When cheaper and easier isn’t better

“By not studying sex differences, researchers could be missing out on potential new treatments for both men and women”,  says Rhonda Voskuhl.  Finally, Science Magazine is speaking our language!  I felt like I was reviewing talking points from one of my own presentations when reading the NewsFocus article titled, “Of Mice and Women: The Bias in Animal Models”  http://www.sciencemag.org/cgi/content/full/327/5973/1571.  Unfortunately, it is no surprise to us at the Institute for Women’s Health Research that basic scientists are not designing studies that include both male and female animal models.  One reason our Institute was established was to break down this barrier by providing funding to the NU research community to design studies with sex and gender in mind, in addition to stressing the importance of analyzing results based on sex.

You might be asking, it’s 2010, why would researchers only study one sex?  Cost and ease.  It’s cheaper to house less animals in a research facility, the NIH may not provide enough funds to conduct studies in both sexes, researchers don’t want to deal with the estrous cycle (which in rodents is every 4 days) and the data is “cleaner” because the hormones responsible for the estrous cycle DUE effect biology.

A few important points this article highlights:

  • The vast majority of journal articles published in 2009 reported results of research in male animals only.
  • Many articles fail to report the sex of subjects at all.
  • In studies that include both males and females, 2/3 fail to analyze the results based on sex.

The results from animal studies in basic science laboratories are what help determine the design of clinical research studies in humans.  If we don’t include female animals from the start, then male-only data is what gets transferred into the clinical arena.  Then, there is the issue of recruiting equal numbers of men and women into clinical trials.  If trials are predominantly made up of male participants then once again, the results that get published and become the foundation for drug and medical device development are applicable in men, but may not (and often times do not) apply to women.

What suggestions are provided in the article?

  • If the NIH set guidelines to channel limited resources to areas that show clear sex differences such as cardiovascular disease or pain, researchers would have to include both sexes in order to get money.
  • Mining NIH data from large patient trials could help identify sex differences in people that would be worth studying in animals.
  • The Office for Research on Women’s Health could provide targeted funding opportunities.
  • Pressure from academic journals to adopt a set of guidelines for studies using animals, including the expectation to provide rationale for studying only one sex and the implications for not studying the other, could force authors go back to the drawing board.

We hope that articles similar to this will continue to be published in high impact journals and finally “get scientists thinking about the issue of sex bias” and its implications for how we practice medicine today.