For decades, researchers have tried to enroll more women in clinical trials so research into drugs and medical treatments reflects sex differences and detects possible risks of newly developed cures.
Using federal data covering over 1,400 device and drug trials and more than 300,000 participants between 2016 and 2019, researchers looked into each trial’s representation of female participants. They found concerning gaps in research related to three of the most important areas: cardiovascular disease, psychiatric disorders and cancer.
The researchers chose those diseases because of their effects on women. Cardiovascular disease and cancer are the top two leading causes of death of American women, and psychiatric disorders disproportionately affect, and disable, females.
In each area, the number of female participants fell short of the percentage of females affected by those diseases and disorders. While women make up 50.8 percent of the U.S. populace, only 41.2 percent of the clinical trial participants were female. Forty-nine percent of people with cardiovascular disease are women, yet only 41.9 percent of participants in cardiovascular research are female. Although 51 percent of cancer patients are female, only 41 percent of cancer trial patients are female.
The starkest difference, however, was in the number of female participants in clinical trials related to mental health. Sixty percent of people with psychiatric disorders are women, but just 42 percent of participants in trials for psychiatric drugs were female.
Although the study looked at biological sex, the researchers say it is important to look at gender identity in future research. The researchers also said trial participant recruitment methods should be examined further.
Including women in clinical research isn’t just a friendly nod to gender parity — it is the law. Since 1993, federally funded drug trials and other clinical research have required female participants and must also determine whether the treatment being tested affects females differently than males.
“The rise of female participants in clinical trials is certainly promising, but our work is not complete,” said Primavera A. Spagnolo, scientific director of Brigham and Women’s Hospital’s Connors Center for Women’s Health and Gender Biology and a co-author of the study, in a statement. “We simply cannot rest.”