The National Hospital Ambulatory Medical Care Survey (NHAMCS)

Database Name: The National Hospital Ambulatory Medical Care Survey (NHAMCS)

Data Source

National Center for Health Statistics (NCHS)

Overview of data contents

National survey of discharges from hospital emergency and outpatient departments. Data is provided in 2 separate files: emergency department (ED) and outpatient (OPD).

Patient ages included

Patients of all ages.

Practice setting

Ambulatory care services in hospital emergency and outpatient departments and in ambulatory surgery centers (beginning 2009).

Date range available


Relevant Work

Example publications

Smith SS, Kern RC, Chandra RK, Tan BK, Evans CT. Variations in antibiotic prescribing of acute rhinosinusitis in United States ambulatory settings. Otolaryn Head Neck Surg. 2013 May; 148(5):852-9.

Smith WM, Davidson TM, Murphy C. Regional variations in chronic rhinosinusitis, 2003-2006. Otolaryngol Head Neck Surg. 2009 Sep;141(3):347-52.


Cost estimate(s)


Contact/website information

About Ambulatory Healthcare Surveys

Contact CDC-INFO

Phone: (301) 458-4600


Ease of use

Clean data, good for beginner programmer with knowledge of survey weights. Excellent documentation provided an NCHS analysts are responsive to questions.

Data analysis

Downloadable data files are available for SAS, SPSS, and Stata. Survey weights are necessary. Individual patients or providers cannot be followed longitudinally.


Data can be combined across years and can be combined with NAMCS data.


Limited amount of data that is clinically relevant to otolaryngology.