Every couple of years a group of experts lowers the level of blood pressure required to diagnose and treat hypertension. On the face of it, the advice seems reasonable: obesity and diabetes are on the increase across the globe and both are related to hypertension and its result, cardiovascular disease. So, dropping the upper limits of normal blood pressure by nearly 20% over the last decade seems reasonable to prevent deaths and disability.
Is it time to rethink routinely measuring blood pressure at all?
Or does it? Measuring blood pressure is not simple and is fraught with many potential errors. The last time you had your blood pressure measured, did your health care professional stop all conversation? Tell you to uncross your legs? Make sure your bladder was empty? Check that the cuff was the right size for your arm? Place it on your bare arm which was supported at heart level. Make sure you were seated with your back and feet supported?
Failure to adhere to any one of these guides can lead to artificially high readings and the potential for over-diagnosis and over-treatment. On the other hand, ensuring compliance with each and every one of these recommendations could drive anybody’s blood pressure to rise. There is already a well know phenomenology called “white coat hypertension,” when a patient’s blood pressure artificially balloons because going to the doctor makes them nervous.
Then there is the problem of persisting discrimination. The majority of larger studies are still conducted only on men, usually white, or with majority of male subjects. Women and people of color are almost always excluded or marginalized.
In some studies, there at least 5 times as many male subjects – which not only skews the results, but can lead to major biases. For example, contraceptive use, which is known to raise blood pressure, is rarely taken into account.
About the only time research focuses on women is when they are pregnant. But the blood pressure of women, whose blood volume significantly increases during pregnancy, provides no guidance on diagnosis or treatment of non-pregnant women, which is of course the majority of us.
Older women patients suffer double jeopardy. As we age the elasticity of our arteries and so our capacity to regulate our blood pressure decreases. Blood pressure can fall more than 15% after 2–3 minutes of standing, which makes the lower levels even more dangerous in the elderly.
At a minimum, research must start equally focusing on both genders and all races. In addition, is it time to rethink routinely measuring blood pressure at all? After all, we can easily diagnose diabetes and obesity, the two comorbidities most associated with cardiovascular disease?