Different patterns of duplicate publication: an analysis of articles used in systematic reviews

Ref ID 517
First Author E. von Elm
Journal JAMA
Year Of Publishing 2004
URL https://jamanetwork.com/journals/jama/articlepdf/198260/joc31171.pdf
Keywords Transparency
Problem(s) Data extraction errors and double counting
Number of systematic reviews included 141
Summary of Findings Authors of 40% of 141 systematic reviews acknowledged identification of duplicates. Data from 60 articles were published twice, data from 13 articles were published three times, data from 3 article were published four times, and data from 2 articles were published five times. 63% of the duplicates had no cross-reference at all, indicating a high level of covert duplication.
Did the article find that the problem(s) led to qualitative changes in interpretation of the results? Not Applicable
Are the methods of the article described in enough detail to replicate the study? No