Overviews are a relatively new phenomenon borne out of the need to combine a number of systematic reviews for clinical decision making and policy development. Even though great strides have been made in overview methodology, considerable heterogeneity pertains to this form of evidence synthesis. For example, when to conduct a network meta-analysis versus an overview, decisions around selection criteria and assessment of quality of evidence. We propose workable solutions to these and other known limitations of overview methodology.
To generate workable solutions to known limitations of overview methodology.
We identified known limitations to overview methodology via an extensive search of literature pertaining to overview methodology and from hands-on experience of conducting an overview. Sensible, workable solutions have been proposed to methodological challenges of overviews that currently lack consensus, based on best evidence and application of sound reasoning.
We propose criteria that will aid in the decision-making process around the grey area of when to conduct 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 (Table 1).
Overview methodology lacks consistency. We have developed workable solutions which will be tested through the 'hands on' experience of conducting an 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.
Patient or healthcare consumer involvement:
There was healthcare consumer involvement in the production of subsidiary reviews to populate an overview which is currently under production. This overview is informing the development of generic methods outlined in this abstract.