Disclosure of duplicative studies: damned if you don't.

Duplicative publication requires duplicative editorializing. There are many forms of lesser redundancy such as unacknowledged secondary analyses of randomized clinical trials, fragmentation of studies with concurrent submission to various journals, and serial updating of observational studies. These practices result in publication bias. We have revised our instructions to authors to include disclosure of similar articles that are published, in press, or submitted to other journals to the editors upon submission.