1998 National Hospital Ambulatory Medical Care Survey Data File and File Documentation WARNING - DATA USE RESTRICTIONS! Read Carefully before Using The Public Health Service Act (Section 308 (d)) provides that the data collected by the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC), may be used only for the purpose of health statistical reporting and analysis. Any effort to determine the identity of any reported case is prohibited by this law. NCHS does all it can to assure that the identity of data subjects cannot be disclosed. All direct identifiers, as well as any characteristics that might lead to identification, are omitted from the dataset. Any intentional identification or disclosure of a person or establishment violates the assurances of confidentiality given to the providers of the information. Therefore, users will: 1. Use the data in this dataset for statistical reporting and analysis only. 2. Make no use of the identity of any person or establishment discovered inadvertently and advise the Director, NCHS, of any such discovery. 3. Not link this dataset with individually identifiable data from other NCHS or non-NCHS datasets. By using these data, you signify your agreement to comply with the above-stated statutorily based requirements. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Please continue to next page. - 1 - The files listed below comprise the 1998 National Hospital Ambulatory Medical Care Survey with complete file documentation, all in ASCII format. The 1998 NHAMCS dataset includes two files, one for emergency department data and another for outpatient department data. These are located in: /public/pub/Health_Statistics/NCHS/Datasets/NHAMCS The documentation files for the 1998 NHAMCS dataset are located in: /public/pub/Health_Statistics/NCHS/Dataset_Documentation/NHAMCS For ease of transmission, these files have been converted into a self- extracting compressed format. To load and expand the NHAMCS data files, do the following: first, copy the compressed file onto your hard drive into an appropriate subdirectory (for example, NHAMCS). Then go to the DOS prompt in that subdirectory and type the name of the file (ED1998) without its extension. Do the same for the OPD1998 file. The eleven documentation files listed below have been compressed into a single self-extracting file. To load and expand them, follow the steps above, using the file name DOC98 instead of ED1998. Size (bytes) File Name File Description Compressed Uncompressed ED1998.EXE NHAMCS Emergency department file 1,495,328 16,076,375 OPD1998.EXE NHAMCS Outpatient department file 1,406,408 19,552,330 DOC98.EXE NHAMCS documentation files 146,581 479,651 The documentation file (DOC98.EXE) will expand to include the following: DESCRIPT Description of the NHAMCS 59,898 EDFORMAT Format of the emergency department micro-data file 66,196 OPFORMAT Format of the outpatient department micro-data file 65,807 MARGINAL Marginal data 16,662 RSE Relative standard errors 5,975 TERMS Definition of terms used in the NHAMCS 12,100 PRF Patient Record forms - instructions and definitions 39,350 RVC Reason for Visit Classification 88,686 GENCODES List of generic codes and names 49,113 MEDCODES List of drug entry codes and names 69,121 NDC List of National Drug Code Directory drug classes 6,743 Total compressed file size (data and documentation) = 3,048,317 Total inflated file size = 36,108,356 CAUTION - Because the NHAMCS is a sample survey, the application of weights to the sample data is REQUIRED to produce national estimates of outpatient and emergency department visits, as well as to accurately assess the sampling error of statistics based on the survey data. Please refer to the appropriate documentation files (DESCRIPT, RSE) for informa- tion on how to apply the weights and to obtain relative standard errors of national estimates. Please continue to the next page. - 2 - IMPORTANT UPDATE: The 1998 NHAMCS public use file was updated in February, 2002 to include sample design information that will permit data users to use statistical software such as SUDAAN and STATA. The new information has been appended to the data file. A supplemental document (SUPP97-99) containing the file layout for these new variables and describing changes to the 1997, 1998, and 1999 public use files is downloadable at this web address: ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NHAMCS/ For questions, suggestions, or comments concerning NHAMCS data, please contact the Ambulatory Care Statistics Branch at (301) 458-4600. These and other survey data are also available on CD-ROM and public use data tape, as well as in published summaries. For additional information on NCHS data products, contact the: Data Dissemination Branch, NCHS 6525 Belcrest Rd. Hyattsville, MD 20782 Tel: (301) 458-4009 E-mail: nchsquery@cdc.gov Internet: http://www.cdc.gov/nchs/ - 3 -