Peer Reviewer Bias Pressures Researchers to Perform Animal Experiments and Delays Adoption of Powerful Nonanimal Approaches

Catharine E. Krebs, PhD, director of medical research at the Physicians Committee for Responsible Medicine, has been leading the way to shine a light on this issue. Known as "animal methods bias," this phenomenon is the focus of her team’s recent research, which documents evidence of this bias in scientific publishing and identifies strategies to mitigate it

Animal methods bias occurs when research is unfairly evaluated because it doesn't include animal experiments. To better understand this issue, Krebs's team conducted a survey of 189 researchers who use nonanimal methods. Half of the respondents reported being asked by peer reviewers to add animal experiments to their nonanimal studies. Most of the time they refused the suggestion but still experienced negative consequences, such as publishing in lower-impact journals, manuscript rejection, and publication delays. Perhaps most surprisingly, one-fifth of respondents admitted to conducting animal experiments they didn't think were necessary, solely in anticipation of reviewer demands.

To corroborate these personal accounts, the team analyzed more than 1.1 million publications from 2009 to 2023, confirming that studies using animals were published at higher rates and in journals with higher impact factors than purely in vitro studies.

Animal methods bias penalizes researchers using nonanimal methods and pushes them to conduct unnecessary animal experiments just to secure publication. And because it disincentivizes nonanimal methods use, it impacts the entire research ecosystem by limiting the dissemination of important findings and the ability of other scientists to learn about nonanimal approaches, ultimately slowing the adoption of these powerful tools. As governments around the world increasingly shift research policies and funding toward human-based approaches to improve clinical translation and reduce animal use, animal methods bias must be addressed.

Krebs leads the Coalition to Illuminate and Address Animal Methods Bias (COLAAB), which works with stakeholders across research, publishing, and government to promote bias mitigation. Among the actions the COLAAB recommends is for research institutions to de-emphasize journal impact factor and other metrics, which have been shown to poorly represent research quality and to bias research evaluations.

The COLAAB also recommends that journal editors actively intervene when reviewers request animal experiments. As a result of the group's outreach, two journals recently updated their policies to more explicitly encourage nonanimal submissions and discourage reviewer requests for animal experiments.

Researchers interested in learning how they can navigate peer review hurdles can consult the COLAAB's Author Guide for Addressing Animal Methods Bias in Publishing