Last fall the National Institutes of Health announced it has given out roughly $10 million in research funding aimed at correcting gender imbalance in medical research. It's not the gender gap among the researchers themselves that's at stake here, rather a bias toward conducting research with male cell lines, lab animals and study subjects. Janine Austin Clayton, M.D., associate director for women’s health research at the National Institutes of Health, co-authored a paper in the journal Nature pointing out that even in the earliest stages of research, lab studies tend to use more male cells than female--and that can lead to gaps in our understanding of how the two sexes develop illness and how they respond to treatments. Here, Dr. Clayton discusses the goal of the NIH's supplemental funding program and the flaws of a male-biased approach to research.
Sound Medicine: What type of gender bias exists in pre-clinical studies?
Janine Austin Clayton: [In the past] looking for differences between male and female cells or even male and female animals has not been considered in research—and that leaves gaps in our knowledge. We don't know as much about female cells and female animals. The good news is we can fill those gaps. And where we are today is that we know is that sex is a fundamental variable in biomedical research that must really be considered from the very start.
SM: Why would it make a difference whether a cell was female or male?
JAC: Because of scientific advances we now know that every single cell in your body has a sex. So for men every cell is XY or male, and for woman every cell is XX--[including] your lung cells, your liver cells, and your kidney cells. And when we look at the actual biochemical reactions and biology of those cells, we see significant differences in many traits that could be of clinical importance.
SM: In past researchers generally chose male cells--why the preferences?
JAC: There was misperception that the female hormone cycle would cause undue variability in experiments and mask the results, so it was an attempt to control everything except what you were testing. We now know that in fact, females are not intrinsically more variable than males for many traits that we study and in fact for many of them males are more variable than females. In some ways it was a blind spot. Scientists were not aware that the sex of the animals made a difference. Because we know more now--we can examine the inside of cells in ways we could never do before--we know now those differences between and XX and a XY cell can be scientifically important and biologically important, but most significantly can be clinically important.
SM: What problems is the NIH trying solve with the supplemental funding when it comes to clinical trials?
JAC: All NIH clinical research must include women and minorities. But every study doesn't necessarily have enough women or enough men to answer all the questions. For example does treatment X work equally in men and women? So sometimes we need to increase the total number of subjects to be sure that our finding is true for men and women. We know that's really important. When you go to the doctor you want to know the drugs you're prescribing have been tested in both men and women and that it's the right dose for me.
SM: How underrepresented are girls and women in clinical trials and what are the benefits of representing them equally?
JAC: In NIH funded research, which is only a portion of research that's done, over 50 percent of participants are women or girls. But in some areas, other entities like pharmaceutical companies and other funders fund research as well and that data may be different. When we do include women and look at the data from females and males separately, we learn new things. We learn that aspirin has different effects in men and women, for instance. It helps prevent heart attacks in men; it helps prevent stroke in women. So we've got a lot to learn when we study both sexes. We think science is better with both sexes and by studying males and females we learn to best deliver the patient-centered care that Americans need.
SM: Is it difficult or costly to add women to trials?
JAC: This is an investment in the health of the nation and researchers are in the best position to design experiments that take sex into account. And we have to think about the other costs. the costs of patients going misdiagnosed, the costs of treatments not working, the cost of failed clinical trials. this is about doing the best science and getting the most complete and accurate data that we need. And right now we can do better.