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National Ambulatory Medical Care Survey, Restricted data, 1973, 1975-1981, 1985, 1989-2016, 2018-2019
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The National Ambulatory Medical Care Survey (NAMCS) is a national survey designed to meet the need for objective, reliable information about the provision and use of ambulatory medical care services in the United States. Findings are based on a sample of visits to non-federally employed office-based physicians who are primarily engaged in direct patient care. Physicians in the specialties (including designated sub-specialties) of anesthesiology, pathology, and radiology are excluded from the survey. The survey was conducted annually from 1973 to 1981, again in 1985, and annually since 1989. Data collection from the physician, rather than from the patient, provides an analytic base that expands information on ambulatory care collected through other NCHS surveys. Data about the physician and their practice characteristics are collected during a survey induction interview. For survey years 1973 to 1991, there are two data files: one for patient visit data and a second for drug mention 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 through 2011, one main data file was produced annually that contains both patient visit and drug information.
Detailed Methodology
Findings are based on a sample of visits to nonfederally employed office-based physicians who are primarily engaged in direct patient care. The sampling frame for NAMCS (core sample, not including CHC delivery sites) was composed of all physicians listed in the master files maintained by the AMA and AOA who met the following criteria: -- Office-based or hospital-employed, as defined by the AMA and AOA; -- Principally engaged in patient care activities; -- Nonfederally employed; -- Not in specialties of anesthesiology, pathology, or radiology -- Younger than 85 years of age at the time of the survey. Physicians whom the AMA classifies as “hospital-employed” were added to the sampling frame starting with the 2014 NAMCS. This expansion of the NAMCS physician sampling frame is due to concerns that NAMCS was not covering visits made to office-based practices which are owned by hospitals, and to increases in reported hospital purchases of physician practices in recent years.