Non-publication and publication bias in animal research are prominent topics in current debates on the “reproducibility crisis” and “failure rates in clinical research”. To date, however, we lack reliable evidence on the extent of non-publication in animal research. In this article, Wieschowski and colleagues analysed the publication rate of 210 animal study protocols obtained from two major German UMCs (university medical centres). The authors found an overall publication rate of 67%, including doctoral theses, which was independent of the animal type (rodents vs non-rodents) or the scope of research (basic vs preclinical).
Thus, this study confirms that the non-publication of results from animal studies conducted at UMCs is relatively common. The authors concluded that the non-publication of 33% of all animal studies is problematic for the following reasons: a) the primary legitimation of animal research, which is the intended knowledge gain for the wider scientific community, b) the waste of public resources, c) the unnecessary repetition of animal studies, and d) incomplete and potentially biased preclinical evidence for decision making on launching early human trials.
It is also possible that selective publication contributes to the the Chrysalis effect that was described before by O’Boyle and colleagues as the doubling of the ratio of supported to unsupported hypotheses from dissertations to journal articles.

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