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National Ambulatory Medical Care Survey (NAMCS) Public-Use Data Files

Survey description 
Data file description
List of data file variables at a glance
Data file technical characteristics
Geographic coverage
Data availability
Ordering information
Documentation contents
Related reports
Contact
Ambulatory Health Care Data Web Page

^{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)

Drug mention data

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.

Notice, NAMCS CD-ROM Users

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.

Related reports
Detailed survey results are published in Vital and Health Statistics Series 13 reports, and are also available in less detail in Advance Data reports. A comprehensive list of all published reports from NAMCS is available. Information concerning future reports may be obtained by calling the Ambulatory Care Statistics Branch.

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

This page last reviewed March 16, 2009