.m~~� &_ � � 

From Vital and Health StatMlcs of the National Center for Health Statistics Number 69 .April 1,1981- * 

(%13PERW QF ~E “ 

Pu2JcAT/Q/i!s
 BRANCH


EDITORIAL
 UBRARY


Office Visits for Preventive Care, National Ambulatory 

Medical Care Survey: United States, 1977-78 

by Beulah K. Cypress, Ph. D., Division of Health Care Statistics 

-e 

-a 

This report provides an estimate of public utilization of office-based physicians for purposes of 

preventive care. Its focus is on visits for certain 

examinations and tests that are likely to be undertaken because of the patient’s interest in good health 

maintenance or early detection of disease. 

Data on visits for such health-monitoring activities 

are collected in the National Ambulatory Medical 

Care Survey (NAMCS) of the National Center for 

Health Statistics. In this survey the patient’s complaint, symptom, or other reason for visit, expressed 

nearly as possible in the patient’s own words, is 

scorded by the physician in item 6 of the data 

collection form. Physicians are instructed to record 

key words or phrases verbatim to the extent possible. 

Figure 1 is a facsimile of the 1977-78 Patient Record 

used by participating physicians to record information about office visits. The principal reason (the 

reason that is listed first in item 6) is the one that in 

the physician’s judgment was most responsible for 

the patient making the visit. Data on reasons were 

classified and coded according to a ~ason for visit 

classification system presented in another report. I 

NAMCS is a probability sample survey conducted 

yearly by the Division of Health Care Statistics. Since 

the estimates presented in this report are based on a 

sample rather than on the entire universe of officebased physicians, the data are subject to sampling 

variability. The technical notes at the end of this 

report provide a brief explanation of sampling errors 

and guidelines for judging the precision of the estimates presented as well as definitions of certain terms 

used in NAMCS. A more detailed description of the 

lNational Center for Health Statistics: A reason fOr ViSit Cksificatbn 

for ambulatory care, by D. Schneider, L. Appleton, and T. McLemore. 

Vital and Health. Statistics. Series 2-No. 78. DHEW Pub. No. (PHS) 

9-1 3S2. Public Health Service. Washington. U.S. Government Printing 

ftlce, Feb. 1979. 

sample design and additional definitions have been 

published elsewhere.z The reader should note that 

estimates of numbers of visits contained in this report are for a 2-year period, but ratios and rates 

represent average annual estimates. 

Pain, discomfort, and other morbidity-related 

symptoms classified in the symptom module of the 

reason for visit classification system, because of 

their compelling nature, were the reasons given 

most frequently by patients. These reasons constituted 56 percent of all office visits during the 2-year 

period 1977-78 (table 1). Visits for diagnostic, 

screening, and preventive care-usually made by 

asymptomatic patients for reasons other than 

illness-made up the second largest group, accounting 

for about 18 percent. The examinations and tests 

. listed in table 2 composed the major part of the 

diagnostic, screening, and preventive care group and 

were responsible for about 17 percent of all visits. 

These specific reasons for visits were selected for this 

analysis because they are likely to be patient motivated rather than physician initiated; they are also the 

reasons for visits that are least likely to be related to a 

morbid condition. Thus they offer a measure of 

patients’ interest in preventive care. 

As a group, illness-related reasons in the symptom 

module exceeded those not necessarily related to 

illness. bong all specific reasons, however, two 

nonillness reasons were predominant, ranking first 

and second. These were general medical examinations and routine prenatal examinations, which 

accounted for about 5 percent and 4 percent of 

visits, respectively (table 2). For women, prenatal 

2National Center for Health Statistics: The National Ambulatory 

Medical Care Survey, 1977 summary: United States, January-December 

1977, by T. Ezzati and T. McLemore. Vital and Health Statistics. 

Series 13-No. 44. DHEW Pub. No. (PHS) 80-1795. Public Health 

Service. Washington. U.S. Government Printing Office, Apr. 1980. 

U.S. DEPARTMENT OF HEALTH AND HUMA~ SERVICES, Public Health service, Office of Health Research, Statistics, and Technology 
,, 2 aduancedata 

1 ASSURANCE OF CONF ID ENTIALITY-AII information. which would permit identif icarion of an individual, 

a pracxice, or an establishment will be held confidential, will be uwd onlv. bv Per$OnS en.qa9ed in and for A 033 the purposes of the survey and will not be disclosed or released to other persons Or used for any other purPosm 012

1.DATE OF VISIT PATlENT RECORD 

/ / NATIONAL AMBULATORY MEDICAL CARE SURVEY 

Mo Day/ Yr 

2. DATE OF BIRTH 3. SEX 4. COLOR OR 5. WAS PATIENT 6. PATIENT% COMPIAINT(SJ, SYMPTOM(S), OR OTHER 

RACE REFERREO FOR 

THISVISITBY ~ :%%%)::::;’’s” 

, n WHITE ANOTHER 

, n FEMALE * n NEGRO/ PHYSICIAN? a. MOST 

* BLACK IMPORTANT 

2 a MALE 1 � YES 

j � OTHER b. OTHER 

I 4 n UNKNOWN I 2DN0 I 

]. PHYSICIAN’S DIAGNOSES 9. HAVE YOU SEEN 

PATlENT BEFORE? 

a. PRINCIPAL DIAGNOSIS/PROBLEM ASSOCIATE WITH 

I 

7. TIME SINCE ONSET 

OF COMPLAINT/ 

SYMPTOM IN ITEM Sa 

(Check one) 

j � LESS THAN 1 OAY 

2 � 1-6 OAYS 

~ •1 1-3 WEEKS 

� � 1-3 MONTHS 

MORE THAN 50 3 MONTHS 

* � NOT APPLICABLE 

10. SERIOUSNESS OF 

CONDITION	 IN 

ITEM Sa (Check one) 

I � VERY SERIOUS 

z � SERIOUS 

SLIGHTLY 3CI 

SERIOUS 

* � NOT SERIOUS 

ITEM 6s 

b. OTHER SIGNIFICANT CURRENT OIAGNOSES 

~ 

* IF YES, FOR THE 

CONDITION IN 

ITEM 86? I “-

l“”s ‘“No 

I 

, 

13. DISPOSITION THIS VISIT 14. DURATION OF 

(Check all that apply)	 THIS VISIT 

(Time astuallv 

1 � NO FOLLOW-UP PLANNEO spent with 

a � RETURN AT SPECIFIED TIME physician] 

‘ n RETuRN IF NE EOED, P.R. N. D 

11.	 DIAGNOSTIC SERVICES THIS 

VISIT (Check all ordeted or provided) 

I D NONE


I � LIMITEO ExAM/HISTORY


J � GENERAL EXAM/HISTORY 

4 � PAP TEST 

, � CLINICAL LAB TEST 

$ � X. RAY 

7 ~ EKG 

$ � VISION TEST 

� � EN OOSCOPY 

,0 � BLOOO PRESSURE CHECK 

I I � OTHER (Spectfv) 

IRA-34.2 

:EV. 9.76 

12.	 THERAPEUTIC SERVICES THIS 

VISIT (Check all ordered or provided) 

I � NONE 

~ � iMMuNIZATION/ 

DESENSITIZATION 

3 � ORUGS (PREsCRIPTION/ 

NONPRESCRIPTION) 

*	 � OIET COUNSELING 

J � FAMILY PLANNING 

t � ME OICAL COUNSELING 

7 •l PHYSl OTHERApy 

~ � OFFICE SURGERY 

9 � PSYCHOTHERAPY/ 

THERAPEUTIC LISTENING 

10 D OTHER (Specify) 

DEPARTMENT OF HEALTH, ED UCATIO 

PuELICHEALr HSEHVl( 

HEALTH RESOURCES AOMINIS’ 

NATIONAL CENTER,FOa HEALTH 

4 � TELEPHONE FOLLOW-UP PLANNEO 

5 � REFERREO TO OTHER PHYSICIAN 

*	 � ‘E TuRNEo TO REFERRING PHYSICIAN 

‘ � ADMIT TO HOSPITAL 

‘ � OTHER ($ecifv) 

IANO WELFARE


E


RATION


STATISTICS


Patient Record Form: 1977-78 

MINUTES 

L

, (-t. M.8. =6 B-R1498 

Figure 1. National Ambulatory Madicel Care Survey 

— 

Table 1. Number and percent distribution of office visits by reason for 

visit module: United States, 1977-78 

Number of Percent 

Reason for visit module and R VC code’ visits in distribution 

thousands of visits 

All modules . . . . . . . . . . . . . . . . ...1.154,550 100.0 

Symptom module. . . . . . . . . S001 -S999 648,990 56.2 

Disease module . , . . . . . . . .DOOI-D999 100,902 8.7 

Diagnostic, screening, and 

praventiva module. . . . . . . . X1 OO-X599 211,690 18.3 

Treatment module . . . . . . . . T100-T899 103,586 9.0 

Injuries and adverse effects 

module . . . . . . . . . . . . . . JOOI-J999 48,941 4.2 

Test results module. . . . . . . . RI 00-R700 6,237 0.5 

Administrative module. . . . . .A100-A140 19,029 1.7 

0ther2 . . . . . . . . . . . . . .. U990-U999 15,185 1.3 

1 ~aSed on tie ~eaSon for visit classification ( RVC). See reference 1. 

21nclude~ blankS, problams and complaints nOt elsewhere classified, 

entties of “none,” and illegible entries. 

examinations were proportionately more frequent 

than general medical examinations. A rough measure 

of patient motivation toward health care is the ratio 

of return visits to new-problem visits. On the average, 

patients giving prenatal care as the reason for visit 

made about 5.3 return visits for each new-problem 

visit. Because of these and other sex-specific examtiations, the preventive measures shown in table 2 

accounted for about 20 percent of visits made by 

women, compared with 11 percent of those made by 

men. 

Table 3 presents the percent distribution and . 

average annual rates of visits for the selected preventive care measures by sex and age of patients. When o 

the visits were for general medical examinations, eye 

examinations, or family planning, visit rates for 

females in all age groups exceeded those for their 
dmcedaa3 

8 

bl~ 2. Number of office visits and percent of visits for preventive 

care, by, sex of patient and selected principal reasons for visit: 

Visits for blood pressure tests were more common 

among men 15-44 years of age than among women 

United States, 1977-78 the same age, but the comparison is reversed for ages 

and RVC code’ saxes Female Mafe were as likely to visit for blood pressure tests as men 

were. Figure 3 highlights this phenomenon. Additional 

Principal reason for visit Both 55 and over. During the middle years, 45-54, women 

Number of visits in thousands information on blood pressure measurement (not All reasons. . . . . . . . . . . . . . . . . 1,164,550 694,431 460,119 necessarily related to the reason for visit) has been 

Percent of visits published earlier.s 

General madical examination . . X1OO 5.1 5.0 5.3 Women 25-44 years of age had higher visit rates 

Well-baby examination. . . . . . Xl 05 1.2 1.0 1.5 

Prenatal examination, routine. . X205 3.5 5.8 . . . for gynecological examinations and Pap smears than 

Postpartum examination. . . . . X215 0.4 0.6 . . . women in other age groups had. Although professional 

8reast examination . . . . . . . . X220 0.1 0.1 *0.O opinions vary regarding the optimal age and interval 

Gynecological examination . . . X225 1.2 1.9 . . . 

Eye examination . . . . . . . . . X230 1.0 1.1 1.0 for testing for cervical cancer, it appears from these


Blood pressure tast . . . . . . . . X320 2.1 2.0 2.2 data that women in the childbearing years are more


Papsmear . . . . . . . . . . . .. X365 0.7 1.1 . . . likely than other women to have concern for this


Prophylactic inoculations . . . . X400 0.7 0.6 0.8


Family planning. . . . . . .X500-X51 O 0.7 1.0 0.2 aspect of health status.


Table 4 presents data on the utilization for pre1 Baaed on the reason for visit classification ( RVC). See reference 1. ventive care of the four most visited physician specialties. More than half the visits to specialists kI 

male counterparts. Figure 2 demonstrates how visit 

rates for general medical examinations increased with 

advancing age of the patients, regardless of sex. Rates 3Nationa] Center for Health Statistics: Office vklts for diseases of ‘e 

for well-baby examinations and prophylactic inocu- circulatory system, the National Ambulatory Medical Care Survey: 

United States, 1975-76, by B. K. Cypress. Vital and Health Statistics. lations were similar for both sexes, as might be Series 13-No. 40. DHEW Pub. No. (PHS) 79-1791. Public Health 

expected. Service. Washington. U.S. Government Printing Office, Jan. 1979. 

Table 3. Number, percent distribution, and average annual rate of office visits for preventive care by sex and age of patient, 

according to selected principal reasons for visit: United States, 1977-78 

Number of ‘oti Female Male 

Principal reason for visit visits in sexes, 

and RVC code~ thousands all Under 15-24 25-44 45-64 65 years Under 75-24 25-44 45-64 65 years 

ages 15 years years years years and over 15 years years years years and over 

Percent distribution of visits 

General medical examination. . . Xl 00 59,115 100.0 17.7 5.4 12.5 13.5 10.0 17.0 2.5 5.3 9.6 6.6 

Well-baby examination. . . . . . . X105 13,726 100.0 48.9 . . . . . . . . . 51.1 . . . . . . . . . . . . 

Prenatal examination, routine . . X205 40,394 100.0 “0.5 47.2 51.8 �0.4 ::: . . . . . . . . . . . . . . . 

Postpartum examination. . . . . . X215 

Breast examination . . . . . . . . . X220 

4,114 

915 

100.0 

100.0 

*3.6 

-

43.1 

� 12.8 

52.6 

“35.1 

�0.7 

�35.7 

. . . 

*15.2 

. . . . . . 

- -

. . . . . . “;:3 

Gynecological examination . . . . X225 

Eye examination. . . . . . . . . . . X230 

13,262 

11,952 

100.0 

100.0 

‘0.1 

7.6 

19.7 

10.0 

50.9 

12.7 

25.1 

19,7 

4.3 

12.5 59 56 ;:1. . . . 

11.0 8:0 

Blood pressure test . . . . . . . . . X320 23,696 100.0 “0.6 � 0.4 4.7 26.0 26.5 ‘0.1 ‘0.9 6.8 20.5 13.6 

Papsmear . . . . . . . . . . . . . .. X365 

Prophylactic inoculations . . . . . X400 

7,631 

8,152 

100.0 

100.0 

‘0.7 

22.9 

21.5 

5.4 

50.6 

8.0 

23.3 

9.5 

�4.1 

7.2 239 � 3+ 69 . . . 

4.9 

Family planning . . . . . . .X5OO-X51O 7,948 100.0 �1.5 40.9 46.6 �1.3 *0.8 - ‘0.6 �1.2 

Average annual visit rate per 1,000 persons 

General medical examination. . . X1OO . . . 139.6 209.8 79.1 128.1 176.2 224.4 193.4 38.1 58.3 137.6 211.3 

Well-baby examination. . . . . . . X105 . . . 2758.4 27 fjo.1 . . . 2758.3 -.. . . . . . . . . . 

Pranatal examination, routine . . X205 . . . 3184.2 �3.9 473.6 3632 *36.:. ::: . . . . . . . . . . . . . . . 

Postpartum examination. . . . .. X215 . . . 318.8 ‘3.0 44.0 37.6 90.3 . . . . . . . . . . . . . . . . . . 

Breast examination . . . . . . . . . X220 . . . 2.2 - * 2.9 �5.6 �7.2 �5.3 - - ‘0.6 

Gynecological examination . . . . X225 . . . 3605 ‘0.2 64.7 117.3 73.6 21.6 . . . . . . . . . 

Eye examination. . . . . . . . . . . X230 . . . 28.2 18.2 29.7 26.4 52.1 56.5 13.6 17.1 15:; 3i :9 51.3 

Blood pressure test . . . . . . . . . X320 . . . 56.0 �2.6 �2.3 19.4 136.4 238.2 “0.4 �5.2 30.1 117.5 173.9 

Papsmear . . . . . . . . . . . . . .. X365 . . . 334.8 “1.0 40.6 67.0 39.3 ‘11.8 . . . . . . . . . 

Prophylactic inoculations . . . . . X400 . . . 19.3 37.5 10.9 11.3 17.2 22.2 37.5 *7.9 13:6 21.4 

* Family planning . . . . . . .X500-X510 . . . 18.8 �2.3 90.0 70.5 �2.4 “2.4 - �1.2 �2.8 

1 ~a$ed on the reason for visit classification (R VC). see reference 1.


2Base~ on the population under 3 years of a9e.


3~a~ed on the female pOpulatiOn onw.

--

4


/ 

30- ( b 

Male . 

, 

E 20 — 

z 

; 

: \ 

a 

$j \ 

1% 10 \ 

\ 

/0

\ 

4“ \ -e.e* 

0. I I I I I I I I 

Under 15 15-24 25-34 354 45-!54 55-64 65-74 75 and 

over 

Age in years 

Figure 2. Average annual rate of office visits for general medical examinations, by sex and age of patient: United States, 1977-78 

30- 0’ 

~m 

i

al Q 

0

0 

~ 

R 

m 

II 10 

--+ 

0 

15-24 25-34 35-44 45-54 55-64 65-74 75 and 

over 

Again years 

Figure 3. Average annual rate of office visits for blood pressure tests, by sex and age of patient: United States, 1977-78 

obstetrics an,d gynecology were for preventive care, 

with prenatal examinations the predominant type of 

visit. Because of the large proportions of general 

medical examinations and well-baby examinations, 

about one-fourth of the average pediatrician’s practice included visits chiefly for preventive care. Internists and physicians in general and family practice 

provided proportionately about the same amount 

of preventive care (about 14 percent of visits for the 9 

former and 13 percent for the latter). However, 

general medical examinations and blood pressure 

ests constituted a larger share of preventive care 
admcxMa5 

a Table 4. Number of office visits and percent of visits for preventive care, by physician specialty, type of practice, and selected 

principal reasons for visit: United States, 1977-78 

Physician specialty Type of practice 

General Principal reason for visit and R VC codel Obstetrics

and Internal 

family medicine Pediatrics end solo 

gynecology practice 

Number of visits in thousands 

All visits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433,936 133,281 114,921 104,412 683.404 

Parcent of visits 

General medical examination . . . . . . . . . . . . . . . . . . . X1OO 4.3 7.7 316.0 5.5 4.6 

Well-beby examination . . . . . . . . . . . . . . . . . . . . . .. X105 0.9 . . . 48.5 . . . 0.8 

Prenatal examination, routine. . . . . . . . . . . . . . . . . . . X205 2.2 0.0 80.1 28.1 2.5 

Postpartum examination . . . . . . . . . . . . . . . . . . . . . . X215 0.2 3.0 0.3 

Breast examination . . . . . . . . . . . . . . . . . . . . . . . .. X220 “0.0 :0.1 “0.2 0.1 

Gynecological examination . . . . . . . . . . . . . . . . . . . . X225 0.3 0.1 :0.1 11.1 0.7 

Blood pressure test . . . . . . . . . . . . . . . . . . . . . . . .. X320 3.2 5.5 0.0 “0.1 2.4 

Papsmear . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. X365 1.0 0.4 “0.0 2.2 0.6 

Prophylactic inoculations . . . . . . . . . . . . . . . . . . . . . X400 0.9 0.5 1.2 “0.2 1.0 

Family planning . . . . . . . . . . . . . . . . . . . . . . . .x500-x510 0.4 0.1 “0.0 1.7 0.6 

Othe? 

471,146 

5.8 

1.7 

4.9 

0.5 

0.1 

1.8 

1.6 

0.8 

0.3 

1.1 

1 ~asd on the ~eaSon for visit classification (RVC). See reference 1. 

21ncludes partnership, group practice, and Other3 Includes petients 3 years of age and over. 41ncl”de$ p*t@tSunder 3 years of a9e. 

‘ visits for internists than they did for generrd and fame ily practitioners, probably because internists see 

- proportionately more older patients. 

Eye examination is not included in table 4 since 

94 percent of such visits were to ophthalmologists. 

Eye examination as a reason for visit was responsible 

for 19 percent of the visits to ophthalmologists. 

According to the data on type of practice shown 

in table 4, certain types of preventive care are more 

common in offices with practice arrangements other 

than solo. Except for breast examinations, prophylactic inoculations, and blood pressure tests, preventive care visits made up a smaller proportion of 

visits to solo practitioners than of visits to physicians 

with other practice arrangements. Blood pressure 

tests were proportionately more frequently the 

reason for visits to physicians in solo practice than to 

others. It is not possible to determine from NAMCS 

data why visits for certain kinds of preventive care 

were more common in group than in other practice 

arrangements. However, the availability of more 

than one specialty may be a factor since, according to 

an American Medical Association report, multispecialty groups constituted 59 percent of group 

practice arrangements in 1975.4 

Often, patients who visit primarily for iUnessrelated pro-blems also seek p-inventive care. The 

* 

4Goodman,L,. J., Bennett, E. H., and Orkm R. J.: GrOUPJfedicaI 

Practice in the U.S., 1975. Chicago. Center for Health Services Research 

and Development. American Medic at Association, 1976. 

secondary reason for visit is also recorded on the 

Patient Record (figure 1). It is noteworthy that the 

kinds of preventive care shown in table 5 were 

mentioned as second reasons for 19.6 million visits 

in 1977-78. There were almost as many visits with 

breast examination mentioned second as there were 

with the same examination given as @e principal 

reason. Obtaining a Pap smear was also frequently 

a second reason for a visit. A well-baby examination 

or a routine prenatal examination was likely to be 

the sole reason for a visit since a relatively small 

number of records listed either of them second. 

An exhaustive list of preventive care activities 

comprises more than the examinations and tests 

discussed in this report. Depending on the definition 

of p~ventive care that is used, NAMCS preventive 

Table 5. Number of office visits with preventive care as second reason 

for visit: United States, 1977-78. 

Number of Second reason for visit 

visitsin and R VC coda’ 

thousands 

General madical examination . . . . . . . . . . . . . . . XIOO 2,936 

Prenatal examination, routine. . . . . . . . . . . . . . . X205 773 

Breast examination . . . . . . . . . . . . . . . . . . . .. X220 852 

Gynecological examination . . . . . . . . . . . . . . . . X225 1,480 

Eyeexamination . . . . . . . . . . . . . . . . . . . . .. X230 852 

Blood pressure test . . . . . . . . . . . . . . . . . . . .. X320 4,252 

Pap smear . . . . . . . . . . . . . . . . . . . . . . . . .. X365 4,395 

Prophylactic inoculations . . . . . . . . . . . . . . . . . X400 1,727 

Family planning. . . . . . . . . . . . . . . . . . . .X5OO-X51O 2,345 

1 Based on *= reaSon for visit classification (RVC). See reference 1-
6 fiCk3ncedata 

care visits also include visits for such reasons as pa- coming rep ort from the Vital and Health Statistics 

tient education, diet and nutritional counseling, series. Questions regarding this report may be die social problem counseling, and glucose level deter- rected to the Ambulatory Care Statistics Branch by 

mination. Additional data on these and other types calling 301-436-7132. 

of preventive care as well as on other reasons for 

visit will be presented in more detail in a forthTechnical notes 

Source of data estimate by the estimate itself and is expressed as a 

percent of the estimate. Relative standard errors for The information presented in this report is aggregate statistics are shown in tables I and II. 

based on data collected in the National Ambulatory Standard errors for estimated percents are shown in 

Medical Care Survey (NAMCS) during 1977 and tables III and IV. 

1978. The NAMCS universe is composed of office 

visits made within the conterminous United States by 

ambulatory patients to nonfederally employed 

Table 1. Approximate relative standard errors of es~imated numbers of 

officeVkitsbased on all physician specialties: NAM(%, 1977-73 

physicians who are principally engaged in office 

practice and are not in the specialties of anesthesiology, pathology, or radiology. The National Opinion 

Relative 

Estimated number of office standard 

visits in thousands error in 

, 

Research Center, under contract to the National percent 9 

Center for Health Statistics, is responsible for the 500 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.9 

NAMCS field operations. 1,000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.7 

2,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.7 

5,000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3 

Sample design 10,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 

20,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8 

50,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8 NAMCS utilizes a multistage probability design 200,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 

that involves samples of primary sampling units 1,000,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 

(PSU’S), physician practices within PSU’S, and patient 

visits within physician practices. For 1977-78 a Example of use of table: An aggregate of 15,000,000 visits has a relative standard error of 5.5 percent, or a standard error of 825,000 sample of 6,007 non-Federal, office-based physicians visits (5.5 percent of 15,000,000). 

was selected from master fdes maintained by the 

American Medical Association and the American Table 11. Approximate relative standard errors of estimated numbers of 

Osteopathic Association. The physician response office visits based on an individual physician specialty: 

rate for this period was 75.1 percent. Sampled NAMCS, 1977-78 

physicians were requested to complete Patient Relative 

Records (figure 1) for a systematic random sample Estimated number of office standard 

of office visits taking place during a randomly as- visits in thousands error in 

signed weekly reporting period. During 1977-78, percent 

98,335 Patient Records were completed by respond- 500 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.0 

ing physicians.	 1,000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.6 

2,000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5 

5,000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3 

Sampling errofs	 10,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5 

20,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4 

50,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7 The standard error is primarily a measure of the 100,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 

sampling variability that occurs by chance because 400,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 9 

only a sample, rather than the entire universe, is 

sampled. The relative standard error of an estimate Example of use of table: An aggregate of 7,500,000 visits has a relative standard arror of 9.4 percent, or a standard error of 705,000

is obtained by dividing the standard error of the visits (9.4 percent of 7,500,000). 
---

a Table II L Approximate standard errors of percents of estimated numbers 

of office visits based on all physician specialties: NAMCS, 1977-78 

Base of percent 

Estimated percent 

(number of office I or 5or 10or 200r 3~~ 50 

vi$its in thousands) 99 95 80 80 

Standard error in percentage points 

500 . . . . . . . . . . . . . ...2.5 5.4 7.4 9.9 11.4 12.4 

1,000 . . . . . . . . . . . . ...1.7 3.8 5.3 7.0 8.0 8.8 

2,000 . . . . . . . . . . . . ...1.2 2.7 3.7 5.0 5.7 6-2 

5,000 . . . . . . . . . . . . ...0.8 1.7 2.3 3.1 3-6 3.9 

10,000 . . . . . . . . . . . ...0.6 1.2 1.7 2-2 2.5 2.8 

20,000 . . . . . . . . . . . ...0.4 0.9 1.2 1.6 1.8 2.o 

50,000 . . . . . . . . . . . ...0.2 0.5 0.7 1.0 l-l 1-2 

200,000 . . . . . . . . . . ...0.1 0.3 0.4 0.5 0.6 0.6 

1,000,000. . . . . . . . ..- . 0.1 0.1 0.2 0.2 0.3 0-3 

Example of use of table: An estimate of 20 percent based on an aggregate of 15,(300,000 visits has a standard error of 1.9 Percent, or a relative stendard error of 9.5 percent ( 1.9 percent + 20 percent). 

Table IV. Approximate standard errors of percents of estimated numbers 

of office visits based on an individual physician specialty: 

NAMCS, 1977-78 

Base of percent 

Estimated percent 

(number of office 1 or 5or 10 or 20 or 3~~ 50 

visits in thousends) 99 95 90 80 

e Standard error in percentage points 

500 . . . . . . . . . . . . . ...2.6 5.7 7.9 10.5 12.1 13.1 

‘- 1,000 . . . . . . . . . . . . ...1.9 4.1 5.6 7.4 8.5 9.3 

2,000 . . . . . . . . . . . . ...1.3 2.9 3.9 5.3 6.0 6.6 

5,000 . . . . . . . . . . . . ...0.8 1.8 2.5 3.3 3.8 4.2 

10,000 . . . . . . . . . . . ...0.6 1.3 1.8 2.4 2.7 2-9 

20,000 . . . . . . . . . . . ...0.4 0.9 1.2 1.7 1.9 2.1 

50,000 . . . . . . . . . . . ...0.3 0.6 0.8 l-l 1-2 1-3 

100,000 . . . . . . . . . . ...0.2 0.4 0.6 0.7 0.9 0.9 

400,000 . . . . . . . . . . ...0.1 0.2 0.3 0.4 0.4 0.5 

Example of use of table: An estimate of 90 percent based on an aggregate of 3,500,000 visits has a standard error of 3.2 percent, or a relative standard error of 3.6 percent (3.2 percent+ 90 percent). 

Definitions 

Ambulatory patieizt.-An ambulatory patient is 

an individual presenting himself for personal health 

services who is neither bedridden nor currently 

admitted to any health care institution on the premises. 

O~fice.-An office is a place that the physician 

identifies as a location for his ambulatory practice. 

Responsibility over time for patient care and professional services rendered there generally resides 

with the individual physician rather than an institution. 

Visit.–A visit is a direct personal exchange between an ambulatory patient and a physician, or 

between a patient and a staff member working 

under the physician’s supervision, for the purpose 

of seeking care and rendering health services. 

Physician.–A physician is a duly licensed doctor 

of medicine (M.D.) or doctor of osteopathy (D.O.) 

currently in office-based practice who spends time in 

caring for ambulatory patients. Excluded from 

‘NAMCS are physicians who are hospital based; physicians who specialize in anesthesiology, pathology, 

or radiology; physicians who are federally employed; 

physicians- who treat only institutionalized patients; 

physicians employed full time by an institution; and 

physicians who spend no time seeing ambulatory 

patients. 

Symbols 

Data not available 

. . . Category not applicable 

Quantity zero 

0.0 Quantity more than O but less than 0.05 

*	 Figure doas not meet standards of 

reliability or precision 
,’ &


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No. 67. Headache as the Reason for Office Visits, National Ambulatory Medical Care Survey: United States, 1977-78 (Issued: 

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No. 66. 1979 Summary, National Ambulatory Medical Care 

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