Sex matters: Closing the gender gap in research and medicine
Association President Stacey E. Rosen, MD, calls on the stroke community to turn sex-based science into meaningful gains for women’s health.
For decades, cardiovascular and cerebrovascular medicine operated under a simple but deeply flawed assumption: Hearts functioned the same regardless of sex. In her Presidential Address, Stacey E. Rosen, MD, FAHA, challenged that history head-on, arguing that true equity in medicine begins with a foundational question the field can no longer afford to ignore: How does sex matter?
“In the fall of 1992, at a hospital in New York City, two babies were born, around the same time on the same day,” she said. “One of those babies was a girl. The other was a boy.” Though separated by a single chromosome, she noted, their biological sex placed them on “vastly different paths with respect to our understanding of their cardiovascular and cerebrovascular health.”
For much of modern medicine, that difference went unexamined. Up until approximately the time those children were born, it was believed that human hearts were human hearts, Rosen said, describing a male-centric research model in which findings from men were assumed to apply universally. That approach persisted until the mid-1980s, when advances in treatment finally led to lower cardiac mortality — but only in men.
Data showing that more women than men were dying of heart disease marked a turning point. “This wake-up call sparked a series of important initiatives,” Rosen said, setting the stage for a gradual but meaningful shift in how sex is considered in research and care.
Rosen framed that progress through the lifespan of the two children born in 1992 — her own children, Rebecca and Max. “They were in grade school when the Institute of Medicine report ‘Does Sex Matter?’ came to the resounding conclusion that it does!” she said. As the children grew into teens and young adults, researchers began asking not only whether sex differences exist, but how those differences should inform prevention, diagnosis and treatment.
“Now they are 33 years old,” she said. “Should either develop health problems, science is prepared to deliver care that is more precise because it will be more appropriate to their biologic sex.”
That evolution did not happen quickly — or easily. While preparing her remarks, Rosen said she posed a simple question to leaders across cardiology: Why had a male-centric model been accepted for so long? “The answer I heard time and again: ‘We didn’t think it mattered.’ Isn’t that wild?” she said.
Rosen acknowledged that neurology has long recognized sex differences in stroke incidence, prevalence and risk-factor potency. “That’s great — such a head start,” she said. Still, she emphasized that awareness alone is not enough. There is still room for improvement. “It all starts with asking the question, ‘How does sex matter?’”
She highlighted three areas in which answering that question could significantly improve outcomes for women. The first is hypertension, the most common modifiable risk factor for both heart disease and stroke. Women, she noted, experience a faster age-related rise in blood pressure, and stroke risk becomes significant at lower thresholds than in men. Citing the REGARDS study, Rosen said the association between increasing hypertension severity and ischemic stroke was almost twice as large in women compared with men.
“These epidemiological facts must lead us to a deeper understanding of biological mechanisms,” she said, pointing to the need for more data and the potential for sex-specific treatment recommendations across a woman’s lifespan.
Her second focus: atrial fibrillation. While men have a greater lifetime risk of AFib, women with the condition face higher stroke rates and all-cause mortality. By asking how sex matters, researchers have uncovered differences in left atrial structure, fibrosis patterns and electrophysiologic disruption. “We have learned that obesity in women results in a more prothrombotic profile in women than men,” Rosen said, underscoring the need to refine risk assessment tools and explore the influence of sex hormones and chromosomes.
The third — and, she argued, most impactful — area is the underrepresentation of women in clinical trials.
“The only way to know how sex matters is by studying each sex,” she said. Despite progress, women account for only 40% of participants in stroke trials globally, and just 36% of randomized controlled trials report results by sex. “If you don’t disaggregate the data by sex, you’re missing a critical opportunity to identify differences,” she said.
Rosen stressed that better representation won’t happen by accident. It requires intentional trial design and patient-centered strategies to ensure meaningful inclusion.
“The next wave of progress is making the question ‘How does sex matter?’ a foundational question in everything we do,” she said.
