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Women are still under-represented in medical research

Written by: Stacey Colino
Published on: Dec 9, 2024

Women unrepresented in medicine
Photo Credit: Flamingo Images - stock.adobe.co

 

Historically, medical research has been male-dominated in terms of subjects as well as researchers, even though women make up half of the world’s population. As a result of this gender bias, insights into various diseases and findings about medications have often been extrapolated from men and applied to women. But women aren’t just smaller men. Women’s bodies are decidedly different from men’s, with unique organs, genes, hormones, and other key differences.

It’s not surprising, then, that men and women experience many of the same diseases but develop different symptoms. With heart attacks, for example, the most common symptom is chest pain for men and women—but women may be more likely to experience other symptoms, such as shortness of breath, nausea or vomiting, or jaw pain. Women and men also metabolize and respond to many drugs differently. And there are gender-based variations in the physiological mechanisms underlying pain.

Some of these differences have been revealed through research that features gender parity. But many basic questions remain about how different health conditions and responses to drugs, vaccines, and other interventions are influenced by biological sex. “Within the last 10 years, there has been major progress on sex-informed research,” says Dr. Hadine Joffe, executive director of the Mary Horrigan Connors Center for Women’s Health and Gender Biology at Brigham and Women’s Hospital and a professor of psychiatry in the field of women’s health at Harvard Medical School. But “it’s a mixed story because there’s still such a long way to go.” 

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Still, progress is being made. In March of 2024, a major advance occurred when President Joe Biden signed an executive order for the White House Initiative on Advancing Women’s Health Research and Innovation with the goal of “getting women the answers they need about their health” and providing greater funding for this research. This follows the passage of a 1993 law, mandating the inclusion of women in human clinical trials for all research funded by the National Institutes of Health. That was a big step in the right direction, but the same standard didn’t apply to animal studies—and a gender gap persists in non-human research, too. In a study in a 2017 issue of the journal ENeuro, researchers reviewed 6,636 research articles in six journals and found that while sex omission in studies using mice or rats declined from 2010 to 2014, sex bias persists, as more articles focus exclusively on males.

On the upside, Joffe points to the National Institutes of Health (NIH) initiative Sex as a Biological Variable (SABV), which launched in 2016: It spells out the expectation that when researchers are seeking funding from the NIH for studies with animals and humans, they will factor sex into their research design, data analysis, and reporting of results. This is a tremendous development in principle but it doesn’t always play out the way it could or should. “Sometimes people don’t follow through on it because this is complicated research to do,” Joffe says. The gap may be even wider for women of color, research suggests. 

In general, “women are still under-represented in research—female representation isn’t proportionate to the burden of disease in many clinical trials,” says Dr. Jecca Steinberg, a maternal-fetal medicine fellow at Northwestern University Medical School in Chicago. In a study published in a 2021 issue of JAMA Network Open, Steinberg and colleagues reviewed female participation in 20,020 clinical trials that had more than five million participants: They found that clinical trials in oncology, neurology, immunology, and nephrology had the lowest female representation relative to the burden of disease in women.

The findings in that study aren’t a fluke. In a 2022 study in Contemporary Clinical Trials, researchers evaluated the enrollment of female participants in 1,433 clinical trials of drugs and devices in the U.S. between 2016 and 2019. Of the 302,664 participants, on average 41% were female; this was true in cardiovascular disease and cancer. In psychiatry, the gap was even greater: While women comprise 60% of people with psychiatric disorders, the mean participation of women in psychiatric clinical trials was 42%.

These days, “many investigators are reluctant to emphasize sex differences in their research because of the emotional turmoil surrounding the evolving complexity of what gender means and what sex means,” says Dr. Marianne J. Legato, emerita professor of clinical medicine at Columbia University and founder and director of the Foundation for Gender Specific Medicine. “It’s one of the elephants in the room of why gender-based research or male-female differences are not being more courageously investigated.” 

The issues of gender self-identification and gender fluidity are compounding these challenges. “It’s an extraordinarily and emotionally fraught topic,” Legato says.

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