National Survey of Ambulatory Surgery: 1994, 1995, 1996, and 2006 (ICPSR 27461)
Published: Jan 18, 2011
The National Survey of Ambulatory Surgery (NSAS) was first conducted during the years 1994, 1995, and 1996 in response to the dramatic increase in the number of ambulatory surgery centers during the 1980's and early 1990's. The purpose of the first three years of the NSAS was to collect data on ambulatory (outpatient) surgery procedures performed in hospitals and free-standing ambulatory surgery centers in the United States. General demographic data pertaining to age, sex, and race were collected. Additionally, the 1994-1996 NSAS collected data on hospital diagnoses, outpatient procedures, the type of anesthesia used during the aforementioned outpatient procedures, and the payment methods for the procedures. Following a ten year hiatus, the NSAS was once again conducted in 2006. This iteration of the survey expands on the previous years' data collections. Like the 1994-1996 NSAS, the 2006 NSAS collected general demographic information on age and sex along with data on hospital diagnoses, outpatient procedures, and the type of anesthesia used during outpatient procedures. The 2006 NSAS collected additional data on patient symptoms, types of insurance, various time measures related to the medical procedures, and multiple measures pertaining to the status and health of the patients.
In preparing the data file for this collection, the National Center for Health Statistics (NCHS) has removed direct identifiers and characteristics that might lead to identification of data subjects. As an additional precaution, NCHS requires, under section 308(d) of the Public Health Service Act (42 U.S.C. 242m), that data collected by NCHS not be used for any purpose other than statistical analysis and reporting. NCHS further requires that analysts not use the data to learn the identity of any persons or establishments and that the director of NCHS be notified if any identifies are inadvertently discovered. ICPSR member institutions and other users ordering data from ICPSR are expected to adhere to these restrictions.
Date of Collection
Data Collection Notes
Starting in 2007 the National Survey of Ambulatory Surgery (NSAS) will no longer be conducted as an individual study. Beginning in 2009 the NSAS will henceforth be incorporated into the National Hospital Ambulatory Medical Care Survey (NHAMCS).
The 1994-1996 NSAS used a multistage probability design with some facilities selected with certainty and others sampled with varying selection probabilities. Independent samples of hospitals and free-standing surgery centers were drawn. Noncertainty facilities were selected using a stratified cluster design employing 198 Primary Sampling Units (PSU's) and stratification by facility type, ambulatory surgery status of hospitals, facility specialty, and geographic region. The 2006 NSAS sampled facilities using a multistage probability design with facilities having varying selection probabilities. Independent samples of hospitals and free-standing ambulatory surgery centers were drawn. The 2006 NSAS did not employ the stratified cluster design used by the 1994-1996 NSAS. Like the 1994-1996 NSAS, the 2006 NSAS stratified facilities according to facility type, ambulatory surgery status of hospitals, facility specialty, and geographic region.
The hospital universe includes noninstitutional hospitals exclusive of federal, military, and Department of Veteran's Affairs hospitals, located in the 50 States and the District of Columbia. Additionally, only short-stay hospitals (hospitals with an average length of stay for all patients of less than 30 days) or those whose specialty was general (medical or surgical or children's general) were included in the survey. Lastly, the hospitals must have had six beds or more staffed for patient use. The free-standing ambulatory surgery center (FSASC) universe includes only those facilities regulated by states or the Health Care Financing Administration (HCFA), for Medicare participation.
Mode of Data Collection
Original Release Date
2011-01-18 The 2006 National Survey of Ambulatory Surgery (NSAS) public use data set was revised in April 2010 to correct an error in the calculation of the AGEINYRS variable for children under 1 year of age. The days and months of these children were incorrectly counted as years in the previously released public use NSAS file. This problem affected about 500 of the approximately 52,000 unweighted records in NSAS, and resulted in children under 1 year of age being misclassified into older age groups. This mistake was discovered when the age distribution obtained using the AGEINYRS variable was different from the one obtained using the AGER10 variable.
2010-03-08 ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major statistical software formats as well as standard codebooks to accompany the data. In addition to these procedures, ICPSR performed the following processing steps for this data collection:
- Performed consistency checks.
- Created variable labels and/or value labels.
- Performed recodes and/or calculated derived variables.
The public-use data files in this collection are available for access by the general public. Access does not require affiliation with an ICPSR member institution.
This study is maintained and distributed by the National Archive of Computerized Data on Aging (NACDA), the aging program within ICPSR. NACDA is sponsored by the National Institute on Aging (NIA) at the National Institutes of Heath (NIH).