Research Methods & Reporting

A multicomponent decision tool for prioritising the updating of systematic reviews

BMJ 2013; 347 doi: (Published 13 December 2013) Cite this as: BMJ 2013;347:f7191
  1. Yemisi Takwoingi, research fellow1,
  2. Sally Hopewell, senior research fellow23,
  3. David Tovey, editor in chief of the Cochrane Library4,
  4. Alex J Sutton, professor of medical statistics5
  1. 1Public Health, Epidemiology and Biostatistics, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
  2. 2Centre for Statistics in Medicine, University of Oxford, Oxford, UK
  3. 3INSERM, U738, Paris, France
  4. 4Cochrane Editorial Unit, London, UK
  5. 5Department of Health Sciences, University of Leicester, Leicester, UK
  1. Correspondence to: Y Takwoingi y.takwoingi{at}
  • Accepted 18 October 2013

There is no formal consensus on when to update a systematic review, and updating too frequently can be an inefficient use of resources and introduce bias. A multicomponent tool could help researchers decide when is best to update such reviews

Evidence evolves as new research becomes available, and thus systematic reviews should be kept up to date to maintain their relevance and validity. However, the decision to update a systematic review should be made carefully because updating is potentially resource intensive, and updating too soon could introduce bias.1 In contrast, if reviews are not updated frequently enough, doctors and policy makers could act on evidence that is out of date. There is currently no consensus on when to initiate updating.2

Traditionally, the Cochrane Collaboration used a biennial updating policy,3 yet many Cochrane reviews are out of date (fig 1); only about 20% of reviews are updated every two years. As of February 2013, the Cochrane Database of Systematic Reviews, published in the Cochrane Library, contained 5418 reviews.4 This number implies that 2700 Cochrane reviews will need to be updated per year to comply with the updating policy, in addition to producing new reviews. Despite the emphasis on Cochrane reviews in this paper, updating is a common challenge, and methods are needed to prioritise reviews that are most in need of updating.

Fig 1 Number of active and updated reviews published in the Cochrane Library from 1995 to 2012. Active reviews are the total number of published reviews excluding reviews that have been withdrawn. Therefore, it is expected that these reviews will be considered for updating within two years of the last date of publication

A methodological review of different methods for identifying when to update a systematic review found that existing methods were …

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