Gender equality in clinical research – are we already there?

One would think that gender equality in medical research has been a reality for a long time, right? Let's have a look at the facts.

Is the fact that women are still underrepresented in clinical research a cause for concern? Or does it make no difference? The evidence suggests that every female needs to be concerned.

Jill Becker, a senior research scientist at the University of Michigan, explained in a New York Times article: “One of the underlying assumptions has been that females are simply a variation on a theme […] that if you’ve learned about the male you’ve learned enough to deal with both males and females.” However, we know this is not always the case. In fact, women often react differently than men to the same drug.1

A study from 2001 reported that female patients have a 1.5 to 1.7-fold greater risk of developing adverse drug reactions than men. According to the authors the reasons for this increased risk included gender-related differences in pharmacokinetics as well as immunological and hormonal factors.2 It is known that psychotropic drugs like painkillers or antidepressants have gender-specific effects. Anticonvulsants might be less effective in young women because a liver enzyme, responsible for metabolizing these drugs, is especially active in this group.3 On the other hand, other drugs might have a stronger or longer lasting effect in women. For example, in 2013 the FDA recommended that women should reduce their dose of a particular sleeping pill, as it takes them longer to eliminate the substance from their bodies.4

In order to completely close the gender-gap in medical innovation, there is still a need for education for all stakeholders, from researchers in the lab to those who design late-stage clinical trials.

Despite these differences, women continue to be underrepresented in clinical trials. One reason offered by some investigators is that men are cheaper and easier to study as the female estrus cycle has to be considered in the study design; moreover, there is the fear that inclusion of women of childbearing age might endanger potential unborn children.5 Although action should be taken to avoid any complications, women can’t be excluded from clinical trials for these reasons anymore.

To address the underrepresentation, the US National Institutes of Health (NIH) established the Office of Research on Women’s Health (ORWH) in 1990. Since 1993 all NIH-founded clinical research projects are required to include women in representative numbers.6 In the European Union, the Clinical Trials Regulation states that a clinical trial has to represent the population groups that are likely to use the investigated product.7 However, despite these legislative guidelines, women continue to be underrepresented, especially in early phases of experimental drug studies.8

The gender gap differs between disease areas. In some fields it has already closed, but in others it is still a big issue and is inadequate to ensure that evidence-based sex-specific recommendations can be made.9 As reported in the Journal of Women’s Health, in the US almost half of the study participants in post-approval studies for medical devices for ear, nose and throat conditions were female. However, in cardiovascular studies only 32% were women.10 A European study came to the same conclusion and also found that approximately half of the trials did not report an analysis of the results by gender. The reason for this might be the misconception that cardiovascular disease is a male disease, although it is also a leading cause of death in women.11

The need for inclusion doesn’t just start at the clinical trial phase. In pre-clinical research, scientists often prefer single-sex studies with only male cell lines or animals because they reduce variability and make it easier to detect the effect being studied.12 As well as putting women at risk, insufficient representation of female cells and animals in experiments and inadequate analysis of data by sex may contribute to the observed rise of irreproducibility in pre-clinical biomedical research.6 Adding female cell lines and animals to experiments requires the whole study to be scaled up in order to maintain statistically representative numbers for each sex, which implies higher costs for the research teams. To address this, in 2014 the NIH announced that they would provide 10.1 million USD in grants to more than 80 scientists to ensure that sufficient women are included in their clinical trials, that the early pre-clinical research is representative of both genders and that gender differences are analyzed in the resulting data.

In clinical as well as pre-clinical research, things are moving in the right direction. However, in order to completely close the gender-gap in medical innovation, there is still a need for education for all stakeholders, from researchers in the lab to those who design late-stage clinical trials.

What is the situation in your field of expertise? Are women adequately represented? We would be happy to hear about your experience! Follow this link and join the discussion.



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