e 

FROM VITAL & HEALTH STATISTICS OF THE NATIONAL CENTER FOR HEALTH STATISTICS 

—— 

US DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE � Publ!c Health Service I Number 28 . April 28,1978 

Office Visits for Hypertension, National Ambulatory Medical 

Care Survey: United States, January 1975-December 1976a 

According to data collected in the National 

Ambulatory Medical Care Survey (NAMCS), an 

estimated 46.1 million visits with a principal 

diagnosis of essentizdbenign hypertension (EBH) 

were made to office-based physicians during the 

two-year period January 1975 through 

December 1976. 

NAMCS is a sample survey conducted 

annually by the Division of Heiilth Resources 

Utilization Statistics in the National Center for 

Health Statistics. The estimates in this report are 

based on information recorded by participating 

physicians on the “Patient Record” during 

sampled office encounters. A facsimile of this 

encounter form may be found in an earlier 

report. 1 A brief description of the sample design 

and an explanation of the sampling errors associated with selected aggregate statistics may be 

found in the Technical Notes of this report. 

Visits for which EBH was the principal, or 

�

first-listed, diagnosis comprised 4 percent of the 

over 1.1 biIIion estimated visits made in calendar 

years 1975 and 1976 and ranked first among 

visits for all morbidity related principal diagnoses. While many of the estimates presented in 

this report deal chiefly with visits for which 

EBH was the principal diagnosis, it is important 

to note that for an additional 28.6 million visits, 

EBH was the diagnosis listed second or third in 

order of importance at that encounter. In’ addition, there were clearly more visits in which 

EBH was a disabling factor than are reflected by 

the visits in which EBH was a listed diagnosis. 

aThis report was prepared by Beulah K. Cypress, 

Ph. D., Division of Health Resources Utilization Statiso tics. 

For example, of the 26 million visits reported 

for chronic ischemic heart disease that are not 

included in this report, over one-third were recorded by the physician as chronic ischemic 

heart disease with hypertensive disease. Moreover, another 1.6 million visits for some cardiovascuku- sequelae of EBH, such as hypertensive 

heart disease and angina pectoris with hypertensive disease, are not included in this report 

although hypertension is clearly a factor in these 

diagnoses. Therefore the estimates only reflect 

visits wherein the organic consequences of proIonged or untreated hypertension, for example, 

hypertensive heart disease, had not yet manifested themselves to the degree that the principal diagnosis of hypertension was superseded 

by its cardiovascular or cerebrovascular sequelae. 

The coexistence of EBH with obesity, diabetes meIlitus, neuroses, osteoarthritis, arthritis, 

art enosclerosis, bronchitis, emphysema, and 

asthma is suggested by the visit data. Table 1 

indicates the frequency of coincidence of these 

diseases listed as second or third diagnoses when 

EBH was Iisted first by the physician, and the 

frequency of their assignment to principal diagnosis when EBH was the diagnosis listed second 

or third. In both cases, these diseases appeared 

as the most frequent in combination with EBH. 

For example, obesity was the diagnosis Iisted 

second or third in over 10 percent of all visits 

where EBH was listed as the principal diagnosis. 

On the other hand, obesity was the primary 

diagnosis in 5 percent of all visits where EBH 

was Iisted as a second or third dia~osis. Diabetes mellitus figured as an additional diagnosis 

in about 5 percent of all EBH visits. When EBH 

was a condition listed second or third, a striking 
2 achancedata 

9


Table 1. Number and percent of	 office visits for essential benign hypertension listed as principal and second or third diagnosis, by other 

most frequent diagnosis: United States, January 1975-December 1976 

Diagnosis and ICDA codel 

Obesity ................. .....................................................................277 

Diabetes mellitus .......................................................................25O 

Neuroses ....................................................................................3OO 

Arthritis, unspecified ............................................ ................ .....7l5 

Osteoarthritis and allied conditions ...........................................7l3 

Arteriosclerosis ..................... .....................................................44O 

Bronchitisr emphysema, ashma ..........................................49O.493 

. 

Hypertension as 

principal diagnosis 

Number of 

visits in 

Percent thousands 

for second or of visitsz 

third diagnosis 

4,674 

2,054 

1,380 

992 

845 

649 

576 

Hypertension as second 

or third diagnosis 

Number of 

visits in Percent 

thousands of visits3 for principal 

diagnosis 

10.1 1,425 5.0 

4.5 4,038 14,1 

3.0 1,125 3.9 

2.2 1,017 3.6 

1.8 1,328 4.7 

1.4 * 343 *1.2 

1.3 943 3,3 

1 Based on Eighth Revision International 1 Cbssification of Diseases, Adapted for Use in the United States (ICDA). 

2Percents based on total number of visits where hypertension was listed as the principal diagnosis, 46,128,000. 

3Percents based on total number of visits where hypertension was listed as second or third diagnosis, 28,590,000. 

14 percent of those visits were diagnosed primar- Vkits by white females dominated other race 

ily as diabetes mellitus. and sex combinations in all age groups over 45 

Figure 1 reveals the dramatic differences in years, with visits by white males second. The 

proportions of visits with a principal diagnosis of 

EBH by race and sex within selected age groups. 

Figure 1. PERCENT OF OFFICE VISITS FOR HYPERTENSION, BY 

SEX, RACE, AND AGE: UNITED STATES, JANUARY 1975-

DECEM8ER 1976 

~ White fenrde ~ White male 

= clack and other female = clack and other male 

2.a 1.9 

Less than 45 45-54 55.64 65.74 75 and over 

AGE IN YEARS OF VISITING PATl ENT 

reader is cautioned that the frequency of visits 

for members of the black race is comparatively 

small, and therefore sampling error is increased. 

Furthermore, there is evidence that members of 

the black race avail themselves of ambulatory 

medical care rendered in hospitaI clinics and 

emergency rooms, settings not included in 

NAMCS, at a higher rate than do members of 

the white race. According to data from the 

Health Interview Survey (HIS), about 9 percent 

of ambulatory medical care visits by white persons were to hospital clinics or emergency 

rooms, whereas 21 percent of visits by members 

of other races were in similar settings.2 

Visit rates for both sexes by age are illustrated in figure 2, There is a marked difference 

in visit rate by sex beginning at about age 44, 

with the femzde rate peaking in age group 65 to 

74 years, about 10 years later than the highest 

rate for males. The HeaIth and Nutrition Examination Survey (HANES ) revealed that hypertension was more prevalent among women aged 

65 to 74 years than among men of the same age,~ 

Data from HIS indicate that females 65 years of 

age and older were the highest proportion of hypertensive in the population.A The higher female 

visit rate in NAMCS is therefore consistent with 

the higher EBH prevalence rate among females. 

9 
� 

Figure 2. VISIT RATE PER 100 PERSONS FOR ESSENTIAL BENIGN 

HYPERTENSION, BY SEX AND AGE UNITED STATES, JANUARY 

1975-DECEMBER 1976 

60 

r 

iess 35.44 45.54 55.64 65.74 75 and 

than 35 over 

AGE IN YEARS OF VISITING PATIENT 

The advanced female age at visits as opposed 

to the younger male age at visits may be related 

to greater susceptibility of males to other cardiovascular diseases which preempt EBH as primary 

diagnosis. The Framingham Study demonstrated 

that for persons with definite hypertension the 

incidence rates of diseases such as coronary 

heart disease, myocardial infarction, and congestive heart failure were substantially higher for 

males than for femaIes of the same ages Therefore, while the diagnosis may remain EBH as 

females age, a principal diagnosis of EBH for 

maIe visits may have been supplanted earIier by 

other diagnoses. 

The results of HIS and HANES studies in 

conjunction with visit data from NAMCS provide some insight into the utilization of ambulatory medical care resources by those in need of 

treatment. According to the findings of HANES, 

an estimated 23.2 million aduIts aged 18-74 

years had definite hypertension, 23.4 milIion 

had borderline hypertension, and 81.4 million 

were n ormotensive. However, HANES also 

o showed that of the borderline and normotensive 

groups 8.9 percent and 2.0 percent, respectively, 

acklncedata 3 

took regular medication for high blood pressure, 

leading to an assumption in the HANES report 

that an additional 3.7 milIion adults had controlled hypertension, or a totdl EBH prevalence 

of 26.9 million. NAMCS estimates for 1975 and 

1976 show 74.7 million visits by patients aged 18 

to 74 years with EBH as a diagnosis listed first, 

second, or third, that is, EBH was a recognized 

and diagnosed condition regardless of the pnncipaI reason for the visit. If 37.3 miIlion (onehalf of 74.7 milIion), the average yearly visits in 

which EBH was a diagnosis is divided by the 

HANES EBH prevalence of 26.9 million, there 

was an estimated average minimum visit rate of 

1.4 visits to office-based physicians per year for 

each person aged 18 to 74 years in the population who has hypertension. This utilization 

rate provides a model and a benchmark for estimating and evaluating utilization of physician 

resources by the segment of the population 

needing treatment for EBH, One reason for the 

Iow rate of utilization may well be due to the 

fact, shown in HANES, that 55 percent of the 

population estimated to have definite hypertension were never diagnosed as hypertensive. As 

consumer education reduces this number, the 

rate of utilization may increase. 

Since EBH, is a chronic condition requiring 

continuous care and maintenance therapy, it is 

not surprising that over 89 percent of visits were 

made by returning patients with EBH as a principaI and recurring problem. Nor is it unexpected, in view of the high proportion of 

return visits, that in responding to the item on 

the Patient Record which calls for the chief 

complaint as nearly as possibIe in the patient’s 

own words, 40 percent of alI EBH visits were 

designated as “progress Visits”b and an additional 27 percent as abnormally high bIood pressure (table 2). Both of these reasons given by the 

patient are an indication of his prior awareness 

of the condition. Headache, vertigo, and fatigue, 

which are sometimes symptomatic of EBH, motivated another 14 percent of visits for EBH. 

bAccording to the symptom classification developed for use in hTAMCS, “progress visit” was the 

appropriate category if the patientstated that the reason 

for visit was “hypertension check” or “blood pressure 

check. ” It does not necessarily represent all foHowup 

visits which may be otherwise coded. 
.................................

4 acklmecklta o 

Table 2. Number and percent distribution of hypertension 

diagnosed office visits by patient’s principal problem, complaint, or symptom: United States, January 1975-December 

1976 

Patient’s principal problem, Number of 

Percent complaint, or symptom and visits in of visits NAMCS codal thousands 

All principal problems .... ....... 46,128 100.0 

Progress visits,,, ................ 980,985 18,336 39.8 

Abnormally high blood pressure..205 12,582 27.3 

Headache.., ................................O56 2,759 6.0 

Vertigo-d izziness ....................... 069 2,471 5.4 

Fatigue . ....004 1,216 2.6 

General madical exam ...............9OO 973 2.1 

Nervousness .............................. 810 696 1.5 

All other problems . ........................ 7,096 15.4 

1 Based on ~ sym~tom classification develooed for use in 

NAMCS. 

2CategorY 9s0, progress visit-specified condition includes 

“check for hypertension”; Category 985, progress visit-unspecified 

condition, includes “blood pressure check. ” These categories do 

not necessarily reflect the total number of followup visits for 

hypertension, which may be otherwise coded. 

31nclude5 1.3Mif]ion~~itscoded4<~0ne7~ or “unkno~n.>>

Periodic blood pressure measurement is 

important both in treating EBH and as a 

screening device for hypertension detection and 

control.6 The degree to which this diagnostic 

technique was used, as well as the number of 

types of diagnostic and therapeutic services rendered during EBH visits, are shown in table 3. 

About 80 percent of EBH visits included a blood 

pressure check. This may be an underestimate 

due in part to measurement error in that visits 

for hypertension often include a limited or general examination in which blood pressure is routinely measured but not separately recorded. 

Drugs were the most frequent form of therapy 

(61 percent of EBH visits), while medical counseling was an aspect of treatment in almost 15 

percent of EBH visits. 

Since detection of hypertension as early as 

possible is crucial to its control, investigation of 

the use of the sphygmomanometer or other 

measuring device during visits for conditions 

other than EBH is revealing. According to the 

data given in table 4, one-third of all physician 

visits included blood pressure checks. However, 

as a proportion of EBH visits only, blood pressure checks increased considerably, as would be 

Table 3. Number and percent of office visits for principal 

diagnosis of essential benign hypertension, by diagnostic and 

therapeutic services ordered or provided: Unitad States, 

January 1975-Decamber 1976 

Diagnostic and 

therapeutic service 

All visitsl ............................... 

Diagnostic services 

Limited history -exam...............,....,.. 

General history -exam........,,..........,.. 

Clinical laboratory test ........... ........ .. 

X.ray.. d............................................. 

8100d pressure check ....................... 

Electrocardiogra m .... ........................ 

Therapeutic services 

Drug administered or prescribed . ... 

injection .......................................... 

Immunization .................................. 

Medical counsel ing ........................... 

Psychotherapy or therapeutic 

listen ing ........................................ 

Other services provided .................... 

Number of 

visits in Percent of 

visits thousends 

46,128 100.0 

25,301 54.9 

5,919 12.8 

9,483 20.6 

2,167 4.7 

36,861 79.9 

3,540 7.7 

28,141 61.0 

3,691 8.0. 

834 1.8 

6,747 14.6 

901 2.0 0 

1,931 4.2 

1 F,gures ~11 not add to totals, since more than one service 

might be provided. 

.21ncludes prescription and nonprescription drugs. 

expected. It is interesting to note that in those 

specialties that treated few or no cases of hypertension, such as neurology, urological surgery, 

and ophthalmology, blood pressure checks were 

made in a fair percentage of visits. It is not unexpected to find that specialists in cardiovascular diseases made more frequent use of the 

blood pressure check (72 percent of visits) than 

did any other specialist. Blood pressure was also 

measured in about 60 percent of visits to both 

int emists and obstetrician-g ynecologists. 

Table 5 lists number and percents of visits for 

principal diagnosis EBH by visit status, seriousness of the patient’s principal problem, and disposition. Because most visits for EBH were 

return visits and because EBH is so often asymptomatic, it is reasonable that although EBH is a 

condition requiring continuous medical care, 

only 22 percent of visits were judged “serious” @ 

or “very serious” by the physician. The highest 
� 

� 

6 dwmdata’ 5 

Table 4. Number and percent of blood pressure checks made during office visits for all diagnoses and for visits with hypertension as first, 

second, or third diagnosis, by selected specialties: United States, January 1975-December 1976 

All diagnoses Hypertension diagnosis 

Specialty Blood Percent Blood Percent of 

pressure of pressure hypertension checks in visits checks in visits 

thousands thousands 

All blood pressure checks ...................................................... 

General and family pra@ice ........ ................................. .................... 

Intarnal medicine ............................................................................. 

General surgery ................................................................................ 

Obstetrics.gynecology ................................................. ..................... 

Cardiovascular diseases .................................................................... 

Pediatrics ......................................................................... ................ 

Orthopedic surgery .................................................... ...................... 

Urological surgery ..... .................... ........ ........................................... 

Psychiat~ ........................................................................................ 

Neurology ... .......................................... ........................................... 

Ophthalmology ......... .................. ............................................... ...... 

~olaryngology ....................x .............. ............................................ 

All other specialties .......................................................................... 

383,359 33.2 58,665 78.5 

190,139 41.3 34,431 79.6 

77,859 59.7 16,674 80.5 

17,732 23.0 2,618 73.8 

57,920 59.7 973 74.9 

9,679 71.6 1,840 

* 

82.7 

* 9,712 

690 

9.1 

1.5 � * 

* * 2,797 13.5 * * 1,639 5.4 * * 848 22.4 * * 1,094 2.0 * * 496 1.8 

12,754 7.4 1,406 66.6 

Table 5. Number, ~ercent distributions, and mean duration in minutes and standard error of mean duration of hypertension diagnosad 

office ”v”isitsbyvisit status, seriousnessof problem, and disposition: United States, January 1975-December 1976 

Visit status, degree of 

seriousness, and disposition 

All visits ........................ ....... ................................................. 

Visit status 

New patient ..................................................................................... 

Returning patient: 

New problem .............................................................................. 

Recurring problem .......................................................... ............ 

Degree of seriousness 

Very serious ...... ............................................................................... 

Serious .......................................... .................. ................................. 

Slightly serious ......... ........................................ .................... ............ 

Not serious ...................................................... ..................... ............ 

Disposition 

No followup planned ........... ................................. ................... .. ....... 

Return visit: 

Specified time ............................................................................. 

If needed ... ...... .................................... .................. ...................... 

Referral toanother physician oragency .......................................... 

0ther2 .............................................................................................. 

Number of Percent Standard 

visits in distributions Mean duration error of 

thousands of visits in minutes mean duration 

46,128 100.0 14.3 .29 

2,254 4.9 24.0 1.62 

2,709 5.9 18.7 1.12 

41,165 89.2 13.5 .29 

765 1.7 17.8 1.84 

9,479 20.6 14.9 .42 

21,373 46.3 14.0 .43 

14,510 31.5 14.3 .42 

1,189 2.6 . . . . . . 

39,708 86.1 . . . . . . 4,734 10.3 . . . . . . 

832 1.8 . . . . . . 

1,161 2.5 . . . . . . 

lFigures Ml]notadd to totals because more than onedisposition wasp ossibIe.


Z[nc]udes telephone followup, returned to referring physician, and admitted to hospital.

proportion (46 percent) were considered “slightly 

serious,” with 32 percent assigned to the “not 

serious” category. 

While the average visit for EBHlasted about 

14 minutes, which is about the same as the average duration of all physician visits in NAMCS, 

duration of EBH visits was affected by the status 

of the problem. When EBH was presented as a 

new problem to the physician, either during an 

initial encounter or by a patient the physician 

had seen before, the visit lasted longer (24.0 

minutes and 18.7 minutes, respectively) than did 

visits involving returning pat ients with EB H as a 

recurring problem (13.5 minutes). The duration 

of the new patient encounter was significantly 

longer than that of the returning patient with a 

new problem. This may be due to the need for 

more intensive workup in new patient visits. 

For example, .57 percent of all initial visits for 

EBH included a general examination as opposed 

to 23 percent of return visits for a new problem 

and only 10 percent of visits for an old problem. 

Seriousness did not significantly affect visit duration. 

The instruction by the physician to return at 

a specified time, which was given in 86 percent 

of EBH visits, was no doubt heeded by the patient, since it very closely reflects the proportion 

of return visits made. An additional 10 percent 

were told to return if needed, and 2 percent 

were referred to another physician. In only 3 

percent of EBH visits was no followup planned, 

and most of these visits were “not serious. ” 

Attesting to the chronic and asymptomatic naFigure 3, PERCENT DISTRIBUTION OF OFFICE VISITS FOR 

ESSENTIAL BENIGN HYPERTENSION BY SPECIALTY VISITED: 

UNITED STATES, JANUARY 1975-DECEMBER 1976 

Other mecialtlm 5.5% T 

Cardiwasculm d 

General surgery 

ture of most EBH visits, the disposition of very 

few visits was admittance to a hospital. 

Most EBH visits (87 percent) took place in 

the office of either the general and family practitioner or the internist, with the remaining 13 

percent distributed among the practices of 

specialists in cardiovascular diseases, general surgery, and other diseases (figure 3). 

Table 6 displays EBH visits by region, location, and type of practice. While office-based 

physicians in the least populated West Region 

had the fewest visits for hypertension, visit rates 

were substantially alike for all regions. Division 

of visits for EBH by metropolitan or nonmetropolitan areas was parallel to the average for all 

NAMCS visits. 

Hypertension patients tended to visit physicians in solo practice more frequently than did 

patients presenting all diagnoses combined (70 

percent of hypertension visits were to physicians 

in solo practice as opposed to 60 percent for all 

other diagnoses). 

Table 6. Number of office visits and percent distributions end o 

average annual visit rate for essential benign hypertension by 

location and type of practice: United States,’ January 1975-

December 1976 

Location and type 

of practice 

All visits ...................... 

LOCATION OF PRACTICE 

Region 

Northeast..., .......................... 

North Central ........................ 

Ruth.., ................................. 

West,..................................... 

Type of area 

Metropolitan ......................... 

Nonmetropolitan .................. 

TYPE OF PRACTICE 

Solo ....c...............!................. 

Other . ................................. 

Number 

Percent of visits in 

of visits thousands 

46,128 100.0 

12,456 27.0 

13,376 29.0 

12,894 28.0 

7,402 16.1 

33,079 71.7 

13,049 28.3 

32,170 69.7 

13,967 30.3 

Arinual 

rate per 

100 

personsl 

11.1


12,8 

11.8 

9.7 

10.2 

11.7 

9.8 

!,. 

. . . 

lThe base populations used in computing the rates are 

national estimates published by the U.S. Bureau of the Census 

for the civilian noninstitutionalized population as of July 1, 1975, � in Series P-25, No. 614, and as of July 1, 1976, in Series P-25, 

Nos. 643 and 646, of Current Population Reports. 

21ncludes partnerships and group practices. 
REFERENCES 

1National Center for Health Statistics: Ambulatory 

medical care rendered in physicians’ offices: United 

States, 1975, by H. Koch and N.J. Dennison. Advance 

Data From Vital and Health StatMics, No. 12. DHEW 

Pub. No. (HRA) 77-1250. Health Resources Administration. Hyattsville, Md., Oct. 12, 1977. 

2National Center for Health Statistics: Physician 

visits: Volume and interval since last visit, United 

States-1 971, by K.M. Danchik. VitaI and Health Statistics. Series 1O-NO. 97. DHEW Pub. No. (HRA) 75-1524. 

Washington. U.S. Government Printing Office, Mar. 

1975. 

3National Center for Health Statistics: Blood pressure levels of persons 6-74 years, United States, 

1971-1974, by J. Roberts and K. Maurer. Vital and 

Health Statistics. Series 1l-No. 203. DHEW Pub. No. 

(HRA) 78-1648. Health Resources Administration. Washington. U.S. Government Printing Office, Sept. 1977. 

“4 National Center for Health Statistics: “-Hypertension: United States, 1974, by A. Moss and G. Scott. 

Advance Date From Vital and Health Statistics, No. 2. 

DHEW Pub. No. (HRA) 77-1250. Health Resources 

Administration. Rockville, kfd., Nov. 8, 1976. 

5 National Institutes of Health: Some characteristics 

related to the incidence of cardiovascular disease and 

death: Framingham Study, 16-year follow-up, by D. 

Shurtleff in Kannel, W. B., Gordon, T. eds, The Framingham Study. Pub. No. 74-599. Public Health Service. 

Washinaon. U.S. Government Printing Office, 1974. 

6National Heart, Lung, and Blood Institute: Report 

of the Joint National Committee on detection, evaluation, and treatment of high blood pressure. DHEW Pub. 

No. (NIH) 77-1088. National Institutes of Health. 

Bethesda, Md. 

SYMBOLS I I 

Quantity more than O but less than 0.05 ......... 

Figure does not meet standards of reliability 

= 

TECHNICAL NOTES 

SOURCE OF DATA: The information presented 

in this report is based on data collected in the 

Nat ion al Ambulatory Medical Care Survey 

(NAMCS) during 1975 and 1976. The target 

population of NAMCS encompasses office visits 

within the conterminous United States made by 

ambulatory patients to physicians who are principally engaged in office practice. 

SAMPLE DESIGN: NAIMCS utilized a multistage probability design that involves samples of 

primary sampling units (PSU’S), physician practices within PSU’S, and patient visits within practices. Each year a sample of practicing physicians is selected from master files maintained by 

the American Medical Association and the 

American Osteopathic Association. These physicians are requested to complete Patient Records 

(brief encounter forms) for a systematic random 

sample of office visits taking place within their 

practice during a randomly assigned weekly reporting period. (A facsimile of the Patient 

Record used is shown in a previous issue of Advance Data From Vital and Health Statktics, No. 

12, October 12, 1977.) Characteristics of the 

physician’s practice, such as primary specialty 

and type of practice , are obtained during an 

induction interview. A detailed description of 

the NAMCS design and procedures has been in 

Series 13, Number 33, of Vital and Health StaSAMPLING ERRORS: Since the estimates for 

this report are based on a sample rather than the 

entire universe, they are subject to sampling variability. The standard error is primarily a measure 

of sampling variability. The relative standard error of an estimate is obtained by dividing the 

standard error of the estimate by the estimate 

itself and is expressed as a percent of the estimate. Relative standard errors of selected aggregate statistics are shown in table I. The standard 

errors appropriate for the estimated percentages 

of office visits are shown in table II. 

ROUNDING: Aggregate estimates of office visits 

presented in the tables are rounded to the nearest thousand. The rates and percents, however, 

o Table 1. Approximate relative standard error of estimated 

numbers of office visits, NAMCS 1975-76 

Estimate Relative standard 

in error in 

thousands percentage points 

600 ... . ... .. . .. ... .. .... ... ... .. .. .. .. .... .. . 30.2 

1,000 .................. ........ ...... .... .. . 23.5 

2,000 .............. ...... ................... 16.7 

4,000 .......... ................ ........ ..... 12.0 

10,000” ............. ...... .. .... ........ .... 8.0 

40,000 .... ................................. 4.8 

200,000 .................. ................. 3.4 

1,000,000 ..... .. ...... ................. .. 3.1 

Example of use of table: Ars aggregate estimate of 

25,000,000 visits has a relative standard error of 6.4 percent or a 

standard error of 1,600,000 visits (6.4 percent of 25,000,000). 

GPO 9a7 63 I 
.

8 acimncedata 

Table II. Approximate standard errors of percentages for services who is neither bedridden nor currently 

estimated numbers of office visits, NAMCS 1975-76 admitted to any health care institution on the 

premises. Estimated percentage Base of percentage An ojj$ce is a place that the physician identi­

(number of visits 1 or 5 or 10or 20 or 30 or so fies as a ~ocation for his ambulatory practice. in thousands) 99 95 90 80 70 Responsibility over time for patient care and 

Standard .ror in percentage points professional services rendered there generally 

resides with the individual physician rather than 

1,000..................... 

2,000 .................... 

2.3 

1.6 

5.1 

3.6 

7.0 

4.9 

9.3 

6.6 

10.7 

7.5 

11.6 

8.2 A visit is a direct personal exchange between 

4,000 ..................... 

10,000 ................... 

40,000 ................... 

1.2 

0.7 

0.4 

2.5 

1.6 

0.8 

3.5 

2.2 

1.1 

4.7 

2.9 

1.5 

5.3 

3.4 

1.7 

5.8 

3.7 

1.8 

an ambulatory patient and a physician or a staff 

member working under the physician’s super200,000 ................. 0.2 0.4 0.5 0.7 0,8 0.8 vision for the purpose of seeking care and 

1,000,000.............. L 

0.1 0.2 — UL 

0.2 0.3 0.3 0.4 refidenng health services. 

600 ........................ 3.0 6.5 9.0 12.0 13.8 15,0 an institution. 

Example of use of table: An estimate of 20 percent based A physician is a duly licensed doctor of 

on an aggregate estimate of 80,000,000 visits has a standard medicine (M.D.) or doctor of osteopathy (D.O.) error of 1.3 percent. The relative standard error of 20 percent is currently in practice who spends time in caring 6.5 (1.3 percent + 20 percent) for ambulatory patients at an office location. 

Excluded from NAMCS are physicians who 

were calculated on the basis of original, un- specialize in anesthesiology, pathology, radirounded figures. Due to rounding of percents, ology; physicians who are federally employed; 

the sum of percentages may not equal 100.0 per- physicians who treat only institutionalized 

cent. patients; physicians employed full time by an 

DEFINITIONS: An ambulatory patient is an in- ;nstitution; and physicians” who spend no time 

dividual presenting himself for perspnal health seeing ambulatory patients. � 

P’ 

Recent Issues of Advance Data From Vital and Health Statistics 

No. 27. Health Characteristics of Minority Groups, National Ambulatory Medical Care Survey, United 

United States, 1976 (Issued: April 14, 1978) States, 1975 (Issued: March 22, 1978) 

No. 24. Utilization of Selected Me&lcal Practitioricrs: 

No. 26. Contraceptive Efficacy Among Married Wom- United States, 1974 (Issued: March 24, 1978) en 15-44 Years of Age in the United States, 1970-73


(Issued: April 6, 1978) No. 23. Office Vk.its to General Surgeons: National


Ambulatory Medical Care Survey, United States, 1975 

No. 25. Office Vkits to Doctors of Osteopathy: (Issued: March 24, 1978) 

A complete list of Advance Data From Vital and Health Statistics is available from the Scientific and Technical 

Informati& Branch. 

o 

NCHS POSTAGE ANO FEES PAID 

U.S. DEPARTMENT OF HEALTH, EDUCATION, 

Public Health Service 

AND WELFARE U.S. DEPARTMENT OF HEW 

HEW 390 * National Center for Health Statistics 

3700 Eaat.WestHighway FIRST CLASS MAIL ‘L 

HyattsviUe, Mmflsnd 207a2 

OFFICIAL BUSINESS 

PENALTY FOR PRIVATE USE, S300 

DHEW Publication No. 

(PHS) 78.1250 

To receive this publication regularly, 

contact the National Center for Health 

Statistics by callin~ 301 -436 -NCHS.