High blood pressure is one of the commonest medical conditions in the world. Tablets to lower blood pressure are also one of the most frequently taken medicines, because left unchecked, the condition can trigger heart attacks and strokes.
Now, research suggests we may need to take a tougher approach, as reaching lower blood pressure targets seems to give greater protection for the heart.
But some doctors say we are already overtreating blood pressure, meaning people have to take multiple tablets a day, which sometimes leads to dangerous side effects. How do the benefits of intensive treatment stack up against the risks?
UK doctors have long been more hands-off about blood pressure than in some other countries, such as the US and parts of Europe. In other words, American doctors tend to intervene in milder cases and are more likely to prescribe multiple kinds of tablets so their patients eventually reach a lower blood pressure target.
You might wonder why British doctors don’t follow their lead, to reduce as many heart attacks and strokes as possible, but all medicines come with risks as well as benefits.
In the case of blood pressure tablets, side effects can include having a dry mouth and frequent urination.
More serious problems arise when these medicines can arguably be too effective. That’s because if blood pressure gets too low it can cause people to feel dizzy or faint, which is particularly dangerous for older people, where a broken hip can send them to hospital for months.
It doesn’t help that blood pressure can be variable, usually peaking around midday and falling lower in the afternoon, as well as falling when people stand up. It is also tends to be higher when measured by a doctor than if people can use a machine for home monitoring.
In the US, doctors usually aim to get below 130 millimetres of mercury (mm Hg) for a measure called systolic blood pressure. By contrast, in the UK, GPs usually aim to get below 140 mm Hg or below 150 mm Hg for people aged 80 or over.
In the latest study, published this week in the medical journal, The Lancet, doctors in China compared aiming for a target of 140 mm Hg to an even more intensive approach of aiming for 120 mm Hg.
In the trial, involving over 11,000 people, those in the intensive treatment group had a 13 per cent lower rate of heart attacks, strokes or cardiovascular deaths over the next three years.
There was no difference between the two groups in their rate of injuries from falls or episodes of low blood pressure, and while those who got intensive treatment did sometimes have a serious faint, this only happened in 0.4 per cent of them.
This might be because the doctors were advised to raise people’s medication doses gradually and cautiously, said Dr Jing Li, at Fuwai Hospital in Beijing, who was one of the researchers. “If a physican has concerns, they let the patients maintain their current blood pressure, observe for a period and then decide whether to further lower blood pressure,” she said.
The findings show that aiming for lower blood pressure saves people’s lives, said heart disease expert Professor Ian Wilkinson at the University of Cambridge, who wasn’t involved in the study.
“The paper tells you that the negative side, in terms of falls, fainting, having very low blood pressure, is tiny, so we shouldn’t let that put us off,” he said.
Healthy habits
It isn’t just medicines that can be used to lower blood pressure – lifestyle changes are also advised. People who are overweight will often be advised to try to lose weight, although this may not be easy.
Even if you can’t lose weight, building more physical activity into your daily routine can also be helpful, for instance, by doing a daily brisk walk or some stair climbing.
A recent finding is that a specific kind of exercise called isometric strength training is especially beneficial. This involves holding a strenuous position for as long as possible. The best known example is the “plank”, where you hold yourself above the ground, resting on your toes and forearms.
The chief dietary change for lowering blood pressure is reducing the amount of salt in your diet. Food will seem more bland at first, but tastes generally adjust within a few weeks.
Raising the amount of potassium in your diet can also help, probably because it encourages the excretion of sodium – the harmful component of salt – in urine.
Most salts sold as “heart healthy” replace some of the sodium with potassium, which is doubly beneficial.
But Dr Jane Masouli, a geriatrician at the University of Exeter said as the people in the Chinese study had an average age of 65, there could be a higher rate of side effects like falls and fainting in people who are older and have other health conditions. “People who are older and frailer are more at risk of blacking out,” she said.
The results from this trial are unlikely to change the practice of UK doctors overnight, but it may tip the balance towards aiming for lower blood pressure targets, said Professor Philip Chowienczyk at King’s College London. “It will be another piece of evidence suggesting that lower is better than higher,” he said. “It will be weighed up for sure.”