Blood pressure fluctuations linked to increase stroke risk, study finds

Greater variation in blood pressure readings over time was associated with a higher risk of death and, for some measures, stroke, according to a study of more than 57,000 people.

The findings were observational, meaning they show associations but do not establish that fluctuations in blood pressure directly cause stroke or death.

Study lead Dr Fariba Ahmadizar said: “Our findings suggest that changes in blood pressure over time may provide information beyond the average blood pressure readings in routine care.

“However, more research is needed before blood pressure variability can be recommended for routine clinical use.

“Questions that need answering include whether it is possible to reduce these fluctuations—and if doing so reduces the risk of stroke or death.”

The study, led by Dr Ahmadizar of Amsterdam University Medical Center in the Netherlands, analysed data from 57,611 UK Biobank participants who had blood pressure measured at their initial assessment and at least one later visit.

Participants had an average age of 55.4 years and 52 per cent were women. At the start, 50,744 had normal blood sugar, 5,397 had prediabetes and 1,470 had type 2 diabetes.

Prediabetes refers to blood sugar levels that are higher than normal but not high enough to be classified as diabetes.

Researchers assessed how much blood pressure varied between visits while accounting for the time between measurements.

Participants were followed for a median of 5.1 years from the first visit at which blood pressure variability could be calculated. During follow-up, 571 had a stroke, 319 developed dementia and 1,460 died.

Greater variability in all four measures studied, systolic blood pressure, diastolic blood pressure, mean arterial pressure and pulse pressure, was associated with a higher risk of death from any cause.

The associations remained after researchers adjusted for average blood pressure, blood sugar status and other factors.

Each one-standard-deviation increase in systolic blood pressure variability was associated with an 11 per cent higher risk of death. For diastolic blood pressure variability, the increase was 8 per cent.

A standard deviation describes how much blood pressure variability differed between participants, so these figures cannot be translated directly into a specific change measured in mmHg.

Greater variability in diastolic blood pressure and mean arterial pressure was also associated with stroke.

The likelihood of stroke was 12 per cent higher for each one-standard-deviation increase in diastolic blood pressure variability and 10 per cent higher for mean arterial pressure variability.

Researchers also examined blood sugar status alongside blood pressure variability.

Compared with participants who had normal blood sugar and low systolic blood pressure variability, those with type 2 diabetes and high variability were 2.8 times as likely to die during follow-up.

Those with prediabetes and high systolic blood pressure variability had a 62 per cent higher risk of death than participants with normal blood sugar and low variability.

The researchers stressed that these comparisons combined differences in blood sugar status and blood pressure variability, so the increased risk could not be attributed to blood pressure variability alone.

They estimated the 10-year risk of death at about 1.0 per cent among people with normal blood sugar and low systolic blood pressure variability, compared with about 2.9 per cent among those with type 2 diabetes and high variability.

No statistically significant associations were found for dementia.

Ahmadizar said that because the study was observational, it did not prove causality.