Publication bias and clinical trials

K. Dickersin, S. Chan, T. C. Chalmersx, H. S. Sacks, H. Smith

Research output: Contribution to journalArticlepeer-review

488 Scopus citations


A study was performed to evaluate the extent to which the medical literature may be misleading as a result of selective publication of randomized clinical trials (RCTs) with results showing a statistically significant treatment effect. Three hundred eighteen authors of published trials were asked whether they had participated in any unpublished RCTs. The 156 respondents reported 271 unpublished and 1041 published trials. Of the 178 completed unpublished RCTs with a trend specified, 26 (14%) favored the new therapy compared to 423 of 767 (55%) published reports (p < 0.001). For trials that were completed but not published, the major reasons for nonpublication were "negative" results and lack of interest. From the data provided, it appears that non-publication was primarily a result of failure to write up and submit the trial results rather than rejection of submitted manuscripts. The results of this study imply the existence of a publication bias of importance both to meta-analysis and the interpretation of statistically significant positive trials.

Original languageEnglish (US)
Pages (from-to)343-353
Number of pages11
JournalControlled clinical trials
Issue number4
StatePublished - Dec 1987
Externally publishedYes


  • meta-analysis
  • publication bias
  • randomized clinical trials

ASJC Scopus subject areas

  • Pharmacology


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