The typical Cochrane review: How many trials? How many participants?

Susan Mallett, Mike Clarke

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Objectives: To describe the number of trials and participants in a typical systematic review from The Cochrane Database of Systematic Reviews. Methods: The number of trials in 1,000 Cochrane systematic reviews in issue 1, 2001 of The Cochrane Database of Systematic Reviews was counted for three categories of trial: included trials, ongoing trials, and trials awaiting assessment for inclusion. (The term trialis used in this paper, although a small number of Cochrane reviews include studies that are not trials.) The total number of participants in included trials was extracted from a sample of reviews. Results: A total of 9,778 trials were included in the Cochrane reviews. There were a further 356 ongoing trials and 1,138 trials awaiting assessment for inclusion. A typical review contained six included trials. Forty percent of the reviews listed ongoing trials and/or trials awaiting assessment for inclusion. Based on a sample of 258 reviews, the median number of participants per review was 945 (interquartile range, 313 to 2,511) per review and 118 (interquartile range, 60 to 241) per trial. Conclusion: This report is a descriptive study of the number of trials and participants in a typical Cochrane review from The Cochrane Library, issue 1, 2001.

Original languageEnglish
Pages (from-to)820-823
Number of pages4
JournalInternational Journal of Technology Assessment in Health care
Volume18
Issue number4
DOIs
Publication statusPublished - 01 Jan 2002
Externally publishedYes

Keywords

  • Cochrane Collaboration
  • Meta-analysis
  • Randomized trial
  • Systematic review

ASJC Scopus subject areas

  • Health Policy

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