NATIONAL AMBULATORY MEDICAL CARE SURVEY DATA FILES FOR 1973, 1975-1981, 1985, 1989-1992 WITH CORRESPONDING 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 National Ambulatory Medical Care Survey for the survey years 1973, 1975-1981, 1985, and 1989-1992. A public use file was not issued for 1974. For survey years 1973-1979, there is one data file for each year, where each record contains information on a sampled patient visit. From 1980-1991, there are two files for each year -- one for patient visit data as noted above, and a second file for drug mention data where each record represents a single drug mention along with its associated visit data. The second file is limited to those visits with mention of medication therapy. For the 1991 data, it is possible to link information on the drug file with information on the patient visit file. Beginning with the 1992 survey year, only one data file is produced annually that contains both patient and drug information. Data on the patient visit file reflect the NAMCS instrument, or Patient Record form. Each record contains an inflation factor (also referred to as the patient visit weight). This weight must be used to obtain national estimates of health care utilization from the sample data. The drug files concern only those visits at which one or more medications were ordered, administered, or provided. There is one record for each drug mentioned or entered on the Patient Record form. A single office visit in 1985, for example, could have up to 5 drugs mentioned on the form, resulting in five separate records on the file. On the other hand, if there were no drugs mentions for a particular office visit, there would be no records on the drug file for that visit. Each record on the drug files contains an inflation factor which must be used to obtain national estimates of drug utilization from the sample data. A list of file variables for all of these survey years is available in the NCHS Electronic Data Products Catalog at this Internet address: http://www.cdc.gov/nchs/products/catalogs/subject/nmfi/namcs.htm For ease of transmission, the data files have been converted into a self- extracting compressed format. To load and expand the NAMCS data files, do the following: first, copy the compressed file onto your hard drive into an appropriate subdirectory (for example, NAMCS). Then go to the DOS prompt in that subdirectory and type the name of the file (NAMCS73) without its extension. The documentation files are in pdf format and are not compressed. Size File Name File Description Compressed Uncompressed NAMCS73.EXE 1973 NAMCS dataset 403 KB 2.7 MB NAMCS73DOC.PDF 1973 NAMCS documentation file 849 KB NAMCS75.EXE 1975 NAMCS dataset 859 KB 5.8 MB NAMCS75DOC.PDF 1975 NAMCS documentation file 912 KB NAMCS76.EXE 1976 NAMCS dataset 711 KB 4.8 MB NAMCS76DOC.PDF 1976 NAMCS documentation file 817 KB - 2 - NAMCS77.EXE 1977 NAMCS dataset 735 KB 4.6 MB NAMCS77DOC.PDF 1977 NAMCS documentation file 2.2 MB NAMCS78.EXE 1978 NAMCS dataset 688 KB 4.3 MB NAMCS78DOC.PDF 1978 NAMCS documentation file 2.0 MB NAMCS79.EXE 1979 NAMCS dataset 667 KB 4.5 MB NAMCS79DOC.PDF 1979 NAMCS documentation file 2.7 MB NAMCS80.EXE 1980 NAMCS dataset 1.1 MB 6.6 MB NAMCS80DOC.PDF 1980 NAMCS documentation file 1.6 MB NAMCS80D.EXE 1980 NAMCS dataset - drug mentions 1.3 MB 13.0 MB NAMCS80DRUG.PDF 1980 NAMCS documentation file 7.3 MB NAMCS81.EXE 1981 NAMCS dataset 987 KB 6.2 MB NAMCS81DOC.PDF 1981 NAMCS documentation file 1.7 MB NAMCS81D.EXE 1981 NAMCS dataset - drug mentions 1.2 MB 11.6 MB NAMCS81DRUG.PDF 1981 NAMCS documentation file * NAMCS85.EXE 1985 NAMCS dataset 1.4 MB 10.4 MB NAMCS85DOC.PDF 1985 NAMCS documentation file 3.5 MB NAMCS85D.EXE 1985 NAMCS dataset - drug mentions 1.8 MB 16.2 MB NAMCS85DRUG.PDF 1985 NAMCS documentation file 5.1 MB NAMCS89.EXE 1989 NAMCS dataset 797 KB 5.9 MB NAMCS89DOC.PDF 1989 NAMCS documentation file 4.5 MB NAMCS89D.EXE 1989 NAMCS dataset - drug mentions 968 KB 9.2 MB NAMCS89DRUG.PDF 1989 NAMCS documentation file 4.8 MB NAMCS90.EXE 1990 NAMCS dataset 901 KB 6.6 MB NAMCS90DOC.PDF 1990 NAMCS documentation file 4.1 MB NAMCS90D.EXE 1990 NAMCS dataset - drug mentions 1.1 MB 10.3 MB NAMCS90DRUG.PDF 1990 NAMCS documentation file 4.9 MB NAMCS91.EXE 1991 NAMCS dataset 811 KB 6.0 MB NAMCS91DOC.PDF 1991 NAMCS documentation file 3.2 MB NAMCS91D.EXE 1991 NAMCS dataset - drug mentions 1.2 MB 10.0 MB NAMCS91DRUG.PDF 1991 NAMCS documentation file 5.0 MB NAMCS92.EXE 1992 NAMCS dataset 1.1 MB 12.1 MB NAMCS92DOC.PDF 1992 NAMCS documentation file 4.0 MB * Not yet available in pdf format. Hardcopy is available from the Ambulatory Care Statistics Branch by calling 301-458-4600. - 3 - CAUTION - Because the NAMCS is a sample survey, the application of weights to the sample data is REQUIRED to produce national estimates of office visits, as well as to accurately assess the sampling error of statistics based on the survey data. Please refer to the appropriate sections of the documentation files for information on how to apply the weights and to obtain relative standard errors of national estimates. IMPORTANT: In working with these public use files, especially some of the earlier years, certain anomalies have been discovered. These are outlined below and have to do mainly with errors or ambiguities in the file documentation. Also, in some of the earliest years (1973 and 1976, for example) there were some cases of strange visit dates that look like miskeyings. There are also occurrences of ambiguous codes found in some of the drug fields on early drug files. Unfortunately, because of the changing nature of drug products and the age of the files in question, we are not able to go back and attempt to edit these files at this time. While most of the drug data appear to be sound, there will be some oddities in the early files that the user may encounter. Please feel free to contact the Ambulatory Care Statistics Branch if you have any problems using these files. 1973 - The record length is listed in the documentation as 92. However, the file layout ends at 85, as does the data record. 1975 - There are anomalous data in col. 76 of the data file. Col. 76 should reflect "Other disposition" of the visit, but instead, the entire column is unreadable. 1980 Visit File Layout - add Age of Patient in Days, in cols. 139-143, field length = 5, range = 1-36,656 1989 Visit File Layout - add Metropolitan Statistical Area, in col. 153 1 = MSA, 0 = Non-MSA Diagnosis Coding Survey years prior to 1978 used the Eighth Revision, International Classification of Diseases, Adapted for Use in the United States (ICDA). One of the differences between the ICDA and the ICD-9-CM used to code diagnoses currently is that the Supplementary Classification codes which are currently prefixed with a "V" were prefixed with a "Y" in ICDA. The NAMCS diagnosis data for 1973-1977 use different coding conventions, which are not always clearly stated in the file documentation. Here is a brief supplement to what is provided in the file documentation about coding conventions in use in the early years: - 4 - 1973 - Diagnosis codes have a field length of 4. They range from 0000-9999 for illness and injury, and Y000-Y302 for the supplementary classification. There is an implied decimal after the first three positions (eg 4270 = 427.0 ; Y004 = Y00.4). One anomaly found here was that the code 0000, used to denote blank diagnoses, conflicts with an actual ICDA code for classic cholera (000.0). Also, codes without a fourth digit in the ICDA were zerofilled in the survey data (eg 428 = 4280). Special codes that were developed by NCHS staff for use with the data were: 0000 = Blank diagnosis Y997 = Diagnosis of "none" Y998 = Noncodable diagnosis Y999 = Illegible diagnosis 1975-76 - The same as in 1973, except that instead of a "Y" to prefix codes in the supplementary classification, an ampersand (&) was used. 1977-78 - Same as above, except that the prefix character is a dash (-). Note that the Marginals in the documentation (which were first used for the 1977 survey year) include data for first-listed diagnosis. However, the coding conventions used in the marginal data do not match the conventions in use with the actual public use file data. It is necessary to read the Marginal section in the documentation to note the differences. For questions, suggestions, or comments concerning NAMCS 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 3311 Toledo Road Hyattsville, MD 20782 Tel: (301) 458-4009 E-mail: nchsquery@cdc.gov Internet: http://www.cdc.gov/nchs/ - 5 -