Context: Determining the authorship of scientific papers can be difficult and authorship disputes are common. Less experienced authors may benefit from clear advice about authorship from journals while both authors and readers would benefit from consistent policies between journals. However, previous surveys of authors have suggested that there are no universally known or accepted criteria for determining authorship.
Objective: To review instructions to contributors from a broad sample of biomedical journals to discover how much guidance they provide about authorship and whether their advice is consistent with one another and with international guidelines.
Design: Review and analysis of published instructions to authors.
Setting: Biomedical journals that publish instructions in English on the Internet.
Methods: I examined the instructions to contributors from 234 biomedical journals (randomly selected from the membership list of the World Association of Medical Editors and from Medline).
Results: Of the 234 instructions examined, 100 (41%) gave no guidance about authorship, 68 (29%) were based on the International Committee of Medical Journal Editors' (ICMJE) criteria, 33 (14%) proposed other criteria, and 33 (14%) said nothing except that all authors should have approved the manuscript. Of those instructions that were based on the ICMJE criteria, 18/51 (35%) cited an outdated version. Only 21 of the journals (9%) required individuals' contributions to be described.
Conclusions: Journals do not provide consistent guidance about authorship and many editors are therefore missing an important opportunity to educate potential contributors and to improve the accuracy, fairness, and transparency of author listing.