This study is maintained and distributed by the National Archive of Computerized Data on Aging (NACDA), the aging program within ICPSR. NACDA is sponsored by the National Institute on Aging (NIA) at the National Institutes of Heath (NIH).

National Ambulatory Medical Care Survey, 2009 (ICPSR 31482)

Principal Investigator(s):


The National Ambulatory Medical Care Surveys (NAMCS) supply data on ambulatory medical care provided in physicians' offices. The 2009 survey contains information from 32,281 patient visits to 1,293 physicians' offices. Data are available on the patient's smoking habits, reason for the visit, expected source of payment, the physician's diagnosis, and the kinds of diagnostic and therapeutic services rendered. Other variables include information on the following: drugs/medications ordered, administered, or provided during office visits; information on medication code, generic name and code, brand name, entry status, prescription status, federal controlled substance status, composition status, and related ingredient codes. Information is also included on the physician's specialization and geographic location. Demographic information on patients, such as age, sex, race, and ethnicity, was also collected.

Series: National Ambulatory Medical Care Survey Series

Access Notes

  • These data are freely available.


WARNING: This study is over 150MB in size and may take several minutes to download on a typical internet connection.

Study Description


United States Department of Health and Human Services. Centers for Disease Control and Prevention. National Center for Health Statistics. National Ambulatory Medical Care Survey, 2009. ICPSR31482-v3. Ann Arbor, MI: Inter-university Consortium for Political and Social Research[distributor], 2011-11-17.

Persistent URL:

Export Citation:

  • RIS (generic format for RefWorks, EndNote, etc.)
  • EndNote XML (EndNote X4.0.1 or higher)

Scope of Study

Subject Terms:   ambulatory care, doctor visits, health care services, medical care, medical evaluation, medical records, medications, patient care, patients, physicians, prescription drugs, smoking, treatment

Geographic Coverage:   United States

Time Period:  

  • 2009

Date of Collection:  

  • 2009

Universe:   Office visits made within the United States by patients of nonfederally-employed physicians who were primarily involved in office-based patient care activities, but not engaged in the specialties of radiology, pathology, or anesthesiology.

Data Types:   administrative records data, medical records

Data Collection Notes:

Per agreement with the National Center for Health Statistics (NCHS), ICPSR distributes the data file and text of the technical documentation for this collection as prepared by NCHS.

The Stata dataset (.dta file) made available by ICPSR does not contain all of the value labels found within the .do file supplied by ICPSR. Specifically, the value labels that are composed primarily of ICD-9 codes have been omitted from the .dta file. Those data users interested in applying the value labels to the dataset will be able to edit the Stata setup files, which include the aforementioned labels, provided by ICPSR.


Sample:   The 2009 NAMCS utilized a multistage probability sample design. Primary sampling units (PSU's) were selected in the first stage; physician practices within PSU's in the second stage; and patient visits to selected physicians in the third stage. Additional information regarding sampling methodology can be found in the study documentation.

Time Method:   Cross-sectional

Weight:   Microdata file users should be fully aware of the importance of the "patient visit weight" (PATWT) and how it must be used. Information about the patient visit weight, along with a "physician-level weight" (PHYSWT), is presented in the codebook. If more information is needed, the staff of the Ambulatory Care Statistics Branch can be consulted by calling (301) 458-4600.

Mode of Data Collection:   record abstracts

Data Source:

medical records

Response Rates:   62.1 percent unweighted response rate, 62.4 percent weighted response rate

Extent of Processing:  ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major statistical software formats as well as standard codebooks to accompany the data. In addition to these procedures, ICPSR performed the following processing steps for this data collection:

  • Created variable labels and/or value labels.
  • Created online analysis version with question text.
  • Performed recodes and/or calculated derived variables.
  • Checked for undocumented or out-of-range codes.


Original ICPSR Release:  

Version History:

  • 2011-11-17 User guide documentation was added to the study.
  • 2011-10-06 Value labels that were not previously provided have been added to the dataset.

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