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Screening for Hypertension
Recommendation:
Blood pressure should be measured regularly in all persons
aged 3 and above (see Clinical Intervention).
Burden of Suffering
Hypertension may occur in as many as 58 million Americans.1
It is a leading risk factor for coronary artery disease,
congestive heart failure, stroke, renal disease, and
retinopathy. These complications of hypertension are among
the most common and serious diseases in the United States,
and successful efforts to lower blood pressure could thus
have substantial impact on population morbidity and
mortality. Heart disease is the leading cause of death in
the United States, accounting for over 765,000 deaths each
year, and cerebrovascular disease, the third leading cause
of death, accounts for 150,000 deaths each year.2
Hypertension is more common in blacks and the elderly.1
Efficacy of Screening Tests
The most accurate devices for measuring blood pressure
(e.g., intraarterial catheters) are not appropriate for
routine screening because of their invasiveness, technical
limitations, and cost. Office sphygmomanometry (the blood
pressure cuff) remains the most appropriate screening test
for hypertension in the asymptomatic population. Although
this test is highly accurate when performed correctly,
false-positive and false-negative results (i.e., recording
a blood pressure that is not representative of the
patient's mean blood pressure) do occur in clinical
practice.3 A recent study found that 21% of persons
diagnosed as mildly hypertensive based on office
sphygmomanometry had no evidence of hypertension when
24-hour ambulatory recordings were obtained.4
Errors in measuring blood pressure may result from
instrument, observer, and/or patient factors.5 Examples of
instrument error include manometer dysfunction, pressure
leaks, stethoscope defects, and bladders of incorrect width
and length for the patient's arm size. The observer can
introduce errors due to sensory impairment (difficulty
hearing Korotkoff sounds or reading the manometer),
inattention, inconsistency in recording Korotkoff sounds
(e.g., Phase IV vs. Phase V), and subconscious bias (e.g.,
digit preference'' for numbers ending with zero or
preconceived notions of normal'' pressures). The patient
can be the source of misleading readings due to posture and
biological factors. Posture (i.e., lying, standing,
sitting) and arm position in relation to the heart can
affect results by as much as 10 mm Hg.5 Biological factors
include anxiety, meals, tobacco, temperature changes,
exertion, and pain. Due to these limitations in the
test-retest reliability of blood pressure measurement, it
is commonly recommended that hypertension be diagnosed only
after more than one elevated reading is obtained on each of
three separate visits.1
Additional factors affect accuracy when performing
sphygmomanometry on children; these difficulties are
especially common when testing infants and toddlers under
age 3.6 First, there is increased variation in arm
circumference, requiring greater care in the selection of
cuff sizes. Second, the examination is more frequently
complicated by the anxiety and restlessness of the patient.
Third, the disappearance of Korotkoff sounds (Phase V) is
often difficult to hear in children and Phase IV values are
often substituted. Fourth, erroneous Korotkoff sounds can
be produced inadvertently by the pressure of the
stethoscope diaphragm against the antecubital fossa.
Finally, the definition of pediatric hypertension has
itself been uncertain because of confusion over normal
values during childhood. Previous criteria using population
data to define the 95th percentile at different ages were
erroneously high.7 Revised criteria for pediatric
hypertension, based on data from over 70,000 children, have
recently been published6 (see Clinical Intervention).
Effectiveness of Early Detection
There is a direct relationship between the magnitude of
blood pressure elevation and the benefit of lowering
pressure. In persons with malignant hypertension, the
benefits of intervention are most dramatic; treatment
increases five-year survival from near zero (data from
historical controls) to 75%.8 The efficacy of treating
moderate hypertension (diastolic blood pressure above 104
mm Hg) is also clear, as demonstrated in the Veterans
Administration Cooperative Study on Antihypertensive
Agents.9-11 In this randomized double-blind controlled
trial, middle-aged men with diastolic blood pressure above
104 mm Hg experienced a significant reduction in
cardiovascular events after treatment with antihypertensive
medication.
Persons with mild hypertension (diastolic blood pressure of
90-104 mm Hg) also benefit from treatment. This was
confirmed in the Hypertension Detection and Follow-Up
Program, a randomized controlled trial involving nearly
11,000 hypertensives.12 The intervention group received
standardized pharmacologic treatment (stepped care'') while
the control group was referred for community medical care.
There was a statistically significant 17% reduction in
five-year all-cause mortality in the group receiving
standardized drug therapy; the subset with mild
hypertension experienced a 20% reduction in mortality.12
Deaths due to cerebrovascular disease, ischemic heart
disease, and other causes were also significantly reduced
in the stepped care group.13 Similar results have been
reported in other studies, such as the Australian National
Blood Pressure Study14 and the Medical Research Council
trial.15 Although treatment of hypertension is associated
with multiple benefits, the greatest effect appears to be
in the prevention of cerebrovascular disease.16 Improved
treatment of high blood pressure has been credited with the
greater than 50% reduction in age-adjusted stroke mortality
that has been observed since 1972.1,17
Although the efficacy of antihypertensive treatment has
been well established in clinical research, certain factors
may influence the magnitude of benefit achieved in actual
practice. First, the benefits of treatment may be less
significant or less well proven in certain population
groups, such as children. Second, nonpharmacologic
first-line therapy (e.g., weight reduction, exercise,
sodium restriction, decreased alcohol intake) may be less
effective than drug therapy in achieving significant and
consistent blood pressure reductions. Although it is known
that weight reduction and sodium restriction can lower
blood pressure,18,19 the magnitude and duration of
reduction in actual practice may be limited by biological
factors (e.g., hypertensives who are not salt-sensitive'')
and the difficulties of maintaining behavioral changes
(e.g., weight loss). Finally, compliance with drug therapy
may be limited by the inconvenience, side effects, and cost
of these agents.20,21
Recommendations of Others
Revised recommendations for adults from the National Heart,
Lung, and Blood Institute were issued recently by the Joint
National Committee on Detection, Evaluation, and Treatment
of High Blood Pressure,1 and similar recommendations have
been issued by the American Heart Association.22 These call
for routine blood pressure measurement at least once every
two years for persons with a diastolic blood pressure below
85 mm Hg and a systolic pressure below 140 mm Hg.
Measurements are recommended annually for persons with a
diastolic blood pressure of 85-89 mm Hg. Persons with
higher blood pressures require more frequent measurements.
The Canadian Task Force recommends that all persons aged 25
and over receive a blood pressure measurement during any
visit to a physician.23 The American Academy of Pediatrics
and the National Heart, Lung, and Blood Institute recommend
that children and adolescents receive annual blood pressure
measurements from ages 3-20.6
Discussion
It is clear from several large clinical trials that
lowering blood pressure is beneficial and that the
population incidence of several leading causes of death can
be reduced through the detection and treatment of high
blood pressure. An average diastolic blood pressure
reduction of 6-8 mm Hg across the population could reduce
the incidence of coronary artery disease by 25% and the
incidence of strokes by 50%.24 At the same time, it is
important for clinicians to minimize the potential harmful
effects of detection and treatment. For example, if
performed incorrectly, sphygmomanometry can produce
misleading results. Some hypertensive patients thereby
escape detection (false negatives) and some normotensive
persons receive inappropriate labeling (false positives),
which may have certain psychological, behavioral, and even
financial consequences.25 Treatment of hypertension can
also be harmful as a result of medical complications,
especially related to drugs. Clinicians can minimize these
effects by using proper technique when performing
sphygmomanometry, making appropriate use of
nonpharmacologic methods, and prescribing antihypertensive
drugs with careful adherence to current guidelines.
Clinical Intervention
Blood pressure should be measured regularly in all persons
aged 3 and above. The optimal interval for blood pressure
screening has not been determined and is left to clinical
discretion. Current expert opinion is that persons thought
to be normotensive should receive blood pressure
measurements at least once every two years if their last
diastolic and systolic blood pressure readings were below
85 mm Hg and 140 mm Hg, respectively, and annually if the
last diastolic blood pressure was 85-89 mm Hg.1
Sphygmomanometry should be performed in accordance with
recommended technique.*1 Hypertension should not be
diagnosed on the basis of a single measurement; elevated
readings** should be confirmed on more than one reading at
each of three separate visits. Once confirmed, patients
should receive counseling regarding exercise (see Chapter
49), weight reduction, dietary sodium intake (Chapter 50),
and alcohol consumption (Chapter 47).1 Other cardiovascular
risk factors, such as smoking and elevated serum
cholesterol, should also be discussed (Chapters 2 and 48).
Antihypertensive drugs should be prescribed in accordance
with recent guidelines1 and with attention to current
techniques for improving compliance.20,21
Notes
*Guidelines for Sphygmomanometry
Patient should be seated with arm bared, supported, and
positioned at heart level.
Patient should have refrained from smoking or ingesting
caffeine within 30 minutes before measurement.
Measurement should begin after five minutes of quiet
rest.
An appropriate cuff size (child, adult, large adult)
should be selected; the rubber bladder should encircle at
least two thirds of the arm.
Measurements should be taken with a mercury
sphygmomanometer, a recently calibrated aneroid manometer,
or a validated electronic device.
Both systolic and diastolic pressures should be recorded;
the disappearance of sound (Phase V) indicates the
diastolic pressure.
Two or more readings should be averaged; if the first two
differ by more than 5 mm Hg, additional readings should be
obtained.
**In adults, current blood pressure criteria for the
diagnosis are a diastolic pressure of 90 mm Hg or greater
or a systolic pressure of 140 mm Hg or greater.1() In
children, the criteria vary with age:6
Pediatric Blood Pressure
Age (Yrs) Diastolic (mm Hg) Systolic (mm Hg)
0-2 74 112
3-5 76 116
6-9 78 122
10-12 82 126
13-15 86 136
References
1.
1988 Joint National Committee. The 1988 report of the Joint
National Committee on Detection, Evaluation, and Treatment
of High Blood Pressure. Arch Intern Med 1988; 148:1023-38.
2. National Center for Health Statistics. Advance report of
final mortality statistics, 1986. Monthly Vital Statistics
Report [Suppl], vol. 37, no. 6. Hyattsville, Md.: Public
Health Service, 1988. (Publication no. DHHS (PHS)
88-1120.)
3.
Tifft CP. Are the days of the sphygmomanometer past? Arch
Intern Med 1988; 148:518-9.
4.
Pickering TG, James GD, Boddie C, et al. How common is
white coat hypertension? JAMA 1988; 259:225-8.
5.
Kirkendall WM, Feinleib M, Freis ED, et al. Recommendations
for human blood pressure determination by
sphygmomanometers. Subcommittee of the AHA Postgraduate
Education Committee. Circulation 1980; 62:1146A-55A.
6.
Task Force on Blood Pressure Control in Children. Report of
the Second Task Force on Blood Pressure Control in
Children--1987. Pediatrics 1987; 79:1-25.
7.
Mehta SK. Pediatric hypertension: a challenge for
pediatricians. Am J Dis Child 1987; 141:893-4.
8.
Hansson L. Current and future strategies in the treatment
of hypertension. Am J Cardiol 1988; 61:2C-7C.
9.
Veterans Administration Cooperative Study Group on
Antihypertensive Agents. Effects of treatment on morbidity
in hypertension. III. Influence of age, diastolic pressure,
and prior cardiovascular disease: further analysis of side
effects. Circulation 1972; 45:991-1004.
10.
Idem. Effects of treatment on morbidity in hypertension:
results in patients with diastolic pressures averaging 115
through 129 mm Hg. JAMA 1967; 202:1028-34.
11.
Idem. Effects of treatment on morbidity in hypertension.
II. Results in patients with diastolic pressures averaging
90 through 114 mm Hg. JAMA 1970; 213:1143-52. 12.
Hypertension Detection and Follow-Up Program Cooperative
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Follow-Up Program. I. Reduction in mortality of persons
with high blood pressure, including mild hypertension. JAMA
1979; 242:Idem. Persistence of reduction in blood pressure
and mortality of participants in the Hypertension Detection
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14.
Management Committee of the Australian National Blood
Pressure Study. The Australian therapeutic trial in mild
hypertension. Lancet 1980; 1:1261-7.
15.
Medical Research Council Working Party. MRC trial of
treatment of mild hypertension: principal results. Br Med J
1985; 291:97-104.
16.
MacMahon SW, Cutler JA, Furberg CD, et al. The effects of
drug treatment for hypertension on morbidity and mortality
from cardiovascular disease: a review of randomized,
controlled trials. Prog Cardiovasc Dis [Suppl] 1986;
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1987; 258:214-7.
17.
Garraway WM, Whisnant JP. The changing pattern of
hypertension and the declining incidence of stroke. JAMA
1987; 258:214-7.
18.
Nonpharmacological approaches to the control of high blood
pressure. Final report of the Subcommittee on
Nonpharmacological Therapy of the 1984 Joint National
Committee on Detection, Evaluation, and Treatment of High
Blood Pressure. Hypertension 1986; 8:444-67.
19.
Stamler J, Stamler R. Intervention for the prevention and
control of hypertension and atherosclerotic diseases:
United States and international experience. Am J Med 1984;
76:13-36.
20.
McClellan WM, Hall WD, Brogan D, et al. Continuity of care
in hypertension: an important correlate of blood pressure
control among aware hypertensives. Arch Intern Med 1988;
148:525-8.
21.
National Institutes of Health. The physician's guide:
improving adherence among hypertensive patients. Working
Group on Health Education and High Blood Pressure Control.
Bethesda, Md.: Department of Health and Human Services,
1987.
22.
Grundy SM, Greenland P, Herd A, et al. Cardiovascular and
risk factor evaluation of healthy American adults. A
statement for physicians by an ad hoc committee appointed
by the Steering Committee, American Heart Association.
Circulation 1987; 75:1340A-62A.
23.
Canadian Task Force on the Periodic Health Examination.
1984 update. Can Med Assoc J 1984; 130:2-15.
24.
Blackburn H. Public policy and dietary recommendations to
reduce the population level of blood cholesterol. Am J Prev
Med 1985; 1:3-11.
25.
MacDonald LA, Sackett DL, Haynes RB, et al. Labelling in
hypertension: a review of the behavioral and psychological
consequences. J Chron Dis 1984; 37:933-42.
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