A blood pressure reading a day shouldn’t keep the patient away

Raised blood pressure (hypertension) affects about one in three adults in the developed world, that’s around 16 million people in the UK and nearly 80 million in the USA.

In England, high blood pressure is the second biggest risk factor for premature death and disability, given the condition can lead to other more serious conditions like cardiovascular disease and stroke. Diseases caused by hypertension are estimated to cost the NHS over £2 billion every year, and account for 12 percent of all visits to GPs. Bringing down high blood pressure by 5mmHg can reduce someone’s risk of stroke by more than 20% - showing that even quite small reductions in blood pressure are worthwhile.

In the UK, around a third of people with hypertension self-monitor their own blood pressure at home, so a number of measurements can be taken over time with little or no disturbance in their lifestyle. This is currently recommended in NICE guidelines, and anyone who visits a pharmacy will see how readily available off-the-shelf monitors have become – it’s easy to keep a close eye on blood pressure in this way.

Yet while clinical trial evidence overall shows self-monitoring can lower blood pressure, the results from these studies range from no effect on blood pressure to a large and significant reduction (9mmHg). So is it really worth it, and who has the most to gain from self-monitoring?

We wanted to investigate the difference between the studies in terms of the population involved to determine which patient groups would benefit most, given there’s some ambiguity over who to offer self-monitoring to. Importantly, we also wanted to understand more about the support offered alongside blood pressure monitoring from a doctor, nurse or pharmacist, to see what worked best.

We pulled together data from 10,487 patients across 25 large randomised trials - what became really clear from all these studies was just how effective home blood pressure monitoring can be when its combined with this individually tailored support like medication checks, education and lifestyle counselling.

When patients receive additional support, the data shows us much more significant reductions in blood pressure over 12 months when compared with usual care – an average of 6.1mmHg. Those who receive no support only reduce their blood pressure by an average of 1.0mmHg.

Much of the effect appears to be associated with having this more personalised approached from a healthcare professional combined with medication intensification. While the mechanisms for this are still unclear, lifestyle changes, patients remembering to take their medication, and prescribing more medication are likely to be behind it.

We found that anyone can potentially benefit from home-monitoring and additional support, but it was most effective in people on fewer medications for their hypertension and in those with higher blood pressure before self-monitoring (up to 170 mmHg systolic). It was equally effective in men and women and in patients who had other conditions, like diabetes, chronic kidney disease, and following myocardial infarction.

In the UK, hypertension is predominantly managed in general practice and GPs will routinely interact with patients who monitor their blood pressure at home. Many patients do not discuss their readings with their doctor, but this research shows that increased collaboration between a patient and either their GP, a nurse, or pharmacist can result in important and beneficial decreases in blood pressure as well as improved control. 

The research was funded by the NIHR School for Primary Care Research. The views are expressed are those of the authors and not necessarily those of the NIHR, the NHS or the Department of Health.