UNC Health Care
unequal sign between male figure and female figure

It’s a Man’s World, and It’s Taking a Toll on Women’s Health

In medical research, there’s a persistent and problematic tendency to underrepresent women, says Melina Kibbe, MD, chair of the UNC Department of Surgery (and the first woman to hold that role).

Dr. Kibbe sifts through medical studies and trials looking at female involvement from beginning to end. She notes whether a man or woman led the study, if female or male cells and animals were tested, and how many women were recruited for clinical trials.

Her work shows that the lack of focus on women and female subjects is hurting women’s care and inhibiting medical breakthroughs. We asked her to walk us through this important topic.

What is sex bias in research?

In research, sex bias is when one sex is dominant in a given study or trial. In biomedical research, males make up the majority of study authors and study participants.

When we’re doing research to develop new drugs or new therapies for patients, roughly 80 percent of those studies are done or conducted in male animals or male cells.

Why is that a problem? Or rather, why do females need to be included in research?

Men’s and women’s bodies are different down to their cells. Male cells have XY chromosomes and female cells have XX chromosomes, which means they are made up of different DNA and function differently. Since most research starts out at the cellular level, only testing cells from males will never allow researchers to know how it works on cells from females. That sex imbalance only continues as research advances to animals and people.

The presence of estrogen in female bodies also causes women to react differently than men to medicine, treatments and procedures. The fact that men and women can experience different results from the same surgery or treatment is exactly why females should be equally represented throughout the research process.

If females aren’t substantially included from the beginning of the process, we’re not going to know how these drugs react in women.

How does this affect women?

One of the most startling facts that I’ve learned in my years of advocating on this topic is that the majority of drugs pulled from the market by the FDA (Food and Drug Administration) are removed because of adverse reactions in women. One high-profile example of a drug with an adverse reaction in women is the sleeping pill Ambien. After a string of women on Ambien were involved in car crashes, researchers learned the recommended dosage on the labels was much too high for women. The FDA changed the label.

There are so many differences between the sexes when it comes to how they respond to disease, how they metabolize drugs and how they respond to surgery. There are lots of factors that we just don’t know about yet. If we don’t study sex differences, we won’t know. If we don’t know, women could continue to have adverse reactions to medications and poor outcomes after surgery.

What does your research show?

My research has shown that 80 percent of the investigators doing surgical biomedical research were studying male-only cells or animals. We analyzed thousands of peer-reviewed research articles in our studies and found less than a third analyzed the data by sex, and less than a quarter included a discussion of sex-based results. Less than 10 percent of the articles included an equal number of men and women.

We have learned some promising information through our analysis as well. We’ve found that articles authored by women included proportionally more female participants in their studies compared with articles authored by men. Also, studies that discussed data by sex or those that had an equal number of men and women participants were discussed and cited more in the scientific community. These more inclusive studies achieved greater prominence.

What can women do to help?

You can start with your own health care. If your doctor wants to put you on a new medication, ask him or her if that medicine has been studied in women and do your own research. (FDA’s For Women site is a good start.)

If you want to get more involved, you can sign up for a clinical trial. If more women are willing to participate in these studies, then we can have more inclusive and accurate results, which will lead to better outcomes for clinical trials in general.

You can also get political. The Research for All Act was first introduced in Congress in 2015 and has been stuck in committee since then. It would amend the Public Health Service Act to enhance the consideration of sex differences in basic and clinical research. Call your local Congress members and express your support for the bill.


Are you interested in participating in a clinical trial? Healthy volunteers are needed, too. Learn more by visiting Join the Conquest and signing up for the clinical trials registry.