Wednesday, October 24, 2018

The curse of wisdom—making sense of the ever-changing blood pressure targets Part 2

The curse of wisdom—making sense of the ever-changing blood pressure targets
Part 2

BP targets according to comorbidities and CV risk calculators- too much of a good thing?

Given the scope and thoroughness of trials in the field of hypertension, why has the post-SPRINT landscape been littered with such controversy?

1)      A uniform protocol for measuring blood pressure remains unresolved. Many physicians have become disenfranchising citing their frustration with not only having to keep up with the guidelines but now qualifying BP readings according to how they were ascertained (i.e. via the auscultatory or oscillometric method). However, the clinician should not assume that the methodology for measuring BP has been an overlooked technicality within the specialty. Whether it be the debate as to the width of the BP cuff or the validation protocols for ensuring BP machine accuracy (the AAMI validation protocol is 125 pages), researchers continue to dedicate their lives to answering these questions and have created journals (e.g. Blood Pressure Monitoring) to disseminate their findings
2)      The rapid succession of discordant guideline statements. In 2004, JNC 7  recommended a universal BP goal of ≤ 140/90 mm Hg. Because JNC 8 was not published for another decade (2014), the JNC 7 guidelines were widely circulated and institutionalized. As such, when JNC 8 recommended a BP of ≤ 150/90 mmHg for those older than 60, many felt a law of nature had been violated (In defense of the JNC 8 authors, the panel was charged with generating recommendations based exclusively on “definitive evidence.” It was therefore limited with respect to the trials and publications it could cite). Just 12 months later, SPRINT  furthered this sense of tumult. It not only showed the benefit of treating to previously unheard-of levels (120/80 mm Hg) but stood in sharp contrast to the BP targets found in the JNC 8 guidelines published 1 year earlier. Just 2 years after SPRINT, the ACC/AHA guidelines appeared (2017), incorporating treatment to ≤130/80 mm Hg in high risk populations, an affirmation that lower targets were to be immediately implemented. 
3)      The demise of a universal blood pressure target. Further serving to agitate matters, the determination of BP goals now requires the prescriber to quantify a patient’s cardiovascular risk level (yet an additional calculation) and consider which medical condition one should tailor BP therapy to (the optimal BP for secondary prevention of stroke is different from that for preventing kidney disease progression). This latter, treat-by-comorbid approach quickly loses its intuitive appeal when patients suffer from multiple comorbids, each with a distinct BP target (i.e. a kidney disease patient with a prior stroke).

 Given the frustration and confusion generated, should we resign ourselves to the “more questions than answers” doctrine emblematic of modern medicine? Should we wax nostalgic for days gone by?  For our patient’s sake and the survival of our specialty, we should not. These variations in treatment goals represent the ongoing maturation of the field of hypertension and the source of perpetually declining CV event rates. Just as Part 1 of this piece highlighted the early challenges of accepting that hypertension was a pathologic process, the challenge of our times is to relinquish some of our clinical autonomy in order to integrate (complex) treatment algorithms. The oncology community has been at the vanguard of leveraging these developments. With distinct chemotherapeutic regimens based on the hormonal and genetic profiles of phenotypically similar cancers, they have come to appreciate that this “complexity” is the foundation of precision medicine. 

Guest Post by
Hillel Sternlicht, MD
Author, Concepts in Hypertension Newsletter

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