Home blood-pressure monitoring better than doctors’ readings

Not uncommonly in practice I see individuals who have a diagnosis of possible ‘hypertension’ (high blood pressure) hanging over their heads. Usually what has happened here is that a doctor has noted a high or borderline high reading, which has been ‘confirmed’ again on another visit. Perhaps not surprisingly, individuals can be quite uptight about the fact that they may have raised blood pressure. There’s a risk that this anxiety can push up blood pressure when being tested in a doctor’s office. The end result, sometimes referred to as ‘white coat hypertension’, is that readings taken in the clinical setting overestimate blood pressure, and possibly lead to unnecessary treatment and undue concern.

For this reason, when I see someone with a suspicion of raised blood pressure in practice, I tend to give two pieces of advice. These are that they might consider getting a self-test blood pressure monitor that they can use calmly and quietly at home. If this reveals consistently elevated readings, then it might be prudent to have further investigations (e.g. automatic 24-hour monitoring of blood pressure). However, if self-testing reveals normal blood pressures (as it very often does), then this basically puts the person in the clear for hypertension. Then they (and their doctor) can, generally speaking, stop worrying about it.

I was interested to read about a recent study in which the usefulness of blood pressure home-testing was assessed [1]. A group of 2000 men and women aged 45-74 were assessed over a 7-year period. During this time, the individuals measured their own blood pressure at home (with a Omron HEM-722c), and also had regular physical examinations including blood pressure measurement with a doctor. Over the course of the study, there were a number of fatal and non-fatal ‘cardiovascular events’ such as heart attacks and strokes.

It turns out that the home-measured blood pressure readings were a much better predictor of these events than the readings taken in the doctor’s office.

What level of blood pressure is healthy? Well, conventional advice is generally that blood pressure should be lower than 140/90 mmHg. The British Heart Foundation here suggests that blood pressure should be lower than 140/85, but “if you’ve had a heart attack, stroke, have diabetes or diagnosed with coronary heart disease, your blood pressure should be below 130/80.”

Some doctors have suggested that with blood pressure, “lower is better.” However, there is at least some evidence that this is not necessarily the case. See here for more about this.

References:

1. Niiranen TJ, et al. Home-Measured Blood Pressure Is a Stronger Predictor of Cardiovascular Risk Than Office Blood Pressure. The Finn-Home Study. Hypertension 12 April 2010 [epub ahead of print]

9 Responses to Home blood-pressure monitoring better than doctors’ readings

  1. Jamie 3 May 2010 at 10:25 pm #

    John,

    I have spent a number of years working as a Personal Trainer/Gym Instructor. It is compulsory to check every individual’s blood pressure prior to the commencement of using the gym as part of their pre-exercise screen.

    ‘White-coat hypertension’ was common in that setting too. The common procedure, should an individual throw a BP reading over 140/90, was to not let them commence exercise until they have obtained permission from their GP. Invariably, if you did manage to pack a client off to their GP, they would return from the GP with the advice to commence an exercise programme. The whole process seemed a bit pointless.

    After a few years, I changed my screening process. Should an individual throw a high BP reading in the consultation room, I would put them on either a stationary bike or treadmill and get them moving at a level similar to normal walking pace. BP would be checked at 5, 10, & 15 minute intervals with an increase in intensity after each reading.

    Almost without exception I would see a steady decrease in diastolic BP as blood vessels dilated & peripheral resistance dropped, and systolic BP would either remain the same or increase slightly with increasing HR.

    On the rare occasion when SBP/DBP remained unchanged or both increased, the test would be stopped and the client sent away to their doctor for further investigation & advice.

    I found this system far more useful than reacting to a one-off BP test in someone who was clearly anxious about the setting they found themselves in.

    Jamie

  2. Chris 4 May 2010 at 5:46 pm #

    “What if humans cast aside processed foods and saturated fats in favour of the sort of diet our ape-like ancestors once ate? Nine volunteers gave it a go… and were glad they did so.”

    I recall a BBC TV series, ‘The Truth About Food’, for which Lynne Garton and Jill Fullerton-Smith devised an ‘experiment’ which placed nine middle aged volunteers in an enclosure at Paignton Zoo and fed them on an ‘Evo’ diet mostly of raw fruit and veg for 12 days. The exercise, of course, was a popular recreation of a more series study.
    The notable results of the experiment were reductions in commonly valued ‘markers’ for ill health and heart disease namely; reduced cholesterol, reduced BP, and weight loss. It was reported that the team interpreted the results as being attributable to the diet being low in salt, low in saturated fat, and high in soluble fibre.
    For all I acknowledge the foregoing attributes of the diet I cannot help thinking that the diet could also be judged by other metrics. The diet was a major reduction in GL vs the modern convenience diet, it was high in soluble fibre and the dietary quality of the fibre was significantly ‘better’ for being consumed raw. Then while the team report only about saturated fat the whole fat profile of the diet was changed. Actually, veg, green leaves especially, still supplies a component of saturated fat. I find it an omission that monosaturated fat and polyunsaturated fats were not openly referenced. I’d hazzard a guess that the diet supplied a proportionate increase in monosaturated fats and a significant decrease in polyunsaturated fats compared to the more typical modern diet.

    I find it interesting that emerging opinion and explanation for much modern chronic illness references the role of inflammation in contributing to such illness. Also I find it interesting that amongst the possible causes of inflammation cited by parties involved are elevated levels of insulin and too much of certain fats in the diet.
    Eating a diet of low GI or GL is one way to restore control over insulin and reduce a possible pro-inflammatory factor. With fats it may be quality may be more important that quantity. Addressing over-consumption of certain pro-inflammatory fats belonging to the polyunsaturated and omega-6 groups is possibly another way to reduce to pro-inflammatory load from the diet. Consider what these MAY do for blood pressure:
    “The group’s average blood pressure fell from a level of 140/83 – almost hypertensive – to 122/76. Though it was not intended to be a weight loss diet, they dropped 4.4kg (9.7lbs), on average.”

    John, I’d agree, if BP is such a ‘mobile’ metric it doesn’t seem wise to place too much singular importance upon it as many GPs may seem to. Several years ago my own GP noted I was mildly hypertensive but could not really give guidance upon the cause or how to address it. If my BP rose further the course of action would be to prescribe BP lowering drugs which I would “then be on for life.”
    On the other hand, if the inflammation hypotheses turn out to be as valuable as they seem and IF in the future studies and consensus affirm BP is a reliable indicator of inflammation then BP is a potentially valuable metric that could be set and used in context.

  3. pjnoir 4 May 2010 at 7:48 pm #

    My readings at home on a fairly decent BP machine is always lower than in the office. The office numbers are always HIGH (especially the diastolic number) and my doctor dismisses my readings becasue its done at home by Me, not by his staff. I do have a higher diastolic number must of the time. I have been cutting back on my BP meds at times and still seem to do VERY well ( im a low carb diabetic ). Same doctor wanted to but me on a Statin when my TC went from 130- to 137 with a 12 pt rise in the HDL. I don’t know who to trust anymore.

  4. audrey wickham 8 May 2010 at 8:40 am #

    After three visits to my GP and having a highish blood pressure I was given tablets. I took them. My blood pressure was just about normal on my subsequent visits to the surgery.

    My cousin in Australia emailed me that the blood pressure tablets she was taking were making her ill. I was taking the same brand of tablet so stopped and thought about it.

    I realised that because my GP’s surgery had only three parking spaces in a busy road and that it took me ages to find a parking space which when added to a short fuse sent my blood pressure up. I now get to the surgery with enough time to park and sit down for ten minutes (often longer) my blood pressure is fine and I don’t have to take the tablets.

  5. helen 9 May 2010 at 11:39 pm #

    pjnoir, as to whom you should trust – read as much information as you can cope with from both sides of the issue especially from independant researchers because they are not pushing any particular barrow & then make up your own mind. Never just trust someone because they have a degree without first checking information for yourself. I am sure you are an intelligent person and honestly if you try you can get through all the medical texts and papers with out much difficulty it is just a matter of getting used to the lingo! You will find as I did that opinion and research findings differ so much that it really all boils down to what is correct for you – take notes at the doctors look stuff up and then discuss what you find with them next time just don’t get pressured into a course of treatment that you are not one hundred percent sure about after all it is your body and your health not theirs. I often find that those who are not open to discussing and exploring every option not just the current politically correct line probably don’t have a very good grasp of their profession. If you have to resort to ‘bullying’, ‘fear’ and ‘I know more than you’ & ‘you just don’t understand’, type arguements then be very sceptical that your best interests are really being taken into consideration.
    After all other professionals like lawyers and accountants and teachers study just a long and hard to get their degrees yet you don’t trust them without question do you? or assign all your power over to them so why do it with doctors?.
    Apart from the few like Dr Briffa who have questions and seek answers and have an interest in knowledge above and beyond what they were taught at school, mostly you will find that doctoring is just a job like every other job, not some saintly profession entered into for noble reasons of self sacrifice!!! how did that myth stay entrenched in society anyway? It has been many decades since doctors were poor, working all hours and made home visits to their sick patients!!!

  6. Sharon 22 May 2010 at 3:27 am #

    I appreciate this article as one that can probably set a lot of minds (including my own) at ease when they run into those slightly elevated readings at their physician’s office.

  7. AP 27 June 2012 at 4:22 pm #

    I know this post is quite old, but I have a BP at home of around 120-130 over 68-75 but in a clinical setting or in fact if anyone else but me takes my BP I have seen 190-200 over 80. I have a low pulse rate (hopefully) due to the amount of excercise when I tell the Dr I am anxious about BP machine they check the pulse rate on the machine and it might be 65 so discount anxiety. Yet my relaxed pulse is 48..

    I really am at a loss of what to do, when I get one of these high reading it can take a week or two for me to get normal readings even at home, I can feel the stress the minute the BP machine turns on.

  8. Alinajagger 11 March 2013 at 12:24 pm #

    Really a nice article and it will clear all doubts

    Thanks Dr John Briffa

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