Data from the

NATIONAL HEALTH SURVEY

Series 11

Number 150

BloodPressureof

Persons18=74Years

United States, 1971-72

●

Preliminary findings for systolic and diastolic blood pressures

of adults by age, ~ex, and race, from the first Health and

Nutrition Examination Survey during 1971-72.

DHEW Publication No. (H RA) 75-1632

U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE

Public Health Service

Health Resources Administration

National Center for Health Statistics

Rockville, Md. April 1975
I

Library of Congress Cataloging in Publication Data I

I

Roberts, Jean I

Blood pressure of persons 18-74 years, United States, 1971-72.

(Data from the National Health Survey, series 11, no. 150) (DHEW publication no.

(HRA) 75-1632)

Includes bibliographical references.

Supt. of Dots. no.: HE 20.2210:11/150

1. Blood pressure--Measurement. 2. United States--Statistics, Medical. I. Title. II. Series:

United States. National Center for Health Statistics. Vital and health statistics. Series 11:

Data from the National Health Survey. Data from the health examination survey, no. 150.

III. Series: United States. Dept. of Health, Education, and Welfare. DHEW publication no.

(HRA) 75-1632. [DNLM: 1. Age factors. 2. Blood pressure. 3. Blood pressure determination.

4. Sex factors. W2 A N148vk no. 150]

RA407.3.A347 no. 150 [RC74] 312’.0973s [312’.6]

ISBN 0-8406-0031-3 74-19260
NATIONAL CENTER FOR HEALTH STATISTICS

EDWARD B. PERRIN, Ph. D., Direc tor

PHILIP S. LAWRENCE, SC.D., Deputy Director

GAIL F. FISHER, Associate Director for the Cooperative Health Statistics System

ELIJAH L, WHITE, Associate Director for Data Systems

IWAO M. MORIYAMA, Ph. D., Associate Director for International Statistics

EDWARD E. MINTY, Assoczizte Director for Management

ROBERT A. ISRAEL, Assocti te Director for Operations

QUENTIN R. REMEIN, Associate Director for Program Development

ALICE HAYWOOD, Information Officer

DIVISION OF HEALTH EXAMINATION STATISTICS

ARTHUR J. McDOWELL, Director

JEAN-PIERRE HABICHT, M.D., Ph. D., Special Assistant to Director

PETER V. V. HAMILL, M.D., Medical Adviser

JEAN ROBERTS, ChieJ Medical Statistics Branch

ROBERT S. MURPHY, Chiej Survey Planning and Deve~opment Branch

ARNOLD ENGEL, M.D., Medical Adviser, Adult Program

COOPERATION OF THE BUREAU OF THE CENSUS

In accordance with specifications established by the National

Health Survey, the Bureau of the Census, under a contractual

agreement, participated in the design and selection of the sample,

and carried out the first stage of the field interviewing and certain

parts of the statistical processing.

Vital and Health Statistics-Series 1l-No, 150

DHEW Publication No. (HRA) 75-1632

Library of Congress Catalog Card Number 74-19260
CONTENTS

Page

Introduction ----------------------------------------------------------

Blood PressureMeasurements ------------------------------------------

Findings -------------------------------------------------------------

Systolic Pressure --------------------------- -------.- --------- -----

Diastolic Pressure --------- ------------------- -----------------------

Race ------- ------- -------- ------- ------- ------- ------- ------- -----

Elevated Blood Pressures -------------------------------------------

Comparison With Previous Studies --------------------------------------

Summary -------------------------------------------------------------

References -----------------------------------------------------------

List of Detailed Tables -----------------------------------------------

Appendix. Statistical Notes --------------------------------------------

~e Survey Design --------------------------------------------------

Nonresponse -------------------------------------------------------

Missing Data ------------------------------------------------------

Small Numbers -----------------------------------------------------

Sampling and Measurement Error ------------------------------------

1

2

4

4

4

7

7

8

11

12

13

20

20

21

22

22

22

...

Ill
SYMBOLS

I

Data not available ---------------------------------------- --- I

Category not applicable ------------------------------- . . .

I

Quantity zero ---------------------------------------------- -

I

Quantity more than Obut less than 0.05 ----- 0.0

Figure does not meet standards of

reliability or precision ---------------------------- *

Iv
BLOOD PRESSURE OF PERSONS

18-74 YEARS

Jean Roberts, Division of Health Examination Statistics

INTRODUCTION

This report contains preliminary data on

blood pressure obtained as part of the examination used in assessing the nutritional and related

health status of the U.S. population ages 1 through

74 years. It is one of several preliminary reports

of findings on health status obtained in the first

Health and Nutrition Examination Survey. The

findings here are limited to blood pressures of

adults age 18-74 years.

The Health Examination Survey, in which

these data were obtained, is one of the maj$or

programs of the National Center for Health

Statistics authorized under the National Health

Survey Act of 1956 by the 84th Congress as a

continuing Public Health Service activity to determine the health status of the population.

The programs used to carry out the intent

of the National Health Survey 1 include: the

Health Examination Survey; the Health Interview

Survey which collects health information from

samples of people by household interviews focused

primariIy on the impact of illness and disability within various population groups; the

Heulth Manpower and Facilities surveys which

obtain data on hospitak, nursing homes and other

resident institutions, and the entire range of

personnel in the health occupations; and the

Health Resources Utilization surveys.

Only in the Health Examination Survey are

health data collected by direct physical examination, tests, and measurements performed on

samples of the population. Hence it provides

the best of the survey methods for obtaining

diahmostic data on the prevalence of medicalIy

defined illness. It is the only one of the National

Center for Health Statistics’ programs to secure

information on unrecognized or undiagnosed conditions as well as on a variety of physical,

physiological, and psychological measures within

the population. Also collected are medical history, demographic, and socioeconomic data on

the sample population under study with which

the examination findings may be interrelated.

The Health Examination Survey has been

conducted as a series of separate programs,

called cycles, each of which is limited to some

specific segment of the United States population

and to specific aspects of health. During the

first cycle in 1960-62 the prevalence of certain

chronic diseases and the distribution of various

physical and physiological measures, including

blood pressure, were determined among a de2,3 For that program a

fined adult population.

national probability sample of 7,710, of which

6,67.2 (86.5 percent) were examined, was selected

to represent the 111 miHion civilian, noninstitutionalized adults in the U.S. population at

that time.

The target populations for the second and

third cycles in 1963-65 and 1966-70 were, respectively, the Nation’s noninstitutionalized children 6-11 years of age and youths 12-17 years

of age.4’5 In both, the examination focused primarily on health factors related to growth and

development. For the second program the size

of the probability sample to represent the nearly

24 million U.S. children 6-11 years in the noninstitutionalized population was 7,417, of which

7,1 I 9 or 9(5 percent were examined. In the

youths’ program the national probability sample

size was 7,518, with 6,768 or 90 percent examined, to represent the 22.7 million of that
age in thecivilian, noninstitutionalized population.

The Health and Nutrition Examination Survey

program (HANES), from which the findings in

this report were derived, was designed to measure the nutritional status of the United States

population of ages 1 through 74 years and to

obtain some limited information on general health

status of the entire age group as well as further

information on the health status and medical

care needs of those from 25 through 74 years

in the civilian, noninstitutionalized. population.

A detailed description of the specific content

and plan of operation, including sample design,

has been published.6.

As in previous Health Examination Survey

programs, the Bureau of the Census cooperated

in the sample design and in the initial visits

and interviewing at selected eligible households

in the 65 primary sampling units (PSU’s) throughout the United States. Additional household visiting, interviewing, history taking, and explaining

the examination portion of the program were

performed by members of the field teams of

the mobile examination center. The selected

sample persons for whom an appointment could

be made were brought into the specially constructed mobile examination centers which were

moved into a central location in each of the

primary sampling units. The teams which traveled to the various survey locations throughout

the country included professional and paraprofessional medical and dental examiners along with

technicians, interviewers, and other staff.

The probability sample design used in the

study provided for a higher sampling ratio of

the poor, preschool children, women of childbearing ages, and the elderly than of others

in the civilian, noninstitutionalized population.

It further provided for a nationally representative

subset of 35 of the 65 initially planned primary

sampling units throughout the United States so

that some preliminary national findings could

be published before the total survey was completed. More detailed reports will be forthcoming.

The preliminary findings in this report

are based on the examination of 6,525 persons

aged 18-74 years from the total group of 10,126

examined persons aged 1 through 74 years in

a representative subset of 35 of the 65 PSU’S

which make up the total sample. A sample of

14,147 persons age 1-74 years was selected

to be examined at these 35 locations which

were visited between April 1971 and October

1972. These 14,147 sample persons are a probability sample of the total U.S. population; if

a high proportion of them had been examined,

the examined group could also have been regarded as a probability sample of the total

population of 192.7 million in the civilian, noninstitutionalized population aged 1-74 years of

age at that time. However, despite intensive

efforts, the program succeeded in examining

only 10,126 of these sample persons. This represents 72.8 percent of the sample persons

when adjustments are made for differential sampling rates for the age-, sex-, and incomedefined population subgroups. (The unadjusted

overall response rate was 71.6 percent.)

Surveys of the National Center for Health

Statistics, including all earlier programs of

the Health Examination Surveys, have achieved

higher levels of response than have been reached

for the 35-stand subsample in this first HANES.

The 72.8 percent response rate fails to meet

fully the requirements of the original probability

design. Following a policy of renumeration of

participants adopted after the completion of 20

PSU’S, there has been a significant increase

in participation.

National estimates in this report are based

on weighted observations, i.e., the data obtained

for each examined person are inflated to the

level of the total population. The estimates have

been calculated as though the examined persons

in each of the age, sex, and income classes

are a random subsample of the sample persons

in the same class. While there is evidence from

earlier examination surveys and medical history

data from HANES that this is not an unreasonable

approximation, it is clear that some estimates

are subject to considerable risk of bias, when

more than one-quarter of the sample persons

in a particular age-sex-income class were not

examined.

BLOOD PRESSURE MEASUREMENTS

At the beginning of the examination in the

nutrition screening evaluation, the physician took

2
the examinee’s blood pressure

seated on the examining table.

with the examinee

Blood pressure was measured indirectly

with standard clinical sphygmomanometers, the

instruments usually used in physicians’ offices

and in most surveys obtaining blood pressure.

In 13 of the first 16 examination locations an

aneroid instrument was used. In the remaining

22 locations the standard mercury sphygmomanometer, which is the one used in the continuation of HANES, was employed. The following

guidelines, based on the American Heart Association’s “Recommendations for Human Blood

Pressure Determined by Sphygmomanometers,”

were observed:

. The cuff was at least 20 percent wider than

the diameter of the arm or covered approximately two-thirds of the arm. (An adult

13 cm. and a pediatric 9.5 cm. cuff were

provided.)

. The manometer was at eye level with the

physician.

● The meniscus of the mercury instruments

was checked weekly for zero-level calibration.

. While measuring, the rate of fall in pressure

was maintained at 2-3 mm. Hg per heartbeat, which was slow enough to detect the

first and last sounds but sufficiently rapid

to avoid intermittent trapping of blood between systolic and diastolic levels.

● For diastolic pressure, the level was re-

●

the

bell

and

corded at the point of complete cessation

of Korotkoff’s sounds or, if there was no

cessation, the point of muffling.

Measurements were recorded to the nearest

2 mm. on the scale.

The middle of the cuff was placed over

bulge in the upper right arm. Using the

of his stethoscope, the physician noted

recorded the pressure (systolic) when the

sound was first heard and the pressure (diastolic)

when the sounds disappeared or first became

m ~ffled. For convenience the sphygmomanometer

was fixed to the wall of the examination room.

While the results will be comparable with

clinical findings, the indirect blood pressure

measurements as obtained may differ from’ ‘true”

values, i.e., those obtained by direct (intraarterial)measur ement. The direct and indirect

methods of measurement have been found to

agree closely for systolic pressure if the cuff

size is appropriate to the examinee’s height

and arm girth. For diastolic pressure, however,

the agreement is not as good. Use of the American

Heart Association criterion—the point of complete cessation of sound or, if no cessation,

the point at which it first became muffled-will

tend to underestimate intra-arterial diastolic

blood pressure. However, had the point at which

the sounds first became muffled been used,

there would have been a similar amount of

bias introduced in the opposite direction.7’8

Blood pressure measurements obtained on

more than two-thirds of the examinees in this

present survey with mercury sphygmomanometers did not differ significantly from the levels

obtained on the remaining one-third with the

aneroid instruments. Mean systolic pressures

for the two groups differed by less than 1 mm.

Hg (0.3) while mean diastolic pressures differed by just slightly more than 1 mm. Hg

(1.2), differences that could easily be due to

sampling variability alone and are not statistically significant at the 5-percent probability

level.

Since blood pressure may vary considerably

over a short period of time even under relatively

standard conditions, these single measurements

can be considered as only a rough estimate of

the examinee’s “true” blood pressure.

Comparison is made in this report with

published national estimates for blood pressure

levels of adults from findings of the 1960-62

Health Examination Survey. Several factors may

affect the comparability of these test results

with the single blood pressure readings from

the present survey. Published findings from the

earlier survey are shown as the average of the

three blood pressure measurements made by

the physician during the physical examination.

The first of these measurements was taken

just after the physician met the examinee. The

second was taken midway in the examination,

after auscultation of the heart in the sitting

3
position and before the arthritis examination.

The examinee had just had an electrocardiogram

given by the nurse and had been allowed a few

moments after sitting up for the postural hypotension to disappear. The third measurement was

taken at the end of the physical examination.

The venipuncture was usually made during the

physical examination although the specific point

at which it was taken varied from one examinee

to another. Mean values for the first measurement obtained on an examinee in this and other

studies were higher than those for the two subsequent readings. 9JOJ3 In the present survey

neither a venipuncture nor an electrocardiogram

was taken during the physician’s examination.

The fact that there were a greater number of

examining physicians in the first Health Examination Survey than were employed in the first

35 locations of the Health and Nutrition Examination Survey-39 compared with 23-may also

have affected the variability of measurements

in the two surveys.

While Mood pressure measurements were

taken of children and youths in the 1963-65 and

1966-70 Health Examination Surveys, comparison

with findings for those of like age in the present

survey are not included in this preliminary

report because the testing in those earlier

1963-70 surveys was done by the four nurses

whose techniques could be more carefully monitored and kept in agreement throughout the

survey than was possible with the larger number

of physicians.

FINDINGS

Systolic Pressure

Mean systolic blood pressure among persons

18 through 74 years in the United States increases

substantially with age from 121.3 mm. Hg among

young adults 18-44 years to 148.4 mm. Hg

among older adults 60-74 years, an increase

of 27 percent (table 1). These national estimates

are based on preliminary findings from the

Health and Nutrition Examination Survey among

a probability sample representative of the civilian,

noninstitutionalized population in 1971-72, as described earlier. The yearly increment increased

slightly from 0.7 mm. Hg per year between

younger adults and those 45-59 years, to an

average of 0.9 mm. Hg per year between the

latter group and older adults 60-74 years. A

similar pattern of increment with age is evident

with few exceptions across selected percentile

points in the distribution of systolic blood pressure

shown in table 1 and the Percentage distribution

in table 2.

The variability in systolic blood pressure

as measured by the standard deviation also increases consistently with age from 15.34 mm.

Hg among young adults to 24.48 mm. Hg among

older adults (60-74 years). It is substantially

greater among adults 45-74 years than younger

persons. The relative variability in relation to

the mean value is also substantially greater

among adults 45-74 years (16.4 and 16.5) than

younger adults 18-44 years (12.6). Measures of

variability based on percentiles in the distribution

(semi-interquartile range and its ratio in relation

to the median) also show significantly greater

variability in systolic pressures among those 45

years and older than persons under 45 years.

For both males and females systolic blood

pressure increases substantially with age from

125.2 mm. Hg for young men 18-44 years to

145.3 for men 60-74 years and from 117.7 mm.

Hg for young women 18-44 years to 150.9 for

women 60-74 years. Mean values for men under

60 years are higher than for women of corresponding age. However, only in the 18-44 year

range are the mean differences large enough

to be considered statistically significant. Among

the oldest age group (60-74 years), there is a

reversal in trend with women having, on the

average, significantly higher systolic pressures

than men.

Comparison of the distribution of systolic

blood pressures for men and women in each of

the three successive age groups shows a progressive pattern of increased skewing to the

right with increasing age (table 2 and figure 1).

Diastolic Pressure

Among the U.S. population, mean diastolic

blood pressure increases substantially with age

from 77.8 mm. Hg for young adults 18-44 years

to 85.7 in adults 45-59 years, with a leveling

off at 85.6 in the older adult group 60-74 years

(table 3). This represents an increase oi 10

4
AGE IN YEARS

5

~

w

18-44

x

MEN WOMEN

y 30 30

u

<

$ 20 20

~

0

E 10 10

.

%go o

● 90 120 150 180 .. ‘ 90 120 150 180 ..

5

.x

:

45-59

&

60-74

cSYSTOLIC SLOOO PRESSURE IN mm. Hg (+LESSTHAN 90:. * 200b) SYSTOLIC BLOOO PRESSURE IN mm. Hg [’LESS THAN 90; “’ 200+)

Figure 1. Percent distribution of systolic blood pressure of the population 18-74 years by age and sex: IJnited States, 1971-72

percent in diastolic blood pressure over this 14.8 and 14.9 over the 18-74 year age span.

18-74 age range. A simila; pattern in yearly Among U.S. men, mean diastolic blood presincrement with age is also evident in the median sure increased substantially from 80.7 mm. Hg

values and in the percentage distributions (table 4). for young men 18-44 years to 87.6 for men

As measured by the standard deviation, 45-59 years, then dropped to 85.6 at 60-74 years.

the variability in diastolic pressure also in- For U.S. women, there was a consistent and

creases with age up to 60 years-from 11.50 significant increase in diastolic pressure over

mm. Hg among young adults 18-44 years to the entire age span from 75.1 mm. Hg for

12.80 for ages 45-59 years. The relati-ve vari - young women 18-44 years to 85.7 at ages 60-74

ability in relation to the mean values shows years. Except for the oldest age group (60-74

no consistent pattern with age but varies between years) where the sex difference was negligible,

5
diastolic pressure for men on the average ex- measures among females was found at ages 45-

ceeded that for women. Mean differences were 59 years (13.28) and the least variability at

large enough to be statistically significant for 18-44 years (11.88).

persons 18-59 years of age. As with systolic pressure, the distribution

Variability in diastolic pressure increased of diastolic blood pressures for each successive

slightly and consistently with age for men from age group of men and women tends to become

a standard deviation of 11.12 at ages 18-44 to increasingly more skewed to the right with

12.90 at 60-74; the pattern was le~s consistent increasin~ age (table 4 and figure 2). -

for females. The greatest variability in these

AGE IN YEARS

i8-44

5

: ~~

MEN WOMEN

w

50

x

%~ 40 40

w

a

R 30 30

~

:m

20

%

L

0

> 10 10

:

0

2

0

. m 80 110 . . .

ao 80 110 . .

60-74 F+

E .

50 80 110 .. . so 80 110 ..

DIASTOLIC BLOOD PRESSURE IN mm. Hg (“LESS THAN 50: “’120+) DIASTOLIC BLOOD PRESSURE IN mm. Hg (’LESS THAN 50; “-120+)

Figure 2. Percent distribution of diastolic blood pressure of the population 18-74 years by age and sex: United States, 1971-72

6
Race

Preliminary findings on blood pressure levels

in the U.S. adult population from this study

are shown by race in table 5. While mean values

for the racial groups other than white and Negro

are included, the number in that segment of

the population and hence in the sample of examinees is too small and heterogeneous to

provide reIiable national estimates in any detail

for them. At the time of the study there were

126 miIlion persons 18-74 years of age in the

U.S. civilian, noninstitutionalized population. This

included 111 million or 88 percent classed as

white, nearly 14 million or 11 percent classed

as Negro, and over 1 million or 0.8 percent as

all other races including Chinese, Japanese,

American Indian, and others. The analysis of

the findings will be limited here to those for

the white and Negro racial groups.

Mean systolic blood pressure for white

adults was consistently less than that for the

Negro adults 18-74 years of age and the increase of systolic pressure with age is more

rapid for Negro than for white adults. Mean

systolic blood pressures for Negro adults exceeded those for white adults by values large

enough to be statistically significant and which

increased with age from 3.5 mm. Hg among

younger adults 18-44 years to 11.0 at 45-59 years

and 11.6 at 60-74 years.

Among men, the pattern of racial differences

in systolic blood pressure is similar to that

for the total population but the increase with

age is less marked. Negro men have mean

systolic pressures exceeding values for white

men of corresponding age by 4.3 mm. Hg at

18-44 years, 4.8 at 45-59 years, and 7.1 at

60-74 years.

Systolic blood pressure of Negro women

is also consistently greater, on the average,

than for their white counterparts. However, the

increase in the racial difference with age for

women is substantially greater than that for

men. At 18-44 years of age mean systolic

pressure for Negro women significantly exceeds

that for white women by 3.8 mm. Hg while in

the older age groups 45-74 years the values for

Negro women are over 15 mm. Hg greater.

Negro-white differences in diastolic blood

pressure show a similar but less marked agerelated trend than that for systolic pressure.

From 18 years on, the mean diastolic pressures

for Negro adults are significantly greater than

those for white adults by 3.2 mm. Hg at 18-44

years, 7.1 mm. Hg, at 45-59 years, and 6.6 mm.

Hg at 60-74 years.

Diastolic blood pressures for Negro women

consistently exceed those for their white counterparts by values of 3.8, 9.7, and 7.3 mm. Hg

across the 18-74 year age range; these differences are large enough to be statistically

significant.

As with systolic blood pressure, the differences in mean diastolic blood pressures between middle-aged and older white and Negro

men are slightly less than those for women.

The mean diastolic pressures for Negro men

exceed those for white men by values which

are statistically significant and increase with

age from 3.3 mm. Hg at 18-44 years to 5,9

mm. Hg at 60-74 years.

Elevated Blood Pressures

While no attempt was made with these

preliminary data to identify or determine the

prevalence of hypertension, estimates were made

for the prevalence of substantially elevated blood

pressures. For this purpose persons with systolic

pressure of 140 mm. Hg or greater and/or

diastolic pressure of 90 mm. Hg or greater

were arbitrarily considered to have elevated

blood pressure. On this basis, 25.9 percent or

32.7 million of the U.S. adult population 18-74

years of age would have elevated blood pressure,

i.e., somewhat to substantially above what is

generally considered “normal” (table 6). The

prevalence rate is higher among men than women.

It increases sharply with age to about 45 years

from 16.7 percent among young adults to 38.0

percent among those 45-59 and 38.5 percent at

ages 60-74 years. The increase in the prevalence

of this condition with” age is continuous across

the age range for women but drops off at ages

60-74 for men.

The prevalence” of this degree of elevated

blood pressure is significantly greater among

7
Negro than white adults, with differences large

enough to be considered statistically significant

for the total group and for women but not for

men under 60 years of age. However, the increase in this rate with age is substantially

more rapid for Negro than for white men and

women and the age-specific rates for Negro

adults 18-74 years (men and women) are signif -

icantly greater than for’ white adults. By age

60-74 years over one-half of Negro men and

women (55 percent for each group) had elevated

blood pressures compared with slightly more

than one-third of white men and women (39

and 36 percent).

COMPARISON WITH

PREVIOUS STUDIES

Blood pressure is generally considered one

of the key indicators of a person’s health status.

Elevated blood pressure is associated with arteriosclerosis in coronary, Cerebral, and peripheral vessels 9-11 and there is increasing evidence that this association may be a causal

one.12 Hence it is of value to determine the

distribution of blood pressure in the population as

well as in that distribution over time to provide a

basis for further study of its relationship to other

physical and physiological characteristics, morbidity, the effect of medication, nutritional status,

and other factors in the person’s background that

may be related to or affect it.

Blood pressure levels for adults in the U.S.

civilian, noninstitutionli zed population 18-79

years have been determined previously through

the Health Examination Surveyof 1960-62. Several

reports from the survey related to these findings

have been published. 13-15 Other reportS dSO fTOITI

this survey have dealt with the association

of blood pressure with hypertension, physique,

blood glucose, serum cholesterol, and other

variables in the U.S. adult population.16-18

A brief comparison will be made here

between these preliminary findings from HANES

and the relevant published findings from the

previous Health Examination Survey among adults

more to point up the limitations of the data

at this stage rather than for any thorough analTable A. Mean blood pressures, population estimates , and number of examinees for persons 18-74 years in 1971-72 and 18-74 years in 1960-62, by age: United States

Variable

1971-72

Systolic (mean blood pressure in mm. Ha)------------------

Di,astoli.c (mean blood pressure in mm. Ha)-----------------

Population in millions ------------------------------------

Number of examiners ---------------------------------------

1960-62~

Systolic (mean blood pressure in mm. Ha)------------------

Diastolic (mean blood pressure in mm. Ha)-----------------

Population in millions ------------------------------------

Number of examiners ---------------------------------------

Age in years

-1-- 18-44 45-59

121.3 135.6

77.8 85.7

71.4 34.2

3,444 1,143

121.2 136.5

75.4 83.0

60.8 28.4

3,853 1,682

60-74

lg.:

,

20.6

1,938

150.2

83.1

19.0

995

1Means are average of three readings.

8
ysis of the differences or similarities. These

preliminary HANES findings are based on a national sample size that was slightly less for

the age groups 18-59 but nearly twice as large

for the age groups 60-74 compared with the

Health Examination Survey of 1960-62.

A further limitation in the present HANES

data is that they are based on a single blood

pressure determination. The published findings

from the previous survey of adults were reported,

as the average of three determinations made during the examination? 3~14In the earlier survey the

initial systolic blood pressure was found to be

greater than subsequent determinations for the

examinees-csn the average 1.8 mm. Hg above

the reported mean values. For diastolic blood

pressures, there was only a negligible mean

difference between the first and the average

of the three readings for adults.

Systolic blood pressures of U.S. adults 18-

S9 years in 1971-72 from the preliminary HANES

findings were similar to those for adults of

that age range from 10 years ago in the 1960-

62 national survey (table A and figures 3-5).

Mean values differed by only a negligible amount.

However, if compensation were to be made

for the fact that the 1971-72 data are from a

single determination, these more recent findings

would be significantly lower than those estimates

from initial readings found among that segment

of the population in 1960-62. At ages 60-74

years the mean systolic pressures from the

preliminary HANES are significantly lower than

for that age group of the population 10 years

ago (mean difference ‘of 1.8 mm. Hg) and if

compensation were made for the single reading

the difference would be even greater. For men,

m em systolic pressures are nearly identical

to those of 10 years ago (average of three

readirigs) across the entire age range 18-74

years while for women, only the values win the

younger age range 18-44 years are similar.

At 45-74 years U.S. women in 1971-72 had

systolic pressures significantly lower, by mean

values of nearly 3 and 4 mm. Hg, than those

in the corresponding age range 10 years earlier.

Diastolic blood pressures among U.S. adults

in 1971-72 were consistently significantly greater

across the age range 18-74 years than those

for this age group in 1960-62. Mean differences

m United States,1960.62

= United States,1971-72

160 r

SYSTOLIC

AGE IN YEARS

110

r

DIASTOLIC

1s-44 4s.59 60-74

AGE IN YEARS

Figure 3. Mean swtoiic and diastolic blood oressure for adults

_18-74 years in”1960-62 and in 1971-72: United States

of 2.2-2.7 mm. Hg were large enough to be

statistically significant. The pattern of findings

was similar among “men 18-74 years of age and

among women except at ages 45-59 years where

the mean differences between the present findings and those of 10 years ago were negligible.

The possibility that the noise level in the examining units may have been somewhat higher

because of the additional electrical equipment

used and hence may have affected the accuracy

of the diastolic readings to a greater extent

in the more recent survey, cannot be eliminated.

9
m United States,1960.62

160 ~ - United States,1971.72

18-44 45.59 s074

AGE IN YEARS

110

r

I

DIASTOLIC

1844 45.59 68.74

AGE IN YEARS

~

Figure 4. Mean systolic and diastolic blood Pressurefor men

‘18-74 years in 1960-62, and in 1971-72: UnitedStates

Race .—Among adults, systolic pressures

from the preliminary HANES in 1971-72 are

similar to those from the 1960-62 national

. .

study for white and Negro men and Negro women

across the entire age range 18-74 years and

for white women up to 60 years of age. Mean

systolic pressure for white women 60-74 years

of age in the present study (preliminary HANES)

was significantly lower (4 mm. Hg

found for that age-race group

(table B).

10

less) than was

10 years ago

Figure 5, Mean systolic and diastolic blood pressure for women

16-74 years in 1960-62, and in 1971-72: United States

Diastolic blood pressure for white and Negro

men and women tended to be higher in the 1971-

72 national HANES study than for the corresponding age-sex-race groups in the 1960-62

national Health Examination Survey. However,

only among white men 18-74 years and Negro

men 18-59 years were the mean differences

large enough to be considered statistically significant at the 5-percent probability level.
Table B. Mean systolic and diastolic blood pressures for white and Negro adults 18-74 in

1971-72 and in 1960-62, by age and sex: United States

Blood pressure

and age in years

Systolic

18-44 years ------

45-59 years ------

60-74 years ------

Diastolic

18-44 years ------

45-59 years ------

60-74 years ------

Men Women

White Negro White Negro

1971-72 1960-621 1971-72 1960-621 1971-72 1960-621 1971-72 1960-621

Mean blood pressure in mm. Hg

124.9 125.3 129.2 128.3 117.2 116.8 121.0 122.7

136.2 135.0 141.0 141.8 133.0 135.6 149.4 149.3

144.6 144.0 151.7 153.3 149.6 153.5 165.8 166.6

80.4 76.7 83.7 79.8 74.6 73.4

87.3

78.4

82.7

78.3

91.5 87.8 82.9 81.8 92.6 90.3

85.0 81.4 90.9 88.1 85.1 83.7 92.4 90.7

1

Means are average of three readings.

SUMMARY

This report presents preliminary national

estimates of bloodpressurelevels forthecivilian,

noninstitutionalized adult population of the United

States 18-74 years of age based on findings

from the Health and NutritionExamination Survey

of 1971-72.

For this survey,anational probabilitysample

of 14,147 persons was selected to represent

the 192.7 million persons in the target population

aged 1-74 years. Of these, 10,126 or nearly

73 percent were examined. The findings in this

report are limited to those for the 6,525 adult

examinees 18-74 years of age.

A single measurement of blood pressure

was obtained on each examinee 18-74 years

with the use of a sphygmomanometer. A standard set of procedures was followed by the

examining physicians responsible for the measurements.

Mean systolic pressures increased substantially with age from 121.3 mm. Hg at 18-44

years to 148.4 mm. Hg at 60-74 years, an

increment of 27 percent. Similarly mean diastolic pressures increased substantially but at

a somewhat slower rate from 77.8 mm. Hg

for young adults to 85.7 mm. Hg for adults

age 60-74 years.

Up to 60 years, both systolic and diastolic

blood pressures were higher on the average

for,men than women, but the reverse was found

at 60-7’4 years.

Negro men and women in the U.S. population

had higher mean systolic and diastolic pressures

than did their white counterparts.

Comparisons with previous national estimates obtained from the Health Examination

Survey of 1960-62 among adults are included.

Similarity anddifferences in methods andsample

sizes that may account for agreement or the

absence of it between the present and earlier

findings are noted. In general, without compensating for survey differences, these preliminary

HANES findings show higher mean diastolic

pressures among adults 18-74 years and roughly

comparable mean systolic pressures for adults

18-59 years, but lower systolic means at 60-

74 years than in the previous national survey.

The final reports on blood pressure findings

for the entire 65 stands of examinations in the

first HANES program will investigate the effects

of these differences more thoroughly.

000

11
REFERENCES

1

National Center for Health Statistics: Origin, program,

and operation of the U.S. National Health Survey. Vital arrd

HeaZth Statistics. PHS Pub. No. 1000-Series l-No. 1. Public

Health Service. Washington. U.S. Government Printing Office,

Aug. 1963,

2

National Center for Health Statistics: Plan and initial

program of the Health Examination Survey. Vital and Health

Statistics. PHS Pub. No. 1000-Series l-No. 4. Public Health

Service. Washington. U.S. Government Printing Office, july

1965.

3

National Center for Health Statistics: Cycle I of the

Health Examination Survey: sample and response, United

States, 1960-62. Vital and Healtk Statistics. PHS Pub. No.

1000-Series 1 l-No. 1. Public Health Service. Washington. U.S.

Government Printing Office, Apr. 1964.

4

Natiomd Center for Health Statistics: Phm, operation,

and response results of a program of children’s examinations.

Vital and Health Statistics. PHS Pub. No. 1000-Series l-No. 5.

Public Health Service. Washington. U.S. Government Printing

Office, Oct. 1967.

5

Natiomd Center for Health Statistics: Plan and operation

of a Health Examination Survey of U.S. youths 12-17 years of

age. Vital and Health Statistics. PHS Pub. No. 1000-Series

l-No. 8. Public Health Service. Washington. U.S. Government

Printing Office, Sept. 1969.

6

National Center for Health Statistics: Plan and operation

of the Health and Nutrition Examination Survey, United

States, 1971-73. Vital and Healtk Statistics, Series I-Nos. 10a

and 10b. DHEW Pub. No. (HSM) 73-1310. Washington. U.S.

Government Printing Office, Feb. 1973.

7

Ragan, C., and Bordley, J.: The accuracy of clinical

measurements of arterial blood pressure, with a note on the

auscukatory gap. Bn~f. ]okns Hopkins Hosp. 69(6):504, 1941.

8

Moss, A. J., and Adams, F. H.: Heart Disease in Infants,

Childrwz and ,4 dolescents. Ba]timorc, The Williams and Wilkins

CO., 1968.

9

Gordon, T., and Kannell, W. B.: Predisposition to

atherosclerosis in the head, heart and legs. J.4JIA 221:661-666,

1972.

10 Paffenbarger, R. S., Laughlin, M. E., Gima, A, S., et al.:

Work activity of longshoremen as related to death from

coronary heart disease and stroke. N. Engl. ]. Med.

282:1109-1114, 1970.

11

Epidemiology Study Group: Epidemiology for stroke

facilities planning. Stroke 3:360-371,1972.

12

Veterans Administration Cooperative Study on

Antihypertensive Agents: Effects of treatment on morbidity in

hypertension. JAMA 202:116-122,1967.

13

Natiomd Center for Health Statistics: Blood pressure of

adults by age and sex, United States, 1960-62. Vitul and Health

Statistics. PHS pub. No, 1000-Series 1 l-No. 4. public Health

Service. Washington. U.S. Government Printing Office, June

1964.

14

National Center for Health Statistics: Blood pressure

levels of children 6-11 years-relationship to age, sex, race, and

socioeconomic status, United States. Vital and Hetslth

Statistics. Series 1 l-No. 135. DHEW Pub. No. (HRA) 74-1617.

Washington. U.S. Government Printing Office, Nov. 1973.

15

National Center for Health Statistics: Blood pressure of

adults by race and area, United States, 1960-62. Vital and

Health Statistics. PHS Pub. No. 1000-Series 1 l-No. 5. Public

Health Service. Washington. U.S. Government Printing Office,

July 1964.

16

Acheson, R. M.: Blood pressure in a national sample of

U.S. adults: percentile distribution by age, sex and race. ht.J.

EpidemioL 2(3):293-301, 1973.

17

National C-enter for Health Statistics: Hypertension and

hypertensive heart disease in adults. Vital and Health Statistics.

PHS Pub. No. 1000-Series 1 l-No. 13. Public Health Service.

Washington. U.S. Government Printing Office, May 1966.

18

National Center for Health Statistics: Blood pressure as

it relates to physique, blood glucose, and serum ch olcsterol,

United States, 1960-62. L’ital Wd Health Statistics. PHS Pub.

No. 1000-Series 1 l-No. 34. Public Health Service. Washington.

U.S. Government Printing Office, Oct. 1969,

19

Acheson, R. M. and Baird, Jr., J. T.: Serum cholesterol

in a national sample of U.S. adults: A study from prevalence

data and its relationship to physique, blood pressure, blood

glucose and other variables. Int. J. Epiderniol. 2(3):283-292,

1973.

12
LIST OF DETAILED TABLES

Page

Table 1. Means, selected percentiles, and measures of variability in the distributions of

systolic blood pressure among adults 18-74 years by age and sex: United States,

l97l-72------------------------------------------------------------------------- 14

2. Percentage distributions of men and women 18-74 years by age, according to systolic blood pressure: United States, 1971-72------------------------------------ 15

3. Means, selected percentiles, and measures of variability in the distributions of

diastolic blood pressure among adults 18-74 years by age and sex: United States,

l97l-72------------------------------------------------------------------------- 16

4. Percentage distributions of men and women 18-74 years by age, according to diastolic blood pressure: United States, 1971-72----------------------------------- 17

5. Mean systolic and diastolic blood pressures among adults 18-74 years by age,

race, and sex, with standard errors for totals: United States, 1971-72---------- 18

6. prevalence rates for significantly elevated blood pressure among adults 18-74

years by age, race, and sex, with standard errors: United States, 1971-72------- 19

13
Table 1. Means, selected percentiles, and measures of variability in the distributions of systolic blood pressure among adults 18-74 years by age and sex: United States, 1971-72

Age and sex

Both sexes

18-44 years---------

45-59 years---------

60-74 years---------

~

18-44 years---------

45-59 years---------

60-74 years---------

w

18-44 years---------

45-59 years ---------

60-74 years---------

Percentiles Coefficient Semi-interMean s s;

of varia- quartile 100 SIR

x bility range (sIR)

g g, P,. P,, <5 %(g - P25)

go

100Sxp

Blood pressures in mm. Hg

121.3 15.34 0.72 100.0 112.5 120.6 129.6 150.4

135.6 22.21 1.19 105.6 120.6 132.4 147.4 L80.5

148.4 24.48 1.09 112.4 132.3 145.6 162.4 193.4

125.2 14.21 0.75 104.2 116.6 124.4 133.0 150.7

136.6 19.98 1.49 110.2 122.3 134.1 148.5 175.9

145.3 23.74 1.09 110.2 130.2 140.9 160.4 188.4

117.7 16.46 0.80 95.9 108.4 116.8 126.1 150.”1

134.7 24.44 1.27 100.9 118.8 130.6 146.3 185.1

150.9 25.22 1.63 114.6 134.4 150.2 164.5 198.3

12.6 8.6 7.1

16.4 13.4 10.1

16.5 15.0 10.3

11.3 .8.2 6.6

14.6 13.1 9.8

16.3 15.1 10.7

14.0 8.8 7.5

18.1 13.8 10.6

16.7 15.0 10.0

NOTE: SX= standard deviation; ~ = standard error of mean.

14
Table 2. Percentage distributions of men and women 18-74 years by age, according to

systolic blood pressure: United States, 1971-72

Systolic blood pressure in mm. Hg

Total--------------------------

Under 70-----------------------------

70-79--------------------------------

80-89--------------------------------

90-99--------------------------------

100-109------------------------------

110-119------------------------------

120-129------------------------------

130-139------------------------------

140-149------------------------------

150-159------------------------------

160-169------------------------------

170-179------------------------------

180-189------------------------------

190-199------------------------------

200-209------------------------------

210-219------------------------------

220-229------------------------------

230-239------------------------------

240-249------------------------------

250-259------------------------------

260-269------------------------------

270-279------------------------------

280-289------------------------------

290 and over-------------------------

Men Women

18-44

years

100.0

0.0

1.7

7.6

21.4

29.0

22.0

11.7

4.5

1.6

0.3

0.2

0.0

0.0

45-59 60-74

years years

18-44

years

45-59

years

Percent distribution

100.0

0.4

3*7

10.5

21.4

22.0

18.0

9.4

6.5

3.5

2.3

2.0

0.1

0.2

0.0

100.0

0.5

3.8

6.2

13.3

16.1

17.3

15.3

11.0

7*5

4.1

1.9

1.6

0.6

0.4

0.2

0.2

100.0

1.1

7.8

18.3

28.6

23.7

9.7

5.8

2.6

1.4

0.4

0.4

0.1

0.1

0.0

0.0

100.0

0.8

1.1

6.3

17.4

19.1

15.9

16.4

6.3

7.3

3.5

1.8

0.9

1.8

0.9

0.5

60-74

years

100.0

0.1

0.2

1.3

5.7

9.7

14.2

17.3

16.6

13.1

6,9

7.3

3.1

1.6

1.2

0.7

0.7

0.1

0.1

0.1

0.0

15
Table 3. Means, selected percentiles, and measures of variability in the distributions of diastolic blood pres -

sure among adults 18-7’4years by age and sex: United States, 1971-72

Age and sex

Both sexes

18-44 years ---------

45-59 yeacs ---------

60-74 years ---------

M=

18-44 years---------

45-59 years ---------

60-74 years ---------

a

18-44 years---------

45-59 years ---------

60-74 years ---------

Percentiles Coefficient Semi-interof varia- 100 SIR

!fean s ~

quartile

x bility

P, P,, P,. q, P

range (SIR)

100 s.Ji 112 ( ~-P25 )

P,.

90

Blood pressures in mm. Hg

77.8 11.50

85.7 12.80

85.6 12.64

80,7 11.12

87.6 12.33

85.6 12.90

L

75.1 11.88

84.0 13.28

85.7 12.37

0.40

0,65

0.62

0.55

0.88

0.70

0.38

0.61

0.72

60.5

67.6

67.6

62.3

70.3

66.2

58.1

64.9

68.9

71.4

78.4

78.t

74.1

80.4

78.5

68.6

76.4

78.6

78.0 84.

85.3 93.

84.9 93.

80.6 88.

88.3 96.

85.2 92.

75.5 80.

82.3 90.

84.6 94.

98.3

109.6

108.9

100.6

110.5

108.9

96.0

108.6

108.9

14.8

14.9

14.8

13.8

14.1

15.1

15.8

15.8

14.4

6.6

7.6

7.6

7.2

7,8

7.2

6.2

7.2

8.0

8,5

8.9

9.0

8.9

8.8

8.5

8.2

8.7

9,5

NOTE: S, = standard deviation; Sr = standard error of mean.

16
Table 4. Percentage distributions of men and women 18-74 years by age, according to

diastolic blood pressure: United States, 1971-72

Diastolic blood pressure in mm. Hg

Total-------------.------------

Under 40-----------------------------

40-49--------------------------------

50-59--------------------------------

60-69--------------------------------

70-79--------------------------------

80-89--------------------------------

90-99--------------------------------

100-109--..---------------------------

110-119------------------------------

120-129------------------------------

130-139------------------------------

140-149------------------------------

150 and over-------------------------

Men Women

18-44 45-59 60-74 18-44 45-59 60-74

years years years years years years

Percent distribution

100.0 100.0 100.0

x

9.2

28.?

38.7

14.5

5.2

1.7

0.1

O.c

O.c

.

2.6 6.5

14.3 20.1

36.7 32.7

26.8 23.2

11.1 12.0

5.4 3.0

1.4 1.8

0.2 0.0

0.0

100.0 100.O 100.0

=1=1=

4.7 1.2

21.6 6.4

34.1 25.1

26.8 35.4

8.4 17.4

2.5 9.6

0.6 2.9

0.3 0.9

0.1 0.4

0.3

-d-J!4

0,7

&.5

22.0

35.6

22.1

10.2

3.4

1.1

0,2

0.2

17
Table 5. Mean systolic and diastolic blood pressures among adults 18-74 years by age,

race, and sex, with standard errors for totals: United States, 1971-72

Age and sex

18-44

45-59

60-74

18-44

45-59

60-74

18-44

45-59

60-74

Both sexes

years--------------------------

years--.-----------------------

years----.---------------------

Men

years--------------------------

years-----.--------.-.---------

years--------------------------

Women

years--------------------------

years--------------------------

years-----.--------------------

Systolic Diastolic

White Negro I

Other White Negro

Mean blood pressure in mm. Hg

121.0 124.5

134.6 145.6

147.4 159.0

124.9 129.2

136.2 141.0

144.6 151.7

-L117.2 121.0

133.0 149.4

149.6 165.8

118.1

131.8

144.0

118.7

111.3

140.1

117.2

139.4

150.5

77.5

85.0

85.1

80.4

87.3

85.0

74.6

82.9

85.1

80.7

92.1

91.7

83.7

91.5

90.9

78.4

92.6

92.4

Other

77.0

87.5

79.9

78.1

79.1

76.3

75.2

90.6

86.0

18
Table 6. Prevalence rates for significantly elevated blood pressure among adults 18-74 years by age,

race, and sex, with standard errors: United States, 1971-72

Age and sex

Both sexes

18-44 years-----------

45-59 years-----------

60-74 years-----------

Men —

18-44 years-----------

45-59 years-----------

60-74 years-----------

Women

18-44 ytx3rs-----------

45-59 yea.rs-----------

60-74 vears-----------

Significantly high

blood pressures

Ra~;Oper

persons

16.7

38,0

38,5

21.9

45.0

40.1

11.8

31.5

37.3

‘opulation

:hou;~nds

11,86$

12,972

7,89E

7,50C

7,391

3,607

4,367

5,581

4,291

Standard

error of

rate

1.21

2.2!

2.5:

2.1/

3.1:

2.7!

0.8(

2.1:

2.91

White Negro

15.7

36.7

37.0

21.1

45.0

38.6

10.6

28.8

35.7

Rate per 100 persons

24.[

51.4

54.5

30.6

46,2

54.5

20.5

55.8

55.0

13.1

26.1

24.1

11.1

6.C

18.:

16.6

33.6

33.C

1.44 2.52 9.28

2.17 5.91 37.42

2.64 4.15 20.29

2.38 4.46 12.90

2.72 12.35 30.60

3.04 5.39 18.58

0.92 3.87 8.86

2.26 4.98 40.28

3.04 4.97 37.47 I

lSystolicpressure of 140 mm. Hg or greater and/or diastolic pressure of 90 mm. Hg or greater.

19
APPENDIX

STATISTICAL NOTES

The Survey Design

The sampling plan for the first 65 stands of the

Health and Nutrition Examination Survey (HANES)

followed a stratified, multistage probability design in

which a sample of the civilian, noninstitutionali zed

population, 1-74 years of age, of the conterminous United

States was selected. Excluded from the selection were

persons residing in Alaska and Hawaii and those

within the conterminous United States who were confined

to institutions or resjding on reservation lands of

American Indians. Successive elements dealt with

in the process of sampling were the primary sampling

unit (PSU), census enumeration district (ED), segment

(a cluster of households), household, eligible persons,

and, finally, sample persons.

The starting points in the first stage of this design

were the 1960 decennial census lists of addresses and

the nearly 1,900 primary: sampling units (PSU’S) into

which the entire United States was divided. Each PSU

is either a standard metropolitan statistical area

(SMSA), a single county, or two or three contiguous

counties. The PSI-J’s were grouped into 357 strata for

use in the Health Interview Survey and subsequently

coIIapsed into 40 superstrata for use in Cycles II and

III of the Health Examination Survey and HANES.

Fifteen of the 40 superstrata contained a single

large metropolitan area of more than 2,000,000 popu.

lation. These 15 large metropolitan areas were selected

for the sample with certainty. The 25 noncertainty

strata were classified into four broad geographic

regions of approximately equal population and crossclassified into four broad population density groups in

each region. Then a modified Goodman-Kish controlled

selection technique was used to select two PSU’S

from each of the 25 noncertainty superstrata with the

probability of selection of a PSU proportionate to its

1960 population so that proportionate representation

of specified State groups and rate of population change

classes was maintained in the sample. In this matter

a total first-stage sample of 65 PSU’s was selected.

These 65 sample PSU’S or stands are the areas within

which samples of persons would be selected for examination over a 3-year survey period.

In order to produce national estimates of the

nutritional status of the U.S. population at an earlier

20.

date, a probability subsample of 35 stands of the 65

stands was selected. This 35-stand subsamp]e also made

it possible to produce national estimates of certain

other aspects of health status in the population that

were critically needed at an earlier date and examination component; that for logistic reasons could not

be continued for the remainder of the 65 stands.

Included among the 35 stands were 10 of the 15 large

certainty metropolitan areas and one stand from each

of the 25 noncertainty superstrata. The reduction

from 15 to 10 large metropolitan areas was accomplished

by randomly selecting one stand from multiple-stand

Standard Metropolitan Statistical Areas, e.g., selecting

the southern half of the Chicago SMSA to represent

the entire SMSA. (This selection procedure was based

on operational considerations, and although unbiased,

is recognized as not being statistically optimal). It

is this subsample of 35 stands upon which the findings

contained in this report are based.

Although the 1970 Census data were used as the

frame for selecting the sample within PSU’S ‘when they

became available, the calendar of operations required

that 1960 Census data be used for the 35-stand sample

of HANES. Census enumeration districts (ED’s) in

each PSU were divided into segments of an expected

six housing units each. In urban ED’s the segments

were clusters of six addresses from the 1960 Census

Listing Books. For ED’s not having usable addresses,

area sampling was employed and consequently some

variation in the segment size occurred. To make the

sample representative of the current population of the

United States, the address or list segments were supplemented by a sample of housing units which had been

constructed since 1960.

Within each PSU a systematic sample of segments

was ‘selected. The enumeration districts which fell into

the sample were coded into one of two economic classes.

The first class, identified as the “poverty stratum,” was

composed of “Current Poverty Areas” that had been

identified by the Bureau of the Census in 1970 (pre1970 census), plus other ED’s in the PSU with a mean

income of less than $3,000 in 1959 (based on the 1960

census). The second economic class, the ‘‘nonpoverty

stratum, “ includes all ED’s not designated as belonging

to the “poverty stratum.”
All sample segments classified as being in the

“poverty stratum” were retained in the sample. For

those sample segments in “nonpoverty stratum” ED’s,

the selected segments were divided into eight random

subgroups andoneofthe subgroups waschosento remain

in the HANES sample. This procedure permits a

separate analysis with adequate reliability of those

classified as being below the poverty level and those

classified as being above the poverty level.

After identification of the sample segments, a

list of all current addresses within the segment boundaries was made, and the households were interviewed

to determine the ‘age and sex of each household member,

as well as other demographic and socioeconomic

information required for the survey.

To select the persons in sample segments to be

examined in HANES, all household members aged

1-74 in each segrpent were listed on a sample selection

worksheet with each household in the segment listed

serially. The number of household members in each

of the six age-sex groups shown below was listed on

the worksheet under the appropriate age-sex group

column. The sample selection worksheets were then

put in segment number order and a systematic random

sample of persons in each age-sex group was selected

to be examined using the following sampling rates:

Age in yews Rate

1-5-------------------------------- s

6-19 ------------------------------- M

20-44, male ------------------------ g

20-44, female ---------------------- s

45-64 ----------------------------- ~

65-74 ----------------------------- 1

The persons selected in the 35-stand sample

of HANES comprised a representative sample of

the target population and included 14,147 sample

persons 1-74 years of age of whom 10,126 or 71.6

percent were examined. When adjustments are made

for differential sampling for high risk groups, the

response rate becomes 72.8 percent.

All data presented in this report are based on

“weighted” observations, that is, data recorded for

each sample person are inflated to characterize the

subuniverse from which that sample person wasdrawn.

The weight for each examined person is a product

of the reciprocal of the probability of selecting the

person, an adjustment for nonresponse cases (i.e.,

persons not examined), and a poststratified ratio

adjustment which increases precision by bringing

survey results into closer alignment with known U.S.

population figures.

A more detailed description of the survey design

and selection technique can be found in the Plan and

Operation of a Health and Nutrition Examination Survey,

United States, 1971-73, Vitul and Health Statistics,

Series 1. No. 10a.

Nonresponse

In anY ;lSJI:L examination survey, after the sample

is identified and the sample persons are requested

to participate in the examination, the survey meets

one of its more severe problems. Usually a sizable

number of sample persons will not participate in the

examination. Whether or not an individual participates

is determined by many factors, some of them are

uncontrollable and therefore may be reasonably treated

as an outcome of a random event with a particular

probability of occurrence. If these probabilities of

participation were known and greater than zero for

all persons, then the examined persons would constitute a probability sample from which unbiased

estimates of the target population could be derived.

In this situation, the effect of nonparticipation would

only be to reduce the sample size, thereby increasing

the sampling errors of examination findings. However,

in practice a potential for bias due to nonresponse

exists since the exact probabilities are never known.

A further potential for bias exists if a sizable proportion of sample persons have a zero probability of

participation, that is, they would never agree to

participate in an examination survey of the same

procedures and inducements, and if these persons

differ from other sample persons with respect to

characteristics under examination. It is for these

reasons that intensive efforts are made in HANES

to develop and implement procedures and inducements

that would reduce the number of nonrespondents and

thereby reduce the potential of bias due to nonresponse.

These procedures and inducements are discussed in

the Plan and Operation of the Health and Nutrition

Examination Survey, Series 1, No. 10a.

Despite these intensive efforts 27.2 percent of

the sample persons from the first 35 stands were

not examined. Consequently, the potential for a sizable

bias does exist in the estimates in this publication.

From what is known about the nonrespondents and

the nature of nonresponse it is believed that the

likelihood of sizable bias is small. For instance,

only a small proportion of persons gave reasons

for nonparticipation which would lead to the belief

that they would never agree to participate in examination surveys and that they may differ from examined

persons with respect to the characteristics under

examination. Only 15 percent of the nonrespondents

gave as their reasons for nonparticipation personal

illness, physically unable, pregnant, antidoctor, or

fear of finding something wrong. Typical among the

reasons given by the other nonrespondents were the

following: unable because of work, school, or household duties; suspicious or skeptical of the program;

21
just not interested in participating; and private medical

care sufficient or just visited doctor.

An analysis of medical history data obtained for

most nonexaminees as well as examinees also supports

the belief that the likelihood of sizable bias due to

nonresponse is small. No large differences were found

between the examined group and the nonexamined group

for the statistics compared. For example, 11 percent

of persons examined reported having an illness or condition which interfered with their eating as compared

to 9 percent of persons who were not examined but who

had completed a medical history. The percent of persons examined who reported ever being told by a

doctor that they had arthritis was 20 percent, the

percent for high blood pressure was 18 percent, and

for diabetes was 4 percent. The corresponding percents for nonexamined persons were 17 percent for

arthritis, 21 percent for high blood pressure, and 4

percent for diabetes.

As mentioned earlier, the data in this report

are based on weighted observations, and one of the

components of the weight assigned to an examined

person was an adjustment for nonresponse. Since

the probabilities of participation are not known for

sample persons in HANES, a procedure was adopted

which multiplies the reciprocal of the probability of

selection of sample persons by a factor which brings

estimates based only on examined persons up to a

level which would have been achieved if all sample

persons had been examined. This nonresponse adjustment factor is the ratio of the sum of sampling

weights for all sample persons within a relatively

homogeneous class defined by age, sex, and poverty

status, to the sum of sampling weights for all responding

sample persons within the same homogeneous class.

To the degree that homogeneous groups can be defined

which are also homogeneous with respect to the

characteristics under study, the procedure can be

effective in reducing the potential bias from nonresponse.

For the 35-stand sample of HANES, persons

were grouped into 20 age-sex-poverty status groups

within each stand, yielding 700 separate cells with

an average membership of about 20 sample persons

each. These adjustment factors are distributed among

examined persons as shown in table I.

Missing Data

Examination surveys are subject to the loss of.

information not only through the failure to examine

all sample persons, but also from the failure to

obtain and record all items of information for examined persons. The extent of missing data was generally

very low-only about 1 percent for the 6-74 year age

range— but ranged from 6 percent among children

Table 1. Percent distribution of nonresponse

adjustment fact ors, Health and Nutrf.t ion Ex -

aminati.on Survey, Stands 01-35, 1971-72

Size of factor Percent

distribution

Total ----------------------

F

1.00 -1.24 ------------------------

1.25 -1.49 ------------------------

1.50 -1.74 ------------------------

1.75 -1.99 ------------------------

2.00 -2.49 ------------------------

2.50-2.99------------------------

3.00-3.03------------------------

38.4

31.6

12.9

8.4

6,1

1.2

1,4

6-llyears toless than l percent across the remainder

of the age groups.

No estimates were made for missing data in

this preliminary report on blood pressures. Rather

it has been assumed that the distribution of these

values by age, sex, and race would be similar to that

for those who were measured.

Small Numbers

In some tables magnitudes are shown for cells for

which the sample size is so small that the sampling

error may be several times as great as the statistic

itself. Obviously in such instances the numbers, if

shown, have been included to convey an impression of

the overall story of the table.

Sampling and Measurement Error

In the present report, reference has been made

to efforts to minimize bias and variability of measurement techniques. The potential of residual bias due

to the high nonresponse rate has also been discussed.

The probability design of the survey makes possible the calculation of sampling errors. Traditionally

the role of the sampling error has been the determination of how imprecise the survey resulte may

be because they come from a sample rather than

from the measurement of all elements in the universe.

The estimation of sampling errors for a study

of the type of the Health and Nutrition Examination

Survey is difficult for atleast three reasons: (l) measurement error and “pure” sampling error are confounded in the data—it is not easy to find a procedure

which will either completely include both or treat one

or the other separately, (2) the survey design and

estimation procedure are complex, and, accordingly,

require computationally involved techniques for the

calculation of variances, and (3) hundreds of statistics are presented in the tables in this report,

22
mmy for subclasses of the population for which

there are a small number of sample cases. Estimates

of sampling error are obtained from the sample data

;md are themselves subject to sampling error when the

numkr of cases in a cell is small or, even occasinn;dly, when the number of cases is substantial.

Estimates of the standard errors for selected

st;ltistics used in this report are presented in tables

1, 3, 5, and 6. These estimates have been prepared

by a replication technique which yields overall vari -

abi Iity through observation of variability among random

sukampks of the total sample. Again, readers are

reminded that these estimated sampling errors do

not reflect any residual bias which might still be

present after the attempted correction for nonresponse. The standard error is primarily a measure of

sampling variability, that is, the variations that might

occur by chance because only a sample of the population is surveyed. As calculated for this report, the

standard error also reflects part of the variation

which arises in the measurement process. It does

not include estimates of any biases which might

lie in the data. The chances are about 68 out of

100 that an estimate from the sample would differ

from a complete census by less than the standard

error. The chances are about 95 out of 100 that

the difference would be less than twice the standard

error and about 99 out of 100 that it would be less

than 2!4times as large.

000

23

<tU. S. GOVERNMENTPRE4TING OFFICE :1975 5S4-528/36
Series 1.

Series 2.

Series 3.

Series 4.

Series 10.

Se7ies 11.

Series 12.

Sm”es 13.

Series 14.

Series 20.

Sm”es 21.

Sevies 22.

VITAL AND HEALTH STATISTICS PUBLICATION SERIES

Originul~y Public Health Service publication No. 1000

Programs and collection procedures. —Reports which describe the general programs of the National

Center for Health Statistics and its offices and divisions, data collection methods used, definitions,

and other material necessary for understanding the data.

Data evaluation and methods research. —Studies of new statistical methodology including experimental tests of new survey methods, studies of vital statistics collection methods, new snalydcal

techniques, objective evaluations of reliability of collected data, contributions to statistical theory.

Analytical stu.dies. -Reports presenting analytical or interpretive studies basedon vital and health

statistics, carrying the analysis further than the expository types of reports in the other series.

Documents and committee re#orts.— Final reports of major committees concerned with vital and

health statistics, and documents such as recommended model vital registration laws and revised

birth and death certificates.

Data J20m the Health Interview Survev.— Statistics on illness, accidental injuries, disability, use

of hospital, medical, dental, and other services, and other health-related topics, based on data

collected in a continuing national household interview survey.

Data from the Health Examination Survey. —Data from direct examination, testing, and measurement of national samples of the civilian, noninstitutional population provide the basis for two ~pes

of reports: (1) estimates of the medically defined prevalence of specific diseases in the United

States and the distributions of the population with respect to physical, physiological, and psychological characteristics; and (2) analysis of relationships among the various measurements without

reference to an explicit finite universe of persons.

~ka from the Institutional Population Surveys —Statistics relating to the health characteristics of

persons in institutions, and their medical, nursing, and personal care received, based on national

samples of establishments providing these services and samples of the residents or patients.

Data from the Hospital Discharge Survey. —Statistics relating to discharged patients in short-stay

hospitals, based on a sample of patient records in a national sample of hospitals.

~ta on health resources: manpower and facilities. —Statistics on the numbers, geographic distribution, and characteristics of health resources including physicians, dentists, nurses, other health

occupations, hospitals, nursing homes, and outpatient facilides.

Datu on mortality. —Various statistics on mortality other than as included in regular annual or

monthly reports-special analyses by cause of death, age, and other demographic variables, also

geographic and time series analyses.

Data on natality, mawiage, and divwce. —Various stadsdcs on natality, marriage, and divorce

other than as included in regular annual or monthly reports+pecial analyses by demographic

variables, also geographic and dme series analyses, studies of fertility.

Dati from the National Natality and Mortality Surveys. —Statisdcs on characterisdcs of births

and deaths not available from the vital records, based on sample surveys stemming from these

records, including such topics as mortality by socioeconomic class, hospital experience in the

last year of life, medical care during pregnancy, health insurance coverage, etc.

For a list of titles of reports published in these series, write to: Office of Information

Nat ional Center for Health Statistics

Public Health Service, HRA

RockvilIe, Md. 20852

/
U.S. DEPARTMENT OF

HEALTH, EDUCATION, AND WELFARE ‘O ST AGE AN DFEESPA ID

Pubhc Health Serv(ce

I-S DEPARTMENT OF H.E. W

HEW 390

HEALTH RESOURCES ADMINISTRATION

5600 Fishers Lane THIRD CLASS

Rockv,lle, Md. 20852 BLK. RATE

OFFICIAL 8USINE!3S

Penaltv for Pr,vate Use, $300