Your Blood Pressure Reading Is Likely More Accurate at Home | by heidi

It’s common to have your blood pressure taken at your healthcare provider's office, but new research suggests that you’ll probably get a more accurate reading by doing it in your own home.

For the study, which was published in the Journal of General Internal Medicine, researchers analyzed electronic health record data from 510 adults who visited one of 12 Kaiser Permanente primary care centers in Washington between 2017 and 2019.

The patients, who were at high risk of developing high blood pressure—or hypertension—were divided into three groups: those who received their follow-up blood pressure readings at a clinic, at home, or at kiosks at medical clinics or pharmacies.1

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Every study participant also received 24-hour ambulatory blood pressure monitoring (ABPM), which uses a full upper-arm cuff connected to a waist-carried device that’s worn constantly for 24 hours. The cuff inflates every 20 to 30 minutes during the day and every 30 to 60 minutes at night, allowing the researchers to compare the accuracy of the results of the three other methods.

It’s normal for your blood pressure to rise and fall throughout the day, but having consistently high blood pressure can raise your risk of a slew of serious health issues, including stroke and heart disease. A blood pressure reading is considered normal when it’s less than 120/80 mmHg. Blood pressure is “elevated” when it’s between 120-129/80 mmHg and high blood pressure when it’s 130 and above over 80 mmHg and above.

The researchers discovered that the blood pressure readings taken at home lined up with the ABPM readings. Measurements taken during clinic visits reported significantly lower systolic readings (how much pressure your blood is exerting against your artery walls when the heart beats), causing more than half of people who had hypertension to be missed.

People who had their blood pressure taken at kiosks received readings that were much higher than the ABPM measurements, leading to them having a higher risk of being over-diagnosed with hypertension.

Why Are Blood Pressure Readings More Accurate at Home?

Stephanie Feldman, MD, a cardiologist and assistant professor of medicine at Rutgers New Jersey Medical School, told Verywell that it’s “surprising” that clinic blood pressure measurements were, on average, lower than those taken by the ABPM.

“Previous literature and clinical experience suggest that clinic blood pressures are often higher for many reasons that include patient anxiety, situational stresses, and improper technique,” she said.

But, Feldman said, the technique also matters when comparing numbers.

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"You may get different measurements when using a manual cuff versus an automated cuff or inappropriate cuff size—too small leads to a falsely higher blood pressure reading, too large leads to falsely lower readings,” she said.

Rigved Tadwalkar, MD, a board-certified cardiologist at Providence Saint John’s Health Center in California, told Verywell that the findings “mirror what I often see in practice—that home blood pressure measurements are similar to the gold-standard, 24-hour ambulatory blood pressure monitoring.”

Blood pressure readings can also vary depending on the patient's environment, Feldman said.

“You can imagine if someone is running late to an appointment, is anxious about going to the doctor’s office, or has to wait in a crowded pharmacy to use a kiosk—the blood pressure reading might be higher,” she said.

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That’s also true if you drank caffeine right before your reading or exercised beforehand, Tadwalkar said. “When understanding that any of these variables can overlap with each other, it is possible to see how a blood pressure reading could easily become inaccurate,” he said.

What This Means For You

If you’re at risk for hypertension or know you have the condition, talk to a healthcare provider about monitoring your blood pressure at home.

How to Get an Accurate Blood Pressure Reading

Experts say there are a few things you can do to get a more accurate blood pressure reading.

“To get the most accurate readings when you go to the doctor’s office, avoid exercise, caffeine, and smoking 30 minutes before your appointment,” Feldman advised. “Try to arrive for your appointment early so that you have time to sit and relax in the waiting room and ensure you are seated for five minutes before the office staff check your blood pressure.”

Sit comfortably with both feet on the floor for the reading, make sure the cuff fits comfortably—meaning, it’s not too loose or too tight—and avoid talking while the measurement is being taken. 

If you have high blood pressure, Feldman recommended getting a validated automatic home blood pressure cuff to keep track of your blood pressure at home “to give you and your doctor more information to make sure your blood pressure is at your goal and to help with adjusting your medications safely.”