Background: Moher et al  examined a November 2004 MEDLINE-indexed sample of 300 systematic reviews (SRs) and found that reporting quality was variable. The SR landscape has changed considerably in the subsequent decade, with the publication of a reporting guideline for SRs of randomised trials of health care interventions (PRISMA), methodological developments such as the Cochrane risk of bias tool, and the proliferation of new avenues to disseminate SRs. We considered it timely to evaluate a more recent cross-sectional sample.
Objective: To investigate the epidemiological and reporting characteristics of SRs.
Methods: We searched MEDLINE to identify potentially eligible SRs indexed in February 2014. Citations were screened using pre-specified eligibility criteria. We developed a standardised, pilot-tested data extraction form comprising all items used in , along with additional items to capture issues not previously examined. Example items include focus of the SR (e.g. therapeutic, diagnostic), number of included studies, and reporting of eligibility criteria, search strategy, and statistical analyses. Data in 300 SRs will be independently extracted by one of several reviewers, with a 10% random sample extracted in duplicate. We will compare characteristics of i) Cochrane versus non-Cochrane reviews, and ii) the current versus 2004 sample of SRs.
Results: We identified 698 SRs indexed in February 2014. This suggests an annual publication rate of approximately 8300 SRs (equivalent to 23 SRs per day), which is more than triple the estimated rate in 2004. Cochrane Reviews comprised only 14% of the sample. Reporting characteristics will be presented at the Colloquium.
Conclusion: This study will provide up-to-date data on the different types of SRs being published (e.g. therapeutic, diagnostic, prognostic) and the reporting quality of SRs. The findings will indicate where methodological and reporting guidance for SRs is most needed, and will inform the SR methodology research agenda.
1. Moher D, Tetzlaff J, Tricco AC, Sampson M, Altman DG. Epidemiology and reporting characteristics of systematic reviews. PLoS Medicine 2007;4(3):e78.