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Table 1 Forming an overview question and defining the type and objective of an overview

From: An introduction to overviews of reviews: planning a relevant research question and objective for an overview

Focus of question Question about the effect of intervention(s) Question about diagnostic test accuracy Question about prognosis/prevelence Questions about disease aetiology or risk factors Question about qualitative views or experiences
Population Is the focus on one discrete population, or bringing together evedence from different populations?
Intervention/phenomenon of interest Is the focus on one specific intervention or a range of different possible interventions? Is the focus on one single medical test or a range of different medical tests? Is the focus on overall prognosis, prognostic factors or risk prediction (prognostic models)? Is the focus on associations between disease indices and risk factors, or the impact of risk factors on single/multiple outcomes? Is the focus on qualitative aspects of an intervention, such as views or experiences of a particular group of people?
Outcome Is the focus on one specific outcome (including adverse events) or a range of different outcomes?
Context/setting Describe the context of setting of interest
Type of review Review of RCTs Review of intervention studies Reviews of diagnostic test accuracy studies Review of prognosis/prevalence Reviews of associated risk factors Review of qualitative studies
Type of overview Overview of intervention reviews Overview of diagnostic test accuracy reviews Overview of reviews of prognostic studies Overview of reviews of risk factors Overview of qualitative reviews
Overview objective To summarise evidence from more than one systematic review of different interventions for the same condition or problem; OR To summarise evidence from more than one systematic review of diagnostic test accuracy assessing the same medical test to address the same condition of problem; OR To summarise evidence about prognosis/prevalence from more than one systematic reviews. To summarise systematic review evidence about risk factors not directly aligned to predictive values. To summarise systematic review evidence relating to qualitative views or experiences.
  To summarise evidence from more than one systematic review of the same intervention for the same condition of problem where different outcomes are addressed in different systematic reviews; OR To summarise evidence from more than one systematic review of diagnostic test accuracy assessing different medical tests to address the same condition or problem.    
  To summarise evidence from more than one systematic review of the same intervention for different conditions, problems or populations; OR     
  To summarise evidence about adverse effects of an intervention from more than one systematic review of use of the intervention for one or more conditions.     
  1. Adapted from Becker LA, Oxman AD. Chapter 22: Overviews of reviews. In: Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions. Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from http://training.cochrane.org/handbook and Deeks JJ, Bossuyt PM, Gatsonis C (editors), Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy Version 0.9. The Cochrane Collaboration, 2013. Available from: http://methods.cochrane.org/sdt/handbook-dta-reviews