JNC 7 redefines diagnostic groups, endorses diuretics: controversial 'prehypertension' category includes about 45 million Americans. (Critics Question Focus of Guidelines).
The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) redefines blood pressure categories and favors diuretic-based therapy. Unveiled at the annual meeting of the American Society of Hypertension, the guidelines are based on the results of more than 30 clinical trials conducted since the previous guidelines (JNC VI) were issued in 1997.
In a bold move that has sparked considerable debate, JNC 7 defines an entirely new class of "prehypertension" that applies to patients with a systolic blood pressure of 120-139 mm Hg or a diastolic blood pressure of 80-89 mm Hg. This includes about 45 million Americans, many of whom have previously been told that their blood pressure is normal.
Patients in this group merit attention--in the form of lifestyle-based intervention--because they face a significantly increased risk of developing hypertension and its complications, including kidney damage, cardiovascular disease, and stroke, said Dr. Aram Chobanian, dean of the Boston University School of Medicine and JNC 7 chairman. "To put it into perspective, for every 20/10 mm Hg rise in blood pressure above 115/75 mm Hg, there is a doubling in risk of death from cardiovascular problems," he said.
Mortality rates for heart attack, stroke, and other vascular disease increase progressively starting at blood pressure levels as low as 115/70 mm Hg. Blood pressure tends to rise with age, so patients at 120/80 mm Hg at age 50 have a 90% lifetime risk of becoming hypertensive, Dr. Chobanian said. That points up the need for early intervention in prehypertensive patients and aggressive intervention in hypertensive patients, especially those who have heart disease or are at high risk for heart disease, diabetes, or chronic kidney disease.
But critics of JNC 7 maintain that the guidelines fail to distinguish between etiologies of hypertension and imply that all patients will benefit from the same medications. Instead of unnecessarily creating a new group of prehypertensive patients, the critics argue, the guidelines should have focused on treatment of patients who are truly hypertensive. (See box at right.)
For prehypertension, JNC 7 advises lifestyle changes only. Physicians should explain that a low-sodium diet, exercise, weight loss, and limiting alcohol intake will lower blood pressure and prevent hypertension (JAMA 289:2560-71, 2003).
"The implications and potential benefits of such healthier lifestyles could be great," Dr. Chobanian said, "particularly since about 22% of the adult American population falls into the prehypertensive category."
JNC 7 defines stage 1 hypertension as a systolic blood pressure of 140-159 mm Hg or a diastolic blood pressure of 90-99 mm Hg, and stage 2 hypertension as a systolic blood pressure of at least 160 mm Hg or a diastolic blood pressure of at least 100 mm Hg. The redefined stage 2 combines what were previously called stages 2 and 3.
Treatment goals remain unchanged from JNC VI: Patients with uncomplicated stage 1 or 2 hypertension should strive for blood pressure of less than 140/90 mm Hg; patients with preexisting complications should aim for less than 130/80 mm Hg.
Almost all patients with uncomplicated stage 1 hypertension should start on a thiazide-type diuretic, the guidelines advise. This is based on evidence from the Anti-hypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) that these agents are unsurpassed at lowering blood pressure. The drugs are inexpensive, and patients are highly likely to be adherent. Major studies have shown that diuretics are underutilized in hypertension treatment, the report notes.
ACE inhibitors, angiotensin receptor blockers, [beta]-blockers, and calcium channel blockers also may be considered as first-line therapy in certain high-risk conditions. "The selection of the initial medication is probably less important than the need to achieve blood pressure control," Dr. Chobanian said.
If patients have stage 2 hypertension, or if initial therapy fails to achieve the blood pressure goal, other drugs should be added. Many patients require two, or even three, medications. When pharmacotherapy is initiated with two drugs at this stage, one should generally be a diuretic.
Drug choice is especially important for patients with preexisting comorbid conditions. Clinical trials have shown that certain drugs are particularly effective for hypertension associated with "compelling indications." (See chart above.)
Physicians should be especially vigilant about systolic blood pressure in patients aged 50 years or older, since systolic blood pressure above 140mm Hg in these patients is a more important risk factor than diastolic pressure. The guidelines also stress the need to address other cardiovascular risk factors, including hypercholesterolemia, smoking, and excess weight.
Patient motivation is a key factor, the guidelines note. Patients and physicians should establish a positive relationship based on trust and empathy, then agree on a blood pressure goal and a patient-centered strategy for achieving it. Self-monitoring of blood pressure can be useful, as can physician sensitivity to the patient's culture, beliefs, and experiences.
A summary of the guidelines for clinicians, called "JNC 7 Express," is available online at www.nhlbi.nih.gov/guidelines/hypertension.
Drug Choices for Hypertensive Patients Unresponsive to Lifestyle Changes Goal BP is <140/90 mm Hg, or <130/80 mm Hg for those with diabetes or chronic kidney disease. Hypertension With Compelling Indications Compelling [beta]- ACE Aldosterone Indication Diuretic Blocker Inhibitor ARB CCB Antagonist Heartfailure * * * * * Post-MI * * * High coronary * * * * disease risk Diabetes * * * * * Chronic kidney * * disease Recurrent * * stroke prevention Note: BP=blood pressure; ACE=angiotensin-converting enzyme; ARB=angiotensin receptor blocker; CCB=calcium channel blocker. Source: Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.
RELATED ARTICLE: Critics Assail JNC 7 As Misguided, Misleading
The JNC 7 hypertension guidelines promote a kind of "cookbook" medicine that, at best, will unnecessarily worry millions of healthy Americans and, at worst, may lead to inappropriate pharmacotherapy for truly hypertensive patients, according to two experts who argued their case in editorials in the American Journal of Hypertension.
"The idea of a blood pressure of 120/80 as prehyperrensive is absolute garbage," Dr. Lawrence Resnick, the journal's editor, said in a press briefing at the meeting. "Most physicians in America won't take it seriously and the public shouldn't, either."
Dr. John Laragh, editor-in-chief of the journal, agreed. "By fiat, this has created 45 million more patients with a condition and no treatment," he said of the new "prehypertensive" category covering those with a systolic blood pressure of 120-139 mm Hg or a diastolic blood pressure of 80-89 mm Hg. "They're guessing that lifestyle modifications will be an effective treatment, but they won't." Lifestyle modifications (exercise, low-sodium diet, and weight loss) have never been proven as effective methods of blood pressure control because patients rarely succeed at implementing them.
The new guidelines should have focused more on effective blood pressure control for those who are really hypertensive, Dr. Laragh said.
But that never happened, Dr. Laragh (Am. J. Hypertens. 16:407-15, 2003) and Dr. Resnick (Am. J. Hypertens. 16:421-25, 2003) argued in their editorials.
That's because JNC 7 drew heavily on the results of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), which compared chlorthalidone with the ACE inhibitor lisinopril and the calcium channel blocker amlodipine. The ALLHAT investigators concluded that the diuretic was unsurpassed for lowering blood pressure and preventing heart failure, but often had to be combined with another agent for best results.
But the landmark study didn't look at the efficacy of any angiotensin receptor blocking drugs, which can be effective monotherapy in up to 60% of hypertensive patients, said Dr. Laragh of the Cardiovascular Center at New York Hospital-Cornell Medical Center.
JNC 7's heavy reliance on diuretics reflects none of the advances made in hypertension treatment. "While science has leapt forward, JNC 7 has leapt nowhere," Dr. Laragh said. "These drugs are not harmless. Chlorthalidone produces EKG changes [and] cardiac arrhythmias and induces diabetes in about 10%-15% of cases within a 5-year period. Giving it is not a joke."
ALLHAT failed to discriminate between the etiologies of hypertension; 30%-40% of patients have sodium-mediated hypertension and 60%-70% have ream-mediated hypertension. This failure invalidates the ALLHAT results, according to Dr. Laragh. The JNC 7 recommendation to prescribe a diuretic in almost every case could cause many patients with renin-mediated hypertension to receive an ineffective drug with known long-term adverse events, he said.
One of JNC 7's major points--choosing a first-line drug for uncomplicated hypertension--is "utter nonsense," said Dr. Resnick, an endocrinologist at New York Presbyterian Hospital--Cornell Medical Center.
One way to find out what's best for a patient is to assess the function of the renin system. "In the long term, it s cheaper. The patient's going to be on fewer medicines or lower doses of the same medicines," he said. "The idea that you can deliver efficient, cost-effective health care when you're deaf, dumb, and blind to who your patient really is, is ridiculous."
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|Author:||Sullivan, Michele G.|
|Publication:||Internal Medicine News|
|Date:||Jun 15, 2003|
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