Manual of Clinical Nutrition Management III- 62 Copyright © 2013 Compass Group, Inc.
HYPERTENSION
Discussion
At least 50 million adults in the United States have hypertension (1). According to the Seventh Report of the
Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (referred
to as the JNC 7), 30% of these adults are unaware that they have hypertension, and more than 40% of adults
with hypertension are not receiving treatment (2). The prevalence of hypertension increases with advancing
age. More than half of people aged 60 to 69 years and approximately three fourths of people aged 70 years
and older have hypertension (1). Based on data from the Framingham Heart Study, people who are
normotensive at 55 years of age have a 90% lifetime risk of developing hypertension (3). In African
Americans, hypertension is more common and more severe. It develops at an earlier age and leads to more
clinical complications (2).
Hypertension is an increasingly important medical and public health issue (2). For every 20 mm Hg systolic
or 10 mm Hg diastolic increase in blood pressure, the mortality from ischemic heart disease and stroke
doubles. Data from the Framingham Heart Study indicate that blood pressure values in the range of 130 to
139 mm Hg systolic and 85 to 89 mm Hg diastolic are associated with a more than 2-fold increase in the
relative risk of cardiovascular disease when compared with blood pressure levels below 120/80 mm Hg (4,5).
Based on this emerging data on the lifetime risk of hypertension and the impressive increase in the risk of
cardiovascular complications associated with levels of blood pressure previously considered normal (140/90
mm Hg), the JNC 7 has established a blood pressure classification system that contains a prehypertension
category and ranges for staging hypertension (2). (Refer to Table III- 13 .)
Table III- 13 : JNC 7 Classification of Blood Pressure for Adults Aged 18 Years and Older (2)
Category Systolic (mm Hg) Diastolic (mm Hg)
Optimala
Prehypertensionb
<120
120 - 139
and <80
or 80- 89
Stage 1 hypertensionc
Stage 2 hypertensionc^
140 - 159
> 160
or 90- 99
or ≥ 100
aOptimal blood pressure with respect to cardiovascular risk is less than 120/80 mm Hg. Unusually low readings should be evaluated.
bPrehypertension is not a disease category, rather it is a designation that identifies individuals at high risk of developing hypertension.
Lifestyle modifications are recommended to reduce the risk for developing hypertension. For patients who have diabetes mellitus or
kidney disease, drug therapy should be considered if a trial of lifestyle modifications fails to reduce blood pressure to 130/80 mm Hg
or less.
cBased on the average of two or more properly measured blood pressure readings taken while seated during two or more visits
Classification and Approaches to Treatment
The classification system introduced by the JNC 7 includes a prehypertension category for individuals who
have blood pressure readings of 120 to 139 mm Hg systolic or 80 to 89 mm Hg diastolic. Prehypertension is
not a disease category, rather it is a designation that identifies individuals at high risk of developing
hypertension (2). Individuals in the prehypertension category are advised to adopt lifestyle modifications,
including dietary modifications and physical activity, to reduce their risk of developing hypertension. For
patients who have prehypertension and diabetes mellitus or kidney disease, drug therapy should be
considered if lifestyle modifications fail to reduce blood pressure to 130/80 mm Hg (2).
The JNC 7 does not stratify individuals with hypertension by the presence or absence of risk factors or
target organ damage. The JNC 7 suggests lifestyle modifications as an adjunctive therapy to pharmacotherapy
for all persons who have stage 1 or stage 2 hypertension (2). The treatment goal for individuals who have
hypertension and no other medical conditions is a blood pressure of 140/90 mm Hg or less (2). For
individuals who have hypertension and diabetes mellitus or kidney disease, the treatment goal is 130/80 mm
Hg (2). The JNC 7 indicates that greater attention should be provided to the monitoring and evaluation of
systolic blood pressure as a major risk factor for cardiovascular disease (2). The increase in systolic blood
pressure continues throughout life, in contrast to diastolic blood pressure, which increases until 50 years of
age and then tends to level-off during the next decade. Systolic hypertension is the most common form of
hypertension in people older than 50 years. The diastolic blood pressure is a more potent cardiovascular risk
factor than systolic blood pressure prior to 50 years of age; thereafter, systolic blood pressure is more
important (2). (Refer to Table III- 14 .)