Trying to determine how best to treat a patient, doctors often look to randomized clinical trials to guide their choice of what drug to prescribe. One of the most common illnesses is heart disease, and in recent years it's been proven that, contrary to popular belief, more women have heart problems than men do; similarly, it's more common for older people to have a heart condition than younger people. But do clinical trials reflect this reality?
Apparently not. According to a new study published in Circulation: Cardiovascular Quality and Outcomes by Quoc Dinh Nguyen, a professor at Université de Montreal's Faculty of Medicine, researchers continue to test new heart drugs mostly on men (71 per cent), even though the majority of people affected by heart disease are women. Moreover, the male subjects have an average age of 63, when in fact the average age of people with the two most common heart diseases is between 68 to 69.
In the last 20 years, the sex-and-age gap in drug trials has barely diminished, even though the population is ageing rapidly, said Nguyen, a geriatrician at the Centre Hospitalier de l'Université de Montréal (University of Montreal Hospital Center).
"This under-representation of women and older people in clinical trials could have adverse consequences on care for both of these patient groups. The body of an older person doesn't respond to many treatments and medications like that of a younger person. The correct dosage or intervention are often different for older patients and so, too, are the side effects, but we can't know the specifics unless clinical trials are performed on a significant number of older people. This is also true for women."
"The current lack of representation means that physicians have to apply findings based on a male dominant and younger population without being sure that these results should be extrapolated to women or older people in general."
Nguyen decided to look into the issue while still a resident in geriatric medicine, prompted by discussions with colleagues and the concern they shared about effective treatment of heart disease. Resident physicians in other fields such as anaesthesiology, psychiatry, emergency medicine and cardiology joined him in the effort.
A closer look
Already, 20 years ago, researchers had begun to raise the alarm that the under-representation of many segments of the population, especially women, in clinical trials was problematic. "Our research team wanted to know whether practices had significantly improved since then," Nguyen said.
To find out, his team of residents took a close look at the 25 most frequently cited (i.e. most influential) clinical trials for each year in the 20-year period from 1996 to 2015. They compared the age and sex of participants to data published in the U.S. National Health and Nutrition Examination Survey 2015-2016 on the prevalence of cardiovascular disease in America.
The research team examined data on coronary artery disease, atrial fibrillation, heart failure and hypertension, along with cardiovascular risk factors. It also looked at diabetes, since people with that disease are two to four times more likely to suffer from heart disease as well.
Disappointing results
"Our research team was disappointed to see that, although the situation has improved slightly, it will still take decades to eliminate representational bias in clinical trials," said Eric Peters, an anaesthesiologist at CHU Saint-Justine children's hospital who is the new study's second author. "Based on our calculations, it'll be another 90 years before parity is achieved in studies on coronary heart disease. And that's before we factor in population-ageing, which is accelerating."
In the 500 clinical studies they analyzed, the team found that women represented a median of only 29 per cent of participants and that the average age of participants was only 63. "This is nowhere near the reality of what we see in hospital emergency rooms and departments of internal medicine, cardiology and geriatric medicine," said Nguyen.
Women and older people were least represented in clinical trials for coronary artery disease (CAD) and heart failure, the study shows. Although 54.6 per...
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