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Related Experiment Videos

An e-mail survey identified unpublished studies for systematic reviews.

Ludovic Reveiz1, Andres Felipe Cardona, Edgar Guillermo Ospina

  • 1Colsanitas, General Practice, Edif de Consultorios Clinica Reina, Bogota, Colombia. lureveiz@colsanitas.com

Journal of Clinical Epidemiology
|June 13, 2006
PubMed
Summary

Contacting authors via email is an effective method for identifying unpublished or hard-to-find randomized controlled trials (RCTs). This approach aids systematic reviews by uncovering valuable research data.

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Area of Science:

  • Clinical Research
  • Evidence-Based Medicine
  • Systematic Reviews

Background:

  • Many clinical trials remain unpublished or difficult to locate, posing challenges for systematic reviews.
  • Identifying all relevant studies is crucial for comprehensive and accurate systematic reviews.

Purpose of the Study:

  • To assess the utility of contacting authors via email to find unpublished or hard-to-locate randomized controlled trials (RCTs).
  • To improve the completeness of systematic reviews by identifying previously inaccessible trial data.

Main Methods:

  • A structured search of MEDLINE identified authors of clinical trials and literature reviews (1999-2003).
  • Email questionnaires were sent to a random sample of 525 authors.
  • Searched databases included MEDLINE, EMBASE, Cochrane Controlled Trials Register, LILACS, and ongoing trial registers.

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Main Results:

  • 40 (7.6%) author responses were received.
  • 10 previously unpublished RCTs and 21 unregistered ongoing RCTs were identified.
  • Common reasons for non-publication included time constraints, industry obligations, methodological flaws, and editorial rejection.

Conclusions:

  • Email contact with authors is a valuable, low-cost method for discovering unpublished or ongoing RCTs for systematic reviews.
  • The findings underscore the importance of universal study registration at inception to enhance research transparency and accessibility.