Experts Question JNC 7
Clinicians seek rationale for prehypertension, diuretics
Not a few experts are raising questions on the Seventh Report of the Joint National Committee on the Prevention, Detection, and Treatment of High Blood Pressure (JNC 7) and are wondering aloud whether the committee of the United States National Heart, Lung, and Blood Institute was not influenced by the results of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT).
Today in Cardiology reports in its July issue that some clinicians who attended the annual scientific meeting of the American Society of Hypertension (ASH) in New York City last May expressed concern over the "overemphasis" on diuretics and the creation of the new "prehypertension" classification, which covers individuals with blood pressure of 120-139 mm Hg/80-89 mm Hg (see MEDICAL OBSERVER, June 2003, for details of the guidelines).
JNC 7 was presented in the meeting by Dr. Aram Chobanian, provost of Boston University Medical Center, who said the decision of the committee was unanimous.
Today in Cardiology staff writer Jeremy Moore reports that many delegates questioned why the JNC had emphasized diuretics so heavily and why the committee had created a new classification of prehypertension.
"All my life I've told my patients who had BP of 120 mm Hg/80 mm Hg that they'd walk out of my office happy. Now I have to tell them they have prehypertension syndrome? I don't think the committee appreciates how complicating this is for physicians," Today in Cardiology quotes an audience member.
"This idea of prehypertension is creating a great deal of anxiety around the country, and we do not have the strength of evidence for it," Dr. Jay Cohn, professor of medicine at the University of Minnesota Medical School, is quoted as saying. "We certainly know that not all of those patients are at risk for subsequent development of hypertension, and certainly not all of them are at risk for subsequent cardiovascular events."
But Chobanian said the new prehypertension category was meant to alert people to their real risk for hypertension.
"Bad Medicine"
Today in Cardiology reports that one clinician at the ASH meeting asked whether the recommendation to use diuretics as first-line drug was a "scientific recommendation or just the opinion of the committee." "We have a recommendation to treat all patients, most patients, first with a diuretic, but we have no real clarity as to why," the clinician said.
Chobanian, however, clarified that the JNC reviewed not just ALLHAT but 30 trials published since 1997, and decided that diuretics performed at least as well as other drugs and recommended them as first-line therapy after considering costs. But he stressed that the recommendation should not prevent clinicians from exercising flexibility in deciding which drug to start with.
"Bad medicine," was how the editor in chief of the American Journal of Hypertension reportedly described the influence of ALLHAT on JNC 7.
"Giving the diuretic chlorthalidone to every hypertensive patient, as the ALLHAT authors advise, could well be the wrong first drug more than half the time," the report quotes a statement released the day before JNC 7 was made public by Dr. John H. Laragh, cardiologist at New York Hospital/Cornell University Medical Center.
"There are two types of hypertension, one dependent on too much salt and the other on too much action of renin in the blood. The appropriate first treatment is quite different: a diuretic in one case and an antirenin drug in the other," Laragh's statement said.
Prof. Michael Weber of SUNY Brooklyn considers the ALLHAT conclusion flawed, according to the report. Weber observed that the diuretic advantage seen in ALLHAT might have had as much to do with the fact that patients in the diuretic arm had "a significant, a highly significant, BP advantage because of the set up and design."
Dr. Franz Messerli, editor of Today in Cardiology's Hypertension and Vascular Disease section, points to the guidelines of the European Society of Hypertension (ESH) for evidence of ALLHAT flaws. The ESH authors noted that 90 percent of the patients at randomization were already on antihypertensive treatment, most of them on diuretics. "Thus, ALLHAT tested continuing diuretic therapy versus switching to other drug classes," the report quoted Messerli.
European guidelines suggest that all major classes of antihypertensive agents-diuretics, beta-blockers, calcium antagonists, ACE inhibitors, angiotensin receptor antagonists-are suitable for initiation and maintenance of therapy, Messerli said. "Clearly, this point of view is more thorough and more balanced than the myopic 'thiazidocentric approach' of the JNC 7."
Local View
Local doctors have also expressed reservations about JNC 7.
In a recent symposium, noted cardiologist Homobono Calleja called the prehypertension classification "impractical." Said Calleja: "Who among you ever takes a blood pressure with a figure like 9 or 1? When you read a blood pressure, you jot it down as 90 if it is 89. You know it is impractical."
Dr. Alberto Atilano, associate professor at the University of Santo Tomas, also questioned the appropriateness of diuretics as first-line agent in countries that are hot and humid like the Philippines. "I'm not sure if we will get the same results for tolerance or even compliance," he said, stressing that "our experience [points to] use of diuretics in combination with other [antihypertensive agents]."
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