1. List of Methodological Limitations (Pollock, 2017)
Development of workable solutions to overcome known limitations of Overview Methodology
Broderick J11, Irving C22, Shokraneh F22, Ostinelli EG3, Walshe M1, Mockler D1, Adams C22
1 Trinity College Dublin, University of Dublin, Ireland, 2 University of Nottingham, UK,  3Department of Health Sciences, Università degli Studi di Milano, Italy
Proposed solution
List of Methodological
Limitations (Pollock, 2017)
Include other evidence in absence of updated Cochrane review. Highest form of evidence in hierarchy (Fig. 1) to be included in overview.
1. Is the overview to be limited to Cochrane reviews?
Conduct wider electronic database search, search strategy for each form of evidence has been developed
2. Is the search strategy to be limited to databases of reviews?
Quality assess each and include review scoring highest in quality assessment (AMSTAR as per point 5 below)
3. What action will be taken if there are overlapping reviews?
Consider new primary studies generated from evidence search, if necessary conduct and harmonize subsidiary reviews
4. What action will be taken if included reviews are out of date?
Appears to be most evidence for AMSTAR so this would be the tool of choice
5. What tool will be used to assess the quality of included reviews?
Accept GRADE conducted a priori in Cochrane reviews, apply GRADE to other included reviews, no quality assessment for other forms of evidence
6. How will the quality of evidence within reviews be assessed?
Present overall effect estimates without statistical analysis, only consider network meta-analytic methodology when pre-defined criteria met
7. Is there any statistical analysis to be carried out, using the data extracted from the reviews?
New ways to combine data visually using infographic style where possible have been suggested
8. How will the evidence be brought together into an accessible summary?
BACKROUND
Overviews are a relatively new form of evidence synthesis.
Even though great strides have been made in terms of overview development, a lack of consensus pertains to key methodological areas.
We propose workable solutions to these and other known limitations of overview methodology.
OBJECTIVE
To generate workable solutions to known limitations of overview methodology. 
METHODS
Eight pre-determined methodological limitations or challenges (Pollock, 2017) of overview methodology were used as a focus for this work.
Sensible, workable solutions for each were proposed from a systematic literature search pertaining to overview methodology and sound reasoning based on the hands-on experience of conducting an overview.
RESULTS
6. Other forms of evidence relevant to review e.g. within grey literature
5. Controlled trials
4. Randomized controlled trials
3. Non-systematic or narrative reviews
2. Non-Cochrane reviews
1. Cochrane reviews
Fig. 1
This work has generated criteria that will aid in the decision-making process around when to progress towards a network meta-analysis versus an overview. We have discussed how harmonization of subsidiary reviews may need to take place before an overview can be undertaken. Our work outlines how Cochrane systematic reviews can be included preferentially, but have suggested how lower hierarchical forms of evidence can be searched and presented for hypothesis formation and identification of evidence gaps to produce a true 'bird's-eye' view of the topic area (Fig. 1). We have developed a search strategy to source all hierarchical forms of evidence
CONCLUSION
Overview methodology lacks consistency.
We have developed workable solutions which will be tested
through the 'hands on' experience of conducting an overview
(Yoga for Schizophrenia Overview).
We hope some solutions may be applied generically to future
overviews, or, at the very least, may stimulate discussion
around standardization of overview methodology. 
References:
Pollock A, Campbell P, Brunton G, Hunt H, Estcourt L. Selecting and implementing overview methods: implications from five exemplar overviews, Syst Rev 2017, Jul 18;6(1):14