US, European Hypertension Guidelines: More Alike Than Different

(UPDATED) Leading hypertension experts on both sides of the Atlantic say there is more in common between their two sets of guidelines than there are things that set them apart. Their article, published recently in Circulation, makes the case for “harmonization” as a way forward.

Back in 2017, the American College of Cardiology/American Heart Association (ACC/AHA) issued recommendations for the prevention, detection, evaluation, and management of high blood pressure. Just a year later, in 2018, the European Society of Cardiology/European Society of Hypertension (ESC/ESH) released their own guidance.

The new paper was commissioned by the US and European societies to compare and contrast the two guidelines, said lead author Paul K. Whelton, MD (Tulane University School of Public Health and Tropical Medicine, New Orleans, LA), president-elect of the World Hypertension League and writing group chair for the US recommendations.

“We were very enthusiastic” about the opportunity to explore where the documents converge, Whelton told TCTMD. “The first thing people usually do with guidelines, and it’s kind of a knee-jerk response, is to put them side by side and [ask] what can we find that’s different and then make an awful lot out of that: ‘The experts can’t agree. It’s a crisis situation. Patients have no confidence. Clinicians must be confused, etc.’”

That can limit the impact of the new recommendations, he said. “It sows the seeds of people saying: ‘Well, we don’t know what to do. We’ll just continue doing what we’ve always done.’”

In this case, efforts by some to “stir the pot” are also inaccurate, he continued, “because the vast majority of what we were recommending was very similar. Even in the area of greatest discord, which is classification of blood pressure, when it came to actual management, we were very similar.”

Giuseppe Mancia, MD (University of Milano-Bicocca, Milan, Italy), ESH chairperson for the 2018 European guidelines and a coauthor of the new paper, said that investigators conducting scientific research are often drawn to differences. For them, that’s what’s “more interesting. When everybody agrees, there’s no research anymore, in a way,” he commented to TCTMD. “So the accent is placed on differences, but if you look at the similarities, these are much more important.”

Moreover, not all of the evidence for guidelines comes from randomized controlled trials, with some advice being informed by experience and less-rigorous studies. This opens the door to differing interpretations of the literature, said Mancia.

Calling out the areas of agreement will enable the field to better tackle hypertension, said Whelton. “The more we can harmonize these guidelines and have a common position, a common platform, I think the better our core message is, and the better our opportunities are for really having impact.”

Senior author Bryan Williams, MD (University College London, England), who served as ESC chairperson for the 2018 guidelines and is president elect of the International Society of Hypertension, agreed that debate about guidelines is common and “inevitably seems to focus on and exaggerate differences between them.”

Yet “debate is nearly always good, because it creates noise and awareness and allows free discussion of areas of practice where uncertainty still remains,” said Williams. Recalling such discussions he had at conferences with lead author Whelton, “they were always good natured and hopefully informative,” he noted.

The reality is that not only do the hypertensions overlap more than they diverge, but also “there is greater consensus than there has probably ever been,” Williams told TCTMD via email, adding, “Despite different approaches to guideline development and different healthcare systems, our independent assessments of vast quantities of data have broadly reached similar conclusions. . . . This can only be a good thing.”

Different Cutoffs, Targets

In comparing the guidelines, the most salient disparity is seen in the cutoffs for what constitutes hypertension. The ACC/AHA lowered the threshold for “stage 1 hypertension” to 130/80 mm Hg, whereas the ESC/ESH chose to keep the traditional cut point of 140/90 mm Hg, with the lower range considered “high normal BP.”

Much controversy ensued when the US set that bar, with some worrying that a broader definition of hypertension would contribute to the rapidly rising prevalence of the disease and strain healthcare systems, especially those in low-income countries but also in the United States. Others pointed to the potential to save more than 300,000 lives each year in the US alone. Amid these debates, clinicians raised the alarm that patient care might suffer.

But Whelton pointed out that in fact, despite the specific cutoffs, management strategies weren’t all that different between the US and Europe. In treating patients, first “make sure you are confident that you got the numbers right, that you’re measuring blood pressure properly,” he stressed. “That’s probably the single biggest problem in management of high blood pressure. It’s a common threat around the world.”

For patients with a BP of 140/90 mm Hg, the next step includes lifestyle improvements as well as drug therapy, according to either the US or European guidelines. For patients with a BP of 130/80 mm Hg, though the terminology varies between the two regions, “both parties would say most people in that category should be treated with lifestyle,” said Whelton. “Really in the most-different area we’re pretty similar.”

Within the latter group, the ACC/AHA recommend drug therapy for the 30% who also have clinical atherosclerotic cardiovascular disease or an estimated 10-year CVD risk ≥ 10%, which by default would apply to older patients. The ESC/ESH say drug treatment can be considered in very-high-risk patients with CVD, especially coronary artery disease.

At its heart, “hypertension” typically is used to refer to times when BP is high enough that “drugs are added into the treatment mix,” Whelton explained. “The Europeans are using the term when 100% of people are being recommended drugs, whereas we’re using the term in the context of a category of blood pressure where a sizeable minority would be recommended to receive drugs.”

The more we can harmonize these guidelines and have a common position, a common platform, I think the better our core message is, and the better our opportunities are for really having impact. Paul K. Whelton

Mancia pointed out that “in life there is no cutoff point” for hypertension. “The relationship between blood pressure and risk is continuous,” he explained. “So the practical decision has been to use a cutoff point [based on] what a very famous British epidemiologist in the 70s said. That is: the level at which we can define hypertension is the blood pressure value above which detection and treatment does more good than harm.”

He said the American approach is “more generous, no question about that,” in identifying about 30% of the stage 1 hypertension patients as candidates for drug therapy, as opposed to the around 10% of high normal patients who’d receive drugs under the European definition. “But again, this is not a major difference. It’s just a difference in the number of people. The concept is the same,” Mancia observed.

The other main gap between the two guideline recommendations relates to BP targets that apply to most patients, with some exceptions based on comorbidities. In the US, the goal is to reach 130/80 mm Hg and, if tolerated, bring systolic BP below 130 mm Hg in noninstitutionalized, ambulatory, community-dwelling adults ages 65 or older. In Europe, the initial target is less than 140/90 mm Hg, followed by a cutoff of 130/80 mm Hg if treatment is well tolerated and then lower levels among patients ages 18 to 65 (though no lower than 120/70 mm Hg).

With the targets, too, “Europeans are a bit more conservative. They say, ‘Well, it’s already difficult enough to go below 140/90 mm Hg, so the first goal should be [that],’” said Mancia, noting that most of the reduction in adverse events when lowering BP occurs between 160 and 140 mm Hg, with lesser reductions seen as BP drops further. “So most of the benefit is achieved at higher blood pressure values.”

What They Share

As the new paper’s authors point out, though, there are numerous similarities. Both the US and European guidelines:

• Stress the need for accurate BP measurements
• Use out-of-office BP readings
• Consider CVD risks when deciding to initiate antihypertensive drugs
• Recommend drug therapy for patients with systolic BP ≥ 140 mm Hg or diastolic BP ≥ 90 mm Hg
• Rely on a similar “core strategy” for antihypertensives, with most adults on combination therapy and single-pill combinations preferred
• Involve lower BP targets than did previous guidelines
• Offer strategies to improve adherence and BP control
• Advise treatment of other CVD risk factors

Moreover, the current US and European guidelines already have more in common than did their predecessors, according to Whelton and colleagues. Shared processes and time lines, as well as liaison members across the two writing groups, could promote harmonization, they suggest. Other possibilities include structured opportunities for writing committees to discuss the science, peer review of each other’s documents, and joint presentations/publications.

Together, the two “guidelines have a common purpose of assisting clinicians, the public health community, and the public in achieving the goal of better health. Current rates of treatment and control of hypertension, however defined, remain suboptimal in Europe and the United States. The more convergent the major American and European guideline recommendations are with each other, the more unified the message to patients, clinicians, professional societies, governmental agencies, and the public,” they conclude.

Mancia told TCTMD that the ESH is currently working to develop new hypertension guidelines, with the plan of releasing them in 2023. The ESC, meanwhile, is working on its own set of guidelines, planned for 2024.

Williams expressed unease about these separate efforts.

“The European guideline situation has the potential to become a real mess,” he said. “Whereas the ESC and ESH worked closely and collaboratively to develop prior iterations of the joint ESC-ESH guidelines, over many years, the ESC has decided to adopt a different approach for future guideline development and this means we will end up with two different guidelines in Europe.”

We should never lose sight of the fact that guideline development is only the start of the process of change. Bryan Williams

Having two separate documents is not in the “best interest of doctors or their patients,” as it produces a lack of clarity, particularly if the guidelines turn out to differ in their advice, Williams cautioned. “We should never lose sight of the fact that guideline development is only the start of the process of change. The real challenge comes from their implementation and that requires pragmatism, advocacy, and support from leaders in the field, all working together with a common purpose, and crucially, with a clear message.”

With the current US and European guidelines, things were headed in the right direction, he said. “I am concerned that we may well now move backwards and lose that advantage with two different guidelines in Europe.”