The home measurement of blood pressure allows patients with hypertension to become more involved in their care and allows clinicians to diagnose hypertension and monitor therapy more accurately. Evidence shows that home blood pressure measurements are generally lower than blood pressure measured in a clinician's office.^1,2 The current expansion of telemedicine has increased the need to monitor blood pressure at home and decreased the number of in-office blood pressure measurements.

Historically, blood pressure has been measured in a clinician's office using auscultation and a mercury or aneroid cuff. Many practices now use automated office blood pressure devices that were initially used in clinical studies. In the Systolic Blood Pressure Intervention Trial, patients were placed in a room where an automated device was used to take an average of several blood pressure measurements after a five-minute rest.³ However, out-of-office measurement of blood pressure (notably ambulatory blood pressure monitoring and home blood pressure monitoring) provide additional diagnostic information about blood pressure.

Ambulatory Blood Pressure Monitoring

Ambulatory blood pressure monitoring involves patients wearing a portable device for 24 to 48 hours. Blood pressure is measured at regular intervals while the patient is at home doing normal activities. It is considered the most accurate method for measuring blood pressure and diagnosing hypertension.

Information on how to implement ambulatory blood pressure monitoring has been published in the FPM journal.⁴ Ambulatory blood pressure monitoring requires that a patient obtain a monitoring device from the clinician's office and use it continuously for a full monitoring period. The device is then returned to the clinician so that the data can be downloaded and interpreted.

Higher systolic blood pressure readings on ambulatory blood pressure monitoring positively correlate with total mortality and cardiovascular outcomes.⁵ Ambulatory blood pressure monitoring can also detect blood pressure variables associated with an increased risk of cardiovascular events, such as blood pressure measurements that are higher in the morning than in the evening.⁶

Although ambulatory blood pressure monitoring provides a thorough blood pressure report with validated variables, it is not widely available outside of academic medical centers. Home blood pressure monitoring is an alternative method and the focus of this article.

Home Blood Pressure Monitoring

Home blood pressure monitoring involves patients independently measuring their blood pressure with an electronic device. Combining home blood pressure monitoring with remote or telephone physician monitoring of results (i.e., self-measured blood pressure with clinician support) is a strategy recommended by the Centers for Disease Control and Prevention Community Preventive Services Task Force.⁷

Home blood pressure monitoring is more sensitive (90% vs. 81%) and more specific (84% vs. 76%) than in-office blood pressure measurements for the diagnosis of hypertension when ambulatory blood pressure monitoring is used as the reference standard.⁸ The American Heart Association recommends two measurements separated by at least one minute twice per day to diagnose hypertension using home blood pressure monitoring. Patients should be instructed to record their readings for three (minimum) to seven (ideal) days leading up to their clinic appointment.^9–12 Some guidelines recommend omitting the first day of readings because they tend to be more elevated than other readings.^10,13 The recorded readings should be averaged.

Home blood pressure monitoring received increased attention in 2015 when the U.S. Preventive Services Task Force recommended using out-of-office measurements to confirm hypertension before initiating treatment; this recommendation was reaffirmed in 2021.¹⁴ The 2017 American College of Cardiology/American Heart Association (ACC/AHA) guideline for high blood pressure in adults also recommends out-of-office blood pressure monitoring for confirmation of hypertension and titration of pharmaceutical treatment. However, the guideline states that in-office measurement is acceptable for diagnosis of hypertension if proper techniques are used.¹⁵ The ACC/AHA guideline provides a table that correlates blood pressure measured in the office with the generally lower readings using home blood pressure monitoring and ambulatory blood pressure monitoring (Table 1).¹⁵