With timing that defies coincidence, the American Society of Hypertension (ASH) and International Society of Hypertension (ISH) posted on Dec. 17 new guidelines for hypertension diagnosis and treatment, and on Dec. 18 guidelines addressing the same topic were issued by the group of experts who had previously been called the Eighth Joint National Committee (JNC 8).
The big disagreement between the two was target systolic blood pressure (SBP) for hypertensive patients aged 60 or older. Guidelines from the former JNC 8 panel created an SBP target of less than 150 mm Hg, concluding that no high-quality evidence existed to justify treating these patients to a lower pressure. The ASH-ISH guidelines called for a target SBP of less than 140 mm Hg in patients aged 79 or younger, and they did not present any formal literature review to justify their choice. Their most clearly articulated reason for picking less than 140/90 mm Hg? "Guidelines tend to use 140/90 mm Hg for all adults (up to 80 years)."
Courtesy ML5/Wikimedia Commons
Target systolic blood pressure (SBP) for hypertensive patients aged 60 or older remains a point of controversy among medical societies.
The two guidelines differed just as starkly in their approach. In fact, one interpretation is that the difference in approach largely drove the difference in systolic targets. The former JNC 8 panel said that they focused on high-quality evidence from randomized clinical trials. They spell out their dissection of the evidence in a 300-page supplement to their JAMA paper that includes hundreds of references. The ASH-ISH guideline document has no evidence review, and includes a taut 25 citations as "suggested reading."
"Our group was very evidence based," said Dr. Paul A. James, a family medicine professor at the University of Iowa, Iowa City, and cochair of the former JNC 8 panel.
"To my mind, the purpose of a guideline is for a group of experts to go as far as they can guided by the evidence, and then to use their experience and judgment to make recommendations in the best interests of patients," said Dr. Michael A. Weber, professor of medicine at SUNY Downstate Medical Center, New York, and chair of the ASH-ISH guideline panel.
Was the former JNC 8 panel consistently objective in drawing conclusions from the evidence, or lack of evidence? An editorial that accompanied the former JNC 8 panel’s report noted, "In older populations the majority of the panel interpreted the lack of definitive benefit from RCTs (randomized controlled trials) as grounds to raise the SBP treatment goal recommendation to 150 mm Hg; however, for patients younger than 60 years, the paucity of any trial evidence provided no reason for the panel to change the existing treatment goal at 140 mm Hg."
As Dr. John M. Flack, chief of medicine at Wayne State University in Detroit, told me: "The committee was selective in what they considered could be justified."
"It’s astounding that we don’t have the evidence to say what the right treatment thresholds are even though hypertension is the No. 1 modifiable risk factor" for cardiovascular disease, observed Dr. Eric D. Peterson, the Duke University cardiologist who was lead author on the editorial.
Once concluding that not enough evidence existed to pinpoint a treatment target, the former JNC 8 panel still needed to choose a target. In their JAMA paper they acknowledged the panel’s minority view: "Some members recommended continuing the JNC 7 SBP goal of lower than 140 mm Hg for individuals older than 60 years based on expert opinion" and because "the evidence was insufficient to raise the SBP target from lower than 140 mm Hg to lower than 150 mm Hg in high-risk groups."
But a majority opted for a more controversial target instead.
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