1author.html (accessed 30/3/10)
Competing interests:
None declared
Competing interests: No competing interests
The latest iteration of the CONSORT statement is a significant improvement
on the previous version,
and reflects the organic evolution of this guideline over the past decade. The
2010 version is clearer,
but will demand greater rigour in completing the checklist. Precision is
increased with some checklist
items having been broken into sub-items and authors required to provide
page numbers for each
sub-item on the checklist. IÕm particularly gladdened by the addition of item
1B requiring a structured
summary in line with the CONSORT abstracts recommendation. The author is
required to explicitly
describe the allocation concealment mechanisms and blinding. Where
previously word count was an
issue, full online publication of RCTs without word limits should allow a full
and clear account of the
actual steps taken to ensure allocation concealment, etc. Readability of
reports of RCTs should be
enhanced with the requirement to provide a table of baseline characteristics
of each group.
However the most important additions to the new 2010 CONSORT statement
are the requirement for
prospective trial registration and the making available to the editorial panel
of the trial protocol.
Authors will need to adhere closely to their protocol and will enable
comparison of the conduct and
reporting of the trial with the protocol after publication. Items 23 and 24 can
only improve the quality
of not only trial conduct but also trial reporting. Enhanced transparency of
reporting will improve the
quality of the trials themselves and in turn the veracity of the results upon
which clinicians base the
care of their patients. The CONSORT group is to be applauded.
Competing interests:
None declared
Competing interests: No competing interests
We would like to congratulate you on the 2010 revised version of the
CONSORT Statement. It is indeed essential to regularly evaluate and update
such standards. The CONSORT 2010 Statement (1) included a new item (item
23) on trial registration in which the registration number and name of
trial registry should be reported. We applaud you for adding this very
important item. However, timing of registration is another important issue
to be analyzed. A prospectively registered trial is one where the trial
start date (actual or anticipated) is the same or after the date of trial
registration. Conversely a retrospectively registered trial is one where
the trial start date (actual or anticipated) is before the trial
registration date.
To achieve the principal goal of trial registration (ie preventing
the outcome bias), it is essential that trials are registered
prospectively. However, this is not currently always the case, as
illustrated by the experience of the Australian registry (2), which
reports that more than half (on average 59%) of 2618 trials registered
between 2006 and 2009 were registered with a median delay of 146 days.
Retrospective registration confuses the message about the importance
of prospective registration and may lead some within the research
community to think that retrospective registration is an acceptable long-
term solution. Journal accepting retrospective registration may choose to
alert their readers by publishing an additional “prospective” or
“retrospective” registration note, along with the registration number and
the name of trial registry.
We propose that CONSORT requires such the precision in its
explanatory document.
References
1. Schulz KF, Altman DG, Moher D, for the CONSORT Group. CONSORT 2010
Statement: updated guidelines for reporting parallel group randomised
trials. BMJ 2010;340:c332
2. Received from the Australian New Zealand Clinical Trials Registry
(ANZCTR http://www.anzctr.org.au). Sydney (NSW): The University of Sydney
(Australia); 29 October 2009.
Competing interests:
None declared
Competing interests: No competing interests
Proposed best practice for statisticians in reporting of industry-sponsored trials
We feel recently proposed best practice for statisticians in
reporting of industry-sponsored trials should be highlighted [1, 2]. The
recommendations (an abridged version of which are reproduced below), were
accompanied by two explanatory articles [3,4] which may be of interest.
We feel that the creation of a forum in which Journal Editors, industry
and academic representatives can discuss the issues raised may be
beneficial.
1. The statistical author should be responsible for the statistical
aspects of the paper
The authoring statistician should take responsibility for the
statistical content of the published report of a clinical trial.
2. The person responsible for statistical aspects of the trial should
be recognised as an author
The statistician responsible for the design, conduct, analysis and
reporting of a clinical trial should be identified and named as a co-
author of the publication.
3. Protocols should be published and/or made publicly available in a
timely manner
This will provide a means for Journal Reviewers and Editors to
confirm pre-defined study objectives, endpoints and analysis methods are
reported appropriately in the final publication.
4. Financial and other conflicts of interest should be disclosed
There should be a clear statement identifying who sponsored the
trial. Along with other co-authors, the trial statistician should declare
any financial interest and any potential conflict of interest.
5. The authors should have freedom to act
The primary investigator and other co-authors should not be
pressured, either contractually or otherwise, to suppress or delay the
publication of trial results, or to present the trial results in a manner
that they feel is inappropriate.
6. All authors should have full access to trial data
The authors of the trial manuscript should have appropriate access to
the data collected during the trial, and should have played a full part in
the interpretation of the trial results.
7. The trial results should be published
In line with legal expectation, trials should have their results
published in publicly accessible registries designed for the purpose and,
wherever possible, also in peer review journals.
8. Independent statistical review should be highlighted
If industry-sponsored clinical trials undergo a statistical review by
independent experts and/or regulators the nature and scope of review
should be described in the manuscript.
References
[1]. Matcham J, Julious S, Pyke S, O'Kelly M, Todd S, Seldrup J and
Day S. Proposed best practice for statisticians in the reporting of
industry sponsored clinical trials in medical journals. Pharmaceutical
Statistics 2010 10(1):70-73
[2]. Julious S, Matcham J, Pyke S, O'Kelly M, Todd S, Seldrup J and
Day S Highlighting recent proposed best practice for statisticians in the
reporting and publication of pharmaceutical industry sponsored clinical
trials. Journal of the European Medical Writers Association (The Write
Stuff) 2010; 19(1) 29-31
[3]. Pyke S, Julious S, Day S, O'Kelly M, Todd S, Matcham J and
Seldrup J. The potential for bias in reporting of industry sponsored
clinical trials. Pharmaceutical Statistics 2010 10(1):74-79
[4]. O'Kelly M, Julious S, Pyke S, Day S, Todd S, Seldrup J and James
Matcham. Making available information from studies sponsored by the
pharmaceutical industry: some current practices. Pharmaceutical Statistic
2010 10(1) 60-69
Competing interests: The views expressed are the author's personal views. However, they are endorsed by the Board of Statisticians in the Pharmaceutical Industry (PSI)