Not including enough women in stroke trials could be impacting their treatment

A comprehensive review of clinical trials in stroke over the last 30 years shows women are under-represented, making it harder to interpret what the findings really mean for them. The research, published in the latest issue of Neurology®, the medical journal of the American Academy of Neurology, found that more than three quarters of the trials enrolled less women than the expected proportion that experience stroke in the community.

Lead author Dr Cheryl Carcel from The George Institute for Global Health and a Heart Foundation Fellow, said that while both women and men had the same one-in-four risk of experiencing a stroke in their lifetime, women were much older and in worse health at the time they have a stroke.

“These findings have implications for how women with stroke may be treated in the future, as women typically have worse functional outcomes after stroke and require more supportive care,” said Dr Carcel.

While there have been studies showing varying degrees of representation of women in cardiovascular trials, this issue has only recently started to be examined in relation to stroke trials.

George Institute researchers looked at 281 stroke trials that had at least 100 participants and were conducted between 1990 and 2020. The total number of participants was 588,887, of whom 37.4 percent were women, but the average prevalence of stroke in women across the countries included was 48 percent. The greatest differences were seen in trials involving a particular type of stroke known as intracerebral haemorrhage, those where the mean age of participants was less than 70 years, post-stroke supportive care and rehabilitation trials.

Dr Carcel said that the reasons for this under-representation were complex and most likely due to a number of factors, including recruitment criteria that unintentionally exclude women like age and having other health conditions.

“Patient attitudes and beliefs can also be a factor, and there can even be a potential bias among the clinical staff conducting the study,” she said. “Our previous research indicated that how women were treated in hospital and whether they had been on the right medications before their stroke, could be responsible for their poorer outcomes.”

Co-author Dr Katie Harris said that barriers and facilitators to women’s participation in stroke trials needed to be explored both at the trial and patient level to help redress the balance.

“Achieving a better gender representation in stroke trials can provide a more reliable assessment of the treatment benefits and harms, and inform treatment guideline recommendations for women affected by this serious condition,” she said.

While the United States, Canada and some European countries adopted policies to boost the number of women in clinical trials over the course of the study, the results showed no change over this time.

“Our study suggests those efforts have clearly not translated into action,” Dr Harris added. “It’s now time to put policy into practice so that future research can address our knowledge gaps in the understanding and treatment of stroke in women.”

The Heart Foundation’s Director of Heart Health Strategy, Julie Anne Mitchell, said it was concerning to see the Asia-Pacific region fairing worse than Europe in this study.

“There is clearly still more to do before women are properly represented in clinical trials on stroke and other cardiovascular diseases,” she said. “Women share common risk factors with men, such as high cholesterol and blood pressure, but they also have sex-specific risk factors, including pregnancy-related conditions such as pre-eclampsia and gestational diabetes. We need to understand more about all of these risk factors so we can improve prevention and treatment options for women.

“Equal access to life saving treatments for all Australians remains a priority for the Heart Foundation, and we’re pleased to support research like this.”