New hypertension guidelines: One size fits most?

Limitations and concerns

While the evidence-based nature of the recommendations is a strength, information from observational studies, systematic reviews, and meta-analyses was not incorporated into the formulation of these guidelines. This limits the available evidence, reflected in the fact that despite an extensive attempt to provide recommendations based on good evidence, five of the 10 recommendations (including the corollary recommendation) are still based on expert consensus opinion. Comparing and combining studies from different time periods is also problematic because of different methods of conducting clinical trials and analysis, and also because clinical care in a different period may differ from current standard practices.

Blood pressure targets in some subgroups are not clearly addressed, including those with proteinuria and with a history of stroke. Peterson et al,¹⁹ in an editorial accompanying the JNC 8 publication, commented on the need for larger randomized controlled trials to compare different blood pressure thresholds in various patient populations.

Some health care providers will likely be concerned that relaxing blood pressure goals could lead to higher real-world blood pressures, eventually leading to adverse cardiovascular outcomes, particularly on a population level. This is akin to the “speed limit rule”—people are more likely to hover above target, no matter what the target is.

In another editorial, Sox²⁰ raised concerns about the external review process, ie, that the guidelines were not published in draft form to solicit public comment. Additionally, although the recommendations underwent extensive review, they were not endorsed by the specialty societies that the NHLBI designated to develop guidelines. In its defense, however, the JNC 8 panel has offered to share records of the review process on request, and this should serve to increase confidence in the review process.

The original literature search was limited to studies published through December 2009, which is more than 4 years before the publication of the recommendations. Although a bridge search was conducted until August 2013 to identify additional studies, this search used different inclusion criteria than the original criteria.

With its narrow focus, JNC 8 does not address many relevant issues. The American Society of Hypertension/International Society of Hypertension guidelines, published around the same time that the JNC 8 report was released, provide a more comprehensive review that will be of practical use for health care providers in the community.¹⁰

Ambulatory blood pressure monitoring is increasingly being used in clinical practice to detect white coat hypertension and, in many cases, to assess hypertension that is resistant to medications. It has also been shown to have better prognostic value in predicting cardiovascular risk and progression of kidney disease than office blood pressures.^21,22 The UK National Institute of Health and Care Excellence guideline recommends ambulatory monitoring for the diagnosis of hypertension.²³ However, JNC 8 did not provide specific recommendations for the use of this technology. Additionally, the JNC 8 evidence review is based on studies that used office blood pressure readings, and the recommendations are not necessarily applicable to measurements obtained by ambulatory monitoring.

Other topics covered in JNC 7 but not in JNC 8 include:

• Definitions and stages of hypertension (which remain the same)
• Initial treatment of stage 2 hypertension with two medications
• The J-curve phenomenon
• Preferred medications for patients with coronary artery disease or congestive heart failure
• A detailed list of oral antihypertensive agents—JNC 8 confines itself to the drugs and doses used in randomized controlled trials
• Patient evaluation
• Secondary hypertension
• Resistant hypertension
• Adherence issues.

Contrast with other guidelines

While the goal of these recommendations is to make treatment standards more understandable and uniform, contrasting recommendations on blood pressure goals and medications from various groups muddy the waters. Other groups that have issued hypertension guidelines in recent years include:

• The American Diabetes Association²⁴
• The American Society of Hypertension and the International Society of Hypertension¹⁰
• The European Society of Hypertension and the European Society of Cardiology²⁵
• The Canadian Hypertension Education Program²⁶
• The Kidney Disease: Improving Global Outcomes initiative¹⁴
• The National Institute for Health and Clinical Excellence (UK)²³
• The International Society on Hypertension in Blacks²⁷
• The American Heart Association, the American College of Cardiology, and the US Centers for Disease Control and Prevention.²⁸

Future directions

Despite the emphasis on making treatment decisions on an individual basis and using guidelines only as a framework for a safe direction in managing difficult clinical scenarios, guideline recommendations are increasingly being used to assess provider performance and quality of care, and so they assume even more importance in the current health care environment. As specialty organizations review and decide whether to endorse the JNC 8 recommendations, reconciling seemingly disparate recommendations from various groups is needed to send a clear and concise message to practitioners taking care of patients with high blood pressure.

Although a daunting task, integrating guidelines on hypertension management with other cardiovascular risk guidelines (eg, cholesterol, obesity) with assessment of overall cardiovascular risk profile would likely help in developing a more effective cardiovascular prevention strategy.

Despite the panel’s best efforts at providing evidence-based recommendations, many of the recommendations are based on expert opinion, reflecting the need for larger well-conducted studies. It is hoped that ongoing studies such as the Systolic Blood Pressure Intervention Trial²⁹ will provide more clarity about blood pressure goals, especially in the elderly.

Final thoughts

Guidelines are not rules, and while they provide a framework by synthesizing the best available evidence, any treatment plan should be formulated on the basis of individual patient characteristics, including comorbidities, lifestyle factors, medication side effects, patient preferences, cost issues, and adherence.