title: An e-mail survey identified unpublished studies for systematic reviews.
abstract: OBJECTIVE
  A large number of trials remain difficult to locate or unpublished for systematic reviews. The objective of this article was to determine the usefulness of making e-mail contact with authors of clinical trials and literature reviews found in MEDLINE to identify unpublished or difficult to locate Randomized Controlled Trials (RCTs).
  
  
  METHODS
  A structured search for detecting RCTs in MEDLINE was made from January 1999 to June 2003; a questionnaire was sent to a random sample of 525 author's mails. Those RCTs obtained were sought in MEDLINE, EMBASE, the Cochrane Controlled Trials Register, LILACS, and ongoing registers.
  
  
  RESULTS
  40 (7.6%) replies were received; 10 previously undescribed and unpublished RCTs and 21 unregistered ongoing RCTs were found. The most frequently given reasons for not publishing were: lack of time for finalizing the statistical analysis and preparing the manuscript, contractual obligations with the pharmaceutical industry, methodologic errors in designing, and editorial rejection.
  
  
  CONCLUSIONS
  Using the e-mails of authors detected by the search in electronic databases could contribute toward detecting potentially relevant ongoing or unpublished RCTs enabling rapid, straightforward, low-cost systematic review; in addition, the results of this study support the need of universal registration of all studies at their inception.
authors.affiliation: Colsanitas, General Practice, Edif de Consultorios Clinica Reina, Bogota, Colombia. lureveiz@colsanitas.com
authors.forename: Ludovic
authors.initials: L
authors.lastname: Reveiz
authors.forename: Andres Felipe
authors.initials: AF
authors.lastname: Cardona
authors.forename: Edgar Guillermo
authors.initials: EG
authors.lastname: Ospina
authors.forename: Sylvia
authors.initials: S
authors.lastname: de Agular
mesh_terms: D003430:Cross-Sectional Studies; D034742:Electronic Mail; D019317:Evidence-Based Medicine; D006801:Humans; D016247:Information Storage and Retrieval; D016239:MEDLINE; D011643:Publishing; D016032:Randomized Controlled Trials as Topic; D012107:Research Design