At A Glance

Website

http://www.cdc.gov/nchs/ahcd.htm

Purpose

To collect data about the provision and use of ambulatory care services in hospital emergency, outpatient, and surgery departments in the United States (US).

Target Population

Patients visiting ambulatory care facilities, including emergency rooms, outpatient departments, and ambulatory surgery centers, at noninstitutional general and short-stay hospitals, exclusive of federal, military, and Veterans Administration hospitals, in all50 states and the District of Columbia.

Conducted

Began in 1992. Conducted annually. Most recent year conducted was 2010.

Sponsor

National Center for Health Statistics, Centers for Disease Control and Prevention, US Department of Health and Human Services

Special Note(s)

Unit of analysis is patient visit rather than the patient. Patients may visit the facilities multiple times during the survey period, but each visit is counted separately.

Hospital-based ambulatory surgery centers were first added to this study in 2009, and freestanding ambulatory surgery centers were added in 2010.

See also: National Ambulatory Medical Care Survey (NAMCS)

SystemContact: Esther Hing at esh2@cdc.gov

Sampling

Sample Design

Cross-sectional survey.

Four-stage probability sampling design. Learn more.

Sample Size

Approximately 680 facilities in 2010. Approximately 88,000 visits in 2010. Approximately 480 hospitals.

Special Note(s)

The NHAMCS sample selection procedure involves multiple stages in which representative participants are selected from increasingly specific strata. In the first stage, geographically defined areas are sampled. In the second stage, hospitals within these areas are sampled. In the third stage, clinics within outpatient departments are sampled. All emergency service areas and in-scope ambulatory surgery locations are included. In the final stage, patient visits to these settings are sampled.

The freestanding ambulatory surgery facility sampled includes visits to facilities that are regulated by states, certified by the Centers for Medicare and Medicaid Services, or whose primary business is ambulatory surgery. A two-stage list sample design is used for freestanding ambulatory surgery facilities (facilities, then patient visits to these facilities).

To preclude hospitals from participating during the same time period each year, samples are randomly divided into 16 subsets of approximately equal size. Each subset is assigned one of 16 4-week reporting periods. These continue to rotate across each survey year. Therefore, the entire sample does not participate in a given year, and each hospital is inducted approximately once every 15 months.

Key Variables

Demographic

Name	Methods of Assessment
Patient race/ethnicity	Interview/questionnaire (physician)
Patient sex	Interview/questionnaire (physician)
Patient year of birth	Interview/questionnaire (physician)
Percent practice revenue from Medicaid and other sources	Interview/questionnaire (physician)

Diet-Related

Name	Methods of Assessment
Diet/nutrition counseling provided during visit	Interview/questionnaire (outpatient department visits only)
Lipoprotein cholesterol, blood sugar, and glycohemoglobin (beginning in 2010)	Interview/questionnaire (outpatient department visits only)

Physical Activity-Related

Name	Methods of Assessment
Exercise counseling provided during visit	Interview/questionnaire (outpatient department visits only)

Weight-Related

Name	Methods of Assessment
Height and weight	Interview/questionnaire (outpatient department visits only)
Obesity status	Interview/questionnaire (outpatient department visits only)
Weight reduction counseling provided during visit	Interview/questionnaire (outpatient department visits only)

Geocode/Linkage

Name	Methods of Assessment
Federal Information Processing Standard (FIPS) state code (restricted)	N/A
FIPS county code (restricted)	N/A
Metropolitan statistical area	N/A
Patient zip code (restricted)	N/A

Other

Name	Methods of Assessment
Diagnosis	Interview/questionnaire (physician)
Diagnostic/screening services	Interview/questionnaire (physician)
Medication therapy	Interview/questionnaire (physician)
Patient complaints/reason for visit	Interview/questionnaire (physician)
Procedures	Interview/questionnaire (physician)
Types of providers seen	Interview/questionnaire (physician)
Visit disposition	Interview/questionnaire (physician)

Data Access and Cost

Data Availability

Public-use data are available. Data also are available on CD. Learn more.
Some data files are restricted. These files can be accessed by applying to the National Center for Health Statistics (NCHS) Research Data Center. Learn more.

Cost

Free of charge. Restricted data are fee-based. Set-up fee for restricted data is $750 per day. Learn more.

Special Note(s)

The most recent year for which data are available is not necessarily the most recent year this survey was conducted.

Geocode/Linkage

Geocode Variable(s)

Metropolitan statistical area; Federal Information Processing Standard (FIPS) state code (restricted), FIPS county code (restricted), patient zip code (restricted).

Existing Linkages

NHAMCS data were linked to US Census data on the percent of the population ages 25 years and older with a high school diploma or higher and percent with a Bachelor’s degree or higher, percent of population that is foreign and percent who do not speak English at all or very well, as well median household income using patient zip code. These data are restricted.

Selected Publications

Weight-Related

Branner CM, Koyama T, Jensen GL. Racial and ethnic differences in pediatric obesity-prevention counseling: National prevalence of clinician practices. Obesity 2008;16(3):690-694.

Eneli IU, Keast DR, Rappley MD, Camargo CA Jr. Adequacy of two ambulatory care surveillance systems for tracking childhood obesity practice patterns. Public Health 2008;122(7):700-707.

Rao G. Pediatric obesity-related counseling in the outpatient setting. Ambulatory Pediatrics 2005;5(6):377-379.

Resources

Data Query System

http://www2.cdc.gov/drugs/applicationnav1.asp

Documentation/Codebook(s)

ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NHAMCS/doc08.pdf

http://www.cdc.gov/nchs/ahcd/ahcd_questionnaires.htm

Listserv

http://www.cdc.gov/nchs/ahcd/ahcd_listserv.htm