Different Strokes for Different Folks: Assessing Risk in Women

You may have noticed that men and women are different. I hope you have noticed. As the French say, vive la différence! It’s not just that one has dangly bits and the other has bumpy chests. Or that one has to shave a beard and doesn’t like to ask for directions while the other has menstrual periods and likes to discuss feelings. There are differences in physiology and in the incidence of various diseases. For instance, normal lab values for hemoglobin are higher for men than for women, and autism is more prevalent in males while multiple sclerosis is more prevalent in females.

In the past, women have been underrepresented in clinical studies; when the first studies of aspirin for cardiovascular prevention came out, we knew it was effective for men, but we didn’t have enough evidence to recommend it for women. This is changing; researchers today are more aware of the need to include women in their studies. Now the American Heart Association/American Stroke Association (AHA/ASA) has issued the first evidence-based guidelines for reducing the risk of stroke in women.

Previous guidelines were for all adults, without specifying any differences by sex. Interestingly, those guidelines said stroke was more prevalent in men than in women, directly contradicting what the new guidelines for women say. They say the lifetime risk of stroke in women is higher than in men (20% vs. 17%). In 2009, 60% of stroke-related deaths were in women. Women are different: genetic differences in immunity, coagulation, hormonal factors, reproductive factors, and social factors can influence the risk of stroke and impact stroke outcomes. The new guidelines were needed to reflect risk factors that are unique to women.

They identify 6 sex-specific risk factors:

  • pregnancy
  • pre-eclampsia
  • gestational diabetes
  • oral contraceptive use
  • postmenopausal hormone use
  • changes in hormonal status

There are also four risk factors that are stronger or more prevalent in women:

  • migraine with aura
  • atrial fibrillation
  • diabetes
  • high blood pressure

Here are the new recommendations:

  • Women with a history of high blood pressure before pregnancy should be considered for low-dose aspirin and/or calcium supplement therapy to lower preeclampsia risks.
  • Women who have preeclampsia have twice the risk of stroke and a four-fold risk of high blood pressure later in life. Therefore, preeclampsia should be recognized as a risk factor well after pregnancy, and other risk factors such as smoking, high cholesterol, and obesity in these women should be treated early.
  • Pregnant women with moderately high blood pressure (150-159 mmHg/100-109 mmHg) may be considered for blood pressure medication, whereas expectant mothers with severe high blood pressure (160/110 mmHg or above) should be treated.
  • Women should be screened for high blood pressure before taking birth control pills because the combination raises stroke risks.
  • Women who have migraine headaches with aura should stop smoking to avoid higher stroke risks.
  • Women over age 75 should be screened for atrial fibrillation due to its link to higher stroke risk.

Women generally have lower blood pressure levels than men, but that changes with age. Intervention (treatment of hypertension) in women over 55 reduced strokes by 38% and heart attacks by 25%. The benefit of treatment is even greater in younger and black women. There is no evidence for sex differences in response to medications, and treatment recommendations are the same for both sexes; but in practice, there is a difference in the drugs men and women are given, and fewer women achieve good BP control.

In December 2013 a report from The Eighth Joint National Committee published in The Journal of the American Medical Association found that treatment goals for patients over 60 could be changed from 140/90 to 150/90 without changing outcomes. For patients under 60, they found insufficient evidence to support any systolic BP threshold for drug treatment. There was evidence to support a diastolic goal of less than 90 in those over 30. As with the recent cholesterol guidelines, clinicians are encouraged to make treatment decisions for individuals based on their overall risk status rather than treating to reach a specific BP or cholesterol level. They also stress the importance of prevention: “For all persons with hypertension, the potential benefits of a healthy diet, weight control, and regular exercise cannot be overemphasized.”

Mainstream medicine has always preferred prevention to treatment. For those who accuse doctors of just throwing pills at patients, here’s a quotation from the 2002 guidelines:

The continuing message is that adoption of healthy life habits remains the cornerstone of primary prevention, including the avoidance of tobacco (including secondhand smoke), healthy dietary patterns, weight control, and regular, appropriate exercise. An important role of healthcare providers is to support and reinforce these public health recommendations for all patients.

In the male-dominated fields of science and medicine, women have too often been given short shrift. The situation is radically different today from what it was when the women’s lib movement first started to raise our consciousness of gender inequities. As the Virginia Slims slogan said, “You’ve come a long way, baby” but we need to go still further. The new guidelines point out that risk assessment tables for cardiovascular disease are based largely on data from men; better data and new tables are needed to predict risk in women. I hope these new sex-specific guidelines will be the first of many such efforts, not just in cardiovascular disease but in every aspect of medicine.

This article was originally published in the Science- Based Medicine Blog.

Dr. Hall is a contributing editor to both Skeptic magazine and the Skeptical Inquirer. She is a weekly contributor to the Science-Based Medicine Blog and is one of its editors. She has also contributed to Quackwatch and to a number of other respected journals and publications. She is the author of Women Aren’t Supposed to Fly: The Memoirs of a Female Flight Surgeon and co-author of the textbook, Consumer Health: A Guide to Intelligent Decisions.

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