second leading cause of death among men (second to smoking) (Lloyd-Jones et al., 2009). Hypertension is estimated to contribute to 35 percent of myocardial infarctions and strokes and 49 percent of episodes of heart failure (AHRQ, 2007).

Hypertension is diagnosed by a simple test. Using a sphygmomanometer, blood pressure is typically measured at two points: at peak pressure when the heart is most contracted (this point is referred to as systolic blood pressure) and then when the heart is most relaxed (diastolic pressure). High blood pressure for adults is defined as a systolic pressure of 140 mm Hg or greater or a diastolic pressure of 90 mm Hg or greater or using antihypertensive medication. Using this definition, hypertension is highly prevalent; nearly one in three U.S. adults has hypertension (Fields et al., 2004; Lloyd-Jones et al., 2009). The risk of developing hypertension increases with age. In older age groups it is more common than not; based on data from the Framingham study, the lifetime risk of hypertension is estimated to be 90 percent for people with normal blood pressure at age 55 or 65 who live to be age 80-85, respectively (Cutler et al., 2007; Vasan et al., 2002). Approximately 73 million Americans have high blood pressure, and an additional 59 million have prehypertension, which is defined as blood pressure ranging from 120-139 mm Hg systolic and/or 80-89 mm Hg diastolic. Prehypertension is a new classification introduced by the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (Chobanian et al., 2003)1 because of the increasing amount of data associating cardiovascular complications with what had previously been considered normal blood pressure readings. Figure 1-1 shows the increased risk of heart disease death, and Figure 1-2 shows the increased risk of stroke death, associated with prehypertension and hypertension by decade of life. Starting at a systolic blood pressure of 115 mm Hg, every 20 mm Hg increase in systolic blood pressure is associated with a doubling in the risk of death from both heart disease and from stroke.

Hypertension is highly treatable, and a range of medications—some relatively inexpensive—are available. In the late 1950s and early 1960s, oral diuretics were primarily used to treat hypertension. Since then, additional medications including calcium channel blockers and beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, and angiotensin receptor antagonists can be found among the antihypertensive therapies available

1

The NHLBI administers the National High Blood Pressure Education Program Coordinating Committee, a coalition of 39 major professional, public, and voluntary organizations and 7 federal agencies. An important function of the committee is to issue guidelines and advisories designed to increase awareness, prevention, treatment, and control of hypertension. Reports from this body are referred to by their number: in this case, the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (Chobanian et al., 2003).



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