THE TRANSATLANTIC DIVIDE
Where do the American and European guidelines on hypertension management draw the line?
By Roger R. Badillo II, MD
Correspondent
The continental divide is as geographical as medical. The Atlantic Ocean does not merely separate the miles between the American and the European continents, but the ideological divide is historically palpable. From two world wars fought for and against the battlefields across the channel, cutting through the Maginot and Siegfried lines, American flamboyance and muscle never did sit well with European staidness and reserve.
West of the Atlantic
And so, history repeats itself across continents, even along the politically sterile domains of medicine and health care. In 2003, the Joint National Committee on Prevention, Detection, Evaluation, Evaluation, and Treatment of High Blood Pressure (JNC) of the United States National Institutes of Health released its seventh set of guidelines and recommendations on the rational and appropriate management of hypertension. Presented at the American Society of Hypertension (ASH) 18th Annual Scientific Meeting and Exposition and published in the Journal of the American Medical Association, JNC 7 is the latest by the committee after six years. Some of its key points:
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Beginning at 115/75 mm Hg, the risk of cardiovascular disease (CVD) doubles with each increment of 20/10 mm Hg, and individuals who are normotensive at 55 years have a 90-percent lifetime risk for developing hypertension.
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Patients with systolic BP between 120 and 139 mm Hg or diastolic BP between 80 and 89 mm Hg should be classified as "prehypertensive" and clinicians should require health-promoting lifestyle modifications to prevent CVD.
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Thiazide-type diuretics should be used in drug treatment for most patients with uncomplicated hypertension, either alone or combined with drugs from other classes. Certain high-risk conditions are compelling indications for the initial use of other antihypertensive drug classes.
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Most patients with hypertension will require two or more antihypertensive
agents to achieve a goal BP of <140/90 mm Hg, or <130/80 mm Hg for patients
with diabetes or chronic kidney disease.
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If BP is >20/10 mm Hg above goal, consideration should be given to initiating therapy with two agents, one of which should be a thiazide-type diuretic.
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For patients aged >50 years, systolic BP >140 mm Hg is a stronger CVD risk factor than diastolic BP.
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The most effective therapy prescribed by the most careful physician will
control hypertension only if the patients are motivated.
Before it rises
The new guidelines also combine the previous three stages of hypertension from JNC 6 into two, while it changes high normal to prehypertension (120-139/80-89 mm Hg). Stage 1 hypertensives are those with BP 140-159/90-99 mm Hg, while stage 2 patients have BP >160/100 mm Hg. The reclassification combining stages two and three into one was essentially due to similarity of treatments, while the new prehypertension category alerts affected individuals to a significant risk for hypertension, where most cardiovascular events are likely to occur.
Water makes a diffference
The use of thiazide-type diuretics either alone or in combination as first-line antihypertensive treatment also received considerable attention in JNC 7. The recommendations came on the heels of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). A review of clinical trials showed that diuretics performed at least as well, if not better than, other drugs and were downright less expensive to maintain.
East of the Atlantic
At about the same time, in April 2003, the working group of the European Society of Hypertension-European Society of Cardiology (ESH-ESC) published their "Guidelines for the Management of Arterial Hypertension" in the Journal of Hypertension. Endorsed by the World Health Organization/ International Society for Hypertension (WHO/ISH), the European set initially shares some major agreements with its American counterpart.
Both guidelines emphasize the health risks associated with hypertension while highlighting the benefits of decreasing such risk in preventing both fatal and nonfatal cardiovascular outcomes. They also help to codify professional practice behaviors by providing a reference point for health authorities around different regions of the world. They agree on the measurement procedure for determining BP, emphasizing the use of ambulatory BP monitoring and home BP readings. Both guidelines would also contain BP targets and thrESHolds for treatment, follow-up strategies, and indications for combination drug treatment.
Prescriptive v. informative
There would, however, be significant strategic differences. While the guidelines submitted by JNC 7 are prescriptive in nature, the European guidelines suggest focusing on better detection and control of the presence and/or progression of organ damage. Stratification for total cardiovascular risk (an extension of the 1999 WHO/ISH guidelines) involving risk factors such as blood cholesterol and sugar indicate the added risk in some group of subjects with "normal" or "high" blood pressure, providing approximate estimates of 10-year risk for CVD. The American guidelines do not recommend quantification of such risk.
The type of diagnostic procedure to be employed also differs along continental lines. While the American recommendations tend to be simpler and less expensive, they may also be less adequate to detect end-organ damage. The ESH-ESC guidelines, on the other hand, may have more costly recommendations but provide a comprehensive evaluation of target-organ injury.
The "prehypertension" category in JNC 7 unifies the previous categories of "high normal" and "normal," where nonpharmacologic intervention is recommended. The ESH-ESC group retains the category "high normal," where an assessment of high total risk in this category necessitates antihypertensive drug treatment while moderate risk suggests only lifestyle changes.
Not just water
The JNC 7 guidelines recommend a diuretic for most hypertensive patients, alone or in combination with the other major classes of antihypertensives. The European version, however, states that diuretics, beta-blockers, calcium antagonists, ACE inhibitors, or angiotensin-receptor blockers are all suitable for initiation and maintenance of therapy. Large-scale trials were cited showing all could achieve cardiovascular protection in hypertensive patients. Likewise, most comparison trials show no difference in primary outcome between conventional treatment (i.e., diuretics + beta blockers) and the newer drugs. There was also concern regarding diuretic-induced glucose intolerance and low serum protein levels accompanying long-term diuretic treatment.
Arbitrary numbers
In actual clinical practice, however, what matter to the clinician are not "arbitrary levels of blood pressure defining normotension from hypertension," but the patient requiring medical care whose treatment needs to be individualized, says noted cardiologist Homobono Calleja, director emeritus of the St. Luke's Medical Center Heart Institute. Said Calleja: "The dividing line between normal blood pressure and elevated blood pressure remains unclear. The arbitrary levels define subjects who have increased risk for cardiovascular events and/or who will benefit receiving medical treatment…but the levels of BP are arrived at not from pathophysiological data."
In properly managing patients, numbers are the least important, notes Calleja. "Every person has his magic number. What does it really mean when you say 129 is normal and you say 130 is abnormal? The level of blood pressure that is called hypertension is arbitrary. It has no scientific basis. They label it as hypertension when there are so many clusters of risk factors (comorbidities). But the number alone is not the essential thing."
Individualized management
Therefore, the physician should uncover the underlying causes for elevated pressure and its associated cardiovascular risk factors, including organ damage. Explained Calleja "In both [JNC and ESH recommendations], there are difficulties and some controversies. In any biologic measure, the middle portion is normal. The ends may be normal or abnormal. You cannot predict the extremes. They may still be normal or abnormal. You can play with statistics, but that doesn't really pinpoint the patient that is in front of you."
And it is the basic reason for individualizing treatment; there is a tendency to miss out on patients who might be treated inadequately.
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