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Dear Mohammad and EBHC list,
We recently published an article with some suggestions on when a (systematic) scoping review may be preferred over a traditional systematic review.
Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach
https://bmcmedresmethodol.biomedcentral.com/articles/10.1186/s12874-018-0611-x
We have also previously proposed a typology for systematic reviews here:
What kind of systematic review should I conduct? A proposed typology and guidance for systematic reviewers in the medical and health sciences
https://bmcmedresmethodol.biomedcentral.com/articles/10.1186/s12874-017-0468-4
Both of these articles discuss when you might consider doing a systematic review and what type of review may be best for a particular question. I
hope you find them useful. As always, if there is any feedback or suggestions on the ideas presented in these papers we would appreciate your comments.
Kind Regards,
Zac
Assoc Prof Zachary Munn
Director Transfer Science
Director JBI Adelaide
GRADE Centre
Joanna Briggs Institute
Faculty of Health and Medical Sciences
The University of Adelaide, SA 5005, AUSTRALIA
T: +61 8 8313 3642
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From: Evidence based health (EBH) <[log in to unmask]>
On Behalf Of Kev Hopayian
Sent: Saturday, 12 January 2019 11:12 PM
To: [log in to unmask]
Subject: Re: My question about Indications and Contraindications for conducting Systematic Reviews
Dear Dr Mohammad,
I am not sure about the question. If we think of a systematic review as a synthesis of available research findings, then why would we not
want a synthesis?
On the other hand, there are certain situations in which some types of analysis are inappropriate. The one I can think of is over the issue of whether to pool results or not. Meta-analysis, which pools results, is not appropriate in certain
situations
You can find a manual (free to download) at https://www.york.ac.uk/media/crd/Systematic_Reviews.pdf. but the paragraph relevant state:
"Many systematic reviews evaluating the effects of health interventions focus on evidence from RCTs, the results of
which, generally, can be combined quantitatively. However, not all health care questions can be addressed by RCTs, and systematic reviews do not automatically involve statistical pooling. Meta-analysis is not always possible or sensible. For example, pooling
results obtained from diverse non-randomised study types is not recommended.120
Similarly, meta-analysis of poor quality studies could be seriously misleading as errors or biases in individual studies would be compounded and the very act of synthesis may give credence
to poor quality studies. However, when used appropriately, meta-analysis has the advantage of being explicit in the way that data from individual studies are combined, and is a powerful tool for combining study findings, helping avoid misinterpretation and
allowing meaningful conclusions to be drawn across studies.The planned approach should be decided at the outset of the review, depending on the type of question posed and the type of studies that are likely to be available."
So there are times that the alternative synthesis should be used, what is called a narrative synthesis. I hate the term but that is another matter.
Hope that helps!
Kev
Prof. Kev (Kevork) Hopayian,
MD FRCGP
Clinical Professor, University of Nicosia, Cyprus
RCGP [INT] Educational Consultant
Sessional GP, Suffolk