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National Ambulatory Medical Care Survey (NAMCS)
U.S. Department of Health and Human Services, Centers for Disease Control and Prevention (CDC), National Center for Health Statistics (NCHS).
Mode of Administration
Field personnel meet with participating office-based physicians and instruct them in survey data collection methods. Physicians are asked to complete a one-page questionnaire (Patient Record Form) on a sample of their office visits during their assigned reporting period.
Survey Sample Design
NAMCS is a national probability sample survey of visits to office-based physicians in the U.S. The NAMCS utilizes a three-stage survey design that involves probability samples of primary sampling units (PSUs), physician practices within PSUs, and patient visits within physician practices. Participating physicians are randomly assigned to a one-week reporting period during the survey year, and a systematic random sample of patient visits during that period is selected, using a visit sampling rate that varies by the size of the practice, with the intention of obtaining 30 survey forms per physician. Sample data are weighted to produce national estimates of office visits.
Primary Survey Content
Information is obtained on various aspects of office visits, including physician practice characteristics, patient characteristics, and other visit characteristics. The survey form is redesigned every two to four years to address changing health data needs. Among the items collected are patient's age, gender, race, and ethnicity; patient's expressed reason for visiting the physician; intentionality of injury, if any; physician's diagnoses; diagnostic services ordered or provided; therapeutic services; ambulatory surgical procedures performed; medications; providers seen; visit disposition; time spent with physician; and expected source of payment.
The basic sampling unit is the patient visit. Included in the survey are in-person visits made to the offices of non-Federally employed, office-based physicians who are classified by the American Medical Association or the American Osteopathic Association as being primarily engaged in direct patient care. The specialties of anesthesiology, pathology, or radiology are not included. Also not included are contacts by telephone, visits made outside the physician's office, visits in hospitals or institutional settings, and visits made for administrative purposes only.
Patient's age, gender, race, and ethnicity.
Annual from 1973-81; again in 1985; resumed an annual schedule in 1989.
National, four census regions.
The NAMCS is a visit-based survey rather than a population-based survey. Therefore, estimates of incidence and prevalence of disease cannot be computed. The survey is cross-sectional in nature. Multiple visits may be made by the same person within the sample.
Cherry DK, Woodwell DA. National Ambulatory Medical Care Survey: 2000 Summary. Advance data from vital and health statistics; No. 328. Hyattsville, Maryland: National Center for Health Statistics. 2002.
Woodwell DA, Cherry DK. National Ambulatory Medical Care Survey: 2002 Summary. Advance data from vital and health statistics; No. 346. Hyattsville, Maryland: National Center for Health Statistics. 2004.