Monitoring outside of the doctor’s office may give a more accurate picture.
[Originally published: May 10, 2021. Updated: Jan 30, 2023]
High blood pressure is something that’s mentioned so often—and so casually—on television shows and in books, that it’s easy to forget it is a disease that can lead to serious health issues. It affects almost half of all adults in the United States, even though only 1 in 4 have it under control.
In fact, some doctors worry that the number of cases of high blood pressure may have grown during the COVID-19 pandemic. “It has been a stressful time,” says Erica Spatz, MD, MHS, a Yale Medicine cardiologist. Some people gained weight, and many experienced a lot more stress, and we know those things can raise blood pressure.”
These are all good reasons to have your blood pressure checked at least once a year by a physician—and more frequently if you have certain health issues. “If there's any question during that visit, whether or not your blood pressure is normal, you should talk to your doctor about checking your blood pressure more frequently at home,” says cardiologist Antonio Giaimo, MD.
Yale Medicine doctors offered the following guidance for people who are considering a home blood pressure monitoring routine.
What is high blood pressure?
High blood pressure, also known as hypertension, has been described as “a silent killer.” Most of the time there are no symptoms. But if you have the condition, it means that inside your body, the blood flowing from your heart down through the arteries is exerting too much force on the arterial walls. This extra (high) pressure leads to tears in the walls of the arteries, where fat and cholesterol collect. That leads to the formation of plaque that narrows and blocks the vessels, leading to strokes, heart attacks, and other serious diseases—and even death.
This is why your primary care doctor checks your blood pressure during an annual physical, or more frequently if you’re at risk for (or have) high blood pressure.
“Maintaining a normal blood pressure is critical to good health,” says Aldo Peixoto, MD, a Yale Medicine nephrologist. “It's what we call 'primary prevention.' We are trying to prevent the first heart attack, the first stroke, and the development of heart failure and kidney disease,” he adds. Treating high blood pressure without knowing a patient’s blood pressure numbers is like treating a patient with diabetes without tracking their blood sugar, he says.
"When you know your numbers, blood pressure is one of the most treatable conditions there is," says Dr. Spatz.
Doctors have encouraged many patients to self-monitor their blood pressure for a long time, though many remain reluctant. As a nephrologist, Dr. Peixoto cares for people who have kidney disease, which is closely related to high blood pressure. Hypertension is the second most common cause of chronic kidney disease in the United States, and appropriate blood pressure control decreases the chances that kidney disease will progress to kidney failure.
“In a specialized practice like mine, pretty much everybody checks their blood pressure at home, unless they decline to, and there is a small group of patients who prefer not to self-monitor,” Dr. Peixoto says.
On the other hand, people who don’t see such a specialist—and aren’t even seeing their primary care doctor—may not check their blood pressure at all, he points out
How to check your blood pressure
Measuring your blood pressure is generally a simple process if you have a blood pressure monitor. It has an inflatable blood pressure cuff, which must first be wrapped around your arm—the bottom of the cuff should be placed directly above the bend of the elbow. When you use the machine to inflate it, the cuff will tighten gently while a gauge on it measures your blood pressure. Your reading can be affected by what you eat or drink beforehand, how you sit, and even how nervous you are beforehand. Be sure to talk to your doctor if you have any questions or concerns related to the accuracy of your at-home blood pressure monitoring.
The Center for Disease Control and Prevention (CDC) provides the following tips to ensure your reading is accurate:
- Avoid eating or drinking 30 minutes beforehand.
- Empty your bladder first.
- Before taking a reading, spend at least 5 minutes sitting in a comfortable chair with your back supported.
- Put both feet flat on the ground and uncross your legs.
- Rest the arm that you will wrap the cuff around on a table at chest height.
- Wrap the cuff against your skin, not over your clothes. Make sure it is snug but not too tight.
- Do not talk while measuring your blood pressure.
- Take at least two readings, 1 to 2 minutes apart.
How to interpret blood pressure readings
Blood pressure is measured using two numbers:
- Systolic is the pressure in your arteries when your heart beats (the highest pressure).
- Diastolic is the pressure in your arteries when your heart rests between beats (the lowest pressure).
A normal blood pressure reading would be written as 120 systolic over 80 diastolic, or “120/80 mmHg.” Blood pressure readings that are consistently higher than that suggest the presence of hypertension and are a reason to make an appointment with a primary care provider.
“In a nutshell, if you check it twice a day for one week, that will give you a pretty good idea of what it is. Then you should repeat the process every so often to make sure it remains well-controlled,” says Dr. Peixoto. “But you don’t want to be a slave to the blood pressure machine or drive yourself crazy, which many people do.”
You should ask your doctor how often you should check your pressure if you are in a high-risk category for developing high blood pressure, either because you’re older (over the age of 50), you have a family history of high blood pressure or chronic kidney disease, or you’ve had prior high blood pressure readings in previous visits to the doctor, he adds. In the U.S., Black and Hispanic adults are at a higher risk of hypertension than people of any other racial background. Men are more likely than women to develop high blood pressure until age 64; the trend reverses at age 65, when women are at higher risk.
Even if the numbers you are tracking at home are normal, it’s useful to bring them to your next doctor’s appointment, Dr. Spatz says. “Just write them down—nothing fancy,” she says. “This will be so much more valuable than the one-time blood pressure check in the office. Sometimes you get in the office and maybe it's elevated because you rushed to get there, or you're nervous about being there, or for whatever reason it may be. So, the numbers you track at home are the best indication of whether or not you have high blood pressure, and it’s something you can do on your own.”
Self-monitoring options—and benefits
For those interested in at-home blood pressure monitoring, there are options. Some patients may check their blood pressure at a pharmacy (the CDC recommends finding a pharmacy that has a digital blood pressure measurement machine). But Drs. Spatz and Peixoto say you can get more accurate readings from a basic one that you can buy for $35 to $60. “It’s worth mentioning that these monitors can be used by a few different people in the same household, as long as the data are not syncing into a patient’s medical record,” says Dr. Spatz. “So, a couple could purchase one cuff and each person could still maintain their own data tracking. ”
Measuring your blood pressure at home is associated with a variety of benefits, Dr. Peixoto says. “Not only does it inform us about how well-controlled your blood pressure is, but it's associated with better rates of control. Basically, we’re seeing that as people get more engaged with their care, they’re more likely to follow advice that is given regarding diet, exercise, weight loss, alcohol moderation, taking medications, and so on,” he says.
Another advantage is the “sort of biofeedback” people get from monitoring their own pressure, Dr. Spatz adds. “A person might notice their blood pressure is high and say, ‘Oh gosh, I had such a stressful day.’” The doctor can then talk to the patient about managing stress levels—and stress can indeed drive blood pressure up in some people, she says—or remembering to take medication, since missed doses might be a factor in fluctuating readings.
Technology could improve accuracy of home monitoring
Some doctors are becoming more high-tech about gathering blood pressure data from patients. Yale Medicine and the Yale New Haven Health Heart & Vascular Center joined forces to develop and implement a digital hypertension program that uses Bluetooth cuffs that sync directly with the patient’s electronic medical record through the patient portal MyChart, eliminating the need for patients to write the numbers down.
“We identified patients who had uncontrolled blood pressure and who we determined would benefit from more intense management,” says Dr. Spatz. Patients monitor their blood pressure at home and speak to a pharmacist once a week to review their blood pressure readings and titrate medications. This is now becoming the standard of care in the Yale New Haven Health cardiology fellows' clinic and for women with preeclampsia, and we are working closely with the IT and the telehealth team to expand more broadly, she adds.
She is also working with Dr. Peixoto, Yale Medicine cardiologist Harlan Krumholz, MD, and collaborators at Texas A&M University to develop a wrist-worn, cuff-less blood pressure monitoring system. The project is funded by the National Institutes of Health, and they are currently recruiting patients with hypertension to test the device.
Hypertension is treatable
When you know your numbers, blood pressure is one of the most treatable conditions there is, says Dr. Spatz. There are many prescription medications that can bring down high blood pressure.
But many people who are diagnosed with hypertension early can lower their blood pressure by making lifestyle modifications, such as eating healthier food, cutting back on alcohol and salt, exercising, and losing weight, if necessary. “Lowering salt has some modest effects, but eating healthier is most important,” Dr. Spatz says. She recommends the DASH Diet, which has been shown in research studies to reduce high blood pressure.
Stress management is important, too. “Everyone handles stress differently,” Dr. Spatz says, explaining that some patients she’s seen are able to maintain a normal blood pressure when they are stressed, while others will notice a spike after they’ve been through an especially difficult day or week. “It’s really important to have this insight about yourself, and to know, if you have a blood pressure problem, that your health is important enough to make a change,” she says.
Either way, it’s important to monitor blood pressure, Dr. Peixoto says. While many people will find they are healthy and their blood pressure is stable, “If you're, say, 60 years old and you’ve avoided your doctors’ appointments for more than a year because of the pandemic, now is the time to check your blood pressure,” he says.