Study: Blood Pressure Over Time Is a Better Predictor of Stroke Risk

Assessing trajectories of blood pressure provides a more nuanced understanding of the associations between blood pressure, stroke, and mortality, according to a new study.

“Hypertension is a major modifiable risk factor for stroke,” the researchers said. “Associations of blood pressure with incident stroke are mostly based on single or average blood pressure levels. However, this approach does not take into account long-term trajectories of blood pressure, which can vary considerably in the elderly.”
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Within the population-based Rotterdam Study, the investigators examined trajectories of systolic blood pressure in 6745 participants (60% women, age range 55-106 years) and jointly modeled their risk of stroke and competing causes of death using joint latent class mixed modeling.

They identified 4 trajectories. Class 1 experienced gradually increasing blood pressure from on average 120 to 160 mm Hg over 5 decades (n=4938). Class 2 began with normal midlife blood pressure but then experienced a steep increase (n=822, increasing from 120 to 200 mm Hg). Class 3, characterized by a moderate midlife blood pressure (n=870, average 140 mm Hg) that didn’t change much over time, had a similar risk of death as class 1 but the highest risk of stroke. Class 4, with a high midlife blood pressure (n=115, average 160 mm Hg) that decreased after age 65, had a highest risk of stroke and death from nonstroke diseases (up to age 80), along with class 2.

“In this population-based study on blood pressure trajectories, we had the novel finding that the trajectory with fast increasing blood pressure was related to a high risk of stroke and death,” the researchers concluded. “It shows that single values of blood pressure do not tell the whole story. This may inspire future studies to examine the predictive value of blood pressure trajectories for stroke and mortality. Additionally, future studies are needed to determine the etiologic significance of blood pressure changes.”

—Mike Bederka

Reference:
Portegies MLP, Mirza SS, Verlinden VJA, et al. Mid- to late-life trajectories of blood pressure and the risk of stroke: the Rotterdam Study [Published online May 9, 2016]. Hypertension.