Fluctuations in blood pressure over time linked to death and strokes, analysis of UK data finds

Greater variation in blood pressure between research visits was associated with a higher risk of death in a study of more than 57,000 UK Biobank participants. Variation in some blood pressure measures was also associated with strokes, the Annual Meeting of the European Association for the Study of Diabetes (EASD) in Milan, Italy (Sept 28 - Oct 2) heard.

The researchers from the Netherlands also found that the combination of a high variation in systolic blood pressure and diabetes was associated with a three times higher risk of death from any cause compared to participants with normal blood sugar and low variation.

Unlike average blood pressure, blood pressure variability is not routinely taken into account when assessing health. These results suggest it could help identify high-risk patients who might otherwise be overlooked. However, more research is needed to prove this.

The study, led by Dr Fariba Ahmadizar, Department of General Practice, Amsterdam University Medical Centre, Amsterdam, the Netherlands, included 57,611 participants who had blood pressure measured at their initial assessment and at least one later visit. Their average age was 55.4 years and 52% were women.

At the start of the study, 50,744 participants had normal blood sugar, 5,397 had prediabetes, where blood sugar levels are higher than normal but not high enough to be classed as diabetes, and 1,470 had type 2 diabetes.

The researchers assessed how much blood pressure varied between visits, taking the time between measurements into account. Participants were followed for a median of 5.1 years from the first visit at which variability could be calculated. During this time, 319 of the participants developed dementia, 571 had a stroke and 1,460 died.

Greater variability in each of the four blood pressure 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. These associations remained after adjusting for average blood pressure, blood sugar status and other factors.

In other words, variation in blood pressure between visits was associated with a higher risk of death, even after accounting for average blood pressure.

Each one standard deviation increase in systolic blood pressure variability was associated with an 11% higher risk of death. The corresponding increase was 8% for diastolic blood pressure variability.

Greater variability in diastolic blood pressure and mean arterial pressure was also associated with strokes. The likelihood of a stroke was 12% and 10% higher, respectively, for each one-standard-deviation increase in variability.

A standard deviation describes how much blood pressure variability differed between participants. These percentages therefore cannot be directly translated into a specific change in blood pressure measured in mmHg.

The researchers also examined blood sugar status in combination with blood pressure variability.

Compared with participants with normal blood sugar and low systolic blood pressure variability, those with type 2 diabetes and high systolic blood pressure variability were almost three times (2.8 times) more likely to die during the follow-up period.

Participants with prediabetes and high systolic blood pressure variability had a 62% higher risk of death than those with normal blood sugar and low systolic blood pressure.

These comparisons combine differences in blood sugar status and blood pressure variability, so the increased risk cannot be attributed to blood pressure variability alone, note the study’s authors.

Finally, the researchers estimated that the 10-year risk of death was approximately 1.0% among participants with normal blood sugar and low systolic blood pressure variability, compared with approximately 2.9% among those with type 2 diabetes and high variability.

No statistically significant associations were found for dementia.

Dr Ahmadizar says: “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.”

She adds that as the study was observational, it did not prove causality.