Susan Cheng, MD, MPH, MMSc, on BP Trajectories of Men vs Women Over the Life Course
Findings of a new analysis1 contradict an important conventional notion regarding cardiovascular disease and sex. The analysis found that blood pressure (BP) measures actually progress more rapidly among women than among men and begin early in life.
To gain more insight on these findings, Cardiology Consultant reached out to lead author Susan Cheng, MD, MPH, MMSc, who is the Erika J. Glazer Chair in Women's Cardiovascular Health and Population Science, director of Cardiovascular Population Sciences, and director of Public Health Research at the Smidt Heart Institute at Cedars-Sinai Medical Center in Los Angeles, California.
Here are her answers to our burning questions.
CARDIO CON: For your study, you and your colleagues evaluated whether longitudinal patterns of BP elevation differ between women and men during the life course when considering baseline BP levels as the reference. Can you tell us more about your study and how it came about?
Susan Cheng: We have known for a long time that women and men tend to present differently – and have different outcomes – when it comes to cardiovascular disease. For those of us in clinical practice, we see examples every day of how women tend to present differently than men with heart disease for instance. Then, when we look at the epidemiology, especially given the now bigger and better ways we can capture data on more measures, we see that certain types of cardiovascular diseases are a lot more common among women than men, such as coronary microvascular dysfunction and heart failure with preserved ejection fraction. For these reasons, we were motivated to take a much closer look at blood pressure trajectories over the life course in women compared to men. At the end of the day, the vast majority of cardiovascular disease processes tend to start with blood pressure elevation – or hypertension – as an initial major driving risk factor.
When we looked at historical blood pressure measurements collected from across tens of thousands of people, we found that the previously described patterns of blood pressure change over time were certainly there. But then we started to ask ourselves, “Are we missing something when it comes to sex differences?” When we looked harder at the blood pressure trajectories, we started to ask ourselves, “If women end up having different types of heart disease and other types of cardiovascular disease in later life, what if it is because they really do have different physiology at baseline? If women and men have different physiology at baseline, why are we putting them on the same Y axis? What if we let them be on their own axis and compare older women to younger women, and older men to younger men, rather than to a large group average?” When we looked at the data this way, we realized that it was not just that women were catching up to men, but that rates of acceleration in blood pressure levels were significantly higher in women than men starting quite early in life and well before the menopausal transition, indicating that women really are different from men and that we need to think about them differently when it comes to both health and disease.
CARDIO CON: How do patterns of BP change over the life course and differ between the sexes?
SC: On average, in both sexes, the natural pattern of blood pressure change over the lifespan involves systolic blood pressure rising steadily throughout adulthood and continuing to rise well into older age. Diastolic blood pressure also rises steadily throughout adulthood until about late mid-life when it plateaus and then starts to decrease in conjunction with large artery stiffening, which is represented by an even steeper rise in the difference between systolic and diastolic pressure – also known as pulse pressure – that continues throughout older age. A key difference between the sexes is that the starting point for women is consistently lower than that for men, and the rate of rise for all blood pressure measures is steeper for women than for men.
CARDIO CON: It is well known that cardiovascular diseases affect women differently than men. How has your study helped you better understand why cardiovascular diseases affect women differently than men?
SC: Yes, indeed, we used to think that women tend to present with less severe forms of the same types of cardiovascular disease as men, and that women just tend to present with these diseases later in life. Now, we are becoming aware that the truth is probably not so simple. There are certain forms of cardiovascular disease, ones that are not as easy to recognize, that are likely more common in women—especially younger women compared to younger men – such as coronary microvascular dysfunction. We are still learning about how widespread these conditions are and what the full health ramifications are for those affected. Our study helps us to better understand that arterial physiology is different between the sexes from the start, which is likely why women and men “age” differently in response to chronic stressors. This is likely why we see sex differences in the manifestations of blood pressure related cardiovascular diseases.
CARDIO CON: What other insights have your findings given us?
SC: Our findings suggest that all the ways by which we think about and aim to prevent or treat hypertension likely needs to be more tailored, at least by sex. For instance, if we think about a 45-year-old woman and a 45-year-old man presenting to a clinic on the same day, each with a systolic blood pressure of 140 mm Hg, our research would suggest that the 45-year-old woman’s blood pressure level started out at a lower baseline – probably around 105 mm Hg veersus around 115 mm Hg in the man. Therefore, her blood pressure had to travel farther and faster to get to 140 mm Hg, and the trajectory is likely to continue to be faster for that woman compare to the man.
We still have more work to do to understand exactly what the implications of this research are for outcomes and treatment. Meanwhile, our findings would suggest that we all need to work more effectively on engaging all of our patients on the importance of being aware of blood pressure, keeping an eye on it as a measure of vascular health, and acting appropriately as soon as we see blood pressure levels start to creep up. Younger to middle-aged adults especially need to be more aware that hypertension is not just a condition of older age—that it can begin at a younger age and, when it does, it is especially important to start treating. Our most recent research now indicates that while blood pressure awareness needs to increase among both younger women and younger men, raising awareness is especially important for young women.
CARDIO CON: What is your next step in this research?
SC: We are just getting started and definitely have still more work to do. For instance, we need to better understand why vascular and arterial health—and their responses to stressors—appear to be different among women compared with men. Part of this could be that the relative size and caliber of arteries, large and small, is different in women versus men, even after accounting for differences in body size. There is still much more to learn.
- Ji H, Kim A, Ebinger JE, Niiranen TJ, Claggett BL, Merz NB, Cheng S. Sex differences in blood pressure trajectories over the life course [published online January 15, 2020]. JAMA Cardiol. https://doi.org/10.1001/jamacardio.2019.5306.