Advise Patients On Accuracy of Different Blood Pressure Devices

As hypertension continues to be a growing global health concern, patients are often advised to check their blood pressure at home daily and record their results to show to their primary care provider. However, there are many devices in the market designed to check blood pressure, each of which are designed differently.¹

Blood pressure cuff | Image credit: lesterman - stock.adobe.com

A sphygmomanometer is the most common home blood pressure monitoring device and includes a cuff placed on the bicep, 1 inch above the bend of the elbow, connected to a screen that displays the systolic and diastolic values. Another type of blood pressure device is a device placed on the patient’s wrist.²

Hypertension guidelines recommend using the upper arm as the optimum site to obtain an accurate blood pressure reading. However, patients may find monitors applied to the wrist are more convenient when measuring blood pressure at home, particularly if they face issues attaching the cuff on their upper arm or have trouble determining the best size.³ Regardless of which device patients prefer to use, determining which option is the most accurate should be the ultimate question.

Some studies have shown that obtaining a blood pressure reading from the upper arm instead of the wrist is more accurate to diagnose and treat hypertension. In fact, a study analyzing data from INTERPRESS-IPD collaboration showed that about 12% of individuals with upper arm reading did not fall under the threshold for hypertension diagnosis when measured in the lower arm.⁴

Another study was also conducted with an ambulatory blood pressure monitor (ABPM) evaluated the average blood pressure throughout the day for 24 hours, even during sleep. This study compared 2 versions of ABPMs, including an upper arm and a wrist device. Results have shown that the upper arm monitor had a 92.9% success rate of obtaining an accurate reading during sleep and 86.5% when awake, compared to the wrist monitor with a 66.3% success rate during sleep and 56.2% when awake.⁵ These differences may be significant, especially in patients with uncontrolled hypertension in need of reliable readings to diagnose and determine treatment options.

One possible reason for unreliable blood pressure results from wrist monitors is the wrist’s anatomy. A blood pressure reading in the wrist is obtained when arteries in the wrist are sufficiently occluded. Any misplacement of the device on the wrist or inaccurate cuff size relative to the wrist’s thickness can negatively affect the blood pressure reading. Additionally, the position of the wrist relative to the heart can also produce variability in results when not kept at heart level.⁶

Despite varying accuracy of blood pressure readings between the upper arm and wrist devices, pharmacists should encourage patients to use any device available to them. However, when counseling patients about choosing a device, devices that measure blood pressure in the upper arm would be the best choice for a more accurate and reliable reading. Additionally, although measuring blood pressure at home is more convenient, this does not replace a trip to the primary care provider.

References

1. Monitoring your blood pressure at home. www.heart.org. March 9, 2023. Accessed May 20, 2023. https://www.heart.org/en/health-topics/high-blood-pressure/understanding-blood-pressure-readings/monitoring-your-blood-pressure-at-home.
2. Ogedegbe G, Pickering T. Principles and techniques of blood pressure measurement. Cardiol Clin. 2010 Nov;28(4):571-86. doi: 10.1016/j.ccl.2010.07.006. PMID: 20937442; PMCID: PMC3639494.
3. Whelton P, Carey R, Aronow W, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the ​​Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: Executive Summary. J Am Coll Cardiol. 2018 May, 71 (19) 2199–2269.https://doi.org/10.1016/j.jacc.2017.11.005
4. Clark CE, Warren FC, Boddy K, et al. Higher Arm Versus Lower Arm Systolic Blood Pressure and Cardiovascular Outcomes: a Meta-Analysis of Individual Participant Data From the INTERPRESS-IPD Collaboration. Hypertension. 2022;79(10):2328-2335. doi:10.1161/HYPERTENSIONAHA.121.18921
5. Zeng WW, Chan SW, Tomlinson B. Patient preferences for ambulatory blood pressure monitoring devices: Wrist-type or arm-type?. PLoS One. 2021;16(8):e0255871. Published 2021 Aug 9. doi:10.1371/journal.pone.0255871
6. Kikuya M, Chonan K, Imai Y, Goto E, Ishii M; Research Group to Assess the Validity of Automated Blood Pressure Measurement Devices in Japan. Accuracy and reliability of wrist-cuff devices for self-measurement of blood pressure. J Hypertens. 2002;20(4):629-638. doi:10.1097/00004872-200204000-00019