How Long Should You Keep A Blood Pressure Log?

Routine visits to the doctor’s office typically involve a single blood pressure measurement. For people with borderline hypertension, or high blood pressure, additional checks at the office are often necessary, in conjunction with having more checks done at home. How many exactly?

At least three days' worth, according to a study published in the Journal of the American Heart Association. According to Dr. Natalie A. Bello, the study's lead author and an assistant professor of medicine at Columbia University Irving Medical Center in New York, the study aimed to “…help practicing clinicians figure out what's enough when it comes to the number of measurements for them to feel confident that they have a good representation of patients' blood pressure outside the clinic."

Before an official hypertension diagnosis is given, a common approach after a patient has been screened at a clinic is home blood pressure monitoring. This is because measurements taken in a medical office may occasionally be high. Stress related to being at the doctor's office can be reason enough to affect a spike blood pressure.

The study participants did not have a history of cardiovascular disease, were not on medication for blood pressure, and were otherwise healthy. Over the course of two clinic visits, their blood pressure was measured multiple times, and they were given a home blood pressure monitoring device that stored data from each use. They were also given detailed instructions on how to obtain the most accurate measurement possible. Over two weeks, participants were instructed to take two measurements in the morning and twice again at night.

"Using the average of morning and evening readings, a minimum of three days are needed to reliably estimate out-of-office blood pressure and confirm a diagnosis of hypertension," the researchers wrote in their report.

Using the current blood pressure guidelines, at the time of the study, participants who consistently measured twice in the morning and twice in the evening only needed two days of home measurements. Participants who only took one measurement in the morning and one in the evening, three days was ideal for supporting a diagnosis of high blood pressure. 

The guidelines from the American Heart Association and the American College of Cardiology, which defines hypertension as a measurement of 130/80 rather than the previous 140/90, emphasizes having patients monitor their blood pressure as part of "hypertension diagnosis, treatment, and management."

The average age of participants was 42, excluded from the study were those who had chronic kidney disease, overt cardiovascular problems, and other health conditions. Additionally, the study included a small number of people with diabetes. Blood pressure can easily fluctuate depending on when and how it’s measured.

It's also essential that patients use equipment that has been validated for clinical accuracy, so be sure to bring it along to your next office visit. Use our Log Template to make keeping a log easier!