National Ambulatory Medical Care Survey Series

Investigator(s): U.S. Department of Health and Human Services, National Center for Health Statistics

The National Ambulatory Medical Care Survey (NAMCS), conducted from 1973 to 1981, in 1985, and from 1989 to the present, contains data on medical care provided in physicians' offices. It is a continuously sampled survey based on a nationwide sample of patient records. The survey obtains information on the number of office visits by age, race, and sex of the patient, and on selected physician characteristics such as geographic location, type of practice, and specialization. Data describing the nature of office visits include the patient's problem, prior visit status, referral status, major reason for the visit, physician's diagnosis, diagnostic and therapeutic services provided, and disposition and duration of the visit. The patient's problem or complaint is coded according to a revised symptom classification developed specifically for the NAMCS. The physician's diagnosis is coded according to the EIGHTH REVISION OF THE INTERNATIONAL CLASSIFICATION OF DISEASES ADAPTED FOR USE IN THE UNITED STATES (ICDA) for surveys prior to 1979. The NINTH REVISION OF THE INTERNATIONAL CLASSIFICATION OF DISEASES, CLINICAL MODIFICATION (ICD-9-CM) supplanted the ICDA-8 and was used beginning with the 1979 NAMCS. The National Ambulatory Medical Care Survey Drug Mentions files contain information on all drugs/medications ordered, administered, or provided during office visits. The data items include medication code, generic name and code, brand name, entry status, prescription status, federal controlled substance status, composition status, and related ingredient codes. Starting in 1992, the drug mentions data were incorporated into the main survey file. A related data series, the National Hospital Ambulatory Medical Care Survey (NHAMCS), provides data on the hospital emergency room and outpatient department visits that make up a large part of the total ambulatory care received each year.