Request for Information (RFI): Consideration of Sex As a Biological Variable in Biomedical Research

Notice Number: NOT-OD-14-128

Key Dates
Release Date: September 11, 2014
New Response Date: October 24, 2014 per NOT-OD-15-012. (Previously October 13, 2014)

Related Announcements

Issued by
National Institutes of Health (NIH)



In a May 14, 2014, Nature commentary (see Nature. 2014 May 15;509(7500):282-3.), NIH leadership stated an intention to develop and implement policies requiring applicants to consider sex as a biological variable in the design and analysis of NIH-funded research involving animals and cells.  Although we have made major progress in achieving balance of sex in human studies — women now account for roughly half of the participants in NIH-funded clinical trials — we have not seen a similar pattern in biomedical research.  Animal studies have typically focused on males, and investigators studying cell models have often not reported the sex of the individual from which the cells were obtained.  Even if both sexes are included in a study design, resulting data may not be analyzed or disaggregated by sex. The failure to consider sex as a variable may leave critical knowledge gaps and undermine the quality and  reproducibility of research findings (see Nature. 2014 Jan 30;505 (7485):612-3).  Consideration of sex is a critical component of rigorous experimental design, just like randomization, blinding, sample-size calculations, or other basic design elements.  By developing a policy to ensure that sex is considered in NIH-funded studies, NIH will ensure that sex and sex differences are examined in all aspects of biomedical research. This will lead to a stronger foundation upon which to build clinical research and clinical trials. 

Request for Information

The NIH has formed a trans-NIH working group to inform the development of these policies. This Request for Information (RFI) seeks input from the research community and other interested stakeholders on the following topics regarding the consideration of sex as a biological variable in biomedical research. Public comment is sought for but not limited to the following:

  • Whether consideration of sex as a biological variable is an issue affecting the reproducibility, rigor, and/or generalizability of research findings. 
  • Areas of science (e.g., cancer, neuroscience) or phases of research (e.g., basic, translational) conducted with animals that have the greatest opportunity or need for considering sex as a biological variable. 
  • Areas of science or phases of research conducted with cells and/or tissues that have the greatest opportunity or need for considering sex as a biological variable. 
  • Main impediments (e.g. scientific, technical, and other) to considering sex as a biological variable in research.
  • Ways in which NIH can facilitate the consideration of sex as a biological variable in NIH-supported research.
  • Any additional comments you would like to offer to NIH about the development of policies for considering sex as a biological variable in research involving animals, tissues, or cells.  


Responses to this RFI must be submitted electronically using the web-based form at:  Please do not submit comments by other mechanisms, such as fax or email.

Responses will be accepted through October 13, 2014.

Responses to this RFI are voluntary. Please do not include any proprietary, classified, confidential, or sensitive information in your response.  The NIH will use the information submitted in response to this RFI at its discretion and will not provide comments to any responder's submission.   The collected information will be reviewed by NIH staff, may appear in reports, and may be shared publicly on an NIH website. 

The Government reserves the right to use any non-proprietary technical information in summaries of the state of the science, and any resultant solicitation(s).  The NIH may use the information gathered by this RFI to inform the development of future funding opportunity announcements.

This RFI is for information and planning purposes only and should not be construed as a solicitation or as an obligation on the part of the Federal Government, the National Institutes of Health (NIH), or individual NIH Institutes and Centers.   No basis for claims against the U.S. Government shall arise as a result of a response to this request for information or from the Government’s use of such information.


Please direct all inquiries to:

Liza Q. Bundesen, Ph.D.
Office of Extramural Research
National Institutes of Health
Telephone: 301-594-9085