US studies on risky heart devices are skewed towards men and do not include enough women to accurately judge how they may affect the genders differently, researchers have said.
The under-representation of women is concerning because heart disease affects women in different ways than men, said lead author Rita Redberg of the University of California, San Francisco.
“Women in general have more procedural complications, so they tend to have more adverse events. Women tend to bleed more than men do, so we see more bleeding complications,” she said.
Women also tend to be an average of 10 years older than men when they get heart disease, and multiple studies have shown that risks and benefits from various devices and treatments are not the same in men and women, she added.
The US Food and Drug Administration in 1994 decided that anyone seeking approval for a new device, such as a heart valve or defibrillator, must explain in their submission whether the study subjects reflect the real-life proportion of men and women who have the condition being treated.
They must also discuss differences in how safe and effective the device was for women compared to men.
Despite this policy, Ms Redberg found that 28 per cent of studies did not report the gender of the participants at all, and among those that did, men made up an average of 67 per cent of the trial.
The required statement on gender and the general population was also missing from 59 per cent of studies. Among the 41 per cent that included it, only 26 per cent reported how the device affected men differently than women.
Ms Redberg’s research examined 123 pre-market approval studies for 78 high-risk cardiovascular devices which were approved by the FDA between 2000 and 2007.
“We found no encouraging trends,” Ms Redberg said. “Failure to include women in clinical trials has been a big problem for a long time and it isn’t improving, so further action is needed.”
The study, co-authored by Sanket Dhruva and Lisa Bero, is published in the journal Circulation: Cardiovascular Quality and Outcomes.
It notes that Ms Redberg is a member of the FDA Circulatory System Devices Panel, “but her comments are independent and don’t necessarily reflect the views of the panel or the FDA”.
The FDA said it “is aware of the under-representation of women in clinical trials, an issue which is not isolated to FDA trials,” said a statement.
The reasons are “complex” and may include “less willingness on the part of both women and their physicians to participate in investigational studies and invasive procedures,” the FDA said.