The Response at ASH to the New JNC 7 Guidelines

Linda Brookes, MSc

Disclosures

May 20, 2003

Editorial Collaboration

Medscape &

The new Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7)[1,2,3] was given its debut presentation to hypertension specialists when the JNC 7 executive committee chair Aran V Chobanian, MD (Boston University School of Medicine, Massachusetts) presented the report at a special session of the American Society of Hypertension (ASH) annual Scientific Session, which took place in New York City at the same time as the National Heart, Lung, and Blood Institute Press Conference. It perhaps goes without saying that the presentation of the new guidelines brought forth both praise and criticism from the preeminent international audience assembled for the ASH Scientific Session.

New Blood Pressure Classification Questioned

Many of the ASH delegates commented on the major step that JNC 7 appears to have taken away from the previous consensus on how to classify hypertension. Leading off the critique, Jay N Cohn, MD (University of Minnesota Medical School, Minneapolis), expressed his delight with the report's emphasis on the "high normal" blood pressure group (now classified as "prehypertensive"), because most cardiovascular morbid events occur in that group. Like others, however, he was troubled by the term "prehypertension." He believes that this new category will simply create anxiety in the general population. He pointed out that not all people in the new class are at risk for subsequent development of high blood pressure or for cardiovascular morbid events, which should be the focus of therapeutic efforts. As a result, Dr Cohn believes that a potential problem has been introduced, with physicians now having to deal with almost 50% of the overall population.

Dr. Chobanian replied that a lot of discussion took place before the term "prehypertension" was chosen. Ultimately it was deemed by the JNC 7 executive committee and others to be a more "action-oriented" term than "high normal," based partly on focus group investigations with doctors who said that the term "prediabetic" or "precancerous" resulted in patient responses, but the term "high normal" was ignored.

Another widely expressed concern about the new term was its potential socioeconomic implications, resulting from application of the label "prehypertensive" to individuals previously considered normotensive. Dr. Chobanian agreed that the committee had been concerned about this and had contacted and talked with insurers and employers to ascertain their reactions. They also looked at the issue of "prediabetes" and the effect of that classification. At the end of their discussions, the committee concluded that applying the term prehypertensive would not have an impact on insurability issues.

A question that drew more applause was the issue of how to tell patients with blood pressure of 120/80 mm Hg, who had previously considered themselves healthy, that they are now "prehypertensive." It was believed that patients will interpret this to mean that they now have hypertension. Dr. Chobanian agreed that the JNC 7 report has made physicians' lives "more complicated," admitting that the new concept will not be accepted overnight. It will involve a lot of education and it will take a few years to get the public to understand that prehypertension is something they should do something about, he predicted. He believes that this is an opportunity to affect the lifelong risk for hypertension, however. He further noted that JNC 7 does not recommend drugs, but healthier lifestyles that are healthier for many other reasons, and he also confirmed that for individuals who are in the prehypertension category, JNC 7 sets no goal as to how low their blood pressure should be reduced.

Comprehensive Risk Assessment Preferred

Dr. Cohn continued his critique by stating his preference for a more comprehensive assessment of vascular health, including other measurements -- such as arterial elasticity, funduscopic examination, and microalbuminuria -- before a patient is committed to lifestyle and drug interventions that will last for life. Dr. Chobanian confirmed that microalbuminuria is part of the JNC 7 recommendations, but emphasized that the committee had aimed at making JNC 7 a "simple and straightforward" guide for clinicians, not for hypertension specialists.

Professor Michael O'Rourke, MD, DSc (St Vincent's Hospital, Sydney, Australia), noted that JNC 7 has moved away from JNC 6[4] and from the World Health Organization (WHO)/International Society of Hypertension (ISH)[5] guidelines to measures of arterial pressure rather than measures of risk. He suggested that, given what is known about the inaccuracy of the sphygmomanometric measurements in individual patients and the fact that the root cause of isolated systolic hypertension can be attributed to increasing pressure with age due to the effects of arterial stiffness, consideration might be given to involving other aspects of cardiovascular risk to supplement the cuff-sphygmomanometric measurements in making assessments of when to treat patients. Dr. Chobanian replied that measurements of cardiovascular risk were related to the other major risk factors, such as cholesterol, diabetes, and smoking, and the use of surrogate markers of risk was not included in the recommendations.

Several questioners commented on the absence of left ventricular hypertrophy (LVH) as a compelling indication in JNC 7. Dr. Chobanian confirmed that the issue of whether LVH should be a "compelling indication" was discussed. The committee did not want to downgrade the importance of LVH, and it will be present in the longer report as an important factor, but it was decided that the data were not strong enough to make it a compelling indication.

Drug Recommendations Challenged

Professor Graham A McGregor, MD (St George's Hospital Medical School, London, UK), challenged the JNC 7 recommendation that antihypertensive therapy should be started with diuretics. He noted that simply restricting salt intake (one of the committee's recommendations) doubles the efficacy of an ACE inhibitor or an angiotensin receptor blocker (ARB), and he suggested that with this in mind, most physicians would opt for an ARB and then add a thiazide-type diuretic. While admitting that eventually most patients will probably end up on both drugs, he nevertheless believes that if they restrict salt, many patients can be controlled on an ACE inhibitor and an ARB and it would be illogical to add a diuretic. He also believes that the rate of impotence caused by first-line therapy with diuretics is unacceptable.

Dr. Chobanian responded by making 2 points: first, a low salt diet is very difficult to follow, and second, if an individual develops impotence on any agent, there is no reason not to switch to another drug, considering how many "wonderful" drugs are available.

Several delegates suggested that larger numbers of patients would respond to monotherapy if they were simply tried on different drugs. It was feared that when clinicians see the guidelines, they will start the patients on a diuretic and then add another drug, whereas many patients could be adequately controlled on monotherapy, simply by switching to a different drug. Another concern with diuretics was the possible side effects with lifelong treatment. Dr. Chobanian confirmed that JNC 7 does not advocate substitution of any particular class of drug (eg, diuretics) across the board to find one with a better effect over another. The emphasis from the practical standpoint is to combine therapy to get blood pressure levels down and keep them down, he said. He pointed out that wherever side effects occurred, those drugs should not be used.

European Guidelines Will Retain Old Classification

Comments on the JNC 7 guidelines in the light of the upcoming European guidelines for the management of arterial hypertension were offered at the ASH session by Professor Alberto Zanchetti, MD (University of Milan, Italy). Professor Zanchetti is a past-president of the European Society of Hypertension (ESH) and of ISH, and continues to be a distinguished member of ISH.

ESH, in collaboration with the European Society of Cardiology, has prepared its own guidelines, which will be released at the 13th Congress of ESH, to be held June 13-17 in Milan, and published in the June issue of the Journal of Hypertension. The European societies have some disagreements with the JNC 7 guidelines, Professor Zanchetti revealed. In JNC 7 there is much less emphasis on the total cardiovascular risk in guiding the management of hypertension, unlike JNC 6 and the current WHO/ISH guidelines, whereas this is emphasized in the new European guidelines. The European guidelines will retain the old classification of hypertension, as in the JNC 6 and the WHO/ISH guidelines, including the definition of high normal blood pressure.

The European guidelines will be flexible in their definition of hypertension, Professor Zanchetti noted, quoting the late Geoffrey Rose, who referred to hypertension as "that level of blood pressure at which and about which detection and treatment do more good than harm." The European guidelines will emphasize the concept that what JNC 7 calls prehypertension may be hypertension in diabetic patients or in patients after a stroke or MI, whereas it may be considered normotension in patients with no additional risk factors.

The European guidelines committee was diffident about the term "prehypertension" for both scientific and practical reasons, Professor Zanchetti explained: scientific, because all those patients with SBP 120-140 mm Hg are not necessarily going to become hypertensive; and practical, because such an increase in the population that must now be considered abnormal will reduce the impact of the message about treating hypertension.

With regard to antihypertensive treatment, the European guidelines will be based on much the same evidence as JNC 7, but the conclusions of the European committee were somewhat less rigid and more liberal, Professor Zanchetti said. If most of the recent trials have shown that lowering blood pressure per se is the most important aspect of antihypertensive treatment, then in the choice of the drug to be used in individual cases, many factors other than cost alone should guide the physician's choice, he declared. If an increased adherence to scientific advice is to be the goal, he believes that more flexible guidelines are needed that take more account of the physician's individual choice and the patient's preference.

Professor Zanchetti also pointed to a limitation of all the guidelines, namely that they provide advice for lifelong therapy -- which, in the middle-aged hypertensive, can last for 20-25 years -- based exclusively on evidence accumulated from trials that lasted only 3-5 years. Most of these trials were unable to evaluate the long-term impact of changes in so-called intermediate endpoints such as LVH, microalbuminuria, carotid changes, and new-onset diabetes. This is a problem that is difficult to solve but which must not be neglected, Professor Zanchetti asserted. Overall, to achieve the aim of better treatment of hypertension in practice, guidelines should be more flexible, more informative, more educational, and less prescriptive, he believes.

At this point, the debate and discussion will no doubt continue and intensify, with more content to be incorporated once the ESH guidelines are announced in June in Milan.

References
  1. Chobanian A. JNC VII report. Eighteenth Annual Scientific Meeting and Exposition of the American Society of Hypertension. May 14-17, 2003, New York, NY.

  2. US Department of Health and Human Services. JNC 7 Express. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Available on the NHLBI Web site at http://www.nhlbi.nih.gov/guidelines/hypertension/jncintro.htm or from the NHLBI Health Information Center, PO Box 30105, Bethesda, MD 20824-0105. Phone: 301-592-8573 or 240-629-3255 (TTY); Fax: 301-592-8563.

  3. Chobanian AV, Bakris GL, Black HR, et al, and the National High Blood Pressure Education Program Coordinating Committee, The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. The JNC 7 report. JAMA. 2003;289:3560-3572.

  4. Joint National Committee on Prevention, Detection, and Treatment of High Blood Pressure. The sixth report of the Joint National Committee on Prevention, Detection, and Treatment of High Blood Pressure (JNC VI). Arch Intern Med. 1997;157:2413-2446. Abstract

  5. Guidelines Subcommittee. 1999 World Health Organization-International Society of Hypertension Guidelines for the Management of Hypertension. J Hypertens. 1999;17:151-183. Abstract

Comments

3090D553-9492-4563-8681-AD288FA52ACE

processing....