Clarifications on new NIH requirement to consider sex as a biological variable

This past summer, we reported on a new NIH policy that goes into effect Jan. 25, 2016, requiring a deliberate approach to the consideration of sex as a biological variable (SAVB) in pre-clinical research.

In a Dec. 11 Open Mike blog post, Deputy Director for Extramural Research Michael Lauer, Ph.D., clarified the application and review process and provided additional information on the origins of the policy. A current high-priority focus at NIH is improved rigor and transparency in federally funded biomedical research–and accurate, detailed reporting of experimental conditions, including  consideration of sex, is a key component of responsible practices to that end. By including sex in experimental design, researchers enhance the scientific knowledge base for future studies and help prevent unnecessary and costly duplication of experiments.

NIH has heard many concerns about this policy, including the perception that researchers now need to double the number of animals used or reduce project aims to adjust for additional costs. Some are wondering if all experiments now must be powered for both sexes. Not so, according to Lauer. Considering SABV is not the same as looking for sex differences.

He cites a recent article by Dr. Janine Clayton, Director of the NIH Office of Research on Women’s Health, that dispels some of the misconceptions surrounding the policy and lays out exactly what it is not. Clayton makes it clear that NIH will not require any specific research design or method in its efforts to enhance reproducibility and transparency. Rather, each project and the state of knowledge in a particular research area will determine how the investigator considers SABV. The overarching goal is to add to this knowledge base in order to learn even more about how sex affects human biology beyond reproduction. This concept applies to detecting differences across a wide range of biological variables including age, environmental conditions, and genetics.

Clayton’s article provides a contextual summary of studying both sexes and outlines specific strategies and experimental design approaches to help investigators address this new policy without slowing ongoing research. A graphic included in her article summarizes consideration of SABV at each stage of investigation:


From Studying both sexes: a guiding principle for biomedicine by Janine Clayton, The FASEB Journal article fj.15-279554
From “Studying both sexes: a guiding principle for biomedicine,” by Janine Clayton; The FASEB Journal article fj.15-279554

Still confused? Check out NIH’s guidance or ask questions here.