Hypertension: Definitions and Guidelines

Exactly 100 years ago, Nokolai Korotkoff made one of the most far‐reaching discoveries in cardiovascular medicine: the auscultatory method of blood pressure (BP) measurement. On November 5, 1905, the 31‐year‐old surgeon made a short presentation on the method of BP measurement in the Military Hospital of the St. Petersburg Russian Military Academy. ¹ It took 50 more years for the first effective antihypertensive agents to appear and for many physicians to fully realize that an increase in BP above optimal was not “essential,” but a major cause of fatal and nonfatal cardiovascular diseases. Fifty years after these developments, we arrive at the present, when only about one out of three patients with hypertension has a BP reduced to <140/90 mm Hg—far from optimal for some individuals. ² We are in this situation in spite of enormous advances in understanding the pathophysiology and epidemiology of hypertension and the development of effective and well tolerated medications.

In 1972, the National High Blood Pressure Education Program NHBPEP was officially launched to raise public awareness of hypertension and stimulate BP screenings and treatment. This followed the landmark Veterans Administration study ³ directed by Edward P. Freis, MD, the first controlled clinical trial demonstrating that decreasing elevated BP reduces the rate of strokes and heart attacks. A major achievement of the NHBPEP has been the promulgation of clinical guidelines by the Joint National Committee (JNC) on the Detection, Evaluation and Treatment of High Blood Pressure, which published its first report in 1977. ⁴ Every 4 or 5 years, NHBPEP has issued a report—the latest one, the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC 7), in 2003. ⁵ These reports have synthesized the evidence and unified positions of numerous organizations to send one clear message to the community. Today, 30 years after the first JNC, 69% of hypertensive patients are aware of their condition, 58% are being treated, and about one third are controlled, compared with 51%, 31%, and 10%, respectively, in 1976–1980.^2,5 Concurrently, major declines in the age‐adjusted mortality rates of stroke and coronary heart disease have occurred. Nevertheless, as of the latest National Health and Nutrition Examination Survey (NHANES) data, about one out of four patients with a BP >140 /90 mm Hg is still not aware of having a major cardiovascular abnormality. ²

Most physicians realize that the purpose of treating hypertension is not only to lower BP, but more importantly to prevent serious morbid and mortal events such as heart failure, stroke, myocardial infarction, peripheral vascular disease, and end‐stage renal disease. Physicians are generally aware of the wealth of recent clinical trial evidence indicating that antihypertensive drug therapy lowers the rate of these adverse consequences. Among the causes of the failure to control patients' BP is the fact that professional societies and national and international committees interested in hypertension have not been unanimous and consistent in their recommendations. Guidelines differ with regard to the definition of hypertension, the relative importance of systolic vs. diastolic BP, the level of optimal BP, the identification of patient subsets needing pharmacologic therapy and lifestyle modification and, most important, what is appropriate pharmacotherapy. Of interest is the fact that one or more recommendations promulgated by professional societies and national committees regarding other risk factors such as hypercholesterolemia, the metabolic syndrome, and diabetes are applicable to the majority of patients with hypertension.

Currently, a practicing physician treating a 52‐year‐old patient with an elevated fasting blood glucose and systolic BP, and a low‐density lipoprotein (LDL) cholesterol of 138 mg/dL, may have to read, digest, and synthesize at least three sets of guidelines: JNC 7. ⁵ the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel [ATP] III)⁶; and the American Diabetes Association ⁷ —each of which may be more than 50 pages in length. JNC 7 recommends health‐promoting lifestyle modifications to prevent cardiovascular disease for persons with “prehypertension” (systolic BP 120‐139 mm Hg, diastolic BP 80‐89 mm Hg), a term introduced in JNC 7. ⁵ A 26‐year‐old woman with an LDL and blood glucose of 80 mg/dL, but with a BP of 125/85 mm Hg, would be classified prehypertensive, just as would a 70‐year‐old male smoker with a BP of 125/85 mm Hg and an LDL and blood sugar of 190 mg/dL. Yet the implications of these multiple factors are quite different. Not unexpectedly, these considerations, as well as the changing guidelines across continents, are confusing physicians and patients. In addition, unlike statins in patients with hyperlipidemia, we do not have a silver bullet for patients with high BP. This may also explain, in part, the low rate of control of hypertension. Fortunately, we have come to realize that treatment decisions cannot be based on BP levels alone, but that the absolute global risk is a more important and useful guidepost. Thus, the single‐risk‐factor approach should be replaced by therapeutic decisions based on the global cardiovascular risk.

The new definition of hypertension published in this issue of The Journal of Clinical Hypertension is an important step in clarifying the relationship of BP to cardiovascular risk. ⁸ Antihypertensive therapy should be assessed within the framework of other characteristics of a patient. These include the traditional risk factors and early markers of cardiovascular disease, target organ damage, history of cardiovascular disease, disease biomarkers, functional and/or structural vascular abnormalities, and/or vascular diseases. The new definition also clearly emphasizes that BP alone may be a poor predictor of outcome. At the American Society of Hypertension, Inc. (ASH) meeting in May 2005 in San Francisco, when the new definition of hypertension was presented, it was emphasized that this is a work in progress and that the intent is to further refine these questions.

Eminent physicians with an interest in hypertension have stated that “we have existing guidelines, we just have not applied them; we have existing definitions, but we are not listening to them.” We think that it is an important mission of ASH to enlarge the working group, incorporate members from other national and international groups interested in cardiovascular risk, establish a formal approval process, and promulgate guidelines for cardiovascular risk reduction.

If not us, then who? If not now, when?