Taking a wrist blood pressure monitor with you outside the home is a convenient feature. Blood pressure can be checked anywhere but the accuracy is a concern many people wonder about. Therefore, are wrist blood pressure monitors accurate?
Wrist blood pressure monitors have been shown in studies to be inaccurate compared to an upper arm monitor. The studies indicated a difference between readings of a wrist cuff and an upper arm cuff. The American Heart Association does not recommend using a wrist blood pressure monitor due to their inaccuracy.
This article will examine the accuracy of a wrist blood pressure monitor. In addition, I’ll explore a critical mistake people are making when measuring their BP with a wrist monitor. This error makes the chances of the reading being accurate much less.
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Wrist Blood Pressure Monitors Accuracy
This section will examine the studies which indicate a difference in blood pressure measurements between a wrist monitor and a traditional upper cuff. To sum it up, many people ask, how much higher do wrist blood pressure monitors read?
Studies have shown wrist blood pressure monitors indicated an average higher blood pressure reading between 5-10 mmHg more than an upper arm cuff.
Study
A 2010 study published in the Journal Of Clinical Hypertension found significant differences between the arm and wrist when blood pressure measurements were taken on 261 people.
Many patients had a difference of systolic and diastolic blood pressure readings of 5 or 10 mm Hg or more between the wrist and upper arm. What’s a little scary is approximately one-third had a difference of equal or greater than 10 mm Hg1.
Study
A study in 2013, published in Blood Pressure Monitor, used wrist and arm monitors to automatically measure blood pressure over a 24-hour period. Both the systolic and diastolic blood pressure measurements from the wrist monitor were significantly different at times compared with the arm monitor2.
Study
Another study was published in 2016 in the Journal Hypertension. Researchers trained 721 people to use a wrist blood pressure monitor and a traditional arm cuff monitor.
When the participants used the wrist devices at home, 86% of them had blood pressure measurements at least 5 mm Hg higher at the wrist compared to the arm. Almost 75% of those participants had readings at least 10 mm Hg higher compared to the arm.
The researchers surmised some of these discrepancies were due to the participants inaccurate positioning of their wrists3. You can read more about that problem in the section below, #1 mistake.
Wrist blood pressure accuracy is only one of many monitor topics covered in my article, Home Blood Pressure Monitors – Things To Know. Check out the others which you may find interesting.
Checking My Wrist Monitor’s Accuracy At Home
I decided to conduct my own experiment with my wrist monitor compared to my upper arm monitor. I measured my blood pressure three times with each monitor. I took a one-minute rest between measurements, alternated the monitors and loosened the cuff being unused.
My wrist monitor measured an average of +3 mmHg systolic and +2 mmHg diastolic. The difference in my study was less than the studies indicated above. This may be to my strict compliance with cuff positioning and performing all the steps correctly.
I also think I use an accurate wrist monitor. Many people have asked, what is the most accurate blood pressure wrist cuff? The Omron gold series wrist monitor is the most accurate wrist cuff. The difference in measurements using the Omron gold series is less than the other wrist monitors.
I have found this to be true using different monitors and comparing them over some time. I wrote a review on it which you can check out here, Omron Gold Wrist Blood Pressure Monitor Review. Or you can check it out on Amazon here, Omron Gold Series Wrist Monitor.
Differences Between the Wrist and Upper Arm Blood Vessels
Measuring blood pressure involves stopping the flow of blood through the blood vessels. Which blood vessel is most commonly used to measure blood pressure?
The brachial artery in the upper arm is the most commonly used artery when measuring blood pressure at the upper arm. The less common method, measuring blood pressure at the wrist, uses the wrist’s radial artery.
When using a wrist monitor, one of the reasons why it is not always accurate is due to the blood vessels used.
- The radial artery in the wrist is closer to the surface of the skin than the brachial artery in the upper arm.
- The radial artery is more narrow than the upper arm’s brachial artery.
These two facts about the radial artery can have an affect on the accuracy of blood pressure measurements. This is one of the main reasons why the American Heart Association recommends against using a wrist cuff or a finger monitor4.
A Common Mistake Affecting the Accuracy Of Wrist Cuffs
Regardless of what kind of blood pressure monitor you’re using, there are certain guidelines which must be followed to achieve an accurate reading. The #1 mistake people are doing goes for all monitors but is committed more when people are using a wrist monitor.
The mistake is in regards to the height of the blood pressure cuff at the time of measurement.
To get an accurate blood pressure reading with a wrist monitor, the cuff must be at the same level as the heart. Blood pressure measured below or above the heart will reflect hydrostatic pressure. Hydrostatic pressure in the blood vessels is caused by the weight of the blood above it in the vessels ((Hypertension: Measurement of Blood Pressure in Humans: A Scientific Statement From the American Heart Association)).
It will be lower above the heart where blood has been pushed up against gravity. It will be higher below the heart where the weight of the blood above the measurement point will add to the pressure contributed by the heart.
Having the cuff at heart level is more difficult to achieve when using a wrist monitor. In addition, many people make the mistake of holding their wrist down on their leg or on the arm of the chair. The result is the cuff lower than the heart and an inaccurate measurement.
My Home Experiment
I decided to check my blood pressure with the wrist cuff at heart level and then with the wrist cuff down near my legs. Holding the cuff below heart level and down near my legs raised my blood pressure significantly.
| BP | |
| Wrist Cuff at Heart Level | 127/78 |
| Wrist Cuff Near The Legs | 140/92 |
| Difference | +13 sys/+14 dia |
You can see why the level of the wrist cuff is crucial for accurate measurements ((Harvard Health: Avoid these common blood pressure measuring mistakes)).
Checking The Accuracy Of A Wrist Blood Pressure Monitor
Performing all the steps correctly and keeping the cuff at heart level may not be enough if you have an inaccurate monitor. Therefore, many people have asked, how do I know if my wrist blood pressure monitor is accurate?
The wrist blood pressure monitor can be checked for accuracy by the physician comparing the measurements between the wrist monitor and the physician’s measuring device. The wrist monitor should be taken to the physician once a year and checked for accuracy.
If you have a new wrist blood pressure monitor, take it with you on your next doctor appointment. Your doctor or nurse can check your blood pressure with both a standard upper arm monitor and your wrist monitor.
Both results can be compared to check if your wrist blood pressure monitor is accurate. Bring your device in about once a year to make sure it remains accurate5.
In addition, make sure the wrist blood pressure monitor you own is a validated device. All self-measured blood pressure devices sold in the United States are required to meet standards.
However, even a validated device will not provide accurate readings in all patients. This is just another reason to have your device checked with your doctor once a year.
The new 2017 blood pressure guidelines recommends all blood pressure monitors have peer-reviewed publications indicating they have been tested for the validation of clinical accuracy ((AHA Journals Hypertension: 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: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines)).
The American Medical Association is working with the American Heart Association to create a validated device listing. When that listing becomes published I will add a link to it.
Read Next – More BP Monitor Articles!
Pros and Cons Of Wrist Blood Pressure Monitors
Why Wrist Blood Pressure Monitors Give Higher or Lower Readings
Reasons To Use A Wrist Blood Pressure Monitor
- Wiley: Does ‘‘Hidden Undercuffing’’ Occur Among Obese Patients? Effect of Arm Sizes and Other Predictors of the Difference Between Wrist and Upper Arm Blood Pressures [↩]
- National Center for Biotechnology Information: Comparison of wrist-type and arm-type 24-h blood pressure monitoring devices for ambulatory use [↩]
- Hypertension: Poor Reliability of Wrist Blood Pressure Self-Measurement at Home [↩]
- BCcampus: Nerves, Blood Vessels and Lymph [↩]
- American Heart Association: Monitoring Your Blood Pressure At Home [↩]