CONSORT 2010 Statement: updated guidelines for reporting parallel group randomised trials

  • Kenneth F Schulz1Email author,

    Affiliated with

    • Douglas G Altman2,

      Affiliated with

      • David Moher3 and

        Affiliated with

        • the CONSORT Group

          Affiliated with

          BMC Medicine20108:18

          DOI: 10.1186/1741-7015-8-18

          Received: 17 February 2010

          Accepted: 24 March 2010

          Published: 24 March 2010

          Abstract

          The CONSORT statement is used worldwide to improve the reporting of randomised controlled trials. Kenneth Schulz and colleagues describe the latest version, CONSORT 2010, which updates the reporting guideline based on new methodological evidence and accumulating experience.

          To encourage dissemination of the CONSORT 2010 Statement, this article is freely accessible on bmj.com and will also be published in the Lancet, Obstetrics and Gynecology, PLoS Medicine, Annals of Internal Medicine, Open Medicine, Journal of Clinical Epidemiology, BMC Medicine, and Trials.

          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 [24].

          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 [68]. 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 [68]. 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 (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.
          Table 1

          CONSORT 2010 checklist of information to include when reporting a randomised trial*

          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 changes to methods after trial commencement (such as eligibility criteria), with reasons

           

          Participants

          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 the 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

           

          Numbers 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 outcome, 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 is recommended

           

          Ancillary analyses

          18

          Results of any other analyses performed, 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 the 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], non-pharmacological 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.

          http://static-content.springer.com/image/art%3A10.1186%2F1741-7015-8-18/MediaObjects/12916_2010_Article_277_Fig1_HTML.jpg
          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).

          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 [68]. 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 Appendix 1 and specific changes in Appendix 2. The CONSORT website contains a side by side comparison of the 2001 and 2010 versions.

          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.

          Declarations

          Acknowledgements

          The CONSORT Group contributors to CONSORT 2010: DG Altman, Centre for Statistics in Medicine, University of Oxford; Virginia Barbour, PLoS Medicine; Jesse A Berlin, Johnson & Johnson Pharmaceutical Research and Development, USA; Isabelle Boutron, University Paris 7 Denis Diderot, Assistance Publique des Hôpitaux de Paris, INSERM, France; PJ Devereaux, McMaster University, Canada; Kay Dickersin, Johns Hopkins Bloomberg School of Public Health, USA; Diana Elbourne, London School of Hygiene & Tropical Medicine; Susan Ellenberg, University of Pennsylvania School of Medicine, USA; Val Gebski, University of Sydney, Australia; Steven Goodman, Journal of the Society for Clinical Trials, USA; Peter C Gøtzsche, Nordic Cochrane Centre, Denmark; Trish Groves, BMJ; Steven Grunberg, American Society of Clinical Oncology, USA; Brian Haynes, McMaster University, Canada; Sally Hopewell, Centre for Statistics in Medicine, University of Oxford; Astrid James, Lancet; Peter Juhn, Johnson & Johnson, USA; Philippa Middleton, University of Adelaide, Australia; Don Minckler, University of California Irvine, USA; D Moher, Ottawa Methods Centre, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Canada; Victor M Montori, Knowledge and Encounter Research Unit, Mayo Clinic College of Medicine, USA; Cynthia Mulrow, Annals of Internal Medicine, USA; Stuart Pocock, London School of Hygiene & Tropical Medicine; Drummond Rennie, JAMA, USA; David L Schriger, Annals of Emergency Medicine, USA; KF Schulz, Family Health International, USA; Iveta Simera, EQUATOR Network; Elizabeth Wager, Sideview.

          Contributors to CONSORT 2010 who did not attend the Montebello meeting: Mike Clarke, UK Cochrane Centre; Gordon Guyatt, McMaster University, Canada.

          Funding: We received financial support from United Kingdom National Institute for Health Research and the Medical Research Council; Canadian Institutes of Health Research; Presidents Fund, Canadian Institutes of Health Research; Johnson & Johnson; BMJ; and the American Society for Clinical Oncology. DGA is supported by Cancer Research UK, DM by a University of Ottawa Research Chair, and KFS by Family Health International. None of the sponsors had any involvement in the planning, execution, or writing of the CONSORT documents. Additionally, no funder played a role in drafting the manuscript.

          In order to encourage dissemination of the CONSORT 2010 Statement, this article is freely accessible on bmj.com and will also be published in the Lancet, Obstetrics and Gynecology, PLoS Medicine, Annals of Internal Medicine, Open Medicine, Journal of Clinical Epidemiology, BMC Medicine, and Trials. The authors jointly hold the copyright of this article. For details on further use, see the CONSORT website http://​www.​consort-statement.​org.

          Authors’ Affiliations

          (1)
          Family Health International
          (2)
          Centre for Statistics in Medicine, University of Oxford, Wolfson College
          (3)
          Ottawa Methods Centre, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Department of Epidemiology and Community Medicine, University of Ottawa

          References

          1. Jüni P, Altman DG, Egger M: Systematic reviews in health care: assessing the quality of controlled clinical trials. BMJ 2001, 323:42–6.View ArticlePubMed
          2. Chan AW, Altman DG: Epidemiology and reporting of randomised trials published in PubMed journals. Lancet 2005, 365:1159–62.View ArticlePubMed
          3. Glasziou P, Meats E, Heneghan C, Shepperd S: What is missing from descriptions of treatment in trials and reviews? BMJ 2008, 336:1472–4.View ArticlePubMed
          4. Dwan K, Altman DG, Arnaiz JA, Bloom J, Chan AW, Cronin E, Decullier E, Easterbrook PJ, Von Elm E, Gamble C, Ghersi D, Ioannidis JP, Simes J, Williamson PR: Systematic review of the empirical evidence of study publication bias and outcome reporting bias. PLoS ONE 2008, 3:e3081.View ArticlePubMed
          5. Begg C, Cho M, Eastwood S, Horton R, Moher D, Olkin I, Pitkin R, Rennie D, Schulz KF, Simel D, Stroup DF: Improving the quality of reporting of randomized controlled trials. The CONSORT statement. JAMA 1996, 276:637–9.View ArticlePubMed
          6. 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.View ArticlePubMed
          7. Moher D, Schulz KF, Altman DG: The CONSORT statement: revised recommendations for improving the quality of reports of parallel-group randomized trials. Ann Intern Med 2001, 134:657–62.PubMed
          8. Moher D, Schulz KF, Altman D: The CONSORT statement: revised recommendations for improving the quality of reports of parallel-group randomized trials. JAMA 2001, 285:1987–91.View ArticlePubMed
          9. Plint AC, Moher D, Morrison A, Schulz K, Altman DG, Hill C, Gaboury : Does the CONSORT checklist improve the quality of reports of randomised controlled trials? A systematic review. Med J Aust 2006, 185:263–7.PubMed
          10. Hopewell S, Dutton S, Yu L-M, Chan A-W, Altman DG: The quality of reports of randomised trials in 2000 and 2006: a comparative study of articles indexed by PubMed. BMJ 2010, 340:c723.View ArticlePubMed
          11. Campbell MK, Elbourne DR, Altman DG: CONSORT statement: extension to cluster randomised trials. BMJ 2004, 328:702–8.View ArticlePubMed
          12. Piaggio G, Elbourne DR, Altman DG, Pocock SJ, Evans SJ: Reporting of noninferiority and equivalence randomized trials: an extension of the CONSORT statement. JAMA 2006, 295:1152–60.View ArticlePubMed
          13. Moher D, Hopewell S, Schulz KF, Montori V, Gøtzsche PC, Devereaux PJ, et al.: CONSORT 2010 Explanation and Elaboration: updated guidelines for reporting parallel group randomised trials. BMJ 2010, 340:c869.View ArticlePubMed
          14. Schulz KF, Chalmers I, Hayes RJ, Altman DG: Empirical evidence of bias. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. JAMA 1995, 273:408–12.View ArticlePubMed
          15. Moher D, Pham B, Jones A, Cook DJ, Jadad AR, Moher M, Tugwell P, Klassen TP: Does quality of reports of randomised trials affect estimates of intervention efficacy reported in meta-analyses? Lancet 1998, 352:609–13.View ArticlePubMed
          16. Moher D, Liberati A, Tetzlaff J, Altman DG, for the PRISMA Group: Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ 2009, 339:b2535.View ArticlePubMed
          17. Bossuyt PM, Reitsma JB, Bruns DE, Gatsonis CA, Glasziou PP, Irwig LM, Lijmer JG, Moher D, Rennie D, de Vet HC, Standards for Reporting of Diagnostic Accuracy: Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative. BMJ 2003, 326:41–4.View ArticlePubMed
          18. von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP, for the STROBE Initiative: Strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies. BMJ 2007, 335:806–8.View ArticlePubMed
          19. Standards of Reporting Trials Group: A proposal for structured reporting of randomized controlled trials. JAMA 1994, 272:1926–31.View Article
          20. Rennie D: Reporting randomized controlled trials. An experiment and a call for responses from readers. JAMA 1995, 273:1054–5.View ArticlePubMed
          21. Hopewell S, Clarke M, Moher D, Wager E, Middleton P, Altman DG, Schulz KF, CONSORT Group: CONSORT for reporting randomised trials in journal and conference abstracts. Lancet 2008, 371:281–3.View ArticlePubMed
          22. Chan AW, Hróbjartsson A, Haahr MT, Gøtzsche PC, Altman DG: Empirical evidence for selective reporting of outcomes in randomized trials: comparison of protocols to published articles. JAMA 2004, 291:2457–65.View ArticlePubMed
          23. Sackett DL: Commentary: Measuring the success of blinding in RCTs: don't, must, can't or needn't? Int J Epidemiol 2007, 36:664–5.View ArticlePubMed
          24. Schulz KF, Grimes DA: Blinding in randomised trials: hiding who got what. Lancet 2002, 359:696–700.View ArticlePubMed
          25. Montori VM, Devereaux PJ, Adhikari NK, Burns KE, Eggert CH, Briel M, Lacchetti C, Leung TW, Darling E, Bryant DM, Bucher HC, Schünemann HJ, Meade MO, Cook DJ, Erwin PJ, Sood A, Sood R, Lo B, Thompson CA, Zhou Q, Mills E, Guyatt GH: Randomized trials stopped early for benefit: a systematic review. JAMA 2005, 294:2203–9.View ArticlePubMed
          26. Hollis S, Campbell F: What is meant by intention to treat analysis? Survey of published randomised controlled trials. BMJ 1999, 319:670–4.PubMed
          27. Nuovo J, Melnikow J, Chang D: Reporting number needed to treat and absolute risk reduction in randomized controlled trials. JAMA 2002, 287:2813–4.View ArticlePubMed
          28. Ioannidis JP, Evans SJ, Gøtzsche PC, O'Neill RT, Altman DG, Schulz K, Moher D, CONSORT Group: Better reporting of harms in randomized trials: an extension of the CONSORT statement. Ann Intern Med 2004, 141:781–8.PubMed
          29. De Angelis C, Drazen JM, Frizelle FA, Haug C, Hoey J, Horton R, Kotzin S, Laine C, Marusic A, Overbeke AJ, Schroeder TV, Sox HC, Weyden MB: International Committee of Medical Journal Editors. Clinical trial registration: a statement from the International Committee of Medical Journal Editors. Lancet 2004, 364:911–2.View ArticlePubMed
          30. Lexchin J, Bero LA, Djulbegovic B, Clark O: Pharmaceutical industry sponsorship and research outcome and quality: systematic review. BMJ 2003, 326:1167–70.View ArticlePubMed
          31. Hopewell S, Clarke M, Moher D, Wager E, Middleton P, Altman DG, Schulz KF, CONSORT Group: CONSORT for reporting randomized controlled trials in journal and conference abstracts: explanation and elaboration. PLoS Med 2008, 5:e20.View ArticlePubMed
          32. Boutron I, Moher D, Altman DG, Schulz KF, Ravaud P: Extending the CONSORT statement to randomized trials of nonpharmacologic treatment: explanation and elaboration. Ann Intern Med 2008, 148:295–309.PubMed
          33. Gagnier JJ, Boon H, Rochon P, Moher D, Barnes J, Bombardier C: Reporting randomized, controlled trials of herbal interventions: an elaborated CONSORT statement. Ann Intern Med 2006, 144:364–7.PubMed
          34. Zwarenstein M, Treweek S, Gagnier JJ, Altman DG, Tunis S, Haynes B, Oxman AD, Moher D, CONSORT group: Pragmatic Trials in Healthcare (Practihc) group. Improving the reporting of pragmatic trials: an extension of the CONSORT statement. BMJ 2008,11(337):a2390.View Article
          35. Pre-publication history

            1. The pre-publication history for this paper can be accessed here:http://​www.​biomedcentral.​com/​1741-7015/​8/​18/​prepub

          Copyright

          © Schulz et al. 2010

          This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.