- In planning a Cochrane Review, there are some additional considerations for author teams over and above what is required for other systematic reviews.
- Proposals for new Cochrane Reviews are submitted by author teams to Cochrane Review Groups (CRGs). The CRGs register the proposals, if agreed, and support the author teams and manage the editorial process from registration to publication for the protocol, full review, and updates.
- Authors should establish a team with appropriate experience and expertise in both the topic of the review and systematic review methods.
- All named authors should meet the ICMJE criteria for authorship of a publication.
- Authors are advised to give due consideration to the resources needed to undertake a Cochrane Review, of which the most important resource is time.
- Cochrane authors are expected to follow Cochrane policy for avoiding and declaring potential conflicts of interest.
This chapter should be cited as: Cumpston M, Chandler J. Chapter II: Planning a Cochrane Review. In: Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane Handbook for Systematic Reviews of Interventions version 6.2 (updated February 2021). Cochrane, 2021. Available from www.training.cochrane.org/handbook.
The process of preparing and publishing a Cochrane Review is different from that for other journals. Reviews are typically registered at conception and there is a closer working relationship between Cochrane and the review authors. In addition, Cochrane Reviews follow a highly structured format so that they can be published within the Cochrane Database of Systematic Reviews, and their preparation follows a structured process. This Chapter overviews the procedures and practicalities of starting a Cochrane Review. It aims to supplement the more general and methodological guidance available in Chapter 1 and Chapter 2.
II.1.1 Working with Cochrane Review Groups
All author teams working on Cochrane Reviews work with one of the Cochrane Review Groups (CRGs). There are approximately 50 CRGs. Each CRG focuses on a specific area of health, such as pregnancy and childbirth, schizophrenia, or eyes and vision. CRGs are grouped into Networks, each of which represents a thematic grouping, such as Children and Families, Mental Health and Neuroscience and Public Health and Health Systems.
The collaboration between the review team and the CRG ensures the quality of Cochrane Reviews, with the expectation that authors follow pre-specified minimum expectations (see Chapter 1, Section 1.4). In return, CRGs provide ongoing editorial and other support throughout the preparation of the review from proposal to submission for editorial review and publication. In some cases, CRGs can provide specific services to support the review, such as translation, statistical advice and in many cases expert Information Specialists to assist in developing search strategies and conduct searches of electronic databases. The type of support available varies across CRGs.
Once a protocol or review is completed and submitted, the CRG will coordinate editorial and peer review to determine whether the manuscript should be published, in a similar process to other academic journals. The review must meet Cochrane’s standards, and publication is not guaranteed.
The first step in the Cochrane Review process is the prospective registration of a review proposal with the CRG responsible for reviews in the relevant field of health care. Registration should take place before work on the review starts. The registration process ensures that the scope of the proposed review is appropriate, avoids duplication between different Cochrane Reviews, allows checking of the skills and experience of the proposed author team (see Section II.2 and Chapter 1, Section 1.3), and allows Cochrane to provide early editorial and other support.
The CRG editorial team will assess each proposal for suitability, and for importance of the topic to the CRG in relation to their resources to support the review. CRGs conduct priority-setting activities to identify topic areas and specific review questions that they consider to be a high priority. These activities typically include consultation with stakeholders including consumers, clinical experts and policy decision makers. Given the active support provided to author teams of registered reviews, CRGs may be unable to accept registration of topics outside of their priorities. If this is the case, authors may be advised to proceed with the review outside Cochrane, and publish it in another journal.
If the CRG agrees to register the review, review authors will be asked to develop and submit a protocol (see Section II.1.4 and Chapter 1, Section 1.5). Cochrane’s editorial processes are similar to those of other journals, including both editorial and peer review. CRGs may reject manuscripts that are not of a sufficient standard for publication.
Cochrane Reviews are updated based on need (see Chapter IV). When proposing a new review, author teams should be aware of the commitment needed to prepare a review, the responsibility of responding to post-publication feedback (e.g. comments from readers), and to updating as required.
The title should state succinctly the intervention(s) to be reviewed and the problem at which the intervention is directed. In some cases, the title may also state a specific population or setting. The titles of Cochrane Reviews on the effects of interventions should follow the structure shown in Table II.1.a.
Table II.1.a Structure of titles for Cochrane Reviews of interventions
[Intervention] for [health problem]
Antibiotics for acute bronchitis
Comparing two active interventions
[Intervention A] versus [intervention B] for [health problem]
Immediate versus delayed treatment for cervical intraepithelial neoplasia
Type of people being studied or location of intervention mentioned explicitly
[Intervention] for [health problem] in [participant group/location]
Inhaled nitric oxide for respiratory failure in preterm infants
Not specifying a particular health problem, or if the intervention intends to influence a variety of problems
[Intervention] in OR for [participant group/location]
Planned hospital birth versus planned home birth
Prophylactic synthetic surfactant in preterm infants
Sometimes it is necessary to specify that the intervention is for preventing, treating, or preventing and treating the health problem(s).
[Intervention] for preventing AND/OR treating [health problem]
Pool fencing for preventing drowning in children
Amodiaquine for treating malaria
Vitamin C for preventing and treating the common cold
Preparing a Cochrane Review is complex and involves many judgements. All Cochrane Reviews must have a written protocol, specifying in advance the scope and methods to be used by the review, to assist in planning and reduce the risk of bias in the review process (see Chapter 1, Section 1.5 for a detailed discussion of the rationale for protocols). Cochrane provides a highly structured format for both its protocols and reviews to guide authors on the information they should report (see Box II.1.a).
As with any study, if the methods proposed in the protocol are changed during the course of conducting the review, these changes should be documented and reported. In a Cochrane Review, changes should be described in the ‘Differences between protocol and review’ section of the completed review. Sensitivity analyses (see Chapter 10, Section 10.14) exploring the impact of deviations from the protocol should be undertaken, when possible.
As well as being published in the Cochrane Database of Systematic Reviews in the Cochrane Library, since 1 October 2013, all Cochrane Protocols are automatically registered on the PROSPERO register of systematic reviews, allowing transparency and accountability.
Box II.1.a Sections of a protocol for a Cochrane Review
Figures and Tables
* “Additional references” refers to the standard list of references cited in the text of the protocol (they become ‘additional’ in the context of the completed review, where they supplement references to the included and excluded studies).
II.2 The author team
Cochrane Reviews should be undertaken by more than one person. In putting together a team, authors should consider the need for clinical and methodological expertise for the review, as well as the perspectives of stakeholders. Cochrane author teams are encouraged to seek and incorporate the views of users, including consumers, clinicians and those from varying regions and settings to develop protocols and reviews. Author teams for reviews relevant to particular settings (e.g. neglected tropical diseases) should involve contributors experienced in those settings.
When a proposal for a new review is received, Cochrane’s editorial teams will consider not only the clarity of the review question, but also the skills and experience of the team. First-time review authors are encouraged to work with others who are experienced in the process of conducting Cochrane Reviews and to make use of Cochrane training and guidance resources (see Section II.3.3). See Chapter 1, Section 1.3, on the importance and experience required of the review team and guidance on involving consumers and other stakeholders.
Cochrane follows the International Committee of Medical Journal Editors (ICMJE) criteria for authorship (ICMJE 2018). When deciding who should appear in the byline of a Cochrane Review, only those individuals who have made a substantial contribution to the review (and therefore are listed as authors) can be listed. People who have helped in other ways can be listed in the Acknowledgements section with written permission. The specific contributions of each author should be listed in the ‘Contributions of authors’ section. Including authors who do not meet these criteria, or failing to name significant contributors as authors, is not appropriate. Methodological specialists such as statisticians and information specialists should be included as authors where they meet the ICMJE criteria, particularly where they have been substantively involved in the design and execution of the review’s methods.
For further information, see the Cochrane authorship and contributorship policy.
II.3.1 Identifying resources and support
The main resource required by authors is their own time. Many authors will contribute their time free of charge because it will be viewed as part of their existing research or their efforts to keep up to date with an area of interest.
The amount of time required will vary, depending on the topic of the review, the number of included studies, the methods used (e.g. the extent of efforts to obtain unpublished information), the experience of the authors, and the types of support provided by the editorial team of the CRG. The workload associated with undertaking a review is thus very variable. However, consideration of the tasks involved and the time required for each of these might help authors to estimate the amount of time that will be required. These tasks include training, meetings, protocol development, searching for studies, assessing citations and full-text reports of studies for eligibility, assessing the risk of bias of included studies, collecting data, pursuing missing data and unpublished studies, analysing the data, interpreting the results, writing the review, and keeping the review up to date.
A time chart with target dates for accomplishing key tasks can help with scheduling the time needed to complete a review. Such targets may vary widely from review to review, and authors may find it helpful to work with the editorial team for the CRG to determine an appropriate time frame for the completion and submission of a specific review.
Resources that might be required for these tasks, in addition to the authors’ time, include:
- searching (assistance may be provided by the editorial team of the CRG or a local information specialist (see Chapter 4, Section 4.2.1), but authors share this responsibility and it may be appropriate to search additional databases for a specific review);
- additional library resources, including access to electronic databases for searching and interlibrary loans;
- statistical support for synthesizing (if appropriate) the results of the included studies;
- equipment (e.g. computing hardware and software);
- supplies and services (internet connection, printing, telephone charges);
- office space for staff; and
- travel funds to attend author meetings or present the results of the review (e.g. at a conference).
II.3.2 Funding and conflict of interest
Many organizations currently provide funding for systematic reviews. These include research funding agencies, organizations that provide or fund healthcare services, those responsible for health technology assessment and those involved in the development of clinical practice guidelines. Author teams may wish to identify and seek funding from such organizations operating in their region or field of health care.
Conflict of interest in the funding and authorship of research gives rise to serious issues, which Cochrane takes very seriously (Bero 2018, Tovey et al 2018). Under Cochrane’s policy on conflict of interest, a Cochrane Review cannot be funded or conducted by commercial sponsors or commercial sources with a real or potential vested interest in the findings of a specific review.
All prospective Cochrane authors should complete a declaration of interests form when the review is first proposed, and update these details before publication of the protocol and the completed review. Individuals who are employed by a company that has a real or potential financial interest in the outcome of the Cochrane Review (including, but not limited to, drug companies or medical device manufacturers), or who hold or have applied for a patent related to the Cochrane Review, are prohibited from being Cochrane Review authors. Any other possible conflicts of interest will be reviewed by Cochrane’s Funding Arbiter. If any conflicts change over time authors should contact their CRGs to alert them and determine whether they affect the author’s involvement in the review.
Further discussion of the issues around conflict of interest in research, and in particular how they apply to the studies included within a review, is in Chapter 7, Section 7.8.
While many Cochrane authors have a great deal of knowledge and experience in conducting systematic reviews, others are new to the process or to Cochrane methods, or wish to expand their skills. To assist those contributing to Cochrane Reviews in gaining the knowledge, skills and support they need to meet the conduct and reporting standards, Cochrane provides a range of support services to facilitate learning.
In addition to written guidance, Cochrane provides a range of online training resources, as well as face-to-face events in locations around the world. Details of current resources and events are available at http://training.cochrane.org.
Cochrane Reviews are supported by an ecosystem of software tools to assist with different aspects of the review process (Elliott et al 2014). The primary piece of software is Cochrane’s own Review Manager (RevMan). RevMan is a mandatory tool and free to use for authors preparing a Cochrane Review. The software is developed through a continuing process of consultation with its users and Cochrane methodologists to support good practice for Cochrane Reviews, and provides structured text drafting, standard tables and reference formats, meta-analysis, online help and error checking mechanisms. RevMan is also used to submit review manuscripts for editorial assessment and publication.
Authors may wish to consider other software resources to assist them with different aspects of the review process. A register of tools designed for use in systematic reviews is maintained in the Systematic Review Toolbox. Developments take place rapidly in tools aiming to increase efficiency and reduce the time required to complete a review or update (Elamin et al 2009, Tsafnat et al 2014, O'Connor et al 2018), with some tools able to automate (or semi-automate) some elements of the process.
Software to manage references is usually required during the searching process, and systematic review tools including Covidence and EPPI-Reviewer can be used to assist in the process of screening search results. Advanced processes such as text mining and machine learning to assist in selection are increasingly common, and web-based processes such as crowdsourcing are also available (see Chapter 4, Section 4.6). Cochrane Information Specialists are able to facilitate access to some valuable resources. These include the Cochrane Evidence Pipeline, which incorporates a centralized search for randomized trials, machine learning technology and Cochrane Crowd, a crowd-based system to screen search results. These tools can assist authors of Cochrane Reviews to screen and identify relevant studies for inclusion in reviews (for example, by filtering to identify randomized trials), particularly for reviews with complex searches and large record sets. Authors should contact their CRG for further information.
Software such as Covidence and EPPI-Reviewer can also be used for data collection and other elements of the review process (see Chapter 5, Section 5.5), and both are recommended and freely available to Cochrane authors. Statistical software such as Stata, R and Comprehensive Meta-Analysis may be used to perform statistical analyses that are not available in RevMan. Later in the review process, GRADEpro GDT can be used to create ‘Summary of findings’ tables (see Chapter 14, Section 14.1.4).
The choice of software tools may depend on the authors’ preference, the availability of a stable internet connection, the cost and the extent to which novel methods have been validated for accuracy. Authors are advised to seek methodological advice before incorporating new technologies into their reviews.
Authors: Miranda Cumpston and Jacqueline Chandler
Acknowledgements: We thank previous chapter authors and editors Ginny Brunton, Sally Green, Julian Higgins, Nicki Jackson, Monica Kjeldstrøm, Harriet MacLehose and Sandy Oliver, as well as contributing authors to earlier editions of the Handbook. We thank Toby Lasserson, Chris Cates, Carol Lefebvre, Philippa Middleton, Denise O’Connor and Lesley Stewart for their helpful comments on current and previous versions.
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