[Duplicate publication of articles in the Dutch Journal of Medicine in 1996]

To determine the number of undisclosed/disclosed duplicate publications of original articles (OA) in the Nederlands Tijdschrift voor Geneeskunde (NTvG).

Retrospective bibliometric study.

All biomedical articles published in January 1994-June 1998 and written by the first or second author of the 148 OA published in 1996, were compared with the articles in the NTvG at the editorial office of the NTvG. Resemblances in the objective, study design, study population between the different articles were observed. The researchers assessed whether the same article had been published twice or more and whether this was acceptable or redundant (according to the criteria of the International Committee of Medical Journal Editors).

In 1996 the NTvG published 30 (20%) OA which were also published elsewhere. In 23 cases (77%) the article was first published in another scientific journal and in 7 cases (23%) the article was published once again after its appearance in the NTvG. In 20 duplicate articles in the NTvG a footnote with a reference to the first publication was present. In 10 duplicate articles no such footnote could be found. In comparison with a similar study of the years 1990-1992 the number of duplicate publications was the same but the fraction of correctly disclosed duplicate publications had risen from 5/23 (22%) to 16/22 (73%) (p < 0.001).