Mars vs. Venus: Gender bias in health?

It’s no secret that men and women view the world differently. One bestselling book summed it up like this: “Men are from Mars, Women are from Venus.” Actually, we’re all from Earth, but we’re not all coming from the same place, especially when it comes to medical care.

Researchers at Stanford University demonstrated this in a massive, eye-opening study published a few years ago. They combed through pain ratings from more than 72,000 patients in the Stanford hospital system and found that, for nearly every condition, women reported more-intense pain than men.

Answering an age-old question

“This was probably the largest pain research study ever done,” said Atul Butte, MD, PhD, lead author of the 2012 study.

The researchers first eliminated all conditions — such as pregnancy — that only affect one gender. For nearly every other condition and disease that was left, women reported higher pain scores than men, Dr. Butte said. On average, women’s pain reports were a full point higher on the standard 10-point pain rating scale.

“To put that in perspective, many drug companies use a drop of one point on the pain scale as a successful outcome when they’re testing new pain medicines,” Dr. Butte said.

“But the women were already one point higher than the men.”

“This really is an age-old question: How do men and women differ?” said Dr. Butte, who has since moved to the University of California, San Francisco, where he is director of the Institute for Computational Health Sciences and professor of pediatrics.

There are many possible reasons for this difference, including men underreporting pain in the presence of nurses, who are often female, he says.

Big data, big results

A pain rating scale based on lab tests instead of patient reports would be very beneficial, both in patient care and in research studies, Dr. Butte said.

He is now extending his pain studies on an even larger scale. Using de-identified data from patients at all five University of California medical schools, he plans to examine information from about 13 million people, or about 4 percent of the entire United States population.

In addition to further insights on the differences between men and women, “we’re searching for a biomarker for pain — any blood tests that best match those pain ratings,” Dr. Butte said.

In early findings, the researchers have some evidence that uric acid levels correlate with pain. His research team is investigating further.

One finding that can already be put into practice, Dr. Butte said, is that “stronger efforts should be made to recruit women subjects in population and clinical studies in order to find out why this gender difference exists.”

Same pain, different response?

“Women do report pain more frequently and at a higher level than men, and they are more likely to request pain medication than men,” said Peter A. McCullough, MD, MPH, a cardiologist at the Baylor Heart and Vascular Institute and a physician on the medical staff at Baylor University Medical Center at Dallas.

“They also appear to be treated less than men.”

This is a complex issue, Dr. McCullough points out.

“There are really three components to any pain, and each makes up a third of the problem,” he said.

“On average, women have more doctor’s visits. But the published information suggests that their problems are not taken as seriously by their physicians — particularly chest pain,” Dr. McCullough said.

“One is the physical source of discomfort itself. The next component is how the brain processes that pain signal. And the last is the psychological response.”

The chances are, “the physical stimulus is the same in men and women,” Dr. McCullough said.

“The difference lies in how the brain processes that stimulus and the psychological response to it.”

Different sizes, different doses

Aside from the obvious differences in reproductive organs and reproductive hormones, “the heart, lung, kidneys, intestines and other organs are anatomically similar between women and men,” Dr. McCullough said.

In general, women are shorter, weigh less and have smaller muscle mass than men, he adds.

These variations in body size can mean that men and women do not react in the same way to identical doses of a drug. In 2013, for example, the U.S. Food and Drug Administration responded to widespread reports of increased side effects among women taking Ambien and other sleep aids, cutting the recommended dose for women in half.

“The majority of pills come in a range of sizes, but the majority are not weight-adjusted,” Dr. McCullough said.

Because women generally weigh less than men, “it’s really no surprise that women would require less of a drug like Ambien. You can see the same thing in anxiety medications, cold medications and so on.”

Women and heart disease

Although men and women have anatomically similar hearts, “a woman’s heart is generally smaller, and so are the arteries coming from the heart,” Dr. McCullough said.

That has important treatment implications.

A major study funded by the National Institutes of Health, known as the WISE (Women’s Ischemia Syndrome Evaluation) study, found that millions of women with coronary heart disease don’t build up major cholesterol plaques, as most men do.

Instead, these women “get more microvascular disease,” Dr. McCullough said.

“The big arteries are fine, in other words, but the small blood vessels get clogged with cholesterol and that reduces blood flow.”

Anatomical differences can explain why women who undergo heart bypass surgery tend to have more complications than men, Dr. McCullough said.

It could also help to explain the results of a 2014 study, published in the British Medical Journal, in which researchers found that women are twice as likely as men to die in the weeks immediately after suffering a heart attack.

However, with newer, more sensitive blood tests, these signs of heart trouble are now more likely to be diagnosed. One such test, ultra-sensitive troponin, “is just a better blood test for a protein released in the heart,” Dr. McCullough said.

These tests have shown that the rates of heart attacks in men and women are very similar, Dr. McCullough said.

“Now we are more successful at finding these heart problems in women.”

Are women treated differently?

Women in general tend to seek more health care than men, Dr. McCullough said.

Unfortunately, that doesn’t mean they get more care. “On average, women have more doctor’s visits. But the published information suggests that their problems are not taken as seriously by their physicians — particularly chest pain,” he said.

Studies have shown that female physicians are just as likely to take women’s complaints less seriously as their male counterparts, Dr. McCullough said.

“The biases we see are no different between men and women doctors in how they approach female patients.”

One interesting angle of investigation, Dr. McCullough said, is gender bias in research studies.

“More than 90 percent of research workers and coordinators are women,” Dr. McCullough said.

“These are the people responsible for recruiting patients into research studies, and the majority of people recruited into research studies are men.” Understanding the reasons why recruiting coordinators seem to be biased against women — and correcting that imbalance — are essential, he said.

As of yet, gender-based research hasn’t really “yielded new medications and treatments,” Dr. McCullough said.

“By and large we approach the same problems in the same way. I don’t think gender research holds the hope for dramatically different treatment decisions. But it is very important. Otherwise you get a sense of frustration. Women have a sense that they are not as well understood as men. More research is needed to address that.”

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For more information on heart attack signs in women, visit the American Heart Association at heart.org and search for “Heart Attack Symptoms in Women.”