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Current blood pressure guidelines pick up more isolated diastolic hypertension (IDH), but it might not matter, a study suggested.

Prevalence was estimated at 6.5% in National Health and Nutrition Examination Survey (NHANES) data under the 2017 American College of Cardiology/American Heart Association definition of hypertension as 130/80 mm Hg or greater compared with just 1.3% under the prior 140/90 mm Hg threshold.

That translates to an estimated 12.1 million more U.S. adults being considered hypertensive, John McEvoy, MBBCh, MHS, of the National University of Ireland in Galway, and colleagues reported in JAMA.

However, moving those people into the IDH category -- and thus hypertension overall -- with the new definition would only put 0.6% more in line for antihypertensive treatment (2.2% vs 1.6%), and without any apparent benefit for outcomes.

IDH wasn't associated with developing atherosclerotic cardiovascular disease in the ARIC study's 25 years of follow-up. Nor was there an association with heart failure or chronic kidney disease incidence or elevated cardiovascular biomarkers indicative of subclinical structural damage to the heart. Cardiovascular mortality also held no significant link to IDH in NHANES data with ten years of follow-up or in the CLUE II cohort with 29 years of follow-up.

However, there are implications for patients, the researchers noted. "Classifying a person as hypertensive has psychosocial and financial implications (e.g., insurance premiums may change)."

Prior studies have suggested that IDH is associated with future systolic hypertension, the researchers noted.

"The lack of statistically significant association of IDH with any of the clinical outcomes examined calls into question the pathogenicity of IDH," McEvoy's group argued.

Their analysis relied on data from the 2013-2017 cycle of the nationally representative NHANES, with 9,590 individuals ages 20 and older with complete data for relevant parameters. Analysis also included 14,348 black and white participants in the largely biracial ARIC observational cohort who didn't have preexisting cardiovascular disease and 13,263 from the population-based CLUE II cohort study of cancer and heart disease.

The researchers noted that their study didn't address "whether elevated diastolic BP is harmful per se, rather it evaluated the prognostic implications of a specific BP phenotype (IDH)."

A recent study of Kaiser data found modest associations of both systolic and diastolic hypertension to cardiovascular events for both newer and older definitions of hypertension.

Nevertheless, McEvoy and colleagues' finding that "diastolic BPs between 80 and 90 mm Hg have no adverse prognostic significance when systolic BP is well controlled, appear to be supported indirectly by other observational data and also by the ," which showed no benefit from a strategy to treat diastolic blood pressure to 80 mm Hg versus to 90 mm Hg.

They acknowledged, though, that statistical power to see a modest association may have been limited in their study.

Senior author of the Kaiser analysis, Deepak Bhatt, MD, MPH, of Brigham and Women's Hospital in Boston, suggested this as a possible reason for the difference between the studies.

"The prior Kaiser analysis had over a million patients (with over 36 million blood pressure measurements) in it and leveraged 'big data' to detect a significant association of elevated diastolic blood pressure with worse cardiovascular outcomes, though the effect of systolic blood pressure was greater in that analysis as well," he told 乌鸦传媒.

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