Survey
description
The National Ambulatory Medical Care Survey (NAMCS) is designed to meet the need for
objective, reliable information on the provision and use of ambulatory medical care
services in the United States. Findings are based on a sample of visits to nonfederally
employed office-based physicians who are primarily engaged in direct patient care.
Physicians in the specialties of anesthesiology, pathology, and radiology are excluded
from the survey.
Specially trained
interviewers visit the physicians prior to their participation in the survey in order to
provide them with survey materials and instruct them on how to complete the forms. Each
physician is randomly assigned to a 1-week reporting period. During this period, data for
a systematic random sample of visits are recorded by the physician or office staff on an
encounter form provided for that purpose.
For survey years 1973-91,
there are two data files--one for patient visit data where each record contains
information on a sampled patient visit and a second for drug mention data where each
record represents a single drug mention along with its associated visit data. The second
file is limited to those visits with mention of medication therapy. For the 1991 data, it
is possible to link information on the drug file with information on the patient visit
file. Beginning with the 1992 survey year, only one data file is produced annually that
contains both patient visit and drug information.
Data file description
Patient visit
data
Data on the patient visit file reflect the NAMCS instrument or
Patient Record form. Each file record contains all of the items in the following summary,
including an inflation factor or patient visit weight. This weight must be used to obtain
national estimates of health care utilization from the sample data.
Drug
mentions
The drug file concerns only those office visits at which one or more medications were
ordered, administered, or provided. There is one record for each drug mentioned or entered
on the Patient Record form. A single office visit in 1985 could have up to five drugs
mentioned on the form, resulting in five separate records on the file. On the other hand,
if there were no drugs mentioned for a particular office visit, there would be no records
on the drug file for that visit. Each file record contains all of the items in the
following summary, including an inflation factor or drug weight. This weight must be used
to obtain national estimates of drug utilization from the sample data.
Data file
technical characteristics
The following list shows the
number of records for each data year.
Patient visit data (from
1992, includes drug mention data)
Data
year
Number of
records
2004
25,286
2003
25,288
2002
28,738
2001
24,281
2000
27,369
1999
20,760
1998
23,339
1997
24,715
1996
29,805
1995
36,875
1994
33,598
1993
35,978
1992
34,606
1991
33,795
1990
43,469
1989
38,384
1985
71,594
1981
43,366
1980
46,081
1979
45,351
1978
47,291
1977
51,044
1976
51,224
1975
62,697
1973
29,102
Drug mention
data
Data
year
Number of
records
1991
37,429
1989
43,792
1985
71,182
1981
45,610
1980
51,372
Geographic
coverage
Data are available for the United States as a whole and for the four geographic regions.
Data
availability
The NAMCS began in 1973 and was conducted annually through 1981, again in
1985, and annually since 1989. Public use data files are available for
each survey year except 1974 as downloadable ASCII files from the Ambulatory
Health Care Data website. Drug mention data are available as separate data files for 1980,
1981, 1985, 1989, 1990, and 1991. Beginning with 1992, drug mention data
are included on the public use files for each year. Data on CD-ROM are
available for survey years 1990-2003. Data on CD-ROM are accessed via
Statistical Export and Tabulation Software (SETS) which comes with the CD.
Some years of data are also available on CD-ROM in ASCII format.
Ordering
information
SETS CD-ROMs are available at no charge from NCHS or may be purchased from
the Government Printing Office (GPO) when first released. ASCII data for
individual years may be purchased through the National Technical
Information Service (NTIS). As prices vary, please contact NTIS or GPO for
current order numbers and pricing. For availability, please check the
listing of CD-ROM and Video Products.
Documentation
contents
Complete
documentation for each year of data from 1973-1992
and 1993-2004
is available for downloading. The CD-ROMs for each year contain complete
electronic documentation for the dataset and the SETS software.
Contact
Susan M. Schappert
Ambulatory Care Statistics Branch
Division of Health Care Statistics
National Center for Health Statistics
Centers for Disease Control and Prevention
3311 Toledo Road, Room 3409
Hyattsville, Maryland 20782
(301) 458-4480
E-mail: sds0@cdc.gov