EBM Focus: In Another Episode of Overdiagnosis…

Medical | Katharine DeGeorge, MD, MS| March 18, 2020

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In this EBM Focus, a new evaluation of isolated diastolic hypertension (IDH) in the U.S. shows higher prevalence with the AHA/ACC definition compared to JNC7, but no difference in mortality.

As American culture continues to super-size servings and SUVs, it should come as no surprise that there is a similar trend with medical diagnoses. An additional 12.1 million Americans were recently labeled as “hypertensive” based on isolated diastolic hypertension (IDH) after the 2017 AHA/ACC Guideline for High Blood Pressure in Adults defined high blood pressure as ≥ 130/80 (compared to the 2003 Joint National Committee [JNC7] level of ≥ 140/90). Of those 12.1 million patients, over four million were newly eligible for treatment with antihypertensives based on a diastolic blood pressure of ≥ 80 mm Hg but systolic blood pressure < 130, which defines IDH.

The first systematic review of blood pressure studies analyzed data from seven trials that used lower diastolic blood pressure cut-offs as treatment targets, and concluded that these lower targets did not reduce cardiovascular mortality. However, investigators and guideline development panels still struggle to accept the dichotomy of what should happen based on decades-old observational associations between higher blood pressure and cardiovascular mortality and what the evidence shows does happen.

An Irish group recently examined prevalence data from the National Health and Nutrition Examination Survey 2013-2016 (NHANES) and Atherosclerosis Risk in Communities 1990-2017 (ARIC) studies comparing AHA/ACC versus JNC7 definitions of IDH. Rates of incident heart failure, chronic kidney disease, athersclerotic cardiovascular disease (a composite of nonfatal myocardial infarction, nonfatal ischemic stroke, and cardiovascular death), and all-cause mortality were also validated in two external cohorts (NHANES 1999-2014 and the Give Us a Clue to Cancer and Heart Disease [CLUE] II cohort [baseline 1989]).

Of the 9,590 adults from NHANES evaluated, 1.3 percent met criteria for IDH by the JNC7 definition and 6.5 percent by the AHA/ACC guideline, a difference of 5.2 percent. This difference in prevalence was most pronounced in younger age categories. Fortunately, few patients were recommended by either the JNC7 or the AHA/ACC guidelines to initiate drug therapy based on IDH alone.

The ARIC cohort looked at 14,348 adults aged 46-69 (median age 55), finding IDH in two percent as defined by JNC7 and 11 percent by the AHA/ACC classification. Those with IDH by either definition were less likely than normotensive participants to smoke, but more likely to be younger, black, overweight, or have higher cholesterol.

Comparing the different thresholds for IDH diagnosis, there was no difference in all-cause mortality or cardiovascular mortality in validation analyses combining NHANES III and NHANES 1999-2014 data at median 9.8 years follow-up. Likewise, the CLUE II cohort with median 28.7 years follow-up showed no association between IDH by 2017 ACC/AHA guidelines and all-cause or cardiovascular mortality.

For more information, see the topic Hypertension in DynaMed.

EBM Focus articles provide concise summaries of clinical trials most likely to inform clinical practice curated by the DynaMed editorial team.

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Katharine DeGeorge, MD, MS

This EBM Focus was written by Katharine DeGeorge, MD, MS, Associate Professor of Family Medicine at the University of Virginia and Clinical Editor at DynaMed. Edited by Alan Ehrlich, MD, Executive Editor at DynaMed and Associate Professor in Family Medicine at the University of Massachusetts Medical School, Dan Randall, MD, Deputy Editor for Internal Medicine at DynaMed.

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