High
Blood Pressure Home Page
The terminology
for high blood pressure is changing, as reflected in the table below
and in the information on these pages. In short, the term "hypertension"
corresponds to the clinical condition that requires drug therapy. Previously,
"high blood pressure" and "hypertension" meant the
same thing. Today, however, it is widely accepted than blood pressures
greater than 120/80 mm Hg (or 115/75 mm Hg, according to a stricter
standard defined by the World Health Organization) are problematic--these
are now "high blood pressure" or "non-optimal blood pressures."
Because the risk of caridiovascular disease doubles with each increment
of 20/10 mm Hg above 115/75 mm Hg, and the strength of this relationship
is consistent above and below the threshold for drug therapy, a recent
report from the World Health Organization Global Burden of Disease Study
concluded that
...interventions
only targeting specific subgroups, such as those with a blood pressure
over a certain threshold level, will only partially address the disease
burden. Cardiovascular prevention strategies should include a component
that attempts to lower risk factors such as blood pressure across
the whole population. Even small changes,if experienced across an
entire population, have the potential to result in remarkably large
benefits, particularly if they are complemented by strategies that
aim to focus on identifying and treating individuals at the highest
absolute risk of disease [Lawes
2006].
Approximately 21%
of the adults in San Francisco have been diagnosed with hypertension,
according to the California Health Interview Survey [CHIS].
Among African American San Franciscans the prevalence is approximately
50%. Although this picture reflects national trends, it is at variance
from our national health objective for 2010 of reducing the proportion
of adults with adults to 16% [MMWR
2005].
Between 1991 and
2001, the prevalence of hypertension increased by approximately 3% in
the United States [MMWR
2004]. The higher one's blood pressure the greater the chance of
heart attack, heart failure, stroke, and kidney disease. Hypertension
is a major contributor to cardiovascular disease.
The Seventh Report
of the Joint National Committee on Prevention, Detection, Evaluation
and Treatment of High Blood Pressure (JCN
7) classifies blood pressures as follows:
BP
Classification |
Systolic
mmHg |
Diastolic mmHg |
Lifestyle Modification |
Drug Therapy
(see the most recent expert
guidelines) |
Normal |
<120 |
and <80 |
Encourage |
No |
Prehypertension |
120-139 |
or 80-89 |
Yes |
No, unless
compelling indications |
Stage
1 Hypertension |
140-159 |
or 90-99 |
Yes |
Yes |
Stage
2 Hypertension |
≥160 |
or ≥100 |
Yes |
Yes |
From a public health
perspective [Rose
2001], the "blood pressure problem" is much greater than
the large number of "hypertension cases." Beginning at 115/75
mm Hg, the risk of cardiovascular disease doubles with each increment
of 20/10 mmHg. Worldwide, non-optimal blood pressures (systolic pressures
above 115 mm Hg) account for 65% of stroke, 49% of ischemic heart disease,
and 14% of other cardiovascular disease (including hypertensive heart
disease and hypertensive kidney disease) [Lawes
2006].
A considerable burden
comes from non-optimal blood pressures that are below the arbitrary
cut-off point for drug therapy. In a prospective cohort analysis of
8,960 adults with "prehypertension" (defined in above table),
the relative risk of cardiovascular disease was 2.33 for systolic pressures
130-139 mm Hg and 1.81 for systolic pressures 120-29 mm Hg. At these
blood pressures, the relative risks were much higher for diabetics and
for blacks [Kshirsagar
2006].
Lowering the blood
pressures of the entire population, even by small amounts, holds the
potential for large benefits [Rose
2001; Lawes
2006].