Figure One Flow Chart of a Systematic Review
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Study flow diagrams in Cochrane systematic review updates: an adjusted PRISMA flow diagram
Systematic Reviews volume three, Article number:54 (2014) Cite this commodity
Abstract
Cochrane systematic reviews are conducted and reported according to rigorous standards. A study menstruation diagram must be included in a new review, and there is clear guidance from the PRISMA statement on how to do this. Withal, for a review update, there is currently no guidance on how study menses diagrams should be presented. To address this, a working group was formed to detect a solution and produce guidance on how to utilize these diagrams in review updates.
A number of unlike options were devised for how these menses diagrams could be used in review updates, and besides in cases where multiple searches for a review or review update accept been conducted. These options were circulated to the Cochrane data specialist community for consultation and feedback. Following the consultation period, the working group refined the guidance and made the recommendation that for review updates an adapted PRISMA flow diagram should be used, which includes an additional box with the number of previously included studies feeding into the full. Where multiple searches have been conducted, the results should be added together and treated as one set up of results.
In that location is no existing guidance for using study flow diagrams in review updates. Our adapted diagram is a simple and businesslike solution for showing the menstruation of studies in review updates.
Peer Review reports
Background
A Cochrane systematic review is conducted according to rigorous methods outlined in the Cochrane Handbook [1]. The review begins with a protocol to ascertain the question, the inclusion and exclusion criteria, and the proposed methods, including a comprehensive search strategy to place relevant studies. Cochrane protocols and the completed reviews are published in the Cochrane Database of Systematic Reviews on The Cochrane Library[2]. The Methodological Expectations of Cochrane Intervention Reviews (MECIR) conduct and reporting standards [three], published in 2012, explicitly set out the criteria a Cochrane review must meet if it is to be published on The Cochrane Library. Included in these standards is the requirement that all new Cochrane reviews must include a PRISMA study flow diagram [4].
A distinguishing feature of a Cochrane review is that it is updated regularly in an endeavor to ensure that the well-nigh recent bear witness is incorporated [5]. Historically, the aim was to update Cochrane reviews every two years [6], but recently there has been a movement away from this policy in favour of prioritising the well-nigh clinically important reviews for updating [7]. In some instances a review no longer requires updating, for example if the handling is no longer current, in which case information technology is accounted to be a 'stable' review. In other cases, new trial show continues to emerge over many years, and reviews must be updated multiple times. At present, the MECIR standards only require new reviews to include a PRISMA diagram, but in practice, many author teams do try to incorporate these diagrams into review updates. The original review may already contain a PRSIMA diagram, simply generally this is not the example considering the majority of existing reviews were produced earlier the MECIR standards were published.
For a new review, utilize of the PRISMA diagram template equally shown in the PRISMA statement [4] is recommended. For a review update, the situation is more than complex every bit the diagram needs to take into account studies included when the review was first published, plus any new studies identified in the update. To our knowledge, there is not any published guidance on how to show this in a PRISMA diagram. This led us to develop an adapted diagram specifically for use in a review update.
Main text
Aims
The aim of this publication is to create guidance for using a PRISMA diagram in a review update that clearly shows the search activities performed during the entire lifecycle of a review and the decisions made on the inclusion and exclusion of studies for that update.
Process
At the 2012 annual meeting of the United Kingdom-based Cochrane information specialists, there was a discussion virtually how to incorporate report catamenia diagrams into review updates, which was prompted past an increasing number of queries from review authors who were seeking guidance on this outcome. Following the meeting, the authors of this paper, all information specialists who work with different Cochrane review groups, formed a working group to consider this topic.
At that place are a number of dissimilar situations that arise when a review is updated in relation to the included studies. The original review may already take included studies, but this is non e'er the instance. The review update may place new studies for inclusion, but every bit, it may not. Our written report flow diagram had to be able to cope with all of these situations. Multiple searches are ofttimes conducted before a review or review update is finalised, so we needed to consider how that might be shown in the diagram every bit well. With this in listen, we developed a series of period diagrams, setting out the advantages and disadvantages for each model, and circulated these to the wider Cochrane information specialist customs for consultation. The effect was raised by review authors looking to Cochrane data specialists for advice, and for that reason, nosotros decided to consult with this group.
For review updates, the following three models for a written report period diagram were presented and refined during the consultation period:
- i.
A separate PRISMA diagram for each review update, showing the search results, screening and inclusions for that update only. Generating a separate diagram for each review update is the easiest option; notwithstanding, this would result in multiple diagrams as subsequent updates are published, and would not show the total number of included studies very clearly.
- 2.
A cumulative diagram, where all search results from the original review and subsequent updates are added together in a unmarried figure. Every bit in model 1, this diagram would exist simple to generate, but it would not exist possible to identify the number of new studies that were included in each individual update.
- three.
A single diagram for the current review update, with the number of included studies from the original review or previous update included in the total. Past adding an extra box at the top of the PRISMA diagram template (Figure 1) the number of included studies from the original review or previous update, and the new studies identified for the electric current update can be conspicuously shown. Nonetheless this model does not prove the total number of references screened for the review overall.
Adapted study catamenia diagram. Study flow diagram for a review update with previous included studies incorporated into the results of an updated literature search.
Option 3 was selected past the working grouping every bit our preferred selection every bit this model best reflected the study identification process for the current review update. This option is especially useful when the search history of the original review or previous update is incomplete and does non already incorporate a study flow diagram, which is the example for many reviews due for updating at the time of writing.
The options for dealing with multiple searches for both new reviews, and review updates were similarly laid out:
- 1.
A single diagram where results from multiple searches would be added together. This is the simplest selection, summarising the searching action for the reader in the to the lowest degree complicated mode. It is not a true reflection of the searching action, in that multiple searches volition almost certainly have been conducted; even so, the dates of individual searches could be included in the diagram if desired.
- two.
A single diagram, but with the results of individual searches (for case, the initial search, search update and pre-publication search) represented in the diagram. This format would clearly prove the results of multiple searches and it would be like shooting fish in a barrel to add actress boxes for each search, simply it would complicate the diagram with the potential for a large number of extra boxes.
- 3.
A separate diagram for each search. This format will show the full screening and exclusion process for each search update; however, this could issue in a big number of figures being generated, and it would not necessarily be clear how many studies are included in total.
Option 1 was selected as our preferred option considering it shows the searching activeness in the simplest and clearest way.
Results
During the feedback period of four weeks, we received a response from vii/52 (xiii%) of the Cochrane information specialists. Overall, half dozen of the 7 responders agreed with our preferred options and the give-and-take document was afterwards revised to summarize our recommendations. While the seventh respondent agreed with the use of our adapted diagram when the search history of the original review or previous update is unclear, this respondent suggested that a review could contain both a cumulative diagram showing the overall search history of the review and a diagram for the electric current update. This would involve the publication of two diagrams and each subsequent update would crave the addition of a new diagram, which could get unwieldy. Notwithstanding, this is an thought that some Cochrane groups or individual review teams may wish to consider.
Following the consultation menses, the working grouping recommended that:
- one.
Where multiple searches take been conducted for a review or review update, the results of all searches should exist added together.
- 2.
For a review update, two extra boxes will exist added: 1 for the number of studies included in the original review or previous update and one for the new studies retrieved for the current update (Effigy 1). If multiple searches take been conducted for the current update, the results of all the searches should be added together.
These recommendations were forwarded to the Cochrane Methods Coordinator and will inform the revision of the 'Review Update' affiliate of the Cochrane Handbook. We are encouraging review authors working with our respective Review Groups to try our adapted diagram in their review updates, and we intend to disseminate this work to our colleagues in other Cochrane Groups.
Discussion
At present, the Cochrane standards only require new reviews to include PRISMA diagrams; all the same, taking a best practice approach, it is clear that this should apply to review updates as well. This paper has outlined the process undertaken by Cochrane data specialists to develop guidance for using a PRISMA diagram that can exist applied to review updates, whether in that location are previously included studies or not, together with any new included studies.
This work has been a starting time step, and there are still issues to consider. The adapted diagram does non clearly show the total number of references that take been screened over the lifetime of the review. In fact, this information may not be available, as the bulk of reviews were first written before the current standards for reporting search histories came into strength. Withal, if our recommendations are followed, the number of included studies in the previous version would exist conspicuously shown, together with the number of newly identified included studies. Each subsequent update will comprise an updated version of this diagram. The original review and any previous updates are archived on The Cochrane Library, so information technology will always exist possible to refer back to the previous diagrams if needed.
Whilst the main driver for this project was to identify a solution for documenting the flow of studies in review updates, the issue of multiple searches conducted for a review or review update proved to exist a complicating factor. We determined that the simplest and clearest way to bargain with this is to sum the results of all the private searches from one review version together and treat them as ane ready of search results, whilst acknowledging that this will not always accurately reverberate the searching activity that has taken place.
This work was conducted in response to queries from review authors working with Cochrane Review Groups. The methods we used to produce our adapted diagram were pragmatic in order to solve a problem arising in our day-to-day piece of work. We did not attempt to follow a formal method for the development of reporting guidance as this was across the scope of the time and resources available to us, and we did not consult widely outside the Cochrane information specialist community. We received a low response charge per unit from the consultation, which is a limitation of this paper; however, we promise that further work will be carried out on this important issue. An evaluation of the uptake and use of this adapted diagram, a survey of other methods used, and wider consultation with systematic review authors, editors and other interested parties would all exist valuable projects.
Conclusion
At that place is a lack of guidance on how to report the flow of studies in PRISMA diagrams for review updates. Our adapted PRISMA diagram is a simple and pragmatic solution for showing the menses of studies through a Cochrane or non-Cochrane review update. Further work should be conducted in this area to evaluate the use of this diagram and to seek feedback from a wider audition.
Abbreviations
- MECIR:
-
Methodological Expectations of Cochrane Intervention Reviews deport and reporting standards
- PRISMA:
-
Preferred Reporting Items for Systematic Reviews and Meta-Analyses.
References
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Acknowledgements
We would like to thank the Cochrane information specialists who gave us feedback on the original consultation document. We would also like to thank Dr. Emma Welsh for her comments on an early version of this manuscript. We are grateful to our peer reviewers for their valuable feedback. The National Institute for Health Enquiry (NIHR) is the largest single funder of Cochrane Review Groups in the U.k.. The views expressed in this paper are those of the authors and exercise not necessarily reflect those of our funders.
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Competing interests
ES, DB and ANS are currently employed by a Cochrane Review Grouping as data specialists. RF was previously employed by a Cochrane Review Grouping every bit an information specialist and is now employed by the Cochrane Editorial Unit, also as an information specialist.
Authors' contributions
ES convened the working grouping, contributed to the consultation certificate, collated feedback, wrote the draft manuscript, and critically revised and approved the concluding manuscript. DB participated in the working group, contributed to the consultation certificate, and critically revised and canonical the final manuscript. RF participated in the working group, contributed to the consultation document, and critically revised and approved the final manuscript. ANS participated in the working group, contributed to the consultation document, and critically revised and approved the last manuscript. All authors read and canonical the final manuscript.
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Stovold, East., Beecher, D., Foxlee, R. et al. Study flow diagrams in Cochrane systematic review updates: an adapted PRISMA flow diagram. Syst Rev iii, 54 (2014). https://doi.org/x.1186/2046-4053-3-54
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DOI : https://doi.org/10.1186/2046-4053-3-54
Keywords
- systematic reviews
- review updates
- literature searching
- written report flow diagrams
- reporting standards
- PRISMA argument
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