Women’s Health and Clinical Trials

Thumbnail Health CareBiological differences between women and men sometimes lead drugs, diseases, and treatments to affect them differently. Women make up over half the U.S. population; so why don’t we know more about how they respond to medical treatments? Today’s WatchBlog explores what we found when we looked at women in clinical trials.

The difference between men and women

For years, women weren’t routinely included in clinical research. Until at least the 1980s, treatment protocols didn’t take into account biological differences between men and women.

This matters because some drugs affect women differently than men—sometimes with dangerous effects. You might recall a popular sleep drug making news when FDA lowered the recommended dose for women. The earlier recommended dosage had been based on the drug’s effect in men and was too much for women—putting them at risk of driving while impaired the following day.

It’s not just treatments that differ. Symptoms of cardiovascular disease, lung cancer, depression, and Alzheimer’s disease can all appear differently in women.

When women aren’t included in clinical research, the studies can’t identify potential differences in treatment effects, so health care providers may not have important information for treating women.

Enrolling women

The good news is that more women are enrolled in clinical studies funded by the National Institutes of Health. This is important because NIH is the largest source of public funds for clinical research.

In fact, in each of the past 10 years, more women than men were enrolled in all NIH-funded clinical studies, including phase III trials, the largest trials that most directly affect patient care.

GAO-16-13(Excerpted from GAO-16-13)

Depends what you’re looking for

Having more women in clinical trials is great—if those trials look for differences between men and women. Yet NIH doesn’t know how many trials are explicitly looking for such differences.

So, even with more women in trials, it’s unclear whether this improvement will result in researchers identifying more key differences between men and women, and ultimately, better clinical outcomes for women.

We made 5 recommendations to improve NIH’s oversight of women in clinical trials and NIH plans to take actions to implement them all.


  • Questions on the content of this post? Contact Linda Kohn at kohnl@gao.gov.
  • Comments on GAO’s WatchBlog? Contact blog@gao.gov.
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