Can Monitoring Your Blood Pressure At Home Be Effective?
Remote Health Monitoring
Last November, the NHS announced it’s plan to give 220,000 blood pressure (BP) machines to patients with uncontrolled high blood pressure, as part of its plan to prevent 2,200 heart attacks and 3,300 strokes over 5 years1.
The benefits of remote health monitoring have been highlighted by a global pandemic that has made accessing in person care more complex. Many people are now enjoying being able to speak to a doctor remotely without having to spend time either sitting in a waiting room with others who are unwell, or travelling to the surgery on a crowded bus. Being able to collect your own health data is another, very useful action that can be done from home. When it comes to blood pressure monitoring, the pay-off is even higher, with home blood pressures often being even more useful than readings done in a clinic setting.
Are Home Blood Pressure Machines trustworthy?
There are two important points to make here: First, the national governing body that gives healthcare professionals guidelines, the National Institute for Health and Clinical Excellence, NICE, absolutely makes room for diagnosing high blood pressure based on home readings. NICE actually recommends Ambulatory Blood Pressure Monitoring (ABPM) in the first instance if someone’s BP is raised in clinic – this is when one wears a special type of BP machine for 24 hours, which inflates and checks the blood pressure every 30min or so while they go about their usual day. An average daytime reading is then used to decide whether or not they have hypertension. However, NICE says specifically that “If ABPM is unsuitable or the person is unable to tolerate it, offer home blood pressure monitoring (HBPM) to confirm the diagnosis of hypertension2”. They go on to specify how this should be done, which I will cover later.
So, we know the data from readings done at home can be reliable and useful. But how do we know if our particular machine is giving accurate data? NICE signposts us to the British and Irish Hypertension Society’s (BIHS) list of validated BP machines: you can find their list for home BP machines here3. At the very top of the list are Kinetik’s blood pressure monitors, which are devices that we now sell4.
Additionally, it is worth being aware that these machines can become less accurate with time. It is usually recommended to have them recalibrated or replaced every 12 – 24 months or so, depending on the manufacturer’s advice. Recalibration can be done by sending the machine back to the manufacturer, or using a private calibration service. (For this reason, buying a more inexpensive machine that you can replace later is often preferable to one that is more pricey.)
One final caveat to be aware of is that if you have a condition that gives you an irregular pulse, such as Atrial Fibrillation (AF), this can affect the reliability of the reading that you get with an automatic machine and you may get more accurate results if you have your blood pressure taken manually. Some machines will have an alert to indicate if this might be the case. The BIHS list above does list ‘irregular heartbeat detection’ for the machines that have this function.
What Are the Risks of Raised Blood Pressure?
A quick recap on why it matters whether or not our blood pressure is raised: essentially, a raised blood pressure can cause damage to blood vessels and reduce the amount of oxygen getting carried by them to the organ they are connected to. For blood vessels that are carrying oxygen to the brain, this increases the risk of stroke. If the blood vessels that are damaged are the ones actually supplying the heart with oxygen, this increases the risk of heart attack. If it’s the kidneys, kidney damage. The eyes, problems with eyesight, etc.
In addition to all of this, over time the increased pressure can cause the main muscle of the heart to become overworked and actually less efficient, leading to heart failure, or congestive cardiac disease.
Fortunately, being aware of a raised blood pressure and taking steps to lower it can reduce the risks of all of these conditions.
If you are interested, you can calculate your approximate risk of having a stroke or heart attack in the next 10 years by using a QRISK calculator5.
How often should I be checking my blood pressure?
As discussed earlier, if ambulatory blood pressure is not an option or not tolerable, home blood pressure monitoring is advised. NICE give clear guidance on a schedule for this monitoring in someone who has had raised blood pressure in a doctor’s office. They advise checking the blood pressure with the person seated, morning and evening every day for ideally 7 days. When taking the blood pressure at least 2 consecutive readings should be done, at a minimum of a minute apart. At the end, the readings for the first day should be discarded and the rest used to calculate an average reading2.
The target for this average reading depends on your individual demographics as well as whether or not you have any other relevant medical conditions. Generally, if you have conditions that put you particularly at risk of more severe complications of a raised blood pressure (eg kidney disease or diabetes), the usual targets will be a bit stricter compared to someone else. If you are a bit older, the targets may be looser. Otherwise, for most ‘healthy’ adults, the target average home reading should be <135/85 mmHg. This is 5 mmHg lower than a target reading at a doctor’s office (140/90 mmHg) as we do expect a blood pressure at home to be a bit lower.
The guidance does say that if a healthy person’s blood pressure is fine and not near the cut off, it can be left a maximum of 5 years before being monitored again. Of course, depending on your family history or other risk factors, it may be wise to be keeping a closer eye on things.
The above guidelines were written specifically with regard to diagnosing hypertension for the first time. However, they can also be useful for monitoring blood pressure in someone who has already been diagnosed, or if a previous reading has been borderline. This is especially true for individuals with ‘White Coat Syndrome’ – a tendency towards clinic readings being much higher than home readings.
How do I know if my reading is okay?
As described above, any individual person’s target blood pressure will be potentially influenced by the presence of other medical conditions as well as their overall demographics. A standard home reading for a ‘healthy’ adult should be <135/85 mmHg. However, there are instances where a higher reading may also be acceptable, for example if the adult experiences low blood pressure on standing and is prone to falls, particularly if they are an older adult. Lower readings than this may also be desired in certain circumstances. Ideally a target should be decided between the person and their primary care doctor or specialist based on their own medical history and personal desires also.
As a useful starting point, we are in the process of completing a blood pressure monitoring tool on our CheckUp Health at Home app. After answering a few questions initially to help us identify what your target should be based on NICE guidelines, you can then enter your blood pressure reading on the app for instant feedback. Of course, this shouldn’t be a replacement for medical advice from your doctor but should give you a good indication as to where you may be now in relation to where you should be with your blood pressure.
In addition to this, we have also partnered up with Kinetik Wellbeing to offer blood tests6 analysed by an NHS lab that can be taken at home. Factoring in, for instance, what your cholesterol or sugar levels are, helps your doctor assess your overall risk of complications from an abnormal blood pressure reading, which can in turn help guide you in how aggressively to prioritise lifestyle changes and other treatment options.
For further information and advice about your own blood pressure readings, please speak to your NHS GP or book an appointment with one of our private GPs on our CheckUp Health app – we’d love to help you with any questions you may have and are currently offering free appointments for a limited time. Use code WELCOME when booking an appointment for a £60 discount.
References
- https://www.nhsx.nhs.uk/news/nhs-offers-home-blood-pressure-checks-to-save-thousands-of-lives/
- https://www.nice.org.uk/guidance/ng136/chapter/Recommendations#diagnosing-hypertension
- https://bihsoc.org/bp-monitors/for-home-use/
- https://checkuphealth.co.uk/home-test-kit/
- https://qrisk.org/three/index.php
- https://checkuphealth.co.uk/home-test-kit/
