Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation
BMJ 2015; 349 doi: https://doi.org/10.1136/bmj.g7647 (Published 02 January 2015) Cite this as: BMJ 2015;349:g7647
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Dear Catherine,
Thank you for your comment on PRISMA-P. I wanted to offer a few clarifiications.
To address your first point, unlike typical reporting guidelines, as a guideline for protocols, PRISMA-P is indeed intended to be prescriptive. By their nature, protocols are a prescriptive document, developed by reviewers to guide themselves and contributors through the specific methods and decisions of the review process
To address your second point about the rigidity of PRISMA-P for dealing with amendments, throughout PRISMA-P there is explicit mention that unanticipated changes made during the review process should simply be documented. At no point is it stated in PRISMA-P that changes to methods should not be made. In fact, we explicitly acknowledge that changes can and will occur. Checklist item 4 discusses how to document, or at the very least plan for, protocol amendments in detail. We simply ask that authors be transparent about what was planned before the review started versus what was done. In fairness to readers, making this distinction will help them make their own assessments about potential biases in the review process.
Competing interests: No competing interests
I read this article with interest as most of my work is the conduct and management of systematic reviews. Development of protocols for these are vital in order to focus the review and ensure it is conducted properly. However, I feel that some of the items suggested in the PRISMA-P list of required items are overly prescriptive and would not be able to be pre-specified in real world practice.
For example, Item 13 requires that the reviewer lists and defines all outcomes for which data will be sought. Although at the start of a review, there will be a list of outcomes you seek, you will not know until you look at included studies whether those outcomes will in fact be reported. For example, you might want to know about length of hospital stay in days, but if the included studies do not report that, you may have to report something similar instead, such as proportion discharged within 7 days. This happens all the time in systematic reviews. Researchers could end up with overly long lists of outcome measures to be recorded in the protocol. When the included papers are examined to see what they actually have reported, experienced reviewers would make a pragmatic decision, along with their clinical colleagues, about which of the reported outcomes would be most useful in practice. If you find that during the systematic review conduct, some of the included studies report a useful outcome that was unexpected at the time of writing the protocol, would you be expected to ignore this outcome as it wasn't in the protocol?
Similar issues can occur around exact methods used for meta-analysis or meta-regression. An extension of this difficulty around pre-specification would be during submission of the systematic review for publication. If peer reviewers ask for additional outcomes to be reported, or additional analyses to be conducted, should the reviewers respond that they should not conduct these because these were not pre-specified? It seems a little far fetched. Perhaps it would be better if some leeway was given, in PRISMA-P because of these types of issues?
Competing interests: No competing interests
ETHICS IN (PRISMA-P) 2015: elaboration and explanation
Very nice and useful article. As far as I can see, there are no ethics aspects within items in PRISMA-P.
Should it be of value to obtain a positive report from an Ethics Committee before performing the systematic review or it is just an unnecessary step?
Thanks for such a wonderful paper.
Carlos
Competing interests: No competing interests