Oakland, CA—Based on previous research, the assumption has been that high systolic blood pressure is more likely than diastolic blood pressure to result in adverse cardiovascular (CV) outcomes.

A report in the New England Journal of Medicine might force pharmacists and other healthcare professionals to rethink that conventional wisdom.

A Kaiser Permanente–led study found that both numbers in a blood pressure reading independently predicted the risk of heart attack or stroke in a study that included more than 36 million blood pressure readings from more than 1 million people.

“This research brings a large amount of data to bear on a basic question, and it gives such a clear answer,” said lead author Alexander C. Flint, MD, a Kaiser Permanente stroke specialist and adjunct researcher with the Division of Research. “Every way you slice the data, the systolic and diastolic pressures are both important.”

The current retrospective study is touted as “the largest by far of its kind,” according to Flint. It reviewed blood pressure readings taken during outpatient visits between 2007 and 2016, from 1.3 million adult Kaiser Permanente members in Northern California.

In embarking on the study, researchers suggested that the relationship between outpatient systolic and diastolic blood pressure and CV outcomes was not only unclear but had been complicated by recently revised guidelines with two different thresholds (≥140/90 mmHg and ≥130/80 mmHg) for treating hypertension.

The study team sought to determine the effect of the burden of systolic and diastolic hypertension on a composite outcome of myocardial infarction, ischemic stroke, or hemorrhagic stroke over a period of 8 years, controlling for demographic characteristics and coexisting conditions.

Results indicate that systolic and diastolic hypertension each independently predicted adverse outcomes. Researchers point out that, in survival models, a continuous burden of systolic hypertension (≥140 mmHg; hazard ratio [HR] per unit increase in z score, 1.18; 95% CI, 1.17-1.18) and diastolic hypertension (≥90 mmHg; HR per unit increase in z score, 1.06; 95% CI, 1.06-1.07) each predicted the composite outcome, independent of each other.

Furthermore, the article notes, similar results were documented with the lower threshold of hypertension (≥130/80 mmHg) and with systolic and diastolic blood pressures used as predictors without hypertension thresholds. “A J-curve relation between diastolic blood pressure and outcomes was seen that was explained at least in part by age and other covariates and by a higher effect of systolic hypertension among persons in the lowest quartile of diastolic blood pressure,” the authors explained.

“Although systolic blood-pressure elevation had a greater effect on outcomes, both systolic and diastolic hypertension independently influenced the risk of adverse cardiovascular events, regardless of the definition of hypertension (≥140/90 mmHg or ≥130/80 mmHg),” the study concludes.

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