A new report shows women are still underrepresented in clinical trials despite guidelines and laws requiring better representation set down 30 years ago.
The findings come from the American College of Cardiology Cardiovascular Disease in Women Committee and are published in the Journal of the American College of Cardiology.
They show that since recommendations to increase the number of women in clinical trials were made in the National Institutes of Health Revitalization Act of 1993, the percentage of women included in cardiovascular disease trials remains between 26-36% depending on the specific indication.
Although these numbers have increased over the last few decades, they are not high enough considering that cardiovascular disease is the number one killer of women and that symptoms and drug responses can be different in women compared with men.
“For example, a recent study documented that in heart failure, women obtained optimal benefit from 50% of the goal dose of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and beta-blockers, whereas men obtained optimal benefit from 100% of the goal dose,” write the report authors. “In addition, women were more likely to have side effects at the same doses.”
Some cardiovascular diseases do affect men more than women, and vice versa, but it is possible to correct for that using the participation prevalence ratio, a measure accounting for the sex-specific prevalence of a specific condition being treated in a trial. A measure of 0.8-1.2 shows good representation of women. Trials of congestive heart failure, coronary artery disease and acute coronary syndrome showed trials of treatments for these conditions had particularly low representation of women with average scores of 0.5-0.6, whereas women were better represented in trials studying hypertension and atrial fibrillation.
“Historically, drug therapies for women were determined based on male data that was extrapolated to women,” said Leslie Cho, lead author of the study, a member of the committee, and director of the Women’s Cardiovascular Center and section head of preventive cardiology and cardiac rehabilitation at Cleveland Clinic.
“However, research has shown that women respond differently than men and may even be harmed or experience side effects from some drugs when taken at the same dosage as men. Sex-specific data is essential to optimal care.”
The report authors recommend several steps to improve participation of women in cardiovascular trials. To start with, employing more women in cardiovascular clinical trial leadership should increase the number of women enrolled into trials in this area, as women-led trials tend to recruit more women. Currently less than 10% of first authors or senior authors of clinical trials in this area are women.
Better referrals to cardiologists and specialty programs, as well as greater recruitment of older women into trials would also help, as cardiovascular disease tends to impact women at an older age than men. Also making sure clinicians and researchers are well informed about sex differences in cardiovascular disease presentation.
Improving outreach to all women, particularly those in minority groups, and providing better information about trial participation should also help improve representation. More pregnant and women ‘of child-bearing potential’ should also be included in clinical trials as not enough information is known about how drugs impact this group.
The committee also suggests finding out more information about why women drop out of trials to try and minimize this happening in the future.
“Participation of women in cardiovascular disease drug and device clinical trials remains suboptimal and limits progress of both the development and adoption of new therapies among women,” conclude the authors.
“To address barriers to recruitment and retention of women in CVD clinical trials, a comprehensive and targeted approach that involves partnership with all stakeholders—patients, referring clinicians, research teams (investigators and coordinators), health care systems, the FDA, payers, sponsors, professional, and community organizations—is essential.”