Intended for healthcare professionals

Research Methods & Reporting

A guide to prospective meta-analysis

BMJ 2019; 367 doi: (Published 09 October 2019) Cite this as: BMJ 2019;367:l5342
  1. Anna Lene Seidler, research fellow1,
  2. Kylie E Hunter, senior project officer1,
  3. Saskia Cheyne, senior evidence analyst1,
  4. Davina Ghersi, senior principal research scientist, adjunct professor12,
  5. Jesse A Berlin, vice president, global head of epidemiology3,
  6. Lisa Askie, professor and director of systematic reviews and health technology assessment, manager of the Australian New Zealand Clinical Trials Registry1
  1. 1NHMRC Clinical Trials Centre, University of Sydney, Locked bag 77, Camperdown NSW 1450, Australia
  2. 2National Health and Medical Research Council, Canberra, Australia
  3. 3Johnson & Johnson, Titusville, NJ, USA
  1. Correspondence to: A L Seidler lene.seidler{at}
  • Accepted 8 August 2019

In a prospective meta-analysis (PMA), study selection criteria, hypotheses, and analyses are specified before the results of the studies related to the PMA research question are known, reducing many of the problems associated with a traditional (retrospective) meta-analysis. PMAs have many advantages: they can help reduce research waste and bias, and they are adaptive, efficient, and collaborative. Despite an increase in the number of health research articles labelled as PMAs, the methodology remains rare, novel, and often misunderstood. This paper provides detailed guidance on how to address the key elements for conducting a high quality PMA with a case study to illustrate each step.

Summary points

  • In a prospective meta-analysis (PMA), studies are identified and determined to be eligible for inclusion before the results of the studies related to the PMA research question are known

  • PMAs are applicable to high priority research questions where limited previous evidence exists and where new studies are expected to emerge

  • Compared with standard systematic review and meta-analysis protocols, key adaptations should be made to a PMA protocol, including search methods to identify planned and ongoing studies, details of studies that have already been identified for inclusion, core outcomes to be measured by all studies, collaboration management, and publication policy

  • A systematic search for planned and ongoing studies should precede a PMA, including a search of clinical trial registries and medical literature databases, and contacting relevant stakeholders in the specialty

  • PMAs are ideally conducted by a collaboration or consortium, including a central steering and data analysis committee, and representatives from each individual study

  • Usually PMAs collect individual participant data, but PMAs of aggregate data are also possible. PMAs can include interventional or observational studies

  • PMAs can enable harmonised collection of core outcomes, which can be particularly useful for rare but important outcomes, such as adverse side effects …

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