Blood pressure levels: too low can also be harmful

Blutdruckwerte: Auch zu tief kann schaden

Encouraging everyone to lower their blood pressure levels can also be dangerous, says Sven Streit from the Institute of Primary Health Care at the University of Bern. He calls on doctors to weigh up the benefits and risks, especially for older people.

Which blood pressure levels are said to need treatment?

As a rule, 140/90 mmHg is the critical limit. You should then clarify with your family doctor whether you really do have high blood pressure and if so, which target levels should be aimed for through a change in lifestyle or, if that doesn’t help, with medication. Because one thing’s clear: high blood pressure increases your risk of cardiovascular diseases and, consequently, of mortality too.

Nevertheless, you say that the recommendation “the lower the better” has a catch. Why?

Because it depends on the patient group. According to the latest findings, men and women up to about 80 years of age can certainly benefit from lowering their levels to 130 mmHg or lower, provided they tolerate this well. For the very old and frail, however, a reduction may be dangerous and harmful.

Level Systolic
optimal 120 mmHg 80 mmHg
normal 120 - 129 mmHg 80 - 84 mmHg
high to normal
130 - 139 mmHg 85 - 89 mmHg

How do you arrive at this conclusion?

In an observational study, we followed about 600 patients over the age of 85 for five years. The more their blood pressure levels were lowered with medication, the worse their memory performance was and, in frail people, mortality also increased. Other studies from different countries came to similarly alarming results.

What do these results mean for practice?

They put official guidelines on blood pressure-reducing medications into perspective, because they are only partially applicable to people older than 80 years – the population group that is growing the fastest and which covers a broad spectrum: from people in care with several medical conditions to fit and healthy people who exercise regularly. This spectrum is often not adequately reflected in the guidelines.

Modified guidelines

What blood pressure levels are normal is determined by expert committees such as the Swiss Society of Hypertension. The recommendations are usually based on those of the ESH/ESC (European Society of Hypertension/European Society of Cardiology), in which Switzerland is also represented. The ESH/ESC adapted its guidelines in autumn 2018 – and left one essential point unchanged: high blood pressure continues to start at 140/90 mmHg and not, as in the US, already at 130/80 mmHg. Lowering the limit in autumn 2017 in the US caused heated discussions as the country suddenly had 35 million more hypertension patients.

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