Appraisal of: "Greiner B, Corcoran A, Wheeler D. Clinical trial registry searches are under-utilized in systematic reviews from critical care journals: a bibliometric analysis. J Crit Care. 2020,In Press"

Reviewer(s): 
Short description: 

Searching of clinical trial registries includes useful unpublished research and is recommended to reduce publication bias which may significantly impact the reported results of a systematic review. This study aims to analyse the use of clinical trial registries within critical care systematic reviews to demonstrate how useful their inclusion might be on result reporting.

The study examined systematic reviews from five top critical care journals listed on PubMed published from 1st January 2010 to 18th February 2020 which were then screened for clinical trial registry searching. Studies not conducting clinical trial registry searches then had searches conducted within ClinicalTrials.gov by the authors for potentially relevant trials. Of 326 systematic reviews identified, only 37 (11.3 percent) carried out trial registry searches. 25 randomly selected systematic reviews not carrying out registry trial searches, were then analysed and 56 percent of these had at least 1 potentially relevant trial identified by the researchers that the original systematic review had missed.

The authors conclude that the omission of clinical trial registry searches may have an impact on the accuracy of conclusions in critical care systematic reviews. They recommend clinical trial registry searches are conducted to reduce publication bias in systematic reviews.

Limitations stated by the author(s): 

The authors describe the following limitations of this study:

  • Some of the studies may have intentionally avoided the use of trial registries due to assumed issues around methodological evaluation of unpublished work.
  • The study authors may have not fully understood inclusion/exclusion criteria for some of the systematic reviews.
Limitations stated by the reviewer(s): 
No additional limitations detected by the reviewers.
Study Type: 
Single study
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