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Dataset: National Ambulatory Medical Care Survey (NAMCS )

Basic Information
Dataset full name: National Ambulatory Medical Care Survey
Dataset acronym NAMCS
Summary The National Center for Health Statistics conducts the National Ambulatory Medical Care Survey (NAMCS) to measure the health care utilization and delivery of ambulatory services across various providers in the US. NAMCS is based on a sample of patient visits to a representitive sample of non-federal employed office-based physicians primarily engaged in direct patient care. The physician/office survey collects a wide variety of information at the physician/office level while the patient level data includes detailed information regarding reason for visit, vital signs, diagnosis and treatments. The NAMCS uses a multistage probability sample design. First stage: geographic primary sampling units are selected. Second stage: physician practices within geographic primary sampling units are selected. Third stage: random sample of patient visits to selected physicians is selected. Weights are provided to develop nationally representitive estimates. NAMCS does not include visits to hospital emergency departments, outpatient departments, department of veterans affairs, occupational health clinics, and institutional clinics.
Key Terms Ambulatory, CDC, Physician visit, Statistics, Survey, Physician office
Study Design Cross-sectional
Data Type(s) Survey
Sponsoring Agency/Entity Centers for Disease Control and Prevention (CDC): National Center for Health Statistics (NCHS)
Health conditions/Disability measures
Health condition(s) All (ICD-9 diagnostic codes), Arthritis, Asthma, Cancer, Cerebrovascular disease, Congestive heart failure, Chronic renal failure, Chronic obstructive pulmonary disease, Depression, Diabetes, Hyperlipidemia, Hypertension, heart disease, Obesity, Osteoporosis
Disability Measures
Measures/outcomes of interest
Topics Physician practice characteristics and specialty, Patient characteristics, Reason for visit, Medical providers seen, Time provider spent with patient, Continuity of care, Primary diagnosis at visit, Comorbid conditions, Vital signs, Diagnostic/screening services, Immunizations, Medications, demographic & regional information, non-medication treatments and proceedures performed/provided, Stage of cancer, Laboratory test results, Health education ordered or provided at visit
Sample Population Non-federally employed office-based physicians practices and patient visits
Sample Size/Notes 2008: Number of Physicians :1,334
28,741 Patient Record forms (PRFs)
Unit of Observation Patient (Physician-patient interaction or visit)
Geographic Coverage National
Geographic specificity Region
Data Collection
Data Collection Mode Survey - completed by physician or office staff ** Over half of the Patient Record forms submitted in 2008 were abstracted by Census Bureau staff from patient records (rather than by physician or medical office staff).
Years Collected Annually from 1973 to 1981, in 1985, and annually since 1989 - present.
Data Collection Frequency Annual
Strengths and limitations
Strengths The data includes weights designed to produce national estimates of ambulatory medical care services in the U.S. Contains very detailed information regarding patient reason for visit, diagnosis, vital signs, treatments and medications. Data can be used to measure health care utilization across various types of providers.
Limitations Only includes office visits. Federally employed physicians as well as those practicing in the specialties of anesthesiology, pathology, and radiology are excluded from the sample. Reporting biases due to non-response and incomplete response (physician response/participation rate in 2008 was 59.1% of those found eligible). Approximately 33-35% of race & ethnicity data were missing in 2008
Data details
Primary Website
Data Access
Data Access Requirements Public Use Dataset
Summary Tables/reports NAMCS 2009 factsheets:
NAMCS web tables:
Dataset components (where applicable) NAMCS restricted data : includes additional information and variables masked in the publically available NAMCS public use microdata files:
Selected papers
Technical 2008 NAMCS Micro-data file documentation:
Other Papers NAMCS publication list:

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The Rehabilitation Research Cross-dataset Variable Catalog has been developed through the Center for Large Data Research & Data Sharing in Rehabilitation (CLDR). The Center for Large Data Research and Data Sharing in Rehabilitation involves a consortium of investigators from the University of Texas Medical Branch, Cornell University's Yang Tan Institute (YTI), and the University of Michigan. The CLDR is funded by NIH - National Institute of Child Health and Human Development, through the National Center for Medical Rehabilitation Research, the National Institute for Neurological Disorders and Stroke, and the National Institute of Biomedical Imaging and Bioengineering. (P2CHD065702).

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