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The BMJ’s Impact Factor is 14.093 (ISI Web of Science, 2011). 1,525,134 unique browsers download 6,890,203 pages from bmj.com each month (ABCe audit, October 2011).
Articles should be submitted as "Research" via our online editorial office.
All original research articles are submitted, although we may invite submission (without promising acceptance) if we come across research being presented at conferences, see it in abstract form or on a research registry, or if the authors make an inquiry about the suitability of their work before submission.
However, it is not always possible for us to answer all presubmission inquiries, particularly at busy times of the year, and we hope that this advice may help you decide whether the BMJ is the right journal for your research. In addition, this editorial explains what kind of research we give priority to, and what services we offer to authors of research: Publishing your research study in the BMJ. If you're still unsure about your choice of journal, these tips might help you decide.
We audit the performance of all BMJ research articles, using a wide range of indicators to assess their impact on readers and their dissemination to the wider world.
Research articles should report original research studies that can improve decision making in medical practice, policy, education, or research and will be understandable by general medical readers.
All research studies published in the BMJ should be morally acceptable, and must follow the World Medical Association's 2008 Declaration of Helsinki. To ensure this, we aim to appraise the ethical aspects of any submitted work that involves human participants, whatever descriptive label is given to that work including research, audit, and sometimes debate. This policy also applies on the very rare occasions that we publish work done with animal participants.
To learn more about the kind of research we give priority to, and what services we offer to authors of research, please read this editorial: Why submit your research to the BMJ? And, as it is not always possible for us to answer all presubmission inquiries, particularly at busy times of the year, we hope that this checklist may help you decide whether the BMJ is the right journal for your research. Please note that we welcome studies - even with "negative" results - as long as their research questions are important, new, and relevant to general readers and their designs are appropriate and robust.
Further down this page there are full details on how to prepare research articles for the BMJ, but first please read this information about relevant editorial policies:
All research papers in the BMJ are published with Open Access. Moreover, the BMJ immediately fulfils the requirements of the US National Institutes of Health, the UK Medical Research Council, the Wellcome Trust, and other funding bodies by making the full text of publicly funded research freely available to all on bmj.com and sending it directly to PubMed Central, the National Library of Medicine's full text archive.
Open Access articles may be reused according to the relevant Creative Commons licence. The BMJ's default licence for open access publication of research is the Creative Commons Attribution Non Commercial licence (CC BY-NC 3.0). But where the funder requires it the author can select the Creative Commons Attribution (CC BY 3.0) licence during the submission process (funders who mandate CC BY include the Wellcome Trust, RCUK, and MRC). In brief; users are free to share and adapt Open Access articles as long as the original work is attributed and the reuse in no way suggests that the author or publisher endorses their use of the work. There are restrictions on commercial use for articles published under CC BY-NC.
The BMJ is committed to keeping research articles Open Access. To support this we ask authors to pay an Open Access article publishing charge/fee of £3000 (excluding VAT) on acceptance of their paper. We can offer discounts and waivers for authors who cannot pay. Consideration of the paper is not related to whether authors can or cannot pay the fee. We will only ask for the fee once we have accepted a paper and we will only send an invoice once authors tell us (via firstname.lastname@example.org) they can claim the fee. Seeking and processing fees will not delay editing or publication. Please do not contact editors about Open Access fees: neither editors nor reviewers will know whether a fee is payable, and administrative staff will handle payments and all associated correspondence.
Open Access Institutional Memberships
A number of institutions have Open Access Institutional Memberships with BMJ Group, which either covers the whole cost of Open Access publishing for authors at participating institutions, or allows authors to receive a discount on the article processing charge. For a list of member institutions and their policies on how to receive a discount or to publish free of charge, please visit http://journals.bmj.com/site/authors/openaccess.xhtml
In accordance with the ICMJE uniform requirements, the BMJ will not consider reports of clinical trials unless they were registered prospectively before recruitment of any participants. This applies to trials which commenced after 1 July 2005: for older trials retrospective registration will be acceptable, but only if completed before submission of the manuscript to the journal.
Eligible trials have been defined by ICMJE since 1 July 2008 as "where human participants are prospectively assigned to one or more health-related interventions (including health services and behavioural interventions) to evaluate the effects on health outcomes", and before that were defined more narrowly as trials "where human participants are prospectively assigned to investigate the cause and effect relationship between a medical intervention and health outcome".
This means that:
- trials randomising human participants to investigate the cause and effect relationship between a medical intervention and a health outcome that commenced before 1 July 2005 can be registered retrospectively, but this must be done before submission to the BMJ
- trials randomising human participants to investigate the cause and effect relationship between a medical intervention and a health outcome that commenced after 1 July 2005 must have been registered prospectively, ie before enrolment of any participants
- trials randomising human participants or groups of humans to one or more health-related interventions (including health services and behavioural interventions) to evaluate the effects on health outcomes and that commenced after 1 July 2008 must have been registered prospectively, ie before enrolment of any participants*
* Please note that ICMJE says: " Some trials assign health care providers, rather than patients, to intervention and comparison/control groups. If the purpose of the trial is to examine the effect of the provider intervention on the health outcomes of the providers’ patients, then investigators should register the trial. If the purpose is to examine the effect only on the providers (for example, provider knowledge or attitudes), then registration is not necessary."
We recognise that there is the odd case where a good trial was not registered prospectively because the investigators were unaware of the ICMJE rules. The BMJ is willing to consider pleas from such authors, but we are very unlikely to bend our policy if a) the participants were patients b) the intervention was a treatment or other potentially burdensome intervention and/or c) the trial commenced more than a year after the ICMJE rules came into force. If we did accept such a paper we would ask the authors to register the trial retrospectively, for completeness of the record and to aid discovery of the trial, and to mention in the paper why the trial was not prospectively registered.
The BMJ’s criteria for a suitable public trial registry are: free to access, searchable, and identifies trials with a unique number; registration is free or has minimal cost; registered information is validated; registered entry includes details to identify the trial and investigator and includes the status of the trial; and the research question, methodology, intervention, funding, and sponsorship must all be disclosed at registration.
The BMJ does not consider posting of protocols and results in clinical trial registries to be prior publication.
The ethical and scientific arguments for trial registration were defined in the Ottawa Statement (2005):
Krleža-Jeric K, Chan A-W, Dickersin K, Sim I, Grimshaw J, Gluud C for the Ottawa Group. Principles for international registration of protocol information and results from human trials of health related interventions: Ottawa Statement (part 1). BMJ. 2005 Apr 23; 330:956-958.
Rationale for international trial registration
1. Ethical rationale
1.1. Above all, international trial registration is necessary to fulfill ethical obligations to research participants. When members of the public agree to participate in trials, it is on the understanding that they are contributing to the global body of health-related knowledge. It is thus unethical to conduct human research without ensuring that valid descriptions of the study and its findings are publicly available.
1.2. Potential trial participants, care providers, researchers, institutional review boards/independent ethics committees (IRB/IECs), and sponsors should have access to valid information about trials that have been previously performed.
1.3. Potential trial participants, care providers, researchers, IRB/IECs, and sponsors should have access to valid information about trials that are currently open for enrolment.
1.4. The availability of unbiased information about all initiated trials contributes to global open access to knowledge, which constitutes a public good.
2. Scientific rationalePublic access to trial protocol information (as approved by the IRB/IEC) and results will help to:
2.1. Minimise known risks and potential harm arising from unnecessary exposure to previously tested interventions;
2.2. Accelerate research by making knowledge available about prior experiences with interventions;
2.3. Identify and deter unnecessary duplication of research and publications;
2.4. Identify and deter selective reporting of research (reporting biases);
2.5. Provide a means of comparing the original protocol upon which ethics approval was based with the study as it was carried out;
2.6. Enhance collaboration among researchers by informing them of ongoing trials.
Registration of other studies - particularly observational studies
There are no fixed rules about the registration of studies or about the use and provision of study protocols, other than for clinical trials. However, the BMJ actively supports the registration of protocols and results in publicly accessible registries for all types of study involving human participants, particularly observational studies.
Observational studies, such as cohort and case-control studies, are an important form of medical research but they are vulnerable to bias and selective reporting. When an observational study is submitted to the BMJ we will ask authors for:
- the registration details, if the study has been registered - these should be added to the last line of the paper's abstract. We will also ask for claification about whether the study was registered before data acquisition or analysis began
- the protocol, if one exists - uploaded as a supplemental file to the submitted paper
- a clear statement of whether the study hypothesis arose before or after inspection of the data (and, if afterwards, we will need an explanation of steps taken to minimise bias)
- a completed STROBE checklist - uploaded as a supplemental file to the submitted paper. We will pay particular attention to these items which ask authors to "explain the scientific background and rationale for the investigation being reported" and "state specific objectives, including any prespecified hypotheses."
We appreciate that many new ideas arise from unexpected findings in observational research, and we aim to apply the above policy in a flexible manner. Hence we will not necessarily reject an observational study just because it did not have a prespecified hypothesis, but if it did not we will want the exploratory nature of its research question, and its design, to be fully reported. However the BMJ gives highest priority to studies that provide strong support for inferences applicable to clinical practice and we think the case against data driven observational studies is particularly compelling under these circumstances.
BMJ policy on drugs and devices trials
We welcome submission of any drug or device trial that asks an original research question that will sufficiently aid doctors' decisions.
From January 2013, trials of drugs and medical devices will be considered for publication only if the authors commit to making the relevant anonymised patient level data available on reasonable request (see editorial). This policy applies to any research article that reports the main endpoints of a randomised controlled trial of one or more drugs or medical devices in current use, whether or not the trial was funded by industry.
“Relevant data” encompasses all anonymised data on individual patients on which the analysis, results, and conclusions reported in the paper are based. As for “reasonable request,” the BMJ is not in a position to adjudicate, but we will expect requesters to submit a protocol for their re-analysis to the authors and to commit to making their results public. We will encourage those requesting data to send a rapid response to bmj.com describing what they are looking for. If the request is refused we will ask the authors of the paper to explain why.
Other requirements: please also provide the trial registration details, the relevant completed CONSORT checklist, and the original study protocol for use in confidence during peer review (or a revised protocol along with explanation of the revisions). Please declare the details of all sources of funding for the study; provide statements of competing interests and contributorship; fully describe the role of the study sponsors; provide a statement on the independence of researchers from funders; and state whether all authors had full access to and can take responsibility for the data and analyses. All of these items are explained in more detail below in the general advice about research articles.
Which drug and device trials does BMJ prioritise?
- we give highest priority to trials of the comparative effectiveness of drugs or devices or other interventions head to head against the best current treatment(s) using clinically valid doses/administration of both study and comparator interventions.
- placebo controlled trials often have much more limited relevance to practice than head to head trials and may not sufficiently help BMJ readers' decisions, but we are willing to consider these too if the research questions are sufficiently important and clearly explained.
In addition, we will give greater priority to a drug or device trial if it:
- has a main outcome measure that's sufficiently clinically relevant and, if it's a composite outcome, matters enough to patients
- has important results: please note that we welcome "negative" trials as long as their research questions are important, new, and relevant to general readers and their designs are appropriate and robust.
- is reported fully in line with the CONSORT statement or the relevant CONSORT extension statement (eg for cluster randomised trials), and has sufficient internal and external validity.
- is reported transparently as explained in our detailed advice below on reporting industry-sponsored trials, and particularly in line with the Good Publication Practice (GPP2) guidelines.
- is a phase III trial.
If you are submitting an original article reporting an industry-sponsored clinical trial, postmarketing study, or other observational study please follow the guidelines on Good Publication Practice (GPP2) and on properly reporting the role of professional medical writers. Another resource, the Authors' Submission Toolkit: A practical guide to getting your research published summarises general tips and best practices to increase awareness of journals' editorial requirements, how to choose the right journal, submission processes, publication ethics, peer review, and effective communication with editors - much of which has traditionally been seen as mysterious to authors.
For drug and device trials: from January 2013, trials of drugs and medical devices will be considered for publication only if the authors commit to making the relevant anonymised patient level data available on reasonable request (see editorial). This commitment must be detailed in the article's data sharing statement (see below).
For all research articles: we encourage authors of all BMJ research articles - whether reporting randomised controlled trials or other study types - to link their articles to the raw data from their studies. Our policy on drug and device trials requires data sharing on request as a minimum - if authors of such trials are willing to go further and share the data openly, so much the better.
Where should data be deposited? Authors may choose to deposit their data in an institutional, national, or other repository. The BMJ has partnered with the Dryad Digital Repository datadryad.org to make open deposition easy and to allow direct linkage by doi from the dataset to the BMJ article and back (for BMJ articles' datasets see here)
Why share data? We are keen to maximise the usefulness and usage of data and promote transparency, and to satisfy the requirements of the many research funders that encourage or even mandate data sharing. We understand that many authors wish to guard data until they have published all their papers, and we know that data sharing is hard to do. But we hope that authors will, increasingly, set the data free, perhaps after a set period of personal use.
Confidentiality and consent: we recommend that researchers should seek informed consent to data sharing from research participants upfront, at the recruitment stage. There are good ethical and practical reasons for doing so. Even if the investigators have no current plans to share raw data, at some future time data sharing may become the norm. If so, sharing will be much easier if no one has to try to seek consent retrospectively.
Consent is particularly important because participants may be identifiable in a dataset - even an "anonymised" one that does not contain names or addresses. The combination of three or more indirect identifiers such as age, sex, and an unusual clinical detail may be enough for at least the participant, or another interested party, to recognise themselves.
Data sharing statement
We require a data sharing statement at the end of every research manuscript. For trials of drugs or devices the statement must state, at a minimum, that the the relevant anonymised patient level data are available on reasonable request from the authors.
Options for formatting the statement are suggested here:
"Data sharing: patient level data [and/or] full dataset [and/or] technical appendix [and/or] statistical code [and/or] available at [
If there are no such further data available, please use this wording: "Data sharing: no additional data available". This option is not available for trials of drugs or devices.
BMJ policy on case series
Case series lack formal hypotheses and formal study designs that prespecify the sampling criteria and methods, data collection, and analyses. If they had all these things they would be cohort studies.
Hence a case series is rarely the best design to answer a research question, particularly when describing clinical experience with an intervention. Even when that intervention is the clinical and/or practical response to an event or a disease outbreak, the case series has scientific limitations and allows few generalisable or actionable conclusions to be drawn. A series - even if compared with a control group - cannot answer questions about appropriateness, effectiveness, and adverse effects.
At the early stages of the response to an unusual major event or disease outbreak, however, case series can provide helpful and original preliminary information for clinicians and policy makers. So the BMJ will consider as Research articles case series that are sufficiently informative for clinical and public health practice or policy (preferably internationally) and are compelling, well described, and topical eg describing the management of an outbreak of a new or particularly widespread and contagious infectious disease.
When such a series raises controversial issues for health services and policy, warranting detailed description and discussion, an Analysis article might be the best format.
How to prepare BMJ original research articles (full versions)
No word limit
To encourage full and transparent reporting of research we do not set fixed limits for the length of BMJ research articles. Nonetheless, please try to make your article concise and make every word count. Think hard about what really needs to be in the paper to get your message across accurately and what can be left out. We suggest 4000 words as a guideline for fully reporting a study's methods, results, introduction, and discussion in an average article, although we recognise that some studies may need more space, others less. You will be prompted to provide the word count for the main text (excluding the abstract, references, tables, boxes, or figures) when you submit your manuscript.
Important: The manuscript should include the structured abstract and all tables, figures, boxes, and appendices that are essential to reporting the study design and findings. We may suggest later that you separate out some material into web extras to make the main manuscript clearer for general readers, but for peer review (including editorial and statistical review), the manuscript should be a complete document that fully reports the study.
Abridged research articles
The full text of all accepted BMJ research articles is published online in full, with open access and no word limit, on bmj.com as soon as it is ready. In the print BMJ each research article is abridged, with the aim of making research more inviting and useful to readers.
BMJ pico is our one page abridged format for research papers in the print journal, which some authors volunteered to help us pilot. We designed BMJ pico with evidence based medicine experts to succinctly present the key evidence from each study, to help minimise delay between online and print publication, and to enable us to publish more research in each week’s print BMJ. See frequently asked questions about pico.
There is no need for authors to prepare a BMJ pico to submit along with their full research article. Authors produce their own BMJ pico, using a template from us, as part of the final revisions before acceptance for publication.
Because publication of research on bmj.com is definitive, rather than interim “epublication ahead of print”, authors who do not wish to abridge their articles using BMJ pico will be able to opt for online only publication.
This should give the title of the article, including the study design. Please give for each author his or her name and initials, full address including postal code and one main work position (job title) at the time of writing the paper. We do not need authors’ qualifications. For the corresponding author please provide an email address and the best contact address: this may differ from his or her work address.
If there is a very large number of authors we may ask for confirmation that everyone listed met the ICMJE criteria for authorship. If they did, we may then suggest that the authors form a group whose name will appear in the article byline. MEDLINE guidance explains that group authorship is acceptable, stating "When a group name for a specific consortium, committee, study group, or the like appears in an article byline, the personal names of the members of that group may be published in the article text. Such names are entered as collaborator names for the MEDLINE citation."
Original research articles should follow the IMRaD style (introduction, methods, results and discussion) and should include a structured abstract (see below), a structured discussion, and a succinct introduction that focuses - in no more than three paragraphs - on the background to the research question.
This video slideshow presentation gives more detailed advice on writing each section of a BMJ research paper.
Please report statistical aspects of the study in line with the "Statistical Analyses and Methods in the Published Literature (SAMPL) Guidelines." We also ask you to ensure that the manuscript includes all the information recommended in the relevant reporting statement, for example CONSORT. To find research reporting guidelines and statements such as CONSORT you may find it easiest to go to the website of the EQUATOR network, where they are all available in one place. We do not use reporting guidelines as critical appraisal tools to evaluate study quality or filter out articles. We're simply aiming to make research articles so clear that peer reviewers, editors, clinicians, educators, ethicists, policy makers, systematic reviewers, guideline writers, journalists, patients, and the general public can tell what really happened during a study.
Please scroll down for detailed advice on preparing this.
Please ensure that the discussion section of your article comprises no more than five paragraphs and follows this overall structure, although you do not need to signpost these elements with subheadings:
- Statement of principal findings
- Strengths and weaknesses of the study
- Strengths and weaknesses in relation to other studies, discussing important differences in results
- Meaning of the study: possible explanations and implications for clinicians and policymakers
- Unanswered questions and future research
What other information do we need?
Please see our general requirements for all BMJ manuscripts. For original research articles in particular, please note that we need, as appropriate:
In the manuscript
for an intervention study the manuscript should include enough information about the intervention(s) and comparator(s) (even if this was usual care) for reviewers and readers to understand fully what happened in the study. To enable readers to replicate your work or implement the interventions in their own practice please also provide (uploaded as one or more supplemental files, including video and audio files where appropriate) any relevant detailed descriptions and materials. Alternatively, please provide in the manuscript urls to openly accessible websites where these materials can be found.
A competing interest declaration. This should be composed after each author has filled in the International Committee of Medical Journal Editors' Unified Competing Interest form and the corresponding author should keep the completed forms in case they are required later. Please then add to the manuscript a statement in the following format:
“All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare that (1) [initials of relevant authors] have support from [name of company] for the submitted work; (2) [initials of relevant authors] have [no or specified] relationships with [name of companies] that might have an interest in the submitted work in the previous 3 years; (3) their spouses, partners, or children have [specified] financial relationships that may be relevant to the submitted work; and (4) [initials of relevant authors] have no [or specified] non-financial interests that may be relevant to the submitted work.”
- details of contributors - giving their names and specific roles - and the name of the guarantor(s) for the study
- a statement that any identifiable patients have provided their signed consent to publication. Please submit, as a supplemental file, the signed BMJ patient consent form giving consent to publication in the BMJ of any information about identifiable individual patients. Publication of any personal information about a patient in the BMJ, for example in a case report or clinical photograph, will normally require the signed consent of the patient.
- a statement that the study obtained ethics approval (or a statement that it was not required), including the name of the ethics committee(s) or institutional review board(s), the number/ID of the approval(s), and a statement that participants gave informed consent before taking part.
- a statement giving the details of all sources of funding for the study
- description of the role of the study sponsor(s) or funder(s), if any, in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication
- a statement of the independence of researchers from funders
- a statement that all authors, external and internal, had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis
- a data sharing statement such as "Data sharing: patient level data [and/or] full dataset [and/or] technical appendix [and/or] statistical code [and/or] available at [
/doi] [with open access/with these restrictions] [from the corresponding author at ]. Participants gave informed consent for data sharing [or ...consent was not obtained but the presented data are anonymised and risk of identification is low... or consent was not obtained but the potential benefits of sharing these data outweigh the potential harms because...]". If there are no such further data available, please use this wording: "Data sharing: no additional data available".
- trial registration number and name of register for a clinical trial—in the last line of the structured abstract
- registration number and name of register for any study type, if registered—in the last line of the structured abstract. We are keen to promote registration for observational studies and systenatic reviews
- for articles that include explicit statements of the quality of evidence and strength of recommendations, we prefer reporting using the GRADE system (we encourage but do not insist on this)
- one or more references for the statistical package(s) used to analyse the data eg RevMan for a systematic review. There is no need to provide a formal reference for a very widely used package that will be very familiar to general readers eg STATA, but please say in the text which version you used.
As supplemental files
- the original protocol for a clinical trial or, if the protocol has been published in an open access online journal, its reference and url. We appreciate that studies sometimes deviate from protocols, but please explain any important deviations in the manuscript, particularly those about choice of outcomes and analyses or change in sample size
- the original protocol for an observational study or systematic review, if available. We recommend that protocols for randomised trials are written using the SPIRIT checklist.
- for a randomised controlled trial, the appropriate completed CONSORT checklist showing on which page of your manuscript each checklist item appears, the CONSORT-style structured abstract, and the CONSORT flowchart (CONSORT has several extension statements, eg for cluster RCTs, pragmatic trials)
- PRISMA checklist and flowchart for a systematic review or meta-analysis of randomised trials and other evaluation studies
- MOOSE checklist for a meta-analysis of observational studies
- STARD checklist and flowchart for a study of diagnostic accuracy
- STROBE checklist for an observational study
- GRIPS for genetic risk prediction studies
- CHEERS for an economic evaluation
- original raw data if you think they will help our reviewers (and maybe readers), or if we specifically request them. Please note our policy on data sharing, explained above
- video and audio files that will add educational value to your article, for example by explaining the intervention in a trial
- copies of any non-standard questionnaires and assessment schedules used in the research
- copies of patient information sheets used to obtain informed consent for the study or to comprise or deliver the intervention in a clinical trial
- copies of closely related articles you have published (this is particularly important when details of the study methods are published elsewhere)
- copies of any previous reviewers' reports on this article. We appreciate that authors may have tried other journals before sending their work to the BMJ, and find it helpful if you let us know how you have responded to previous reviewers' comments
In the cover letter
- details of previous publications from the same study - including in scientific abstracts or partial reports by the media at scientific meetings and in foreign language journals
- details of any previous publication of the same study in electronic form. For example, the BMJ does not consider posting of protocols and results in clinical trials registries to be prior publication, but we would like to know if results have been posted, and where (please provide urls or trial registration details). And we are pleased to consider articles based on longer systematic reviews and meta-analyses published at the Cochrane Library or HTA database
- names and contact details (including email addresses) of suitable peer reviewers; we often find authors' suggestions helpful, though this is optional
- assurance that a study funded or sponsored by industry follows the guidelines on good publication practice. These GPP2 guidelines aim to ensure that such studies are published in a responsible and ethical manner. The guidelines cover companies’ responsibility to endeavour to publish results of all studies, companies’ relations with investigators, measures to prevent redundant or premature publication, the roles of authors and contrbutors, and the role of professional medical writers
- assurance that any article written by a professional medical writer follows the guidelines by the European Medical Writers' Association on the role of professional medical writers. The guidelines emphasise the importance of respecting widely recognised authorship criteria, and in particular of ensuring that all people listed as named authors have full control of the content of articles. The role of professional medical writers must be transparent. Please name any professional medical writer among the list of contributors to any article for the BMJ (not only original research articles), and specify in the formal funding statement for the article who paid the writer. Writers and authors must have access to relevant data while writing articles. Medical writers have professional responsibilities to ensure that the articles they write are scientifically valid and are written in accordance with generally accepted ethical standards.
Please ensure that the structured abstract is as complete, accurate, and clear as possible—but not unnecessarily long—and has been approved by all authors. We may screen original research articles by reading only the abstract. For randomised controlled trials please provide all the information required for a CONSORT style abstract.
Please note the general rules for abstracts in the BMJ:
- should be 250- 300 words long: you may need up to 400 words, however, for a CONSORT or PRISMA style abstract. Medline can now handle up to 600 words
- use active voice but avoid “we did” or “we found”
- numbers over 10 do not need spelling out at the start of sentences
- sentences starting with a number do not require a capital letter
- p values should always be accompanied by supporting data and denominators should be given for percentages
- abstracts do not need references
The first few items (objective, design, setting) may be note-like and need not form full sentences. The results and conclusions sections should be written properly. Do not mix notes and full sentences in one section.
If the standard headings do not suit the type of study, substitute something sensible such as "population" as a heading instead of "participants" in an economics article. Please do not simply delete the heading.
For standard original research articles please provide the following headings and information (for RCTs please add the trial registration details - but there is no need to provide the additional subheadings which are used in the CONSORT statement on abstracts, as long as you include all the required information, and the same applies to the PRISMA statement):
- objectives - a clear statement of the main aim of the study and the major hypothesis tested or research question posed
- design - including factors such as prospective, randomisation, blinding, placebo control, case control, crossover, criterion standards for diagnostic tests etc
- setting - include the level of care eg primary, secondary; number of participating centres. Be general rather than give the name of the specific centre, but give the geographical location if this is important
- participants (instead of patients or subjects) - numbers entering and completing the study, sex, and ethnic group if appropriate. Give clear definitions of how selected, entry and exclusion criteria
- interventions - what, how, when and for how long. This heading can be deleted if there were no interventions but should normally be included for randomised controlled trials, cross over trials, and before and after studies.
- main outcome measures - those planned in protocol, those finally measured (if different, explain why)
- results - main results with (for quantitative studies) 95% confidence intervals and, where appropriate, the exact level of statistical significance and the number need to treat/harm. Whenever possible, state absolute rather than relative risks
- conclusions - primary conclusions and their implications, suggesting areas for further research if appropriate. Do not go beyond the data in the article. Conclusions are important because this is often the only part that readers look at.
- trial registration - registry and number (for clinical trials and, if available, for observational studies and systematic reviews)
Please note that confidence intervals should be written in the format (15 to 27) within parentheses, using the word "to" rather than a hyphen.
Abstracts for meta-analyses and systematic reviews should have these headings but should also include all the items required (as recommended in the PRISMA statement):
- objective - what the review set out to determine
- design - type of meta-analysis, systematic review and study appraisal and synthesis methods
- data sources - where included studies were retrieved from
- eligibility criteria for selecting studies - inclusion and exclusion criteria (specifying participants and interventions, as appropriate)
- results - main findings with 95% confidence intervals
- conclusions - primary conclusions and their implications
- systematic review registration - registry and number (if registered)
Abstracts for qualitative research articles should follow the standard style but may need fewer headings:
Quality improvement reports - which are published in the BMJ's Practice section - also have their own style of structured abstract:
- key measures for improvement
- strategies for change
- effects of change
- lessons learnt
“What this paper adds” box
Please produce a box offering a thumbnail sketch of what your article adds to the literature, for readers who would like an overview without reading the whole article It should be divided into two short sections, each with 1-3 short sentences.
Section 1: What is already known on this subject
In two or three single sentence bullet points please summarise the state of scientific knowledge on this subject before you did your study and why this study needed to be done. Be clear and specific, not vague.
For example you might say: “Numerous observational studies have suggested that tea drinking may be effective in treating depression, but until now evidence from randomised controlled trials has been lacking/the only randomised controlled trial to date was underpowered/was carried out in an unusual population/did not use internationally accepted outcome measures/used too low a dose of tea.”
or: “Evidence from trials of tea therapy in depression have given conflicting results. Although Sjogren and Smith conducted a systematic review in 1995, a further 15 trials have been carried out since then…”
Section 2: What this study adds
In one or two single sentence bullet points give a simple answer to the question “What do we now know as a result of this study that we did not know before?” Be brief, succinct, specific, and accurate. For example: “Our study suggests that tea drinking has no overall benefit in depression”.
You might use the last sentence to summarise any implications for practice, research, policy, or public health. For example, your study might have: asked and answered a new question (one whose relevance has only recently become clear) contradicted a belief, dogma, or previous evidence provided a new perspective on something that is already known in general provided evidence of higher methodological quality for a message which is already known.
Summary statistics to clarify your message
We do want your piece to be easy to read but also want it to be as scientifically accurate as possible. Whenever possible, state absolute rather than relative risks. Please include in the results section of your structured abstract (and in the article's results section) the following terms, as appropriate:
For a clinical trial:
- Absolute event rates among experimental and control groups
- RRR (relative risk reduction)
- NNT or NNH (number needed to treat or harm) and its 95% confidence interval (or, if the trial is of a public health intervention, number helped per 1000 or 100,000)
For a cohort study:
- Absolute event rates over time (eg 10 years) among exposed and non-exposed groups
- RRR (relative risk reduction)
For a case control study:
- OR (odds ratio) for strength of association between exposure and outcome
For a study of a diagnostic test:
- Sensitivity and specificity
- PPV and NPV (positive and negative predictive values)
The box stating what is known and what this paper adds (see below) should also reflect accurately the above information. Under what this paper adds please give the one most useful summary statistic eg NNT.
Please do not use the term "negative" to describe studies that have not found statistically significant differences, perhaps because they were too small. There will always be some uncertainty, and we hope you will be as explicit as possible in reporting what you have found in your study. Using wording such as "our results are compatible with a decrease of this much or an increase of this much" or “this study found no effect” is more accurate and helpful to readers than “there was no effect/no difference”. Please use such wording throughout the article, including the structured abstract, and the box stating what the paper adds.
If you are sending us a revised article
Please provide all of the above, as appropriate (if not done earlier), as well as a detailed covering letter explaining how you have responded to editorial and peer review comments and other guidance from the BMJ. All of this should be submitted via your author area at our online editorial office.
Commentaries on research
We often commission editorials linked to accepted research articles. From time to time we may publish original research articles with an accompanying online commentary of up to 500 words and five references, commissioned to help readers interpret the research or place it in context. If we commission a commentary on your article we will send you a copy of it before publication.
If we ask you to write a commentary, please provide in the manuscript a title for your piece; a title page giving your name, position, and contact details including email address; and statements of competing interests and - if appropriate - contributorship and funding. Please say in your covering letter or email which BMJ article you are commenting on and give its BMJ manuscript number.