title: Epidemiology and reporting characteristics of overviews of reviews of healthcare interventions published 2012-2016: protocol for a systematic review.
abstract: Overviews of systematic reviews (overviews) attempt to systematically retrieve and summarize the results of multiple systematic reviews (SRs) for a given condition or public health problem. Two prior descriptive analyses of overviews found substantial variation in the methodological approaches used in overviews, and deficiencies in reporting of key methodological steps. Since then, new methods have been developed so it is timely to update the prior descriptive analyses. The objectives are to: (1) investigate the epidemiological, descriptive, and reporting characteristics of a random sample of 100 overviews published from 2012 to 2016 and (2) compare these recently published overviews (2012-2016) to those published prior to 2012 (based on the prior descriptive analyses).
  
  
  
  Medline, EMBASE, and CDSR will be searched for overviews published 2012-2016, using a validated search filter for overviews. Only overviews written in English will be included. All titles and abstracts will be screened by one review author; those deemed not relevant will be verified by a second person for exclusion. Full-texts will be assessed for inclusion by two reviewers independently. Of those deemed relevant, a random sample of 100 overviews will be selected for inclusion. Data extraction will be either performed by one reviewer with verification by a second reviewer or by one reviewer only depending on the complexity of the item. Discrepancies at any stage will be resolved by consensus or consulting a third person. Data will be extracted on the epidemiological, descriptive, and reporting characteristics of each overview. Data will be analyzed descriptively. When data are available for both time points (up to 2011 vs. 2012-2016), we will compare characteristics by calculating risk ratios or applying the Mann-Whitney test.
  
  
  
  Overviews are becoming increasingly valuable evidence syntheses, and the number of published overviews is increasing. However, former analyses found limitations in the conduct and reporting of overviews. This update of a recent sample of overviews will inform whether this has changed, while also identifying areas for further improvement.
  
  
  
  The review will not be registered in PROSPERO as it does not meet the eligibility criterion of dealing with health-related outcomes.
authors.affiliation: Institute for Research in Operative Medicine, Witten/Herdecke University, Ostmerheimer Str. 200, Building 38, 51109, Cologne, Germany. dawid.pieper@uni-wh.de.
authors.forename: Dawid
authors.initials: D
authors.lastname: Pieper
authors.affiliation: Alberta Research Centre for Health Evidence, Department of Pediatrics, University of Alberta, Edmonton, Canada.
authors.forename: Michelle
authors.initials: M
authors.lastname: Pollock
authors.affiliation: Clinical Pharmacology Unit, Instituto de Medicina Molecular, University of Lisbon, Lisbon, Portugal.|Department of Pediatrics, Santa Maria Hospital, Lisbon, Portugal.
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Fernandes
authors.affiliation: Institute for Quality and Efficiency in Health Care (IQWiG), Cologne, Germany.
authors.forename: Roland Brian
authors.initials: RB
authors.lastname: Büchter
authors.affiliation: Alberta Research Centre for Health Evidence, Department of Pediatrics, University of Alberta, Edmonton, Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Hartling
mesh_terms: D003627:Data Interpretation, Statistical; D006801:Humans; D015203:Reproducibility of Results; D000078202:Systematic Reviews as Topic
keywords: Evidence synthesis; Evidence-based medicine; Knowledge synthesis; Overview of reviews; Review methods; Systematic reviews; Umbrella review