Editor's note: Subsequent to Dr Lin's recording of this commentary, the AAFP elected to not endorse the new AHA/ACC guideline, following a recommendation from their Commission on Health of the Public and Science (CHPS). AAFP continues to endorse the 2014 Evidence-Based Guideline for the Management of High Blood Pressure in Adults, developed by panel members appointed to the Eighth Joint National Committee (JNC 8). AAFP was not involved in the development of the new guideline; however, the announcement noted that CHPS used the same process and criteria to review both the AHA/ACC and JNC 8 guidelines.
Hello, everyone. I'm Dr Kenny Lin, a family physician at Georgetown University Medical Center in Washington, DC, and I blog at Common Sense Family Doctor.
When the SPRINT[1] study investigators announced 2 years ago that treating a high-risk population of adults, age 50 years and older, to a blood pressure target of 120/80 mm Hg prevented more heart attacks and strokes than a traditional target of 140/90 mm Hg, I cautioned in a Medscape commentary that it was premature to apply the trial's findings to most lower-risk adults with hypertension. Both the JNC 8 panel[2] and a subsequent guideline[3] for adults over 60 years of age, from the American College of Physicians and the American Academy of Family Physicians (AAFP), concluded that the predominance of evidence did not suggest additional benefits from treating to systolic blood pressure targets lower than 140.
The new American College of Cardiology/American Heart Association (ACC/AHA) hypertension guideline[4] upends this consensus by redefining "hypertension" as a sustained blood pressure of greater than 130/80 mm Hg and recommending drug therapy for hypertensive adults with an estimated 10-year risk for cardiovascular events of 10% or more. An independent analysis[5] estimated that the new guideline would classify 63% of US adults between ages 45 and 75 as having hypertension and result in more than 20 million becoming newly eligible for drug therapy or intensification of therapy.
For a guideline with such enormous implications for primary care, it is troubling that only one of the panel members (a geriatrician) was identifiable as a primary care physician. The AAFP is carefully reviewing the new guideline.[6] Though I have been involved in the review process, the content of this commentary represents my personal views only.
A review[7] of changes in disease definitions that occurred from 2000 to 2013 for 14 common conditions found that guideline panels have a tendency to widen definitions over time by creating "pre-disease," lowering diagnostic thresholds, and proposing earlier or different diagnostic methods. The ACC/AHA guideline does all three by creating the category of "elevated blood pressure" (a systolic blood pressure of 120-129 and diastolic blood pressure lower than 80); moving both the systolic and diastolic blood pressure cutoffs for stage 1 hypertension down by 10 mm Hg; and emphasizing out-of-office measurements to establish the diagnosis.
Are these changes justified? Just as with blood sugar cutoffs for diabetes and prediabetes, shifting a numerical threshold for disease downward will identify more persons who may benefit from treatment, but it will also cause more to be treated unnecessarily and potentially harmed. Put another way, we already need to prescribe blood pressure–lowering drugs to hundreds of people for several years to prevent a single stroke or heart attack, and the ACC/AHA's more stringent targets will increase the number needed to treat to prevent one bad outcome. It's also important to know that lower blood pressure targets don't save lives.[8]
Earlier this year, an international expert working group proposed an eight-item checklist[9] for guideline panels considering modifying the definition of a disease. It is worth seeing how well the new guideline adhered to some of these items. The panel did a good job delineating the differences between the previous definition of hypertension and their proposed definition, and of explaining the expected benefits that would accrue to patients classified by the new definition.
However, major omissions included a discussion of the overall harms of more intensive treatment, and shared decision-making tools for physicians to weigh the harms and benefits in individual patients.
Cardiologists have the luxury of only needing to be concerned with cardiovascular disease, but the vast majority of my patients with hypertension have comorbid chronic conditions and take several medications. Adding one more anti-hypertensive drug means more potential side effects, medication interactions, and costs to the patient and the health system. So I am in no hurry to implement lower blood pressure targets into my practice, and until the AAFP and other primary care groups have a chance to fully evaluate the new guideline, you shouldn't be, either.
This has been Dr Kenny Lin for Medscape Family Medicine. Thank you for listening.
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Cite this: New Hypertension Guideline: A Case of Guideline Creep? - Medscape - Dec 13, 2017.
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