Considering Sex as a Biological Variable: In the NIH Guide

By Dr. Janine A. Clayton

dr clayton "Turning discovery into health" is NIH's mission in just a few words. This phrase captures so well the essence of what we do here in Bethesda and in the thousands of labs across the country home to NIH-funded research. Preclinical research conducted in animals is designed to pave a potential path for human studies: thus, studying both sexes is a basic principle for ensuring the relevance of findings.

That is the reason why this week's NIH Guide contains a notice announcing our expectation that beginning in fall 2016, scientists will account for the possible role of sex as a biological variable (SABV) in vertebrate animal and human studies. Pending approval from the Office of Management and Budget, the NIH Office of Extramural Research will be updating instructions for applicants as part of NIH's expectations to enhance reproducibility through rigor and transparency. (See OER's Rock Talk blog.) In short, applicants will be asked to include SABV information in the Research Strategy section of applications, and study sections will be reviewing this information.

All animal models are not the same, but studying both sexes is a guiding principle for research that bears on health for human females and human males. Our work needs to be relevant. Appropriate strategies for considering SABV will of course depend on the context of the research question at hand, but they all map back to the basic concept that biological variables like sex need to be considered from hypothesis to publication.

For researchers unfamiliar with studying both sexes in their preclinical studies, we're not asking you to "start over." Some concrete initial steps include:

Consider what is known in your area of interest — do a literature search using the terms sex and gender.
As you conduct your research, report the sexes of animals and collect/analyze sex-based data, even if your study is not powered to detect male-female differences.
Communicate your findings so others may benefit from your investigations — or, at the very least, know what has been done.
Form new hypotheses that consider the possible role of sex in physiological or pathological processes.

In 2015, we must make every research dollar count, and by studying both sexes, we can ensure that NIH funds turn discovery into health for all.