Published online before print April 7, 2008, doi: 10.1161/HYPERTENSIONAHA.108.113746
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(Hypertension. 2008;51:1249.)
© 2008 American Heart Association, Inc.
Editorial |
Hypertension
Pathways to Success
From the Center for Excellence in Cardiovascular Renal Research, Departments of Physiology and Biophysics and Medicine, The University of Mississippi Medical Center, Jackson.
Correspondence to Daniel W. Jones, MD, Vice Chancellor for Health Affairs and Dean, School of Medicine, University of Mississippi Medical Center, 2500 N State St, Jackson, MS 39216-4505. Email djones{at}ovc umsmed.edu
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Introduction |
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Top
Introduction
Precise Blood Pressure...The field of hypertension has enjoyed some remarkable successes in recent years. Better blood pressure management has been an important contributor to the recent rapid decline in the age-adjusted death rates for coronary heart disease (CHD) and stroke.1
Yet, there is yet so much more that could be accomplished through better blood pressure management. CHD and stroke remain the first and third leading causes of death in the United States.2 And only slightly more than a third of those with hypertension in the United States achieve recommended treatment goal blood pressure levels.3 Control rates are even worse in most other countries.4 Better blood pressure management can save many lives. Here, some pathways to success are considered.
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Precise Blood Pressure Measurement Technology |
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Few measurements in medicine are done as poorly and inconsistently as blood pressure measurement. Methods used today in clinical practice and in clinical trials are little changed from the earliest days of measurement.5 Though there is a clear recognition of biological variability, we continue to make decisions largely on measurements taken at random times under poorly controlled conditions. The measurement process is less regulated than measurement of most other major risk factors. Just compare the quality control process for glucose or cholesterol measurement with that for blood pressure measurement in your own local setting.
There are not readily available solutions for this issue. Substantial investments in research in this area should be made by government and commercial entities. We must have reliable, reproducible, convenient, and precise measurement tools for blood pressure. These tools should allow for measurement of the important components of blood pressure and mechanisms for integrating and interpreting influence of time of day, activity, and other variables that are known to influence blood pressure.
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Clear Interpretation of Success |
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An issue closely related to the measurement challenges is the ability to clearly mark success or failure in blood pressure control. Part of clinical inertia in adjusting medication dose is the lack of faith in the single office measurement being representative of blood pressure control.6 The introduction of the use of hemoglobin A1C largely resolved that problem in diabetes treatment decision making.7
As we investigate better blood pressure measurement technology, we need to evaluate whether a reliable marker can be established that might more clearly guide success or failure of a given therapy and better guide treatment decisions. Hypotheses for any given marker could be tested in existing longitudinal population studies measuring mortality.
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Clarity on Blood Pressure Independent Drug Effects |
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Another major factor in clinical inertia in adjusting medication type and dose to reach goal blood pressure is the persistent idea that blood pressure goal may be less important than the type of drug selected and potential blood pressure independent effects associated with them. Despite strong evidence that blood pressure level achieved is more important than the selected drug class, many clinicians still seem to be guided by a belief that goal blood pressure is less important than drug class.8 This pattern of practice is likely exacerbated by marketing practices in our current commercial environment.
Further research to better understand blood pressure independent effects of drugs or drug classes should not be discouraged. But clinical trial evidence should be the principal basis for management guidelines, and we must seek better ways of assuring that more clinicians are treating their patients according to evidenced based guidelines and not responding to marketing pressure from commercial interests.
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Coronary Diastolic Flow Issue Resolution |
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A complex issue that likely is a contributor to clinical inertia in giving more drugs to lower blood pressure is the concern over potential adverse effects of lowering diastolic blood pressure in patients with elevated systolic blood pressure and low diastolic blood pressure. There is substantial observational data that demonstrates an association between low diastolic blood pressure and CHD mortality risk. Because the association seems stronger for CHD than stroke, some are convinced the issue is related to low coronary artery blood flow during diastole.9 Others point to clinical trial evidence that demonstrates no increase in risk at lower diastolic pressures and believe the causation is in the opposite direction—that is, low diastolic blood pressure is caused by severe atherosclerosis associated with stiff arteries.10
Current evidence and guidelines are less clear than desirable. Further research to clarify this issue should lead to clearer adherence to guidelines, less clinical inertia, and lives saved.
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Controlled Clinical Trials on Threshold and Goals |
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During more than 50 years of clinical trials in hypertension, we have learned much about treatment thresholds and goals. The changing recommendations over the course of seven Joint National Committee reports reflect the changing evidence produced through many clinical trials. Yet, there is more we must understand. Observational evidence demonstrates a risk associated with systolic blood pressures above 115 mm Hg.
If using interventions beginning early in life to keep systolic blood pressure in this range will save lives, we need to know that. We already understand that those with diabetes mellitus and chronic kidney disease benefit from lower treatment thresholds and treatment goals. We must continue to explore this fertile area of understanding through well designed clinical trials. The trial designs must continue to contemplate that optimal blood pressure levels may be different in patients with different characteristics.
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Consider Primordial Prevention |
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Some consider complete prevention of hypertension to be impossible. Blood pressure tends to rise with age in all modern cultures. But populations leading a primitive lifestyle with high physical activity, low calorie intake, and a diet high in potassium and low in sodium intake do not have an age associated rise in blood pressure.11 And most people with high blood pressure can be controlled on a diet that is very low in sodium intake or by lifestyle changes that reduce body weight.12
Adopting health policies that favor a low sodium, low calorie diet and high physical activity for all beginning at a very early age would likely reduce hypertension rates and cardiovascular disease mortality rates dramatically. Yet adopting these policies in the absence of strong experimental evidence seems unlikely, and conducting clinical trials to demonstrate benefit seems unfeasible in the current climate. However, we must continue to consider these policies at some level. Continued tolerance of today’s environment encouraging low physical activity and high consumption of calories and sodium will sustain our current epidemic of obesity, hypertension, and cardiovascular disease.
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Continued Search for Mechanisms of Blood Pressure Regulation |
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There is a clearer understanding of basic mechanisms of blood pressure regulation than for most other cardiovascular risk factors. Yet, with the exception of a few forms of secondary hypertension (mostly monogenic forms), treatment approaches are largely empirical for those with primary, or essential, hypertension. Because hypertension in most people is a result of complex multi-gene and multi-environmental interactions, there may not be a single "Holy Grail" mechanism leading to a "cure" or prevention mechanism for all.
Yet, past successes and current knowledge suggest there are better solutions available through scientific discovery. Molecular preemption as a strategy for disease prevention, including hypertension prevention, holds promise. Policy makers must find a pathway for reinvigorating the research enterprise through stronger funding mechanisms. Scientific discovery has led the way to our current knowledge and holds great hope for the future.
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Consensus on the Importance of Blood Pressure as a Risk Factor |
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Amazingly, an issue of great concern is that many patients, health providers, researchers, and policy makers simply do not take hypertension seriously. This is despite the fact that by 2015 there will be more than 1.5 billion persons with hypertension worldwide.13 And this is despite the knowledge that hypertension accounts for 50% of all coronary heart disease and 75% of all strokes worldwide.14
Evidence from experimental, clinical, and population studies has pointed to the risk of hypertension and the certainty of the benefit of hypertension treatment longer than any of the other reversible risk factors for cardiovascular disease. A meta-analysis of one million patients in hypertension clinical trials estimates that a 3- to 4-mm Hg increase in systolic BP would translate to 20% higher stroke mortality and a 12% higher coronary heart disease mortality.15
Leadership in the hypertension community must do what is necessary to convince patients, healthcare providers, researchers, and policy makers that hypertension and its management is a high priority. It is time for us to overcome the inertia of the past and find the pathway to realize all the potential benefits from better hypertension prevention, treatment, and control.
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Acknowledgments |
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Disclosures
None.
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Footnotes |
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The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.
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References |
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