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National Hospital Ambulatory Medical Care Survey (NHAMCS)
U.S. Department of Health and Human Services, Centers for Disease Control and Prevention (CDC), National Center for Health Statistics (NCHS).
Mode of Administration
Hospital staff are asked to complete a one-page questionnaire (Patient Record form) on a sample of their patient visits during an assigned reporting period.
Survey Sample Design
The NHAMCS is a national probability sample survey of visits to emergency departments (EDs) and outpatient departments (OPDs) of non-federal, short-stay, and general hospitals in the U.S. The NHAMCS utilizes a four-stage probability design that involves samples of primary sampling units (PSUs), hospitals within PSUs, clinics within hospitals, and patient visits within clinics and/or emergency service areas. Hospital staff were asked to complete Patient Record forms for a systematic random sample of patient visits occurring during a randomly assigned 4-week reporting period during the survey year. Sample data are weighted to produce national estimates of patient visits. About 400 EDs and 225 OPDs participate each year and approximately 35,000 Patient Record forms are completed in each setting.
Primary Survey Content
The NHAMCS includes two files: ED visits and OPD visits. Information is obtained on various aspects of patient visits, including patient, hospital, and visit characteristics. The survey form is redesigned every 2-4 years to address changing health data needs. Among the items collected are: patient's age, gender, race, and ethnicity; patient's expressed reason for visit;intentionality of injury, if any; physician's diagnoses; diagnostic services ordered or provided; procedures provided; medications; providers seen; visit disposition; immediacy with which patient should be seen; and, expected source of payment. Items collected that are specific to the ED include: mode of arrival, waiting time; duration of time in the ED; initial vital signs; and cause of injury.
The basic sampling unit is the patient visit. Included in the survey are in-person visits made to EDs and OPDs of non-federal, short-stay, and general hospitals, exclusive of Federal, military, and Veterans Administration hospitals, located in the 50 States and the District of Columbia. Telephone contacts and visits for administrative purposes are excluded.
Patient's age, gender, race, and ethnicity.
Annual since 1992.
National, four U.S. Census Bureau regions.
McCaig LF, Burt CW. National Hospital Ambulatory Medical Care Survey: 2002 Emergency Department Summary. Advance data from vital and health statistics; No. 340. Hyattsville, MD: National Center for Health Statistics. 2004.
Hing E, Middleton K. National Hospital Ambulatory Medical Care Survey: 2002 Outpatient Department Summary. Advance data from vital and health statistics; No. 345. Hyattsville, MD: National Center for Health Statistics. 2004.